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      Volume 38,2022 Issue 10
      • LAI Xingfei, WANG Qiong, LI Qiuhua, SUN Lingli, CHEN Ruohong, WEN Shuai, ZHANG Zhenbiao, LIU Xiaohui*, SUN Shili*

        2022,38(10):1-8, DOI: 10.13982/j.mfst.1673-9078.2022.10.1387

        Abstract:

        To study the effects and mechanisms of Yinghong No.9 black tea water-extract (YBTE) for alleviating acute alcohol intoxication (AAI), mice were subjected to one-time intragastric administration of 56° Baijiu (Chinese Liquor) to establish an AAI model. Subsequently, the time required to lose and regain the righting reflex of the mice were recorded. The alanine transaminase (ALT) and glutamic oxaloacetic transaminase (AST) activities in the serum and alcohol dehydrogenase (ADH) activity both in the serum and liver were measured. Moreover, the expression the nuclear factor kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and interleukin-1 β (IL-1β) proteins in the liver were measured using western blot analyses. The results showed that sleep onset latency increased and sleep duration decreased for mice treated with various doses of YBTE compared with the model group. More specifically, the sleep onset latency for the high-dose YBTE-treated group increased to 40.89 min (p<0.01) and their sleep duration was 166.18 min (p<0.01). Moreover, the serum activities of ALT and AST were significantly lower and the ADH activity in the serum and liver were both significantly higher in the YBTE-treated groups than in the control group. In particular, the ALT and AST activities in the high-dose group decreased to 22.89 U/L (p<0.01) and 29.58 U/L (p<0.01), respectively, and the ADH activity in the serum and liver increased to 43.43 IU/mL (p<0.01) and 7.37 IU/mL (p<0.01), respectively. Furthermore, the expression of p-NF-κB p65, TNF-α, and IL-1β in the liver were significantly down regulated. In conclusion, AAI can be effectively relieved with YBTE by promoting ethanol metabolism and down regulating the TNF-α/NF-κB signaling pathway.

      • WEN Mingming, BI Jie*, HE Yanping, DAI Huang, ZHANG Wei, SHU Zaixi, XIAO Anhong

        2022,38(10):9-18, DOI: 10.13982/j.mfst.1673-9078.2022.10.1402

        Abstract:

        The effects of a high-sucrose diet on the lifespan and fertility of male Drosophila melanogaster were studied. The lifespan, exercise ability, and hatch rate of D. melanogaster were measured after fly model establishment. Additionally, T-SOD and CAT activities and MDA content in D. melanogaster were measured by enzyme activity assay. DAPI staining, Raman spectroscopy, and Raman imaging were used to observe changes in the cell structure and biochemical components. Moreover, transcriptome sequencing and fluorescence quantitative PCR were utilized to investigate the mechanisms of these changes at the gene level. The results showed that, compared with those in the control group, the life span of male flies in the high-sucrose diet group was significantly shortened; the median lifespan decreased from 34 days to 29 days (p<0.01). Similarly, the exercise ability of this experimental group decreased significantly, to approximately 46.32% of that of the control group (p<0.01). Moreover, T-SOD and CAT activities of male flies in the high-sucrose diet group significantly decreased to 83.47% (p<0.01) and 79.47% (p<0.01), respectively, compared to those in the control group. However, MDA content of the high-sucrose diet group increased significantly to 1.51 times that of the control group (p<0.01). Furthermore, the embryo hatch rate of male flies significantly decreased, from 88.08% in the control group to 70.77% (p<0.01) in the experimental group. DAPI staining showed abnormal enlargement of the testis and no sperm bundles in the seminal vesicles of the experimental group. Raman spectroscopy revealed that nucleic acid and protein components in the testis tissue of male flies in the high-sucrose diet group decreased significantly compared to those in the control group; additionally, Raman imaging indicated irregular distributions. Transcriptome sequencing suggested that differentially expressed genes were enriched in aspects of stress response, development, and reproduction in the experimental group. Therefore, this study indicates that a high-sucrose diet reduces the longevity, exercise ability, and fertility of male flies and causes damage by aggravating oxidative stress responses.

      • LI Jia, DENG Xinyu, TIAN Xiaobin, HUANG Minru, LI Pan, DU Bing*, HE Qing*

        2022,38(10):19-26, DOI: 10.13982/j.mfst.1673-9078.2022.10.1408

        Abstract:

        The hypolipidemic effects of krill oil and extract from Monascus spp. on rats with hyperlipidemia were examined. Male rats were divided into 12 groups (n=10). The negative control and model groups were given 0.9% saline solutions, whereas the drug-treated group was given 0.01% simvastatin. The krill oil-treated groups were treated with 83.33, 166.67, and 500.00 mg/kg of krill oil daily by intragastric administration, and the Monascus extract-treated groups were similarly given 33.33, 66.67, and 200.00 mg/kg of Monascus extract daily. Similarly, the mixed treatment groups received 166.67+33.33, 166.67+66.67, and 166.67+200.00 mg/kg of krill oil+Monascus extract daily by intragastric administration. The negative control group was given a normal diet, whereas the other groups were given a high-fat diet. Measurements were performed after four weeks of treatment. The results showed that, after treatment with krill oil, Monascus extract, and their mixtures, the levels of blood TC, TG, and LDL-C decreased significantly; this decrease was dose-dependent. Therefore, krill oil, Monascus extract, and their mixtures can assist in reducing lipids in the blood. The serum contents of ALT and AST in the low-dosage krill oil, high-dosage Monascus extract, high-dosage mixture, and simvastatin groups were significantly lower than those in the model group. The group treated with high-dosage krill oil+Monascus extract mixture (166.67+200.00 mg/kg krill oil+Monascus extract) demonstrated the most significant reductions in the levels of TC (from 4.14 mmol/L to 3.37 mmol/L), TG (from 2.77 mmol/L to 1.51 mmol/L), and LDL-C (from 0.37 mmol/L to 0.25 mmol/L). Therefore, the hypolipidemic effect of the mixture of krill oil and Monascus extract is higher than that of the individual components. This finding enables the mixture to be utilized as an auxiliary hypolipidemic agent.

      • MAO Jiaying, BAI Yuying, PENG Linjie, XIE Jing*, TIAN Yang*

        2022,38(10):27-32, DOI: 10.13982/j.mfst.1673-9078.2022.10.1353

        Abstract:

        To explore the effect of Moringa isothiocyanate-4-[(α-L-rhamnosyloxy) benzyl] isothiocyanates (MIC-1) on the lipid accumulation in 3T3-L1 adipocytes and the possible regulatory mechanism, 3T3-L1 preadipocytes were induced in vitro to differentiate into mature adipocytes. After 48 h of intervention with MIC-1, lipid accumulation, triglyceride (TG), glycerol (Gly) and free fatty acid (FFA) contents were determined; qRT- PCR was used to detect the expression of the genes related to lipid metabolism; Western blot was used to determine the phosphorylation level of adenylate-activated protein kinase (AMPK) and the expression level of oxisome proliferation-activated receptor γ (PPARγ). The results show that MIC-1 has no effect on the survival rate of 3T3-L1 preadipocytes; compared with the control group, MIC-1 can reduce the distribution of lipid droplets in adipocytes and the degree of cell coloration, intracellular TG content, and FFA and glycerol overflow. When the concentration of MIC-1 reached 4 mol/L, the concentration of TG and FFA decreased by 64% and 75%, respectively. At the same time, the mRNA expression levels of PPARγ and stearoyl-CoA desaturase 1 (SCD1) in cells were significantly down-regulated (by 46.00% and 62.00%, respectively); the protein expression levels of AMPK protein phosphorylation and down-regulated PPARγ were significantly up-regulated (by 64.47% and 52.10%, respectively). The above results indicate that MIC-1 inhibits lipid accumulation by promoting the decomposition of TG and inhibiting the synthesis of TG. The mechanism may be related to the activation of AMPK.

      • LEI Lu, YU Bo, ZHOU Jingrui, WANG Chuannan, WU Tianxiang*

        2022,38(10):33-39, DOI: 10.13982/j.mfst.1673-9078.2022.10.1359

        Abstract:

        In this study, the effects of the addition of ethanolic extracts of Gastrodin elata Bl. and Tartary buckwheat on the key enzymes, phosphogluconate mutase (PGM), UDP-glucose pyrophosphorylase (UGPase) and phosphogluconate isomerase (GPI) during the synthesis of exopolysaccharide (EPS) from Grifola frondose were investigated. On this premise, animal experiments were conducted to explore further the anti-fatigue effect of Grifola frondosa-derived fermentation broth. The results showed that the addition of a mixture of Gastrodin elata Bl. and Tartary buckwheat alcoholic extracts compound solution could enhance the activities of PGM and UGPase while reducing GPI activity. Compared with the blank group, the activities of PGM and UGPase were increased by 86.98% and 69.12%, respectively, and the activity of GPI was decreased by 65.78%. In addition, the fermentation broth containing Gastrodin elata Bl-Tartary buckwheat alcoholic extract mixture had the greatest anti-fatigue effect, which was significantly higher than that of the blank group (p<0.05) and experimental group (p<0.05). The anti-fatigue effect, was evidenced mainly by the increases in the swimming exhaustion time, hepatic glycogen (HG) content and lactate dehydrogenase (LDH) content, and the decreases in the contents of lactic acid (LA) and blood urea nitrogen (BUN) in mice. The research shows that the addition of the extract mixture could significantly change the activities of key enzymes in the EPS synthesis pathway of Grifola frondose, thereby increasing the content of EPS in the fermentation broth and endows the both with a good anti-fatigue effect.

      • ZHANG Jiaojiao, TUKEZI·Wushouer, HUANG Weiwei, LI Yanhong*

        2022,38(10):40-46, DOI: 10.13982/j.mfst.1673-9078.2022.10.1397

        Abstract:

        This study was aimed at evaluating the antioxidant activities of Prunus cerasifera polyphenols and their protective effects on the livers of obese mice, thereby providing a theoretical basis for the development and utilization of P. cerasifera fruits. First, polyphenols were obtained from P. cerasifera fruits via alcohol extraction. After polyphenol content determination, DPPH, FRAP, and ABTS methods were used to measure the in vitro antioxidant activities of the extracted polyphenols. Next, obese mice models were established and treated with different doses of polyphenols. After eight weeks of treatment, the mice were sacrificed to remove their livers. The liver index was calculated, and the TG, T-CHO, SOD, and MDA concentration in the livers were determined. Moreover, the expression levels of inflammation-related genes were measured via fluorescence quantitative PCR. The results revealed that the total polyphenol, flavonoid, phenolic acid, and flavanol contents in the extracted polyphenols were 439.17, 186.37, 168.27, 68.86 mg/g, respectively. Hence, the total polyphenol content in Prunus cerasifera is relatively high, and the main components are flavonoids. The corresponding DPPH free radical scavenging rate was 97.42%, and the antioxidant activities measured using the FRAP and ABTS methods were 4.36 mmoL/mL and 0.48 mmoL/mL Trolox, respectively, which indicates that the extracted polyphenols had strong in vitro antioxidant activities. Both low and high doses of polyphenols significantly reduced the TG, T-CHO, and MDA contents and enhanced the SOD activity in the livers of obese mice. Furthermore, the polyphenols down regulated the expression of the inflammatory factors interleukin-1 beta, tumor necrosis factor-alpha, and interleukin-6 in the liver tissues. These findings suggest that P. cerasifera polyphenols can improve the antioxidant capacity of the liver, reduce fat accumulation and liver inflammation induced by a high-fat diet, and protect the liver in mice.

      • CHEN Jihong, YAN Sisi, LUO Feijun*, LIN Qinlu, LI Bo

        2022,38(10):47-55, DOI: 10.13982/j.mfst.1673-9078.2022.10.1161

        Abstract:

        In this study, the ameliorating effect of rice oil on the cholesterol metabolism of golden hamster was investigated. Taking golden hamsters as the experimental objects, the effects of lard and rice oil on the cholesterol metabolism in the livers of golden hamsters were examined, n order to provide a scientific theoretical basis for residents to choose edible oils. Thirty Syrian golden hamsters were selected and randomly divided into two groups, which were fed 15% fat in form of lard oil (LD) and rice oil (RD), respectively. The body weight and feed intake were calculated every week. After 12 weeks of feeding, the animals were dissected and the sera were separated for determining the biochemical indexes. The aorta and liver were taken for hematoxylin-eosin (HE) staining. RT-qPCR was used to detect the mRNA expression levels of CYP27A1, LDLrDLr, SR-BI, SLC27A5, sulfotransferase 2A1 and AQP8 in the liver tissues. The results showed that compared with the lard group, the LDL-C level in the serum and the TC content in the liver of golden hamsters of the rice oil group decreased by 46.78% and 41.73%, respectively. Rice oil could improve the pathological morphology of the liver, reduced liver injury, while up-regulating the expressions of LDLr, SR-BI, CYP27A1, SLC27A5, Sulfotransferase 2A1, AQP8 and other genes in the liver tissues of the golden hamsters. The expression levels of LDLr, CYP27A1 and AQP8 increased to 2.04, 2.14 and 2.83 times, respectively. These genes are associated with cholesterol and bile acid metabolism, and their increased expressions can reduce the body’s cholesterol and bile acids. Conclusion: Compared with edible lard, rice oil can improve blood lipid level, reduce liver damage and inhibit high cholesterol in golden hamsters. The cholesterol-lowering mechanism of rice oil is that it can regulate the expressions of genes related to cholesterol and bile acid metabolism in the liver tissues.

      • HE Zeqi, LIN Qianru, HUANG Wen, LIU Guo, HE Liping, MIAO Jianyin, CAO Yong*

        2022,38(10):56-61, DOI: 10.13982/j.mfst.1673-9078.2022.10.0014

        Abstract:

        A commercial available children's growth formula was compared with regular commercially available pure dairy milk (control milk A) in terms of their abilities to promote bone growth. Additionally, its effect on calcium transport was evaluated using a human colon adenocarcinoma cell (Caco-2) monolayer model, and its effects on osteoblast proliferation and mineralization was examined with MC3T3-E1 cells. With regard to the promotion of calcium transport, the Caco-2 cell monolayer model showed that commercially available children's growth formula outperformed control milk A at the various doses tested, but its effect did not differ significantly from that of the blank group (p<0.05). The osteoblast proliferation assay showed that 5~50 μg/mL of commercially available children's growth formula could promote the proliferation of osteoblasts, with a proliferation rate of more than 30%. Moreover, in osteoblasts treated with 50 μg/mL of commercially available children's growth formula, the alkaline phosphatase activity was 7.79 U/g of protein, which was significantly higher than that in the blank group (p<0.01). Commercially available children's growth formula also exhibited a more stable effect than control milk A in enhancing the alkaline phosphatase activity. The osteoblast mineralization assay revealed that 5~50 μg/mL of commercially available children's growth formula could significantly promote the formation of mineralized nodules in the cells. In the osteoblasts treated with 50 μg/mL of commercially available children's growth formula, the Alizarin Red absorbance value (0.180) was 50% higher than that of the blank group, and the degree of mineralization was more stable than that in the osteoblasts treated with control milk A. Collectively, our experimental results demonstrate that although commercially available children's growth formula has no significant effect in promoting calcium transport and uptake in the small intestinal epithelium, it may participate in the growth and development of children by promoting bone growth.

      • XIE Yuan, HU Yeye, LI Fu, HU Weicheng, ZHANG Ji, YANG Xiaojun*, YANG Meng*

        2022,38(10):62-70, DOI: 10.13982/j.mfst.1673-9078.2022.10.1266

        Abstract:

        The neuroprotective effects of a minor saponin extracted from Centella asiatica (CA-1) was investigated using the 6-hydroxydopamine (6-OHDA)-induced differentiated PC12 cells as the in vitro Parkinson's disease (PD) cell model. The chemical structure was identified by high-resolution secondary mass spectrometry, and the effects of common saponins and CA-1 in Centella asiatica on the cell viability of PC12 cells were examined. Further, the expressions of related genes and proteins in PC12 cells were detected by techniques such as semi-quantitative or real-time quantitative polymerase chain reaction (PCR) and western blot. The results showed that in this model, 100 μmol/L CA-1, asiaticoside (AS) and madecassoside (MA) increased cell viability by 28.63%, 16.69% and 17.54%, respectively. The neuroprotective effect of CA-1 was stronger than those of AS and MA (p<0.05). Compared with the model group, CA-1 increased the survival rate of 6-OHDA-treated PC12 cells in a dose-dependent manner (which differed significantly from the model group at a CA-1 concentration of 25 μmol/L p<0.05), decreased the intracellular reactive oxygen species (ROS) level, and up-regulated the gene expressions of Sod1, Cat and Bcl2. Western blot showed that CA-1 increased the protein expression levels of P85, PDK1 and Akt. In this study, the neuroprotective effect of CA-1 was confirmed, revealing that this effect may be through the PI3K/Akt signaling pathway.

      • CHEN Jialun, HUANG Guixia, GAN Dan*

        2022,38(10):71-78, DOI: 10.13982/j.mfst.1673-9078.2022.10.1225

        Abstract:

        To explore the relieving effect of compound Lactobacillus (Lactobacillus rhamnosus LrGG-100, Bifidobacterium longum BL-11, Lactobacillus acidophilus LA-99 and Lactobacillus casei LC-88) for slow transit constipation in mice, loperamide hydrochloride was used to establish a mouse model of constipation. Male BALB/c mice were randomly divided into the healthy group, constipation group, positive group, and low- and high-dose compound lactobacillus groups. After 21 days of gavage with corresponding contents, the mice were sacrificed for sampling, and their gastrointestinal function indicators such as the small intestine propulsion rate, levels of secreted serum cytokines, contents of gastrointestinal regulatory peptides, and transcription levels of AQP3 and c-kit were measured. The results showed that compared with the constipation group, the low- and high-dose compound lactobacillus groups had higher small intestine propulsion rate (increased by 61.45%, p<0.05; 1.22 times, p<0.05), shortened defecation time (decreased by 21.42%, p<0.05; 29.14%, p<0.05), increased number of defecation (increased by 1.5 times p<0.05; 1.52 times, p<0.05), and increased weight of stool (increased by 1.13 times, p<0.05; 1.25 times, p<0.05) in, the transcription levels of AQP3 and c-kit genes of the high-dose group were 1.82 times (p<0.05) and 2.00 times (p<0.05), respectively, those of the constipation group. Intragastric administration of compound Lactobacillus could increase the contents of substance P and motilin in the serum, and decrease the contents of vasoactive intestinal peptides, somatostatin and endothelin-1. Compound Lactobacillus could alleviate constipation symptoms. This effect may be related to the level of gastrointestinal regulatory peptides and the expressions of AQP3 and c-kit.

      • YIN Hanliang, DU Qiu, TAN Yisheng, SUN Junhua, LIU Yang, JIANG Liwen*

        2022,38(10):79-85, DOI: 10.13982/j.mfst.1673-9078.2022.10.1437

        Abstract:

        The traditional culture method combined with high-throughput DNA sequencing was used to analyze changes in the bacterial quantity and community composition with each step in the processing of pickled chicken feet, to determine the main contamination sources and microbial compositions during the process. Sample Y5 (indicative of the slicing step) experiences the most contamination, with the total number of colonies in the sample increasing to 2.20×104 CFU/g. The total number of colonies (30 CFU/g) in sample Y9 (representing the vacuum packaging step) is higher than those of samples Y7 and Y8, and the bacterial diversity in Y9 is the highest (Shannon=7.82). The vacuum packaging process may cause some product contamination. Acinetobacter, Pseudomonas, and Psychrobacter are the dominant bacteria in the processing of pickled chicken feet, with average relative abundance values of 21.50%, 9.29% and 5.99%, respectively. The relatively abundant bacteria genera in Y10 (end-product after sterilization by irradiation) include Acinetobacter (3.23%), Serratia (4.86%), Staphylococcus (6.26%) and Bacillus (4.59%), which produce various proteases and lipases. Some of these genera also include pathogenic strains, which may raise quality and safety concerns for products during storage and sale. These research results contribute to deeper understanding of the microbial community compositions during pickled chicken feet processing, and can provide a theoretical basis guiding efforts to prevent and control microbial food contamination and improve product quality and safety.

      • HU Jing, HUANG Ailan, HUANG Shun, XU Yinghong, CHEN Xiaoman, CAO Fenghong, YANG Junsong, ZHENG Zhi*

        2022,38(10):86-91, DOI: 10.13982/j.mfst.1673-9078.2022.10.1373

        Abstract:

        Lactobacillus plantarum were isolated from Sichuan Paocai and screened for probiotics. The strains were separated using MRS agar medium, and then identified using Gram staining, biochemical identification, and molecular biology methods. The VITEK 2 Corynebacterium identification card (CBC) includes a total of 41 biochemical reactions and enables identification to the species level. Of the 20 strains of bacteria detected, 12 strains were identified as L. plantarum using the CBC cards. These strains were subjected to16S rRNA PCR amplification and sequencing, followed by homologous sequence alignment on the NCBI website. The phylogenetic tree constructed by the neighbor-joining method showed that all 12 strains were clustered with known L. plantarum sequences. Strain No. 6 was clustered with L. plantarum 3356. Strain numbers 4, 5, 14, 15, 23, and 38 had very high sequence similarity with L. plantarum NCU116, L. plantarum MBEL2169, and L. plantarum AN7, with no genetic distance. In conclusion, all 12 strains were identified as L. plantarum. CBC identification cards are an effective method for the identification of L. plantarum.

      • LI Yulin, NI Jie, XUE Luyu, YANG Dongmei, YU Lian*, LIU Xiaoling

        2022,38(10):92-101, DOI: 10.13982/j.mfst.1673-9078.2022.10.1399

        Abstract:

        In order to promote the utilization of the high-value proteins in Penaeus vannamei head byproducts and to reduce the ammonia odor produced during their fermentation. A strain of Bacillus amyloliquefaciens YA289 was identified in a screen of samples collected from a mangrove forest in Beihai. This strain was used for liquid fermentation of the Penaeus vannamei heads. The polypeptide, amino acid nitrogen, and ammonia nitrogen contents of the supernatant were analyzed as indexes. The single factor test, Plackett-Burman test, and Box-Behnken test were performed to optimize the fermentation conditions, which were as follows: 5 g/L glucose, 5 g/L NaCl, a solid-to-liquid ratio of 1:8 (g/100 mL), 5wt% starter culture, pH value 6, a rotational speed of 180 r/min, 34 ℃, and 44 h. Under these conditions, the polypeptide content in the product of shrimp head fermentation was 16.35 mg/mL, which was 2.7 times higher than that before optimization. Bacillus amyloliquefaciens YA289 had a good degradation effect on the proteins in Penaeus vannamei heads and less ammonia nitrogen was released during fermentation. These findings provide an experimental basis to better utilize the protein resources from Penaeus vannamei heads and for the development and utilization of Bacillus amyloliquefaciens YA289.

      • GAO Yansong, WANG Chao, GAO Lei, YANG Ge, ZHAO Yujuan, ZHAO Zijian, NIU Chunhua, LI Shengyu*

        2022,38(10):102-108, DOI: 10.13982/j.mfst.1673-9078.2022.10.0267

        Abstract:

        The probiotic Pediococcus acidilactici strain AS185 was added to Ricotta cheese to yield a Ricotta cheese with probiotic properties. The physicochemical characteristics, texture properties, viable count of Lactobacilli, and volatile components were evaluated to assess the effects of AS185 on cheese quality. After refrigeration at 4 ℃ for 21 days, the fat, protein, and water contents of the probiotic whey cheese with P. acidilactici AS185 were 17.60%, 27.47%, and 49.95%, respectively, and the pH was 4.75. These parameters do not differ significantly from those of the control whey cheese without probiotics. After 21 days of storage, the viable bacterial count of the probiotic whey cheese decreases to 7.45 log CFU/g, which meets the requirements to be considered a probiotic product. The hardness, cohesiveness, adhesiveness, and chewiness of probiotic whey cheese are 723.85 N, 0.97 mm, 699.58, and 699.61 mJ, respectively, which are all higher than those of the control. The texture of the modified cheese is stronger and chewier. Furthermore, a total of 15 components are detected in the probiotic whey cheese. The relative contents of acids, alcohols, and ketones are comparatively higher, being 38.56%, 24.64%, and 13.76%, respectively, exceeding those of the control. There is no significant difference in appearance, color, flavor, and texture between the probiotic whey cheese and the control cheese (p>0.05). However, the overall acceptability of probiotic whey cheese is better than that of the control, and the strain P. acidilactici AS185 positively promotes flavor accumulation. In short, P. acidilactici AS185 is a promising probiotic strain with technical characteristics suitable for Ricotta cheese processing.

      • JIANG Siyu, HAO Gang*, TANG Shanhu, LI Sining, SUN Dong, ZHANG Lin

        2022,38(10):109-116, DOI: 10.13982/j.mfst.1673-9078.2022.10.1320

        Abstract:

        In this experiment, Escherichia coli and Listeria innocua were selected as the representative G- and G+ bacteria to explore the antibacterial mechanism of LAE towards bacterial membranes. The antibacterial mechanism was examined via investigating LAE’s antibacterial curve, the ability of neutralizing endotoxin, and bacterial surface characteristics, and constructing liposomes to simulate the interaction between LAE and phospholipid bilayers and evaluate the ion leakage and the permeability of LAE through G- bacterial outer membrane and cytoplasmic membrane. The experimental results showed that LAE had significant bactericidal activities against both G- and G+ bacteria with the minimum inhibitory concentration as 8 μg/mL. LAE could neutralize up to 96.56%endotoxin through binding to lipopolysaccharide, reduce the zeta potential on the cell surface, enhance hydrophobicity of bacterial surface, and exert a greater impact on G- bacteria. LAE could cause the leakage of a liposome-encapsulated fluorescein, calcein, in a concentration-dependent manner, but LAE didn’t collapse completely the liposome membrane. LAE was able to increase the permeability of the outer membrane of G- bacteria, which made E. coli more sensitive to the antibiotic probes, rifampicin and erythromycin, while disturbed greatly the cytoplasmic membrane, causing the leakage of intracellular contents, thereby inhibiting the growth of bacteria. The results of this study indicate that LAE exerts bacteriostatic effects mainly through changing the cell wall membrane permeability and consequently leading to the leakage of intracellular substances.

      • SONG Mengmeng, LIU Yuan*, WANG Jian*, SONG Pengfei, LI Yunlong*

        2022,38(10):117-123, DOI: 10.13982/j.mfst.1673-9078.2022.10.1336

        Abstract:

        In order to improve the comprehensive utilization value of buckwheat protein and amino acids, three curing methods were used to treat the sweet buckwheat. After the determination of the isoelectric point of buckwheat protein before and after curing and the electrophoresis analysis, the Coomassie brilliant blue method was used to analyze the buckwheat protein before and after curing. The nutritional value of amino acid composition was evaluated by ion exchange chromatography with ninhydrin post-column derivatization. The results showed that the protein content of the unprocessed buckwheat was 12.30%, the protein content of the buckwheat subjected to steaming was 11.5%, the protein content of the buckwheat subjected to frying was 9.70%, and the highest protein content of the cooked buckwheat was 14.80%. There was little difference in the total amount of amino acids among the buckwheat samples cured by different methods. All the three types of cured buckwheat samples contained 7 essential amino acids, with the total amount of amino acids in the fried buckwheat being the highest (10.30 g/100 g), and that for the cooked buckwheat being the lowest (9.43 g/100 g); After steaming and frying, the contents of all the amino acids increased except for Tyr,; after cooking, the contents of Thr, Ser, Gly, Ala and Lle did not change, whilst the contents of Val, Met, Tyr, Lys, His, and Arg all decreased. The research on the effects of curing methods on the protein and amino acid contents of buckwheat can provide a theoretical basis for the application of buckwheat.

      • SHI Zenghui, LIU Liyang, HONG Huili, GOU Dongxia, LIU Duo*

        2022,38(10):124-132, DOI: 10.13982/j.mfst.1673-9078.2022.10.1270

        Abstract:

        The crude polysaccharide of Ostericum sieboldii (WOSP) was extracted, separated and purified to obtain acidic polysaccharide (WOSP-A) and neutral polysaccharide (WOSP-N). The basic chemical properties, basic structural characteristics of the sugar chains, and in vitro antioxidant activities of different polysaccharide components were analyzed. Results showed that the yield of WOSP obtained by water extraction and alcohol precipitation was 6.78%, and the yields of WOSP-A and WOSP-N obtained via separation by ion exchange chromatography were 51.34% and 2.55%, respectively. Monosaccharide composition analysis showed that WOSP was a heteropolysaccharide mainly composed of GalA (11.36%), Gal (41.50%) and Ara (38.08%). Based on both the infrared spectroscopy results and enzymatic hydrolysis results, it was speculated that WOSP-A was a pectin composed of homogalacturonan (HG) and type I arabic galactans (AG-I) domains containing mainly GalA (46.99%), Gal (26.56%) and Ara (19.94%), whilst WOSP-N was a pectin composed of type II arabic galactans (AG-II) domains containing mainly Gal (55.32%) and Ara (30.69%). The comparison of the antioxidant activities of the three polysaccharides from O. sieboldii revealed that the antioxidant activity of WOSP was higher than those of WOSP-A and WOSP-N, and WOSP had higher scavenging abilities for DPPH· and O2-·, (which could reach 96.42% and 86.70% at a polysaccharide concentration of 10 mg/mL). In conclusion, WOSP, WOSP-A and WOSP-N from O. sieboldii all had O-H and C-H functional groups, and possessed certain in vitro antioxidant activities. This study will provide a theoretical reference for the development and utilization of wild vegetables in the Northeast China.

      • LOU Yuhao, CAO Dongmei*, LIU Jinming, ZHANG Dongjie*, CUI Hang, WANG Jifei, YANG Jian

        2022,38(10):133-139, DOI: 10.13982/j.mfst.1673-9078.2022.10.1221

        Abstract:

        The changing trend of deoxynivalenol (DON) content in barley and its removal by various processing technologies were examined through simulating different storage environments and establishing relevant prediction models. Barley samples were stored at different temperatures (5, 15, 25, 35 ℃) and relative environmental humidities (55%, 65%, 75%, 85% RH) for 180, 270, and 360 d, respectively, before being processed via steaming, boiling, and fermentation. Then, the changing trend of the DON content was determined by the enzyme-linked immunosorbent assay, and the radial basis kernel function parameters were optimized by genetic algorithm to construct a support vector machine (SVM) pollution prediction model. The results showed that the DON content increased throughout the whole storage process, and 75%RH was the optimum environment for DON generation. In terms of processing for detoxification, it was found that the removal of DON differed among the three different processes, and the addition of sodium carbonate during processing could effectively promote DON degradation. However, the removal decreased when the added sodium carbonate was up to a certain level. The removal of DON by boiling was the most effective, with the removal rate reaching 50.81%~70.99%. The DON removal rate for the steaming process was lower (only 9.99%~24.37%). In the whole process of beer brewing (germination, saccharification, and fermentation), the DON removal rate first decreased then increased, with the removal rate in the range of 13.15%~41.67%. This study provides technical guidance for optimizing conditions for the safe storage of barley and effective reduction of the DON content during processing.

      • YI Youjin*, HE Xin, LUO Chengyin, HUANG Jiaoli, ZHOU Hongli, CAO Xi

        2022,38(10):140-147, DOI: 10.13982/j.mfst.1673-9078.2022.10.1413

        Abstract:

        To develop a safe plant-derived preservative for harvested peppers, two natural bacteriostatic agents were added to the film-forming agent placed on “Xiangyan No.15” peppers. The preservation effects of the composite coating containing extracts of Syzygium aromaticum and Cinnamomum cassia were evaluated by determining the differences in the rates of weight loss and decay; respiratory intensity; the activity levels of phenylalanine ammonia lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), malondialdehyde (MDA), and catalase (CAT); and the vitamin C, chlorophyll, total phenol, and flavonoid contents of the harvested chili peppers. The results showed that the composite coating effectively reduced the rates of weight loss and decay. Comparison of the composite coating-treated peppers to the clean water-treated (CK1) and untreated (CK2) peppers after 20 days of storage showed that the weight loss rate was reduced by 31.20% and 30.64%, respectively (p<0.05); the decay rate was decreased by 71.43% and 68.07%, respectively (p<0.05); and the activity levels of defense enzymes were significantly increased. In particular, CAT activity was increased by 55.01% and 44.69%, respectively (p<0.05); POD activity was increased by 37.50% and 12.58%, respectively (p<0.05); and PAL activity was increased by 58.37% and 34.14%, respectively (p<0.05). These results indicate that a composite coating containing Syzygium aromaticum and Cinnamomum cassia extracts can effectively improve the disease resistance of chili peppers, which is beneficial for preservation, thereby prolonging their storage period. This study provides theoretical support for the development of new safe preservatives for peppers.

      • LI Sufang, SU Jinlong, ZHANG Chuyao, GUO Wanjun, GAO Hui*

        2022,38(10):148-155, DOI: 10.13982/j.mfst.1673-9078.2022.10.1363

        Abstract:

        In order to investigate the relationship between the reduction of chilling injury in kiwifruit by the melatonin (MT) treatment and the carbohydrate metabolism of the fruit, ‘Xuxiang’ kiwifruit was used as the experimental material. The kiwifruits were soaked in the 0.05 mmol/L MT solution and stored at 0~1 ℃ for 90 d. The chilling injury index, firmness, malondialdehyde content and carbohydrate metabolism-related indicators were measured regularly. The results showed that the MT treatment delayed the increase of fruit chilling injury index, the decrease of firmness and the production of malondialdehyde, thus alleviated chilling injury in the kiwifruits. The total amylase activity was found to be inhibited, and during the whole storage, the total amylase activity of the MT-treated fruit was reduced by 41.27% on average compared with that of the control, thereby causing a delayed conversion of starch to soluble sugars, and consequently a higher retained starch content (1.07%) in the kiwifruits. Moreover, the starch content in the MT-treated fruit was significantly negatively correlated with the fruit’s chilling injury index (r=-0.820, p<0.01). The MT treatment decreased the activities of sucrose phosphate synthase, sucrose synthase, acid invertase and neutral invertase, and at the end of the storage, the activities of the four enzymes in the MT-treated fruit were 9.52%, 9.12%, 8.55% and 9.74% lower than those of the control, respectively. Thus, the synthesis-degradation cycle of sucrose was weakened and sucrose accumulation in the fruit slowed down, which induced, to some extent, the delay of starch degradation in the kiwifruit. The comprehensive analysis suggested that starch may be an important biomarker for the occurrence of chilling injury in kiwifruit, and in the effect of MT on kiwifruit may be a result of the co-regulation of total amylase activity and sucrose synthesis-degradation cycle.

      • ZHOU Feng, JIN Yuhui, MA Mengting, CAO Meng, LI Jianfang*

        2022,38(10):156-161, DOI: 10.13982/j.mfst.1673-9078.2022.10.1351

        Abstract:

        In this study, Lactobacillus plantarum suspensions at different concentrations were used to treat Nanwan bighead carp, and the treated fish samples were placed in PE fresh-keeping bags, for a storage at 4℃ and room temperature, respectively. Every two days their four indicators, TVB-N values, thiobarbituric acid (TBA), pH and sensory scores were measured, to determine the changing trends of the indicators of the fish flesh during storage. The results showed that compared with the control group, the treatments with different concentrations of bacterial suspensions reduced the increasing rates of TVB-N, TBA and pH of the Nanwan bighead carp while increasing the sensory scores of fish flesh during storage. When the concentration of Lactobacillus plantarum suspension was 0.8% and the storage temperature was at 4°C, the quality of the Nanwan bighead carp flesh was the best during storage. After 7 days of storage, the volatile base nitrogen (TVB-N) of fish flesh was 29.40 mg/100 g, with its TBA being 0.17 mg/kg and pH being 6.54. The deterioration time of this fish flesh could be delayed by 2 d compared with the control group as a whole. These results indicate that Lactobacillus plantarum has a certain preservation effect on fish flesh during storage, and can be used as a green biological preservative for storing and preserving Nanwan bighead carp.

      • PU Hongmei, WANG Haidan, YANG Fang, SHUAI Liang, YU Lijuan, LI Xuerui, LI Hong1*

        2022,38(10):162-169, DOI: 10.13982/j.mfst.1673-9078.2022.10.1412

        Abstract:

        This study tested the effects of five exogenous supplement treatments on the preservation of harvested broccoli. Treatments included 200 mg/L gibberellic acid (GA), 200 mg/L GA + inorganic salt nutrient solution, 50 mg/L 6-benzylaminopurine (6-BA), inorganic salt nutrient solution, and 50 mg/L 6-BA + inorganic salt nutrient solution, with water as the control. The appearance (color change), nutrient content (vitamin C, total soluble solids, chlorophyll, and water activity), and other physiological and biochemical characteristics (mass loss rate, relative conductivity, and malondialdehyde content) of broccoli samples in different treatment groups were analyzed and compared over the storage period. The exogenous supplements effectively inhibited increases in mass loss rate, relative conductivity, and malondialdehyde content, as well as suppressed chlorophyll degradation and maintained higher water, vitamin C, and total soluble solid content. In particular, the treatment consisting of 200 mg/L GA + inorganic salt nutrient solution maintained the highest total soluble solid (7.27%) and vitamin C (27.53 mg/100 g fresh weight [Fw]) contents, a high chlorophyll content (5.57 mg/100 g Fw), and the lowest malondialdehyde content (15.31 nmol/g Fw) after 28 days of storage; hence, it is recommended as the best preservation method among the five tested treatments.

      • YU Wentao, QU Shanshan, LI Mengmeng, WANG Guang, ZHU Shijiang*

        2022,38(10):170-177, DOI: 10.13982/j.mfst.1673-9078.2022.10.1466

        Abstract:

        The effects of preharvest application of 100 mg/L abscisic acid (ABA) on the preservation of lychee fruits stored at 20 ℃ were explored. The ‘Jingganghongnuo’ cultivar was selected for this research. Preharvest ABA treatment clearly mitigated increases in browning index, disease index, and fruit decay rate and better maintained the original color (L*, a*, and b*). More specifically, the browning index, disease index, and fruit decay rate of the ABA-treated lychee fruits were 3.38, 1.42, and 37.78%, respectively. After 8 days of storage, the total phenol content in the ABA-treated fruits was 3.54% higher than that in the control group, and the activities of phenylalanine ammonia-lyase, polyphenol oxidase, and peroxidase were 1.38%, 3.22%, and 18.39% higher, respectively. In contrast, relative electrical conductivity, malondialdehyde content, and hydrogen peroxide content were 23.25%, 11.85%, and 18.18% lower in ABA-treated fruits than in the control group, respectively. In addition, after 8 days of storage, the ABA-treated fruits had a total soluble solid (TSS) content of 17.70%, a titratable acid (TA) content of 0.12%, and a vitamin C (Vc) content of 30.14 mg/100 g, which were all higher than those in the control group. These results indicate that preharvest ABA treatment can maintain the appearance of harvested lychee fruits by maintaining cell membrane integrity, reducing the oxidation of phenols, and increasing the activity of antioxidant enzymes, as well as preserving nutritional quality by inhibiting decreases in TSS, TA, and Vc contents. Therefore, preharvest ABA treatment is recommended as a new technology for effectively maintaining the quality of harvested lychee fruits at ambient temperatures.

      • WANG Guoxia, LIU Menglong, LI Xiaobing, GAO Wenxuan, LI Jialin, YAN He*

        2022,38(10):178-186, DOI: 10.13982/j.mfst.1673-9078.2022.10.1392

        Abstract:

        To study the effects of X-ray irradiation on chilled pork quality, irradiation from 0.1 to 1.0 kGy was used to treat cultured pathogens and chilled pork to evaluate changes in microorganism growth, physical and chemical indicators, and sensory characteristics of chilled pork under different irradiation doses and storage times. The number of microbial colonies decreased as the irradiation dose increased. The D10 values of cultured Escherichia coli and Listeria monocytogenes were 0.177 kGy and 0.180 kGy, respectively. After treatment by X-ray irradiation at 0.6 kGy, the number of cultured microbial colonies was significantly reduced by more than 3.0 log value (p<0.05), and the number of inoculated microbial colonies decreased significantly by more than 2.0 log value (p<0.05). Furthermore, when chilled pork was treated with 1.0-kGy X-ray irradiation, the number of inherent microbial colonies declined markedly by more than 2.0 log value (p<0.05) while the shelf life was extended from 4 days to 9 days. There was no significant difference in sensory scores (p>0.05) in the early storage period, but in the later period, the sensory score of the irradiated chilled pork slowly decreased. The rates of TVB-N and pH-value increase dropped significantly during the storage period compared with those of the control (p<0.05). The TBA value of the chilled pork increased in all samples after irradiation, but the rate of TBA-value increase in the control group during storage was greater than that in the irradiated group. In summary, 1.0-kGy X-ray irradiation treatment of chilled pork meets national food safety standards and extends shelf life by 4~5 days. This finding provides a scientific basis for irradiation-based preservation of chilled pork.

      • LI Weiyuan, LIAO Chunyu, YU Haiqing, WEI Wei, LI Wen*, LEI Fuhou

        2022,38(10):187-197, DOI: 10.13982/j.mfst.1673-9078.2022.10.1414

        Abstract:

        The alkaline degradation products of hexoses (HADPs) produced during the production of sucrose increase the color value of the finished sugar, thereby reducing the quality of the latter. In this study, a novel rosin-based anion-exchange resin (RAER) was prepared by suspension polymerization to remove HADPs from sugar solutions. The RAER was characterized by scanning electron microscopy, Brunauer–Emmett–Teller measurement (with nitrogen), and synchronous thermogravimetric analysis. The results showed that the RAER possesses a highly porous structure and exhibits excellent thermal stability. The performance of the RAER toward HADP adsorption was investigated. The results suggested that the removal rate of HADPs (decolorization) was up to 100% (under the following experimental conditions: concentration of added RAER: 0.05 g/mL; temperature: 343 K; reaction time: 10 h; pH: 7.0; and initial HADP concentration: 100 mg/L). After 20 regeneration cycles, the decolorization rate of HADPs by the RAER was still as high as 92.2%, indicating that the RAER can be effectively reused and exhibits high performance over long-term operation. Zeta potential measurement confirmed the existence of electrostatic attraction (ion exchange) during HADP adsorption by the RAER. Studies on the kinetics, isotherms, and thermodynamics demonstrated that the adsorption of HADPs by the RAER agrees well with the pseudo-second-order kinetic model (R2≥0.99) and the Freundlich isotherm model (R2≥0.98), with ΔH=62.321 kJ/mol. These results indicated that HADP adsorption by the RAER follows a multi-layer endothermic process dominated by chemical adsorption.

      • CHENG Junhu*, LIAN Fengli, YU Xucong, SUN Dawen, YU Huaning

        2022,38(10):198-204, DOI: 10.13982/j.mfst.1673-9078.2022.10.1390

        Abstract:

        Reducing salt intake has become a commonly agreed upon key step in achieving a healthy diet. High-temperature steaming is a novel cooking method that is becoming more and more widely used. Cooking loss due to high temperature steaming was determined, and the ratio by which high temperature steaming reduced chloride levels in pickled salmon relative to cooking loss was calculated. A model was then established to simulate cooking loss-mediated salt reduction. Changes in salmon microstructure were also observed by SEM. These results demonstrate that cooking loss increases as cooking temperature and time increase. Moreover, cooking loss is the main factor affecting total chloride content reduction in the cooking process. For both cooking without steaming and cooking with steaming for 6 min, in the range of 180 ℃ to 220 ℃, the ln[-ln(1-P)]-lnt1 linear fitting results are consistent with a mathematical model of mass and heat transfer of porous media. Meanwhile, the salt reduction rate shows a good linear relationship with steaming time. When pickled salmon is heated at 220 ℃ for 18 min and steamed for 6 min, total chloride reduction reaches 26.44%. The SEM micrographs show that, as cooking temperature and time increase, the gaps between fibers decrease. At the same time, myointimal tissue is gradually destroyed, and fiber diameters decrease. Adding as teaming step can also accelerate the denaturation of fish proteins. To some extent, it slows down fiber contraction and decreases the mass transfer resistance of salt, making it easier to remove the salt.

      • GAO Fei, WU Yun*, CAI Huazhen*, HU Ying, DAI Hongyu, WANG Yanling, LYU Ze

        2022,38(10):205-216, DOI: 10.13982/j.mfst.1673-9078.2022.10.1306

        Abstract:

        Beef tendon meat was taken as the research object, and the beef was braised by three methods, namely braising under different vacuums, braising under different ultrasonic powers in synergy with vacuum, and braising under different ultrasonic frequencies in synergy with vacuum. The changes in the salt content, moisture content and weight of the braised beef during the braising processes were measured to examine the mass transfer patterns of the ultrasonic-vacuum braised beef. The results show that the changes in the salt content increased with the increases of vacuum degree, ultrasonic power and ultrasonic frequency, whilst the changes in the moisture content and weight decreased with the increases of vacuum degree, ultrasonic power and ultrasonic frequency. The kinetic parameters associated with the salt content changes of braised beef during braising process, k1 and k2, of variation are related to the vacuum degree, ultrasonic power and ultrasonic frequency. Under the conditions of vacuum degree of -0.043 MPa, ultrasonic frequency of 28 kHz and ultrasonic power of 1 000 W, the maximum effective diffusion coefficient De for the salt content change was 1.42×10-4 m2/s. The mass transfer driving force of the three braising methods had a good positive linear relationship with t0.5/l. Vacuum braising and ultrasonic in synergy with vacuum braising had significant effects on the microstructure of the braised beef. Therefore, ultrasonic in synergy with vacuum braising had a significant effect on the mass transfer in the braised beef and could promote the mass transfer process. The optimal mass transfer conditions for the braising under ultrasonic in synergy with vacuum were: vacuum degree, -0.043 MPa; ultrasonic frequency, 28 kHz; ultrasonic power, 1 000 W; ultrasonic time, 30 min.

      • ZHANG Le, ZHANG Ya, WANG Zhaogai*, SHI Guanying, JIANG Pengfei, ZHAO Lili, WANG Xuzeng

        2022,38(10):217-226, DOI: 10.13982/j.mfst.1673-9078.2022.10.1418

        Abstract:

        To identify the most suitable carrier material and drying technology to reduce or even prevent stickiness during spray-drying of instant Chinese chestnut flour, the effects of different concentrations of carrier materials, such as maltodextrin, whey protein isolate, acacia gum, and β-cyclodextrin, on spray drying were studied. The optimum parameters during spray drying were determined in orthogonal experiments, and the properties of the instant flours were evaluated. The results showed that the optimal conditions for spray drying are as follows: inlet temperature, 190 ℃; feed rate, 20 mL/min; and 5% maltodextrin as a carrier. Range analysis and variance analysis revealed that the factors most affecting product yield are (in descending order): carrier addition, feed rate, and inlet temperature. The water and fat contents of the instant chestnut flour were as low as 1.60 g/100 g and 1.77 g/100 g, respectively, while the protein content was as high as 8.45 g/100 g. The whiteness was 82.18. A total of 38 volatile aroma components were identified, and acids, alkanes, and aldehydes accounted for 42.47%, 19.87%, and 16.81%, respectively, of the total volatile contents. Six key aroma compounds were identified by calculating the odor activity values (OAVs): hexanal, nonanal, (E,E)-2, 4-nonadienal, D-limonene, hexanoic acid, and ethyl maltol. The Instant Chinese chestnut flour produced is nutritionally rich, with a pleasant color, strong flavor, and good tonality and stability.

      • HE Jinxuan, LIU Chong*, ZHENG Xueling

        2022,38(10):227-234, DOI: 10.13982/j.mfst.1673-9078.2022.10.1364

        Abstract:

        In order to solve the problems that the porous structure of fermented vermicelli during fermentation destroys the gluten network structure, the low-temperature drying process can not cause protein denaturation, and the gluten network is well cross-linked, which makes it easy to break and not resistant to cooking. The effect and mechanism of medium-high temperature drying on the quality of fermented dried noodles was investigated. Medium-high temperature drying could promote gluten protein cross-linking and improve noodle quality. The temperature was raised to 65 or 80 ℃ at different stages (beginning, middle and end) of the low-temperature drying process corresponding to different moisture contents of the products (high, medium or low), respectively. The moisture content, colour and flexural properties of the dried noodles were determined, as well as the texture and tensile properties of the cooked noodles. The pasting properties and dynamic rheological properties of starch as well as the changes in the contents of gluten macromers and free sulfhydryl groups were further analysed. Compared with the control group, high temperature drying could improve the flexural strength of dry noodles (up to 39.72%); medium-high temperature drying increased the water absorption of the dry matter in the cooked noodles (up to 27.73%), increased the hardness of the cooked noodles (up to 9.21%) and decreased the surface viscosity (up to 59.16%). The results indicated that high temperature drying promoted protein cross-linking, strengthened the gluten network structure, and reduced starch swelling and granule disintegration. The findings have important implications for improving the quality of fermented noodles.

      • XIAO Ganhong, WANG Min, HOU Chuanli, LIAO Linfeng, ZHANG Ying, REN Jiaoyan*

        2022,38(10):235-241, DOI: 10.13982/j.mfst.1673-9078.2022.10.1385

        Abstract:

        A cyclic temperature change model was used to simulate land transportation conditions [30 ℃ (7 h) → 35 ℃ (6 h) → 45 ℃ (5 h) → 55 ℃ (5 h) → 60 ℃ (1 h) → 30 ℃ (7 h)] to investigate the effects of logistics and transportation on the polyphenol contents and antioxidant activities of blueberry, raspberry, and elderberry extracts. The folin-phenol method was used to determine the polyphenol contents in the three berry extracts under different transportation times. Additionally, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and oxygen radical absorption capacity (ORAC) were used to evaluate the antioxidant activities of the three extracts under different transportation times. The results demonstrate that the initial polyphenol contents of the elderberry, blueberry, and raspberry extracts were 14.96%, 5.11%, and 2.53%, respectively. As the transportation time increased, only the polyphenol content of the elderberry extract increased significantly. Over time, the DPPH· scavenging activities and ORAC of all the three extracts decreased, and the total increased rates of IC50 were all higher than 20%. It is worth noting that the ORAC for all three extracts showed remarkable fluctuations. The total trolox equivalent loss rates of the elderberry, raspberry, and blueberry extracts were 62.76%, 32.74% and 19.72% respectively. The temperature changes and transportation duration times under logistics simulation affected the antioxidant activities of all three berry extracts. The stabilities of the DPPH scavenging activities in ascending order were: raspberry < blueberry < elderberry, while the stabilities of ORAC was blueberry < elderberry < raspberry.

      • LI Yongfu*, LUO Qiqi, TIAN Zhuxi, HE Yangbo, SHI Bin, LONG Mingxiu

        2022,38(10):242-248, DOI: 10.13982/j.mfst.1673-9078.2022.10.0240

        Abstract:

        Thiabendazole is a hydrophobic anti-bacterial drug. However, the water solubility of thiabendazole can be significantly enhanced by its complexation with cyclodextrins. In this study, β-cyclodextrin butenate was synthesized by the esterification of butenoic acid and β-cyclodextrin to improve the solubility of β-cyclodextrin in aqueous solutions. The apparent stability coefficients of thiabendazole-β-cyclodextrin and thiabendazole-β-cyclodextrin butenate complexes were determined by phase solubility tests, and the structures of these complexes were analyzed by mid-infrared spectroscopy. β-Cyclodextrin butenate was synthesized by using N,N-carbonyldiimidazole as the carboxylic acid activation reagent, 4-dimethylaminopyridine as the catalyst, and dimethylformamide as the solvent. The solubility of β-cyclodextrin butenate in water (25 ℃) was 2.05 times that of β-cyclodextrin. At a water temperature of 50 ℃, the apparent stability coefficients of the thiabendazole-β-cyclodextrin and thiabendazole-β-cyclodextrin butenate complexes were 59.35 and 52.43 M-1, respectively; no significant difference was observed between them (p>0.05). β-Cyclodextrin butenate could improve the solubility of thiabendazole in water upon complexation, and its solubilization effect is stronger than that of β-cyclodextrin. The solubility of thiabendazole in water is considerably improved, and the thiabendazole-β-cyclodextrin and thiabendazole-β-cyclodextrin butenate complexes exhibit strong anti-bacterial effects.

      • JIANG Wei, QIANG Yu, LIU Chengjiang, HUANG Feng, ZHANG Chunhui*, HAN Dong1*

        2022,38(10):249-260, DOI: 10.13982/j.mfst.1673-9078.2022.10.1450

        Abstract:

        To identify the tastant compounds contributed by 13 commonly used spices to stewed beef products, reveal the effects of these spices on the taste of stewed beef, and provide technical data supporting the scientific formulation of spices to best preserve stewed beef and optimize its taste, this research analyzed 13 spices, including Chinese pepper, clove, and licorice using beef shanks. An electronic tongue (E-tongue) was applied to record the impacts on taste of cooking stewed beef with each spice. High-efficiency liquid ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS/MS) was conducted to identify taste compounds in spice mixture extracts and cooking sauce extracts when stewed beef is cooked with spice mixtures and brine. The taste compounds that each spice contributes to stewed beef have been identified and quantitated. The E-tongue results reveal that licorice, cinnamon, star anise, chili pepper, and cloves contribute most prominently to sweetness; cumin can, to some degree, enhance savoriness; angelica dahurica, grass fruit, and bay leaf exert obvious effects on bitterness. The UPLC-MS/MS results suggest that the spices impart 22 classes of non-volatile compound to stewed beef, among which 8 compounds are associated with distinct tastes. Neohesperidin, glycyrrhizin, and acetophenone impart a sweet taste; naringin, isoquercitrin, hesperetin, chuantong, and astragalin impart a bitter taste. In short, spices can impart different tastes to stewed beef, including sweetness, savoriness, and bitterness. The effects of different spices on the taste of stewed beef vary. The taste compounds that spice mixtures impart to stewed beef are mainly flavonoids, including neohesperidin, glycyrrhizin and isoquercitrin.

      • YANG Ruoxuan, TANG Kaiwei, ZHU Chenglin, CHEN Juan, DAO Xiaofang, TANG Junni*

        2022,38(10):261-271, DOI: 10.13982/j.mfst.1673-9078.2022.10.1441

        Abstract:

        Samples were collected from a large dairy farm in Chengdu city to study the epidemic characteristics and resistance of Salmonella isolates. Strains of Salmonella were isolated, identified, and seroptyped. Drug susceptibility, virulence, drug resistance, and disinfectant resistance genes were tested. Minimum inhibitory concentrations (MIC) to commonly used disinfectants and effective sterilization temperatures were also determined. A total of 700 samples were collected; 16 strains of Salmonella and four serotypes were isolated (six strains of Salmonella enteritidis, six strains of S. paratyphoid A, three strains of S. typhimurium, and one strain of S. infantis). All strains were sensitive to ceftazidime, levofloxacin, and imipenem. Twenty four drug resistance genes were detected, and the highest detection rate was noted for tetB (93.75%), followed by that of aaC4 (75.00%). There were 12 virulence genes detected, and the highest detection rate was observed for sipA (62.50%); qacEΔ1 showed the highest detection rate of the disinfectant genes (56.25%). The MIC values of 16 Salmonella strains against nine different disinfectants were generally one to three times higher than the recommended concentrations from the manufacturers. The 100% sterilization temperatures of the strains in whole and skim milk were 64.00 ℃ and 63.50 ℃, respectively. The isolated strains of Salmonella on this dairy farm were resistant to some disinfectants, but could be effectively controlled at 64.00 ℃. It is recommended that dairy farms strengthen the prevention and control of Salmonella and the use of disinfectants should be standardized. Key words:

      • MA Qiong, LI Junsheng*, HUANG Guoxia, YAN Liujuan, MA Ji

        2022,38(10):272-282, DOI: 10.13982/j.mfst.1673-9078.2022.10.1361

        Abstract:

        In view of the high toxicity of aflatoxin G1 (AFG1) and the difficulty in decomposing and effectively removing it, an effective method for selective adsorption and elimination of AFG1 was established via intercalation of AFG1 and DNA. The optimum reaction conditions for intercalating AFG1 into DNA molecules were pH 7.4 and 30 ℃, and the DNA binding saturation value and removal rate were 1.66 and 88.14%. After the addition of sodium chloride, calcium chloride, L-aspartic acid, glucose, urea, leucine, lysine or vitamin C, the DNA binding saturation values were 1.45, 1.45, 1.29, 1.05, 1.95, 1.95, 2.32 and 2.90 respectively, with the removal rates being 78.08%, 76.44%, 75.92%, 75.16%, 88.41%, 88.67%, 88.87% and 90.27% respectively. A negatively charged group (such as sodium chloride, calcium chloride, L-aspartic acid and glucose), or a relatively high ionic strength, was not conducive to the intercalation of AFG1 and DNA, whilst substances carrying positively charged groups and similar groups (such as urea, leucine, lysine, and vitamin C) were conducive to the AFG1-DNA intercalation. The removal rate of AFG1 in peanut oil reached over 80%. The kinetic correlation coefficient and adsorption capacity showed that the adsorption process conformed to the pseudo-second-order order model, indicating that the rate-limiting step of the adsorption process was chemical interaction. The adsorption process followed the Freundlich isotherm adsorption model, thus the adsorption process was multilayer adsorption. Thermodynamic results showed that the adsorption of AFG1 by DNA was a spontaneous exothermic process. In conclusion, DNA can selectively adsorb AFG1. Therefore, new DNA materials can be further developed, which is of great significance in the removal of aflatoxin in food.

      • LI Bing, YE Qinghua*, ZHAO Meiping, CHEN Wei, HUANG Yiqing, WU Qingping, ZHANG Junmei*

        2022,38(10):283-289, DOI: 10.13982/j.mfst.1673-9078.2022.10.1366

        Abstract:

        Burkholderia gladioli pathovar cocovenenans (BGC) is a food-borne pathogen with the highest morbidity and mortality found in China. Outbreaks of severe, BGC-caused food-poisoning have been reported every year in Guangdong Province from 2018 to 2020. The prevalence of BGC in commercial wet rice flour products, white tremella, and agaric in Guangzhou and growth and toxin production characteristics of the pathogen under various conditions were determined. One hundred food samples were subjected to qualitative analysis for BGC using the national food safety standard food microbiological examination (GB 4789.29-2020). By measuring the OD600 values and the contents of toxins under different culture conditions, the growth and the toxin-producing abilities of BGC under different incubation temperatures and durations, pH values, and NaCl concentrations were evaluated. Of the 100 food samples, one sample (in agaric) tested positive for BGC. The growth and toxin production of BGC were greatly affected by the culture medium. BGC grew in potato dextrose, but hardly grew in brain heart infusion broth in an alkaline environment (pH value 9.5~10.5) and at NaCl concentrations of 0.02~0.04 g/mL. The toxin production of BGC in potato glucose semisolid agar (231.24 µg/mL) was much higher than that in BHI and LB semisolid agar (38.84 µg/mL). The growth and toxin production temperature and pH value suitable for growth of BGC were 20~37 ℃ and 4~8.5; optimal growth temperature and pH value were 37 ℃ and 6.0; and the optimal toxin production temperature and pH value were 30 ℃ and 7.0, respectively. BGC survived and produced toxins (2.11 µg/mL) at low temperatures (4~15 ℃). The toxin production of BGC was obviously inhibited at high NaCl concentrations. When the NaCl concentration was 0.005 g/mL, the toxin production decreased from 139.80 μg/mL to 52.27 μg/mL; at 0.04 g/mL, no toxins were produced. There is a risk of BGC contamination in agaric in Guangzhou. BGC-caused food-poisoning outbreaks can be reduced by adding NaCl during food processing or storage.

      • GUAN Yeqing, WANG Dong, LI Nan, FU Yaxiong, CHENG Yudou, GUAN Junfeng*

        2022,38(10):290-296, DOI: 10.13982/j.mfst.1673-9078.2022.10.1431

        Abstract:

        To develop a rapid and non-destructive method for detecting the internal quality of the “Shenzhou Peaches”, the SACMI near-infrared analyzer was used in the diffuse reflection for non-destructive measurements of the soluble solid content (SSC), firmness, and pH of fruits ready for harvest. The results were compared with those obtained by traditional methods. The results reveal that, after excluding outliers, the correlations between the predicted SSC values by the non-destructive method and the measured values using traditional methods (R2=0.79, p<0.01, SEP=0.47) are better than those of firmness (R2=0.47, p<0.01, SEP=2.01) and pH (R2=0.40, p<0.01, SEP=0.14). The SSC model (RPD=2.15, RMSEP=0.79%, RSD=6.2%) exhibits better prediction performances and can enable rapid detection. Meanwhile, the pH model (RPD=1.29, RMSEP=0.16, RSD=3.1%) and the firmness model (RPD=1.37, RMSEP=2.37 kg/cm2, RSD=39.4%) gave less satisfactory prediction results. This research has shown that detecting the SSC of “Shenzhou Peach” fruits is feasible with a near-infrared analyzer. This is a real-time, fast and non-destructive method for the internal quality evaluation of fruits. This finding can provide a theoretical foundation and technical support for intelligent future grading and classification of fruits.

      • LI Shiyao*, PENG Qingzhi, WANG Mingqiu, LIU Yan, DONG Wanting

        2022,38(10):297-302, DOI: 10.13982/j.mfst.1673-9078.2022.10.1301

        Abstract:

        In this study, a method for the simultaneous enrichment of Salmonella typhimurium, Staphylococcus aureus and Listeria monocytogenes was developed based on the electrostatic enrichment technology using amino magnetic beads. Three different sized amino magnetic beads (5~200 μg; 1 μm, 300 nm, 100 nm) were added respectively into each bacterial solution (2 mL; 103 CFU/mL), and the enrichment efficiency of each bacteria was detected after the incubation was conducted for 5~90 min. The results of the orthogonal enrichment tests for the single bacteria system were applied to the single factor tests and orthogonal tests of the mixed bacteria system, and the final results were applied to the large-volume experimental system and actual samples (commercially available milk and fruit salad). The results showed that when the addition amount of amino magnetic beads was 50 μg and the incubation time was 30 min, the capture rate for the three kinds of pathogens could reach over 60%. All reactions were performed in PBS at pH 7.4. The bead diameter was selected to be 300 nm (p<0.05). The capture rate was higher than 55% when the minimum concentration of the three mixed bacteria was 2×102 CFU/g (mL) in the actual samples of milk and fruit salad. This result could reach the detection limit of fluorescence quantitative PCR. Compared with immunomagnetic beads, the amino magnetic beads had many advantages, such as high stability over storage, low cost and high efficiency. The ability of untargeted enrichment provides an effective pretreatment enrichment method for the rapid detection of downstream foodborne pathogens.

      • LI Ruotong, HU Jiye*

        2022,38(10):303-309, DOI: 10.13982/j.mfst.1673-9078.2022.10.1375

        Abstract:

        A method for the simultaneous determination of clothianidin and azoxystrobin residues in potatoes was established. Samples were extracted with water and acetonitrile and then cleaned using anhydrous magnesium sulfate and primary secondary amine. The supernatants were filtered through 0.22 μm filters, and the filtrate solutions were subjected to high-performance liquid chromatography-tandem mass spectrometry. Linear regression showed that extraction curves for both clothianidin and azoxystrobin were reasonably close to the standard curves within a concentration range from 0.005 to 0.5 mg/L, with a correlation coefficient higher than 0.997 2. Average recovery rate of clothianidin and azoxystrobin from potatoes spiked with different pesticide levels ranging from 91.47% to 98.13%, with relative standard deviations less than 7.63%. The limit of quantification was 0.01 mg/kg for both analytes. Supervised residue trials were carried out in 12 areas in China according to the Ministry of Agriculture Guidelines for Testing of Pesticide Residues in Crops. Granules of 2% clothianidin + azoxystrobin were applied to the furrows beside the planting spots at the recommended dosage of 900 g a.i./ha before sowing or transplanting of potatoes. Clothianidin and azoxystrobin residues in potato samples at harvest were below 0.17 mg/kg and 0.074 mg/kg, respectively. Subsequently, dietary risk assessments were carried out based on the results of field residue trials, national dietary patterns, and toxicological data. The national estimated daily intakes of clothianidin and azoxystrobin were found to be 0.271 8 mg and 2.625 1 mg, respectively. The dietary risk quotients of clothianidin and azoxystrobin in potatoes were calculated as 4.31% and 20.83%, respectively, both less than 100%. This indicates that the application of granules of 2% clothianidin + azoxystrobin under the recommended Good Agricultural Practice conditions would not pose an unacceptable risk to human health.

      • YANG Feng, LI Yingying, LI Shilei, WANG Shouwei*

        2022,38(10):310-319, DOI: 10.13982/j.mfst.1673-9078.2022.10.1428

        Abstract:

        Animal husbandry accounts for a large proportion of global total land use and greenhouse gas emissions. In addition, prophylactic antibiotics are widely used in the process of large-scale animal breeding, resulting in drug-resistant bacteria, other pathogenic factors, and zoonotic diseases. More importantly, as the human population grows, the ever-growing demand for meat and dietary proteins cannot be satisfied by traditional animal husbandry. Therefore, cell-based meat production technology has emerged and developed rapidly. It displays potential to provide meat protein products without related environmental, ethical and technical issues. Although protein supply shortages due to the growing global population could be solved by cell-based meats, current key breakthrough technologies required for cell-based meat production are limited to laboratory scale research and production. Many technical bottlenecks in mass production of cell-based meat need further investigations. Based on the current status of the traditional husbandry industry and technology development trends within the cell-based meat production field, this review illustrates the potential for cell-based meats to supplement the meat supply provided by traditional animal husbandry, its market positioning, and trends in development of key future technologies.

      • ZHANG Na*, WU Na, YANG Yang, FAN Jing, REN Likun, HE Yinyuan, BIAN Xin, CHEN Fenglian, LIU Xiaofei, YU Dehui, LIU Linlin, GUO Xiaoxue

        2022,38(10):320-328, DOI: 10.13982/j.mfst.1673-9078.2022.10.1383

        Abstract:

        Freezing of dough, as a technique for processing pasta products, has been used in the food industry worldwide to prevent product aging and to facilitate refrigeration and transportation. However, the production and storage of frozen doughs faces many challenges, such as loss of gluten structural integrity, loss of gluten, reduction of yeast activity, and reduction and destruction of dough structure. These challenges can cause deterioration of pasta product quality. This paper reviews the main factors affecting the quality of frozen doughs and summarizes methods that effectively improve the quality characteristics of frozen doughs. The use of additives can now improve the freezing tolerance of yeast and maintain the rheological properties of doughs. Genetic engineering technology can improve the freezing tolerance and fermentation ability of yeast. By optimizing freezing and storage conditions, the yeast activity and network structure of the dough can be maintained within reasonably good ranges, and the damages caused by ice crystals can be minimized. Novel technologies such as ultrasonic-assisted freezing can ensure ice crystal uniformity while accelerating the freezing process, thus protecting the network structure of the dough. Therefore, the main factors affecting the quality of frozen doughs, and effective methods to improve characteristics of frozen dough quality, are summarized in this paper to provide a theoretical basis for improving frozen dough quality and for developing new frozen dough preservation technologies.

      • LI Jie*, LI Caiyun, SHU Jiaxin, JIANG Huiwen, YAN Shoulei, WANG Qingzhang

        2022,38(10):329-336, DOI: 10.13982/j.mfst.1673-9078.2022.10.1444

        Abstract:

        L-ascorbic acid (AA) can not only inhibit oxidation and browning of food but also cause degradation and oxidation of food to produce brown pigments. Therefore, it is very important to completely understand the degradation mechanism of AA in order to maintain the stability of AA in food. In this paper, the self-degradation mechanism of AA under different conditions (oxygen content, temperature, pH, and substrate concentration) and the degradation process via the Maillard reaction involving the oxidation products of AA were reviewed in detail. In addition, the beneficial and adverse effects of dehydroascorbic acid (DHAA), a degradation product of AA, on food properties were summarized. DHAA can be crosslinked with sulfhydryl groups of gluten to improve the properties of gluten. In contrast, DHAA causes the degradation of phenols and reduces the antioxidant capacity of food. Moreover, DHAA can form glycosylation end products with proteins and produce substances harmful to the human body. This review aims to provide a more comprehensive research perspective for the degradation of AA during food processing.

      • ZENG Zhilu, HUANG Daowu, LUO Donghui, HUA Yanglin*

        2022,38(10):337-341, DOI: 10.13982/j.mfst.1673-9078.2022.10.1006

        Abstract:

        In recent years, the increasing pursuit of more sustainable, nutritional, and appealing food has led to a serious imbalance between supply and demand of meat in China. European and American countries have invested a lot of resources in research on artificial meat that may significantly affect the future of food markets in China. Artificial meat is mainly divided into two types, one is plant-based meat synthesized from plant proteins and other plant components, and the other is cell-cultured meat produced using animal stem cells. This substitute for conventional meat shows potential as a delectable and nutritious alternative. Furthermore, it reduces ecological footprint for environmental sustainability. Despite its advantages, there are many technical, safety, and cost limitations in manufacturing artificial meat. This article highlights the discussion around its current research progress and the prevailing challenges, with the aim to guide future research on artificial meat in China.

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      • Inhibitory effects of Total Flavonoids Extracted from Peel of Citrus Sinensis Osbeck cv. Hongjiang on α-glucosidase and Pancreatic Lipase activities

        林海生, Rao Mengwei, Qin Xiaoming, Wu Qingxiao, Zhang Chaohua, Yu Guoshi, Zhang Hailong

        Abstract:

        In order to further utilize the peel of Citrus sinensis Osbeck cv. Hongjiang as potential functional food, the optimum extraction process of total flavonoids was studied by orthogonal experiment and ultrasonic-assisted extraction method using the extraction efficiency of flavonoids as the evaluation index. Then the inhibitory effect on α-glucosidase and pancreatic lipase was investigated. Results showed that the optimum conditions were as follows: ultrasonic temperature of 70℃, solid-liquid ratio of 1:5 and extraction time of 50 min, and the total flavonoids extraction yield was 82.57 mg/g,which was much higher than the one by hot water extraction. The IC50 values of Citrus sinensis peel flavonoids extract (CSFE) with regard to α-glucosidase and pancreatic lipase inhibition were 2.95 mg/mL and 28.54 mg/mL, respectively. The inhibitory activities of CSFE on pancreatic lipase were significantly concentration-dependent within a concentration range from 10 mg/mL to 50 mg/mL, and both the types of inhibition were determined as mixed-type inhibition. Results above indicated that the CSFE possessed good inhibitory activities on α-glucosidase and pancreatic lipase, which provided a theoretical foundation for the development of bioactive health products with hypoglycemic and weight reducing function.

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      • Comparison of the Xanthine Oxidase Inhibitory Activity and Sensory Quality of Different Purple Sweet Potato Steamed Bread

        于鑫, 宋淼, 谷懿潇, Ai Zhilu

        Abstract:

        Eight kinds of purple sweet potato power were used, pH value, titratable acidity (TTA) value and fermentation ability of purple sweet potato dough prepared with 8 kinds of purple sweet potato powder were compared, the differences of the content of active components, xanthine oxidase inhibitory activity, antioxidant activity and sensory quality in 8 kinds of purple sweet potato steamed bread were analyzed, the internal relationship among the contents of active components, xanthine oxidase inhibitory activity and antioxidant activity of purple sweet potato steamed bread was expounded, and a kind of purple sweet potato power which could be used to prepare purple sweet potato steamed bread with potential antihyperuricemic activity was screened in this study. The results showed that the contents of total flavonoids and total anthocyanins, xanthine oxidase inhibitory activity, superoxide anion radical scavenging activity and reducing power in purple sweet potato steamed bread prepared with Jihei No.1 purple sweet potato powder were 195.70 mg RE/100 g, 2.16 mg C3G/100 g, 11.93 μmol AE/100 g, 29.07 mmol TE/100 g and 2.69 mmol VE/100 g,respectively, which were significantly higher than those of the other 7 kinds of purple sweet potato steamed bread (p < 0.05). Correlation analysis showed that the total flavonoids and total anthocyanins were the main reasons for the differences in xanthine oxidase inhibitory activity and antioxidant activity of different purple sweet potato steamed bread. The sensory scores of Jihei No.1 and Jihei No.2 purple sweet potato steamed bread were higher than those of the other 6 kinds of purple sweet potato steamed bread, which were 86.56 and 88.22, respectively. Therefore, Jihei No.1 purple sweet potato steamed bread had the best comprehensive quality, and Jihei No.1 purple sweet potato powder was suitable for the development of purple sweet potato steamed bread with antihyperuricemic activity. This study provides a theoretical basis for the further study on the antihyperuricemic activity of purple sweet potato steamed bread and the development and industrial production of functional purple sweet potato steamed bread.

        • 1
      • Multi-dimensional optimization and validation in high-density culture factors of Lactobacillus gasseri GU-G23

        LIAO Yanting, LI Ruiding, HUANG Guohong, Liang xiaolin, ZhouFan, MA Zhize, SHI Fengcui, Liquanyang

        Abstract:

        In order to improve the biomass of Lactobacillus gasseri GU-G23 with probiotic properties and obtain its high-density culture factors, this paper firstly screened the main growth nutrient factors of this strain as fish peptone, tryptone and triammonium citrate by single-factor experiment and Plackett-Burman experiment. The response surface experimental design combination was used as the training sample for the machine model, and the random forest regression(RFR)and radial basis function neural network(RBF)models were used to predict their culture media formulations. Using the coefficient of determination(R-squared, R2), Mean absolute deviation(MAE), Mean-square error(MSE)and Mean absolute percentage error (MAPE)as model evaluation metrics, the comparison concluded that RBF had better predictive performance in this study. Subsequently, a combination of RBF neural network and Genetic algorithm(GA)was chosen to optimize the main components of the culture medium. The optimized formulation of the medium was obtained as follows: fish peptone 29.89 g/L, tryptone 23.33 g/L, triammonium citrate 4.34 g/L, sucrose 15.00 g/L, xylo-oligosaccharides 15.00 g/L, sodium acetate 5.00 g/L dipotassium hydrogen phosphate 0.40 g/L, magnesium sulfate heptahydrate 0.58 g/L, manganese sulfate monohydrate 0.29 g/L, Tween-80 1.00 g/L. Under this medium condition, the number of viable bacteria in the resulting sample reached 5.21×109 CFU/mL, which was 4.57 times higher than that before optimization. This study provides a new approach to the optimization of microbial high-density culture prediction.

        • 1
      • Change of the metabolism of glucosinolate in postharvest pakchoi (Brassica rapa L subsp. chinensis) under the condition of red light-emitting diode irradiation

        SUNYING, GUOFENG, HANYING, HUHUALI, LIPengxia, LUOSHUFEN

        Abstract:

        To investigate the effect of red light-emitting diodes (LED) irradiation on the metabolism of glucosinolates of postharvest pakchoi (Brassica rapa L subsp. chinensis). Firstly, the materials were treated with different conditions of LED irradiation with different color and density. The results showed that the degradation of chlorophyll and the yellowing of pakchoi were inhibited by red LED irradiation with a density of 6.5 μmol/(m2·s). Then, the red LED irradiation with 6.5 μmol/(m2·s) was selected for treating the pakchoi. Then, the changes of glucosinolate content and relative expression level of genes involved in the glucosinolate metabolism of pakchoi after red LED irradiation were analyzed to explored the possible regulatory mechanism of this treatment. The results indicated that the contents of total glucosinolate and isothiocyanate in petiole of pakchoi were 2.72 times and 1.32 times higher than those in leaves, respectively. Additionally, the relative expression of genes including MYB28, CYP83A1, and GSTF11 were up-regulated by the red LED irradiation, thus promoting the synthesis of glucosinolate such as gluconapin. As a result, the content of total glucosinolate in the treated petiole of pakchoi was 1.62~1.99 times higher than that in the control during 4~8 day of storage. The myrosinase activity in the petiole of pakchoi was also promoted by the red LED irradiation, and consequently, the accumulation of total isothiocyanate in the petiole of pakchoi was increased. Notably, the total isothiocyanate contents in the control group were lower by 77.43%~91.98% than those in the red LED irradiation treated group during 4~8 day. In conclusion, the red LED light treatment could delay the losses of glucosinolates and isothiocyanates in pakchoi, which could be explained by the upregulated relative expression level of genes involved in the synthesis of aliphatic glucosinolate and the increased myrosinase activity in the sample.

        • 1
      • Effect of Hydroxybenzoic Acid with Different Numbers of Phenolic Hydroxyl Groups on the Properties of Chitosan Film

        杨林杰, 周闯, 杨子明, 王超, 何祖宇, 刘运浩, 于丽娟, 屈云慧, 李普旺

        Abstract:

        In this paper, chitosan, a natural macromolecular material, was used as the matrix, and four kinds of hydroxybenzoic acids with different numbers of phenolic hydroxyl groups, salicylic acid (SA), protocatechuic acid (PA), gentisic acid (GTA) and gallic acid (GA) were added to prepare composite films by solvent casting method. The rheological properties of the composite film solutions were investigated. The structure and properties of the composite films were characterized by thermogravimetry (TG), fourier transform infrared spectoscopy (FT-IR) and scanning electron microscopy (SEM). The mechanical properties, barrier properties, total phenol release and oxidation resistance of the composite films were also measured. The results showed that the strong interaction occurred between chitosan and hydroxybenzoic acid, thus leading to a highly compact network structure and forming a uniform and stable composite films. Besides, the composite film of gallic acid which has three phenol hydroxyl groups and chitosan had good ultraviolet barrier, the vapor transmission rate was 1.50×10-9 g/(m·h·Pa), the tensile strength of the film was 23.22 MPa, and the DPPH radical scavenging rate was 71.85%. The above research showed that the performance of hydroxybenzoic acid and chitosan composite film was affected by the hydroxyl number of hydroxybenzoic acid phenol, the more hydroxyl number, the better comprehensive performance of composite film.

        • 1
      • Changes on the Processing Properties of Chinese Chestnut Powder Coordinating with Guar Gum and Ferulic Acid Under Extrusion

        Li Rui, Zheng Bo, Rao Chenlu, Chen Ling

        Abstract:

        The nutritional and quality of chestnut products can be determined by the processing and digestion properties of whole chestnut flour. In this study, we proposed to modify the whole chestnut flour by extrusion treatment with common food additives guar gum and ferulic acid, and its freeze-thaw stability, water absorption, oil absorption, rheological properties and in vitro digestive properties were systematically investigated. The results showed that extrusion coupled with guar gum enhanced the freeze-thaw stability, water absorption and water solubility of the whole chestnut powder, decreased its oil absorption, paste temperature and increased its breakdown value. In addition, this treatment had good regulating effect on the paste stability of whole chestnut powder. As for rheological property, coupling guar gum contributed to improve the rigidity of gel during storage of chestnut whole powder, but it had opposite effect as the addition amount increased. When introducing ferulic acid, the peak viscosity, pasting temperature, breakdown value and anti-digestibility component content would increase, but freeze-thaw stability, water absorption, water solubility and oil absorption changed little. Moreover, the anti-digestibility components of the chestnut powder were increased by 27.00%-32.10% extrusion coupled with 3 wt.% guar gum and 3 wt.% ferulic acid. This study illustrates that extrusion coupling guar gum and ferulic acid treatment has effective influence on processing properties of chestnut powder, which provides basic data for the creation of new chestnut products.

        • 1
      • Research on Crayfish Ready-to-eat Snack Food and its Quality Analysis

        秦佳伟, 谭慧, 邵立业, 杨品红, 韩庆

        Abstract:

        A pre-cooked crayfish tail was used as raw material to develop a kind of crayfish ready-to-eat snack food that is easy to carry for fill the gap of crayfish ready-to-eat snack products. The influence of four factors of salt, pepper and zanthoxylum, monosodium glutamate and chicken essence, and cooking time on crayfish snack food was optimized. Single-factor and orthogonal tests were carried out with sensory scores as indicators, and the texture, nutrition and flavor of the products were evaluated. The optimal process formula was 2.50% salt, 13.30% pepper and 2.98% zanthoxylum, 0.66% chicken essence and 0.66% monosodium glutamate, 4 min cooking time, and a sensory score of 76.66. The hardness of the edible part of the product was 119.83±1.61/N, the elasticity was 3.88±2.74, the cohesion was 0.92±0.11, and the chewiness was 424.99±2.91. The moisture content was 55.85±0.09%, ash was 4.07±0.29%, fat was 14.91±0.60%, crude protein was 18.79±0.21%, and total sugar was 3.87±0.33%. Among the total amino acids (155.93±11.10 mg/g), the essential amino acids accounted for about 20%, and the essential amino acid scores were all more than 1. Unsaturated fatty acids accounted for about 83% of fatty acids. The non-volatile flavor substances free amino acids was 2.529±0.100 mg/g, of which sweetness and umami amino acids accounted for about 80%. The total amount of taste nucleotides was 71.28±6.59 mg/100 g, of which the content of IMP was the highest (58.13±3.45 mg/100 g). The equivalent umami concentration was 0.2898 g MSG/100 g. Crayfish ready-to-eat snack food is rich in nutrients and flavor components, and with the characteristics of good elasticity, suitable hardness and chewing resistance. The development of crayfish ready-to-eat snack food provides a basis for industrialized processing, it will enrich the category of crayfish products and expand the consumer market.

        • 1
      • Molecular Docking Technique to Simulate the Molecular Interaction between Pro/Glu Dipeptides and Umami Receptor

        赵孟斌, GU Huarong, MU Hongtao, GAO Xiangyang

        Abstract:

        In order to explore the molecular interaction between Pro/Glu dipeptides and umami receptors, 12 Pro/Glu dipeptides were synthesized. Based on sensory evaluation, homology modeling and molecular docking technique were used to study the molecular interaction mechanism of Pro/Glu dipeptides with umami receptors Taste receptor type 1 (T1R1), Taste receptor type 3(T1R3) and calcium-sensing receptor (CaSR). The results indicated that the overall umami effect of Pro dipeptides was better than that of Glu dipeptides, Ser-Pro, Ala-Pro, Pro-Ala, Pro-Val, γ-Glu-Met and Gly-Glu were the dipeptides with strong umami. 99.13%, 98.07% and 99.12% of the amino acids in T1R1, T1R3 and CaSR models were in reasonable regions respectively. Asp147, Thr149, Ser172 and Arg277 were the key binding sites of Pro/Glu dipeptides to T1R1which was the key receptor of Glu dipeptides. Glu45, Ser147, Val277 and His278 were the key binding sites to T1R3, and Ser147 was the key binding site between N-γ-Glu dipeptides and T1R3 recrptor. Leu173, Asn176, Gln179, Arg220, Ser244 and Asp275 were the key binding sites to CaSR, and Glu dipeptides were easier to bind to CaSR receptor than Pro dipeptides. The binding between Pro/Glu dipeptides and receptors were mainly through hydrogen bond and hydrophobic interaction. When docking, dipeptides with strong umami were mostly embedded in the depth of the receptor binding pocket, and dipeptides with weak umami were located in the shallow position of the binding pocket and some of their hydrophobic or hydrophilic regions were exposed to the surface of the receptors. Our study elucidated the interaction mechanism between Pro/Glu dipeptides and umami receptors, and laid the foundation for further study of the mechanism of umami peptides.

        • 1
      • Analysis of Structure of Cassava Starch Modified by Different Enzymes

        吴儒龙, 刘钰馨, 梁泽升, 廖梁燕, 李媛媛

        Abstract:

        The cassava starch was taken as the research object, which was modified by changing the type, content and ratio of enzymes. The structures of modified cassava starch were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), polarizing microscope (PLM) and differential scanning calorimetry(DSC). The results showed that with the increase of enzyme content, the ratio of glucoamylase and protease, the particle size of starch decreases and the surface is eroded in a large area to form pits. The crystalline region of starch is also hydrolyzed by enzyme to form hollow structure. The cross extinction of granule of starch was weakened or even disappeared. Different enzyme content, ratio and the addition of protease treatment did not make starch molecules form new functional groups. The diffraction angle 2θ of natural tapioca starch has diffraction peaks at 5.6 °, 15 °, 17.2 °, 22 ° and 24 °, indicating that the formation of B crystal. The starch modified by enzyme showed the A type crystal with diffraction peaks at 15 °, 17.1 °, 18 ° and 23 °. Enzyme modification delayed the gelatinization temperature of cassava starch from 65.43 ℃ to 69.11 ℃. The results show that different enzyme dosage, enzyme ratio and enzyme type will hydrolyze the surface and inside of cassava starch particles, and cause different structural changes. The experiment is helpful to reveal the mechanism of enzyme modification on cassava starch, and provides a theoretical basis for further research on the application of cassava starch.

        • 1
      • Comparative Analysis on the Quality of Chen Pi Tea (Citrus reticulata ‘Chachi’) with Different Storage Years

        Deng Haidan, Shan Baojun, Huang Jiaying, Feng Xinshu, Tang Xiaomin, Ge Yuewei, Liao Peiran, Sun Xiaoming, Yang Quan

        Abstract:

        In order to evaluate the correlation between storage years and quality, the color, taste and major constituents (total flavonoids, total polyphenols, and polysaccharides) of Chen Pi tea with different storage years were examined by spectrophotometer color photometer, electronic tongue, high performance liquid chromatography and UV spectrophotometry. The color values of L*, a*, b* had linear regression relationship with storage years. Based on the PCA analysis of taste, the sourness and umami taste sensors showed the greatest response value (-10.69~-25.73, 4.97~9.88). This could pay the way to distinguish the storage years from one to the others. With the increase of storage years, the contents of total flavonoids, polysaccharides, nobiletin and tangeretin increased, while hesperidin and total polyphenols decreased. Significant correlation between color, taste and compounds contents was attributed to the changes of hesperidin and total flavonoids. The color, taste and major constituents of Chen Pi tea were influenced by storage years significantly, which provide a guidance for identifying storage years.

        • 1
      • Study on Composition and Antifatigue Activity of Tuna Protein Peptide

        李西婷, 张明振, 乔乐克, 江晓路, 王鹏, 张京良

        Abstract:

        In this paper, protein peptides were prepared from tuna meat, and their composition, antioxidant activity in vitro and anti-fatigue activity in vivo were analyzed. The results showed that the protein content of tuna protein peptide was 90.11% and the calcium content was 213 mg/100g. The results of flavorful nucleotide and electronic tongue showed that the main taste of tuna protein peptide was umami, and GMP contributed more to the umami taste of tuna protein peptide. The results of electronic nose showed that the main flavor components were nitroxide compounds, inorganic sulfide, methane and other short chain alkanes, organic sulfide, alcohol ether aldehydes and ketones. In vitro antioxidant results showed that the IC50 of ABTS and DPPH free radical scavenging were 0.52 mg/mL and 4.32 mg/mL, respectively, indicating that tuna protein peptide had good antioxidant activity in vitro. The anti-fatigue results showed that tuna protein peptide in medium dose group could significantly prolong the weight-bearing swimming time (p<0.01), and significantly reduce the contents of serum urea nitrogen (p<0.05) and lactic acid (p<0.01), indicating that tuna protein peptide had good anti-fatigue activity in vivo. In this study, tuna meat was used to prepare high-quality tuna protein peptides with unique flavor, antioxidant and anti-fatigue activities, which provided a research basis for high-value utilization of tuna meat.

        • 1
      • Anti - Parkinsonism Effect of Laver Combined with Madopar and Its Effect on the Gut Microbiota

        Jiang Jiali, ZHOU Sainan, ZHANG Wei, WANG Yuming, TANG Qingjuan

        Abstract:

        The aim of this study was to investigate the anti-parkinsonism effect of laver combined with madopar and its effect on intestinal flora. Forty-eight C57BL/6J mice were randomly divided into 4 groups : normal control group, Parkinson's model group, madopar treatment group and laver combined madopar treatment group. After 2 weeks of intervention, PD mice were fed a diet supplemented with 5% laver. Behavioral test, immunohistochemical analysis, western blot analysis and inflammatory factor determination were performed to characterize the brain function of PD mice. Illumina platform was used to double-end sequencing the DNA fragments of mice intestinal bacteria to explore the changes of intestinal flora. The results showed that compared with madopar alone, laver combined with madopar could significantly improve the brain function of PD mice, in which the number of neurons and the expression of tyrosine hydroxylase (TH) in substantia nigra were increased by 46.95% and 52.91%, respectively, and the expression of α-synapse nucleoprotein (α-syn) was decreased by 34.56%. The serum IL-1β content was significantly decreased and the inflammation level was improved. The results of 16SrRNA showed that the intestinal flora richness and diversity of mice were increased in the treatment group of laver combined with madopar. The ratio of Firmicutes to Bacteroidota decreased by 71.59%; Muribaculaceae and Akkermansia bacteria related to anti-inflammatory levels were significantly enriched, while Blautia, Helicobacter and other inflammatory bacteria were significantly decreased in relative abundance. Compared with madopar alone, combined treatment with laver has better effects on regulating intestinal flora and reducing inflammation, and has more significant anti-Parkinson effect.

        • 1
      • Structural Characteristics and Activity Analysis of Polysaccharides from Different Parts of Hovenia dulcis

        苟敏, 陈芹芹

        Abstract:

        In order to clarify the structure and functional activities of polysaccharides in different parts of Hovenia dulcis, three kinds of H. dulcis polysaccharides (HDP) including whole fruit polysaccharide (HDPW), seed polysaccharide (HDPS) and peduncles polysaccharide (HDPP) were prepared by water extraction and alcohol precipitation method. Their structures were analyzed by UV-Vis spectroscopy, high performance size exclusion chromatography, ion chromatography, fourier tansform infrared spectrometer and scanning electron microscopy. At the same time, the biological activities of the three polysaccharides were evaluated by DPPH, ABTS free radical scavenging model, α-glucosidase inhibition model and IR-HepG2 cell model. All of HDPW, HDPS and HDPP were acidic polysaccharides, which were composed of Fucose, rhamnose, arabinose, galactose, glucose, mannose, galacturonic acid and glucuronic acid with different molar ratios. The molecular weights of HDPW, HDPS and HDPP had three chromatographic peaks, among which the low and medium molecular weight value of HDPs (45.72×104~165.75×104 u) was higher than HDPW (0.34×104~12.53×104 u) and HDPP (0.51×104~21.26×104 u). Infrared spectra showed that HDPW and HDPP contained α-glycosidic bond, while HDPs was a β-glycosidic linked polysaccharides. The median inhibition concentration of DPPH radical, ABTS radical and α-glucosidase were 0.015~0.043 mg/mL, 0.47~1.21 mg/mL and 0.13~9.99 mg/mL, respectively. When the mass concentration of HDPW and HDPP was 0.1 mg/mL or above, the glucose consumption rate of insulin resistant HepG2 cells (IR-HepG2) was significantly increased, and the highest increase was 7.66% compared with the model group. Compared with HDPS, HDPW and HDPP were similar in structure and showed better antioxidant and α-Glucosidase inhibition activity, stronger IR-HepG2 glucose uptake promotion ability. The study provided theoretical basis and data support for the comprehensive utilization of H. dulcis.

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      • Digestion, Absorption, and Utilization of Sialic Acid in Different Edible Bird's Nests in Rats

        Xu Yuhan, Xie Qiaoling, Li Hongwei

        Abstract:

        The digestion, absorption, and utilization of Sialic acid (SA) in peptide-containing and conventional stewed bird's nest products were compared. Male SD rats aged 8 weeks (n=32) were divided into four groups randomly: blank control group (BC), peptide-containing bird's nest group (PB), traditional bird's nest group (TB), and sialic acid standard control group (SC). To evaluate the digestion and absorption of SA, feces and urine were collected over 2 days. Blood was collected intermittently through 60 d consecutive gavage to monitor alteration in plasma free and protein-bound SA, and erythrocyte membrane-bound SA content in order to evaluate exogenous SA utilization. The results of feces and urine did not reveal any significant differences between groups in the SA absorption or retention. The results of 60 d consecutive gavage revealed that plasma free SA concentration (p < 0.005), plasma protein-bound SA content (p < 0.005), and erythrocyte membrane-bound SA content (p < 0.001) were significantly higher in each intervention group compared to the BC group. At 10 d, the protein-bound SA content in the PB group was 36.36% higher than that of BC group (p < 0.05), and the erythrocyte membrane-bound SA in the PB group increased by 28.13% and 13.89% compared to the TB and SC groups (p < 0.05). Sialylation in the blood index could indicate exogenous SA utilization; peptides could promote the utilization of SA; all types of bird's nests with long-term consumption could effectively improve the sialylation level of the body.

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      • Osteogenic Mechanism of Strontium and Research and Development Status of Strontium-Rich Foods

        xixueyao

        Abstract:

        Strontium is an essential trace element that is widely distributed in human tissues, with bone being its largest 'reservoir', in which approximately 99% of strontium is present in ionic form. Strontium can have a wide and far-reaching impact on bone health in many ways, and there is a clinical consensus that the drug strontium ranelate can protect bone health by influencing bone metabolism, but it is a synthetic chemical that is much less safe than natural strontium salts, so the development of strontium-rich foods so that people can achieve the goal of taking care of bone health through daily dietary routes is gradually becoming a hot research topic. This paper reviews the types of common orthopaedic diseases, the mechanism of strontium on bone metabolism and the current situation and development of food-based strontium products, focusing on the dual osteogenic mechanism of strontium regulating both osteoblasts and osteoclasts and the current situation of strontium-rich foods, providing a theoretical basis for the application of strontium in orthopaedic diseases and the better development of strontium-rich foods.

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      • Effects of Different Freezing Methods on the Freezing Characteristics and Quality of Mango Chunks

        李镜浩, 张诗颖, 程丽娜, 余元善, 彭健, 李露, 安可婧, 肖更生

        Abstract:

        Compared with liquid nitrogen spray freezing (LNF-40~-100 ℃), refrigerator freezing (RF-20 ℃), and Normal immersion freezing (IF-20 ℃), the mango chunks were investigated. Freezing characteristics and quality changes. The results show that the glass transition temperature of mango is -17.98 ℃, the exothermic enthalpy △H=-236.8 J/g; The freezing rate (r) and the energy removal rate (Q) are 0.14~1.40 ℃/min, 17.35~161.45 J/min, the freezing rate and the energy removal rate of LNF-100 ℃ were increased by 900%~7.63% and 830.54%~13.45% respectively compared with other groups; Compared with the RF-20 ℃ and IF-20 ℃ groups, the total freezing time and the time of passing through the maximum ice crystal formation zone were shortened by 9042 s, 4657 s, 5475 s, and 870 s, The color was also close to that of fresh mango; The hardness retention rate was 83.12%; Water loss was 2.75%; Total phenol, antioxidant activity and Vc retention rate reached more than 90%; Polysaccharide increased by 0.44 mg/g; The total number of colonies before and after freezing decreased by 0.84 lg CFU/g; Pearson analyzed the effect of different freezing methods on the quality of mango blocks, △E, Water loss, total phenolics, and Vc can be used as the basis for effective evaluation; Cluster analysis (CA) confirmed that LNF-100 ℃ can significantly reduce the quality of mango chunks during freezing deterioration. This study provides theoretical basis and technical guidance for the development of high-quality and high-efficiency frozen mangoes.

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      • Optimization of Preparation Technology and Taste Evaluation of Lanmaoa asiatica enzymatic hydrolysate

        张沙沙, 孙达锋

        Abstract:

        In order to improve the utilization rate of Lanmaoa asiatica. On the basis of single factor test, orthogonal test was used to optimize the hydrolysis conditions and compound ratio of neutral protease, papain and flavor protease by amino acid nitrogen as the indicator, and then amino acid automatic analyzer and high performance liquid chromatography were used to analyze the free amino acid, organic acid, flavor nucleotides. The contribution to taste was evaluated by taste activity value (TAV) and equivalent umami concentration (EUC). The results showed that the optimal enzymatic hydrolysis process was as follows: solid-liquid ratio 1:20 (w/w), pH 7.0, at 50 ℃, hydrolyze for 1.5 h, addition amount by weight ratio was neutral protease 0.60%, flavor protease 0.90%, papain 4.70%. Under the condition, the amino acid nitrogen of the enzymatic hydrolysate was 124.01 mg/100 ml, the total amount of free amino acids was 12.33 mg/g, the total amount of flavoring nucleotides was 96.48 μg/g, and the total amount of organic acids was 4511.59 μg/g, and the EUC is 2.46 g MSG/100 g. Therefore, the Lanmaoa asiatica enzymatic hydrolysate with the optimal process is delicious and nutritious, which met people's needs and provided a theoretical basis for the further processing of Lanmaoa asiatica.

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      • Variation of quality and bacterial composition diversity of Daohua chicken at different storage temperatures

        LIU Mengzhu, XIANG Rong, WEI Qiling, KANG Huahua, TU Du, TIAN YA, WU Junyi, XU Zhihong

        Abstract:

        The pH value, water content, Total number of colonies, Total Volatile Basic Nitrogen (TVB-N) and sensory evaluation of Daohua chicken were studied under 25℃ normal temperature, 4℃ cold storage and 0℃ ice temperature storage。Based on 16S rRNA, the bacterial community structure, succession law and relative abundance of chicken meat before and after shelf life were studied. The results showed that the total number of colonies at 25°C for 12 h at room temperature was 5.00×106 CFU/g, TVB-N was 15.26 mg/100 g, and the sensory score was 12.10, and the moisture content and pH were greatly changed after the 12th hour. The total number of colonies stored in refrigeration for 4 d at 4°C was 6.60×106 CFU/g, TVB-N was 13.64 mg/100 g, and the sensory score was 8.40, and the moisture content and pH were significantly different after the 4th day. The total number of colonies at 0°C was 8.90×105 CFU/g, TVB-N was 15.25 mg/100 g, and the sensory score was 9.90, and the moisture content and pH were greatly changed after the 8th day. Comprehensive quality indicators, the shelf life under the three storage temperatures was 12 h, 4 d and 8 d, respectively. At the end of storage at 25°C, acinetobacter, serratia, multisource bacteria, panomycete and unclassified enterobacteriaceae were the dominant species. The dominant spoilers at the end of the storage at 4°C and 0°C were mainly pseudomonas, acinetobacter, serratia and enterobacteriaceae, but the proportion of abundance was relatively different. The quality, shelf life and bacterial community diversity of Daohua chicken under different storage temperatures provide corresponding theoretical references for the study of prolonging chicken preservation.

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      • Antibacterial activity of chitosan composite preservative against Pseudomonas fluorescens

        Ni Rong, Guo Xuesong, Han Yanxia, Zhang Yan, Li Dandan, Zhang Zhen

        Abstract:

        In this experiment, 1.5% chitosan, 0.14% ε-polylysine and 0.15% Sodium D-isoascorbate were used to form a composite preservative, and Pseudomonas fluorescens was used as the experimental strain to investigate the inhibition performance and mechanism of chitosan composite preservative on the dominant bacteria in aquatic products. Methods:the inhibition activity of the preservatives against Pseudomonas fluorescens was investigated by measuring the minimum inhibitory concentration (MIC), inhibition circle and bacterial growth curve,and the changes of OD260 value, ATP and AKP activities, cellular ultrastructure and SDS gel electrophoresis were used to study the antibacterial mechanism of antistaling agent. The results showed that the minimum inhibitory concentration (MIC) of chitosan composite preservative on Pseudomonas fluorescens was 2.24 mg/ml. Chitosan compound antistaling agent had significant antibacterial activity, chitosan compound antistaling agent increased the permeability of cell wall membrane, destroyed the integrity of cell wall membrane, and inhibited the activities of ATP and AKP in bacteria, which were significantly lower than those in the control group(p<0.05). SDS gel electrophoresis showed that the chitosan composite preservative lightened the color of bacterial protein bands and caused the disappearance of some protein bands;Bacterial ultrastructure (SEM) showed that the chitosan composite preservative deformed and ruptured the bacterial body, and a large number of contents flowed out,resulting in the death of the bacteria. This study investigated the mechanism of chitosan composite preservative and proved the inhibition ability, which provides theoretical support for the edible coating preservation of aquatic products.

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      • Study on the Changes of Aroma Characteristics of Shine Muscat Grape During Storage by GC-MS and Aroma Notes Analysis

        王海军, 成果, 张劲

        Abstract:

        This paper studied the effect of storage temperature on the aroma characteristics of Shine Muscat grape during storage. The headspace-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were used to qualitatively and quantitatively analyze the volatile components of grape fruits at four storage temperatures (0 ℃, 4 ℃, 10 ℃ and 15 ℃). The characteristic substances and aroma characteristics were identified and analyzed by odor activity value (OAV) aroma profiles and aroma notes. The results showed that 55 volatile components were identified by GC-MS, including 20 aldehydes, 6 alcohols, 6 esters, 16 terpenes and 7 others. Specifically, 16 of them were identified as active aroma components (OAV > 1). The characteristic aroma components of Shine Muscat grape were terpenes and aldehydes. The analysis results of aroma profiles and aroma notes showed that the characteristic aroma changes of Shine Muscat grape under ice temperature (0 ℃, 4 ℃) and low temperature (10 ℃, 15 ℃) tend to be consistent respectively. The characteristic aroma changes during storage were mainly floral characteristics, especially the aroma notes of bell, jasmine, orchid, rose and mandarin duck. Ice storage (0 ℃) could keep the fresh fruit flavor of grapes, while the floral characteristics were obviously lost. The characteristic aroma deteriorated after 8 weeks of storage at 4 ℃ and 10 ℃, and after 6 weeks of storage at 15 ℃. Conclusion: Storage at ice temperature caused a sharp decrease in the aroma of flowers at the early stage of storage, and storage at low temperature was difficult to maintain the aroma quality of the fruit during the long storage period.

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      Governing Body:华南理工大学

      Organizer:华南理工大学

      Editor in chief:李琳

      Address:广州天河五山路381号华南理工大学麟鸿楼506室

      Postcode:510640

      International standard number:ISSN 1673-9078

      Unified domestic issue:CN 44-1620/TS

      Domestic postal code:46-349

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