Volume 37,Issue 11,2021 Table of Contents

1 Research Progress on the Cholesterol-lowering Effects of Bile Salt Hydrolase

FENG Xin , DING Yuan , GUO Yibing , LIANG Hongze , LIU Gangqiang , AI Lianzhong , WANG Guangqiang

2021, 37(11):1-7. DOI: 10.13982/j.mfst.1673-9078.2021.11.0346

[Abstract](372) [HTML](939) [PDF 599.80 K](997)

Abstract:
An imbalance in cholesterol levels can cause a variety of diseases and is a threat to individual health. Therefore, controlling cholesterol levels has become a common concern. In addition to pharmacological therapy to lower cholesterol levels, using drugs like statins and ezetimibe, several lactic acid bacteria, such as Lactobacillus plantarum, Lactobacillus casei, and Lactobacillus fermentum, have been shown to effectively reduce cholesterol levels. Numerous studies have shown that one of the primary metabolites produced by lactic acid bacteria, bile salt hydrolase (BSH), is closely associated with the cholesterol-lowering properties of these bacteria. This article summarizes the characteristics and functions of BSH and the mechanism underlying its cholesterol-lowering effects to establish a theoretical basis for further studies on the cholesterol-reducing effects of BSH-producing lactic acid bacteria in humans and provide insights into their development and application as probiotics for cholesterol control.

2 Regulatory Effects of Complex Probiotics Preparation on Composition of Human Intestinal Microbiota

MAO Bingyong , CUI Shumao , PAN Mingluo , HUANG Jie , WANG Jian , WU Wansheng , GUO Renmei , ZHAO Jianxin

2021, 37(11):8-13. DOI: 10.13982/j.mfst.1673-9078.2021.11.0746

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To study the regulation effects of complex probiotics on human intestinal microbiota, 15 healthy volunteers were recruited to intake the synthesized complex probiotics for four consecutive weeks, and high-throughput 16S rDNA amplicon sequencing was performed to analyze the changes in the composition of the intestinal microbiota in their stool samples before and after the intake of complex probiotics. The sequencing results revealed that the Shannon and Evenness indices of human intestinal microbiota remain unchanged after four weeks of compound probiotics intake (p>0.05). However, the relative abundance of two phyla, namely Firmicutes and Actinobacteria, was found to be increased. Similarly, at the genus level, the relative abundance of Lactobacillus and Bifidobacterium increased. Additionally, the relative abundance of intestinal hydrogen-producing bacteria, such as Collinsella, Ruminococcus, Dorea, and Eubacterium was also influenced. Conclusively, the intestinal microbiota can be regulated by the synthesized complex probiotics and the relative abundance of some beneficial bacteria in the intestinal tract is thereby increased.

3 Characterisation of Nitrite Degradation and Mining Related Genes of Lactiplantibacillus plantarum DMDL 9010

HUANG Yanyan , LIU Dongmei , KUANG Jiahua , ZHOU Qinyu , CHEN Yuhan , GAO Xuan , TA Niya , ZHOU Yang

2021, 37(11):14-24. DOI: 10.13982/j.mfst.1673-9078.2021.11.0683

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Abstract:
Whole-genome sequencing of Lactiplantibacillus plantarum DMDL 9010 (LP9010) was first performed, and its corresponding NCBI accession number is CP063986-CP063988. The nitrite degradation performance of LP9010 was preliminarily investigated based on the changes in the physicochemical indicators under different cultivation conditions and medium compositions, which was followed by the whole-genome sequencing analysis. The results revealed that LP9010 can effectively degrade nitrite. The nitrite degradation rate of LP9010 increased with a decrease in the pH. The temperature of 37 ℃ was conducive for nitrite degradation by LP9010. The optimal nitrite degradation performance of LP9010 can be achieved when there is sufficient nutrition, but oxygen and growth factors do not exert significant effects on nitrite degradation (p>0.05). Furthermore, acid tolerance-related genes (nhaC, gadA, argG, and glnR), cold- and heat-tolerance-related genes (cfa, cspA, hrcA, htpX, cplC, clpE, clpP, clpX, and clpL), oxygen tolerance-related genes (catB, trxB, trxA, gor, msrC, msrA, and msrB), and sugar transport-related genes (pstI, Crr, NagE, ScrA, MtlA, ManX, ManY, ManZ, GatA, GatB, GatC, FruA, and FruB) were found in the whole genome sequencing of LP9010. Besides, the nitrite reductase genes (lmrB and pgl) were discovered. Conclusively, LP9010 can degrade nitrite efficiently and it possesses the genes related to nitrite degradation. This article provides a new direction to better understand and elucidate the nitrite degradation mechanism of Lactiplantibacillus plantarum.

4 Increase in the CLA Conversion Rate and Transcription Level of CLA-Related Enzymes in Lactobacillus plantarum p-8 Following Ethanol Stress

QIN Yali , ZHAO Guofen , WANG Dan , ZHANG Heping , ZHAO Wei

2021, 37(11):25-33. DOI: 10.13982/j.mfst.1673-9078.2021.11.0478

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The effects of the presence of linoleic acid (LA) and ethanol on the conjugated linoleic acid (CLA) conversion rates and the transcription level of CLA synthesis-related enzymes of Lactobacillus plantarum p-8 (L. plantarum p-8) were studied. For this, 0.05 mg/mL LA and ethanol at different concentrations were added to MRS media. The results showed that the conversion rates of the three CLA isomers were the highest when 0.50% ethanol was added to the fermentation broth. More specifically, the conversion rate of the cis9, trans11-CLA (c9,t11-CLA) isomer was the highest, reaching up to 2.49%, which was 2.37 times higher than that observed without ethanol. The conversion rate of the trans10, cis12-CLA (t10,c12-CLA) isomer in the fermentation broth was the lowest, regardless of the concentration of ethanol added. The CLA conversion rates were much higher in the fermentation broths compared to those observed in the bacteria, and the CLA conversion rates in the bacteria were very low, but the variations in the CLA conversion rates following ethanol addition were consistent between the fermentation broths and the bacteria. The conversion rate of the c9,t11-CLA isomer was the highest (0.05%) in the bacteria following 0.50% ethanol treatment. This rate is five times higher than that obtained without ethanol treatment. When the ethanol concentration was higher than 0.50%, the conversion rates of all CLA isomers were reduced. The results indicate that CLA is produced in the cytosol and then transferred to the extracellular environment. Meanwhile, the transcription levels of the genes encoding CLA synthesis-related enzymes increased following ethanol stress within a certain concentration range, and accordingly, the CLA conversion rates increased. It is confirmed that the variation in the transcription levels of the CLA synthesis-related enzyme genes is the main reason for the differences in the CLA conversion rates. The results provide a foundation for elucidating the molecular mechanism of CLA production by Lactobacillus plantarum p-8 and for exploring effective regulation methods to improve CLA production.

5 Effects of Functional Oligosaccharides on Fermentation Characteristics and Cold Storage of Fermented Milk Using Lactobacillus plantarum ZDY2013

ZHANG Na , ZHAN Ying , MENG Yingping , LI Yijuan , TAO Xueying , WEI Hua , ZHANG Zhihong

2021, 37(11):34-42. DOI: 10.13982/j.mfst.1673-9078.2021.11.0770

[Abstract](260) [HTML](204) [PDF 940.14 K](559)

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To investigate the effects of functional oligosaccharides on the fermentation characteristics and cold storage of milk fermented using Lactobacillus plantarum (L. plantarum) ZDY2013, the fermentation characteristics and pH variations of L. plantarum in the fermented milk were evaluated upon adding different prebiotic carbohydrates, namely xylo-oligosaccharides, isomaltose oligosaccharides, and their composites, into the fermented milk. At the same time, the water holding capacity and antioxidant activity of the fermented milk during cold storage were analyzed. The results revealed that L. plantarumcan be metabolized with different functional oligosaccharides at different concentrations. Compared with glucose, oligosaccharides added to the fermented milk were found to be more beneficial for the growth of L. plantarum. More specifically, at the composite concentration of 3.0%, the number of viable bacteria in the fermented milk increased significantly, while the pH of the fermented milk reduced. During 21 days of cold storage, the number of viable bacteria in each experimental group reduced, but it was higher than 108 cfu/g. Meanwhile, the pH was relatively stable after 7 days of cold storage, and the water holding capacity increased continually. All the experimental groups exhibited the strongest DPPH radical scavenging abilities on day 7, while the ABTS and hydroxyl radical scavenging abilities are declined. Additionally, at the same concentration, the addition of oligosaccharide composites outperformed that of glucose. The results of this study will provide a theoretical basis for the application of functional oligosaccharides and L. plantarum ZDY2013 in the development of dairy products.

6 Effects of Surface Proteins on the Surface and Probiotic Properties of Lactobacillus Species

LI Jiaxun , ZHANG Qiuxiang , WANG Rui , ZHAO Jianxin

2021, 37(11):43-49. DOI: 10.13982/j.mfst.1673-9078.2021.11.0613

[Abstract](210) [HTML](187) [PDF 1.85 M](472)

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To evaluate the effects of surface proteins on the properties of Lactobacillus, different species containing slp gene were selected through sequence comparison. Subsequently, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to analyze some of them. The expression of slp gene in different Lactobacillus species was evaluated, and then the light absorbance, self-aggregation rate, biofilm formation rate, and co-aggregation rate with other pathogenic microorganisms associated with each of these species were assessed before and after the removal of surface proteins. The results revealed that 4 strains of L. acidophilus, 30 strains of L. crispatus, 3 strains of L. helveticus, and 30 strains of L. rhamnosus contain slp expressed surface proteins that were identified using SDS-PAGE. These surface proteins were found to be closely related to the properties of the strains. For example, the growth of L. helveticus before and after the removal of surface proteins was found to be significantly different. However, the light absorbance of the species of interest differed only slightly (within 0.2) after lithium chloride solution and proteinase K solution treatments. Meanwhile, for co-aggregation with other pathogenic microorganisms, most of the strains demonstrated no significant differences after different treatments. Interestingly, L. rhamnosus 3-1, which exhibits weak self-aggregation, exhibited strong co-aggregation with other pathogenic microorganisms, and therefore, the anti-caries potential of this strain is worth further exploration. This research would provide more information on the surface proteins of Lactobacillus species and lays a theoretical foundation for in-depth exploration of the functions and applications of surface proteins.

7 Screening, Identification, and Biological Characteristics of Potentially Probiotic Lactic Acid Bacteria

HE Yuxing , Qiqirilige , LIU Wei , DUAN Xiaoxia , QIU Chongshun , Wuyundalai

2021, 37(11):50-57. DOI: 10.13982/j.mfst.1673-9078.2021.11.0140

[Abstract](271) [HTML](189) [PDF 1.83 M](541)

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197 strains of lactic acid bacteria isolated from sour horse milk were screened and identified, and their biological characteristics were studied. In acid tolerance assays and bile salt tolerance assays, ten strains with relatively high tolerance were preliminarily selected. The survival rates of the ten strains after three hours of treatment with artificial gastric juice were between 46.48% and 95.86%. Among them, three strains with survival rates higher than 80% were selected and subjected to artificial intestinal fluid treatment for four and eight hours. After that, the numbers of live bacteria were determined: 1.65×109 to 1.81×1010 colony-forming units per milliliter. Furthermore, the three strains all exhibited certain hydrophobicity. Among them, the survival rates of strain 2-33 in artificial gastric juice and artificial intestinal fluid reached 95.86% and 80.80%, respectively, with cell surface hydrophobicity of 42.61%. Thus, strain 2-33 was identified as the target strain (a potential probiotic). An antibiotic sensitivity assay showed that strain 2-33 is resistant to norfloxacin, cefradine, gentamicin, vancomycin, and streptomycin; moderately sensitive to clindamycin; and sensitive to tetracycline, chloramphenicol, erythromycin, and ampicillin. Finally, the 16S ribosomal DNA gene sequence of strain 2-33 was determined by a molecular biological method; this gene’s length was found to be 1432 bp. The accession number in NCBI is MN611708. Stain 2-33 showed 100% homology with Lactobacillus plantarum JCM1149, and sugar fermentation assay results on this strain are consistent with those of GB 4789.35-2016; therefore, the strain was identified as L. plantarum. The results of this study provide data for further research on probiotics and the development of functional foods in the future.

8 Physicochemical Properties and Synergistic Prebiotic Activities of Polysaccharides from Longan Fruits, Goji Berries, and Jujube Fruits

ZHOU Wenjun , CHI Jianwei , YI Yang , ZHANG Mingwei , ZHANG Ruifen , LIU Lei , JIA Xuchao , DONG Lihong , HUANG Fei

2021, 37(11):58-67. DOI: 10.13982/j.mfst.1673-9078.2021.11.0504

[Abstract](270) [HTML](403) [PDF 1.47 M](602)

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The physical and chemical properties and prebiotic activities of polysaccharides from longan fruits, goji berries, and jujube fruits, hereafter referred to as longan polysaccharide (LP), goji berry polysaccharide (GP) and jujube polysaccharide (JP), respectively, were studiedand the existence of their synergistic effects was explored. For this, several features of the polysaccharides, such as the basic composition, molecular weight distribution, monosaccharide composition, microstructure, solubility, particle size and solution potential, were measured, and the effects of the polysaccharides, alone or in combination, on the proliferation of the probiotics were analyzed. The results show that the three polysaccharides mainly contain neutral sugars and a small amount of proteins and uronic acids. More specifically, the neutral sugar contents of LP, GP, and JP are 86.25%, 72.36%, and 82.98%, respectively. The Mw values of LP and JP are 70.73 ku and 185.93 ku, respectively, while the Mw of GP is 120.61 ku and 4.53 ku. Furthermore, LP and GP mainly consist of arabinose, glucose, and galactose in molar ratios of 22.49:56.81:10.18 and 16.84:62.05:11.08, respectively, while JP is mainly composed of arabinose, glucose, and galacturonic acid in a molarratio of 10.63:70.05:10.88. The microstructures of the three polysaccharides are significantly different. LPs were observed as fragmented aggregates, while GPs and JPs showed lamellar and mesh structures, respectively. The particle size, particle size dispersion index, and Zeta potential of the three polysaccharides are different. All the three polysaccharides promoted the proliferation of probiotics significantly and their effectiveness was dose dependent. In particular, at a concentration of 30 mg/mL, the probiotic activities of the three polysaccharides followed the order of JP>GP>LP. The highest probiotic activity was observed when the three polysaccharides, LP, GP, and JP, were used in a mass ratio of 2:3:1, respectively, and this joint effect was far greater than that observed when the three polysaccharides were used alone at the same concentration. The results showed that the mixture of LP, GP, and JP has a synergistic effect on the proliferation of probiotics. Key words:

9 Screening of Traditional Fermented Food Products for Lactic Acid Bacteria with Antibacterial Activity and Stability Analysis of Their Metabolites

HUANG Xiaoying , LI Qiming , WU Huaxing , LIU Rongmei , CAO Jun , WAN Qian , YU Jicheng , TANG Junni

2021, 37(11):68-78. DOI: 10.13982/j.mfst.1673-9078.2021.11.0423

[Abstract](218) [HTML](267) [PDF 1.53 M](666)

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To identify lactic acid bacteria with excellent antibacterial properties, 39 strains of lactic acid bacteria from traditional fermented food products were screened using the Oxford cup method. The growth curve, acid production ability, bile salt tolerance, osmotic tolerance, acid and alkali tolerance, and antibacterial spectrum of each of the selected strains were investigated. Then, the stability of the metabolites of each of the chosen strains was studied. Finally, three strains with good antibacterial properties were identified. They are Lactobacillus plantarum HS011, Lactobacillus delbrueckii HS023, and Streptococcus thermophilus HS033. The pH values of their fermentation supernatants decreased from 5.44, 5.44 and 5.42 to 3.55, 3.54 and 3.57, respectively, after cultivation for 20 h. The three lactic acid bacteria can tolerate less than 0.1% bile salt and 14% NaCl, and grow well within the pH range of 5.0~8.0. All three strains have abroad bacteriostatic spectrum and can effectively suppress the growth of Escherichia coli O157:H7, Bacillus cereus, Listeria monocytogenes, and Enterobacter sakazakii. However, the chosen L. plantarum strains have no inhibitory effects on molds and yeasts. The metabolites of these strains retained their antibacterial activity even after various treatments such as temperature (20~121 ℃), pH (2.0~8.0), papain, trypsin, pepsin, proteinase K, and catalase treatments. The lactic acid bacteria isolated from traditional fermented food products have good probiotic properties, and their metabolites are stable, and can, therefore, be used as starters in fermented products and can be further developed and utilized.

10 Detoxification Effects of Lactobacillus plantarum Z3 on Chronic Organophosphorus-Poisoned Mice

YAO Duntiao , ZHAO Yue , LIU Renjie

2021, 37(11):79-84. DOI: 10.13982/j.mfst.1673-9078.2021.11.0362

[Abstract](269) [HTML](210) [PDF 825.23 K](523)

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A mouse model of chronic organophosphorus poisoning was first established. Subsequently, after 30 days of oral administration of Lactobacillus plantarum fermentation broth, the cholinesterase (ChE) activity in the brain and blood, the reactive oxygen species (ROS) content in brain tissue, the total superoxide dismutase (T-SOD) activity in liver and serum, and the malondialdehyde (MDA) content in liver and brain were determined. Histopathological examination of the liver and brain tissue was carried out to evaluate the detoxification and protective effects of Lactobacillus plantarum against chronic organophosphorus poisoning in mice. Results showed that in L. plantarum Z3-treated mice, the ChE activity in the mouse blood and brain increased by 36.13% and 81.13%, respectively, and the T-SOD activity in the serum and liver increased by 56.93% and 65.14%, respectively, when compared with the model control group. On the contrary, lower MDA and ROS contents were observed in the treatment groups. The contents of MDA and ROS in the serum and the contents of T-SOD in the liver and brain were respectively decreased by 28.91%, 16.46%, and 15.92% compared to those observed in the model group. After the treatment, the damage to liver cells was significantly alleviated, the morphology of brain nerve cells, neurons, and glial cells returned to normal, and the cells attained an orderly arrangement again. It is concluded that Lactobacillus plantarum can partially repair the body damage caused by chronic organophosphorus poisoning from pesticides, and a certain degree of detoxification is confirmed.

11 Protective Effects of Polysaccharides Extracted from Tremella on Cell Membrane and Sugar Metabolism Enzymes of Freeze-dried Lactobacillus plantarum

LI Bingbing , LONG Hui , WU Enhui , LI Yi , XIA Ning , TENG Jianwen , HUANG Li , WEI Baoyao

2021, 37(11):85-95. DOI: 10.13982/j.mfst.1673-9078.2021.11.0608

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To explore the potential effects of polysaccharides extracted from tremella as a probiotic freeze-drying protectant, experiments were conducted using Lactobacillus plantarum in this study. The protective effects of polysaccharides extracted from tremella combined with sodium caseinate upon freeze-drying Lactobacillus plantarum were evaluated through assessing the viable bacterial counts, properties of the cell membrane, and activities of the sugar metabolism enzymes before and after freeze-drying. As a result, the maximum survival rate of the bacteria reached up to 55.39% when the ratio of polysaccharides extracted from tremella to sodium caseinate was 3:1. At the same time, the intracellular Ca2+ fluorescence intensity was found to be significantly reduced to 29.98, whereas the fluorescence intensity of DPH was as low as 4.91. The activities of lactate dehydrogenase, Na+/K+-ATPase, and Ca2+/Mg2+-ATPase were the highest, corresponding to 0.32 U/mL, 121.61 U/g and 45.64 U/g, respectively. The percentage of bacteria with damaged cell membrane reduced from 98.35% to 37.90%. However, there was no significant change observed in the activities of hexokinase and pyruvate kinase before and after freeze-drying. Infrared scans revealed that there were non-covalent interactions between polysaccharides extracted from tremella and sodium caseinate. Additionally, polysaccharides extracted from tremella reduced the surface porosity of the bacterial powder, while sodium caseinate increased its density. Therefore, polysaccharides extracted from tremella exerted a significant inhibitory effect on the damage of Lactobacillus plantarum cell membrane during the freeze-drying process, and they have an evident protective effect on the activities of lactate dehydrogenase, Na+/K+-ATPase and Ca2+/Mg2+-ATPase of Lactobacillus plantarum.

12 Optimization of Prebiotic-rich Meal Replacement Powder Formulation Using the Response Surface Methodology

DING Li’na , LI Shuqian , NING Jie , GU Haiyan , YANG Ying , DING Wenyu , ZHANG Xiandang , WANG Zhibin

2021, 37(11):96-105. DOI: 10.13982/j.mfst.1673-9078.2021.11.0322

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A meal replacement powder formulation rich in prebiotics was optimized using the response surface methodology (RSM) in this study. Since konjac exhibits a high swelling coefficient as well as high satiety and prebiotics, such as inulin, fructo-oligosaccharide, and isomalto-oligosaccharide, which can improve the intestinal flora, it was used to produce the meal replacement powder together with soy protein isolate, phytosterol esters, xylitol, taro powder, and sucralose. The single-factor, Plackett-Burman, and Box-Behnken designs, and steepest ascent method were employed to optimize the meal replacement powder formulation. Subsequently, the optimal formulation of the powder was evaluated based on its sensory quality. The formulation of the meal replacement powder optimized using the RSM included 3.42 g konjac, 0.80 g soy protein isolate, 0.23 g phytosterol ester, 8.00 g prebiotics (combinations of 2.50 g inulin, 2.50 g fructo-oligosaccharide, and 3.00 g isomalto-oligosaccharide), 1.00 g xylitol, 1.20 g taro powder, and 0.005 g sucralose. The actual sensory score of the optimized meal replacement powder was 93.16±0.73, and the powder could fully dissolve in 50±6 s. The meal replacement powder could dissolve well with no particles left, and it exhibited a uniform color, delicate texture, moderate viscosity, pure taste, and no strange smell. Moreover the physical, chemical, and microbial properties of the meal replacement powder were determined according to the national food standards, and the results met the requirements.

13 Screening for Cholesterol-lowering Lactobacillus reuteri Strains and Analyzing Their Probiotic Effectiveness

YU Ping , JIAO Yanping , ZHANG Chunyu , ZHAO Di , SONG Jia , WANG Tingting , JIANG Feng

2021, 37(11):106-113. DOI: 10.13982/j.mfst.1673-9078.2021.11.0403

[Abstract](278) [HTML](263) [PDF 615.99 K](490)

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To obtain probiotic strains with significant cholesterol-lowering performance, strains were isolated from quark produced at the Litongda Pasture in Manzhouli, Inner Mongolia. The cholesterol-lowering ability of each strain was determined by the o-phthalaldehyde method, and the strains with strong cholesterol-lowering abilities were selected. The strains were identified based on the morphology, physiology, biochemistry, and 16S rDNA sequences, and their tolerance for acids, bile salts, and gastrointestinal juice was determined. Finally, five cholesterol-lowering strains were obtained, and one of them showed the best ability to lower the cholesterol level, with a degradation rate of 50.60%. This strain was identified as Lactobacillus reuteri, and named as HCS02-001 (CGMCC No. 19746). The results of the various tolerance tests were as follows. When the strain was cultured at pH 3.0 and pH 2.0 for 17 h, the final survival rates were 86.80% and 85.52%, respectively. Similarly, the survival rates were 97.42% and 95.17% after the strain was cultured for 17 h in 0.3% and 0.5% bile salts, respectively. In addition, the survival rates were as high as 96.74% and 98.41% after three hours of treatment in artificial gastric juice and four hours of treatment in artificial intestinal juice, respectively. In summary, a strain of Lactobacillus reuteri with good cholesterol-lowering performance and showing high tolerance for acids, bile salts, and gastrointestinal juices, had been identified. These findings are of great relevance to the research and development of cholesterol-lowering products.

14 Palmitic Acid Disrupts the Growth, Development and Glucose and Lipid Metabolism of Drosophila melanogaster

ZHANG Jiaqi , WU Jinlan , WU Mingjiang , TONG Haibin

2021, 37(11):114-119. DOI: 10.13982/j.mfst.1673-9078.2021.11.0234

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In order to explore whether or not palmitic acid (PA) causes metabolic syndrome, Drosophila melanogaster was used as the model organism in this study, corn flour yeast standard medium was used as the control group, and the standard culture medium added with 2.50% PA as the experimental group. The larval body weight, pupation rate and eclosion rate, pupal weight, pupal area, pupal volume, adult body weight, adult crawling ability, adult wing area, and the contents of trehalose, triglycerides, Dilp2, Dilp3 and Dilp5 of the third instar larvae of D. melanogaster were determined. The results showed that compared with CTRL group, PA decreased the pupation rate and eclosion rate of D. melanogaster by 3.75% and 10.03%, respectively, with the pupal area and pupal volume of the PA group also decreased. The body weights of female drosophila and male drosophila in the PA group decreased by 0.13 mg and 0.10 mg, respectively, compared with CTRL group. The locomotor activities of female drosophila and male drosophila in the PA group decreased by 41.35% and 22.78%, respectively. For the PA group, the wing area of female drosophila in decreased significantly, but there was no significant change in male drosophila. The contents of trehalose and triglycerides in the PA group increased significantly, while the expressions of Dilp2, Dilp3 and Dilp5 decreased significantly. The above results indicate that PA inhibited the growth and development of D. melanogaster and disrupted the balance of glucose and lipid metabolism in larvae. This study can provide a scientific basis for exploring the mechanism of the metabolic syndrome caused by a high-fat diet.

15 Regulating Effects of Allyl Methyl Trisulfide on Inflammatory Factor and Intestinal Flora in Ulcerative Colitis Mice

WU Ping , LIU Jinqian , WANG Shuo , DONG Jing , FAN Zongqiang , LI Zhen , CHEN Fang

2021, 37(11):120-127. DOI: 10.13982/j.mfst.1673-9078.2021.11.0281

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The regulating effects of allyl methyl trisulfide (AMTS) on inflammatory factor and intestinal flora in ulcerative colitis mice were investigated in this study. Body weight, colon length, disease activity index (DAI) and histological changes were observed. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) contents in serum were detected by ELISA method. And the intestinal flora diversity in mice feces was analyzed by 16s rDNA high throughput sequencing. The results showed that the weight of the model group decreased by 25.59%, and the low-dose, medium-dose and high-dose AMTS groups were decreased by 4.06%, 9.88% and 5.45% respectively. The DAI in model group was 3.51, the three AMTS groups were 2.60, 2.88 and 2.79, respectively. Compared with the model group, three dosages of AMTS groups ameliorated inflammatory infiltration in colonic tissue, and significantly decreased the levels of pro-inflammatory cytokines, like TNF-α, IL-1β, IL-6 (p<0.01, p<0.05). The abundance and diversity of intestinal flora were increased after administration with AMTS. Compared to the model group, the microbial abundance of Bacteroidetes, Proteobacteria were decreased, and the abundance of Firmicutes, Lactobacillus were increased in the AMTS groups. In conclusion, the results indicate that AMTS alleviates the symptoms of ulcerative colitis by reducing the level of inflammatory factors and increasing the abundance and diversity of intestinal flora in mice.

16 Protective Effect of Jie-Gan Tablets on Alcoholic-induced Acute Liver Injury in Mice

XIE Liya , DONG Yu , XU Xiaobo , SHEN Qiong , LI Wenqiang , LI Wei , REN Shen , WANG Zi

2021, 37(11):128-133. DOI: 10.13982/j.mfst.1673-9078.2021.11.0227

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The protective effect of Jie-Gan tablets (JGT) on acute alcohol liver injury mice was explored. A mouse model of acute alcoholic liver injury was established by one-time intragastric gavage (i.g) with 50% alcohol. The serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and triglyceride (TG), and the content of malondialdehyde (MDA) and activity of glutathione peroxidase (GSH-Px) in the liver tissue homogenate of mice were determined. The morphological changes of tissue sections were analyzed by H&E staining, and the hepatoprotective effect of JGT was evaluated. The results showed that the increases of the two serum transaminase levels in mice were significantly inhibited by the pretreatments with different doses of JGT and bifendatatum (p<0.05), and the highest inhibition rate up to 61.81%. The serum TG level was significantly reduced in the JGT high-dose group (p<0.05), with a decrease of 34.73%. Compared with the model group, the increased MDA level was significantly reversed in the positive control group (p<0.01). The content of MDA was reduced in a dose-dependent manner in each of the JGT administration group (p<0.05), and their antioxidant enzyme GSH-Px activities increased (p<0.05). Among which, the MDA content in the high-dose group was reduced to 1.74 nmol/mg, and the GSH-Px activity increased to 828.81 U/mg pro. H&E staining results showed that alcohol-induced liver injury was effectively alleviated by JGT pretreatment. Accordingly, JGT has a certain preventive and protective effect on ALD.

17 Evaluation of Antioxidant Activity of Genistein in Soy Sauce Fermentation Base

LI Yifeng , ZHU Yi , LIANG Xueying , LI Wei , FU Jiangyan , HU Yuanshu , CAI Huitian , PENG Mingjun , CAO Yong

2021, 37(11):134-143. DOI: 10.13982/j.mfst.1673-9078.2021.11.0238

[Abstract](175) [HTML](243) [PDF 1.73 M](430)

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In this experiment, the chemical method and Caenorhabditis elegans model were used to explore the antioxidant activity of genistein in the soy sauce fermentation base. In vitro experiments showed that genistein could effectively scavenge DPPH free radicals, ABTS free radicals, superoxide anion free radicals and hydroxyl free radicals, with IC50 values as 0.35 mg/mL, 0.16 mg/mL, 0.29 mg/mL and 0.72 mg/mL, respectively, indicating significant in vitro antioxidant activities. Further experiments revealed that genistein at 50, 100 and 200 μmol/L could prolong the average lifespan of nematodes (by 17.54%, 20.88% and 17.72%, respectively), increase the total number of eggs laid (by 17.96%, 27.84% and 41.37%, respectively), and improve the motility of nematodes (movement ability, sinusoidal movement and head swing frequency), increase the average lifespan of nematodes under heat stress conditions (by 15.32%, 23.88% and 16.65%, respectively). In addition, genistein at 50, 100 and 200 μmol/L could increase catalase activity (by 144.52%, 253.87% and 295.60%, respectively), superoxide dismutase activity (by 37.32%, 31.51% and 44.05%, respectively) and glutathione in nematodes (by 10.39%, 36.21% and 25.84%, respectively), reduce the amount of accumulated reactive oxygen species (by 31.22%, 38.57% and 41.40%, respectively) and malondialdehyde level (by 46.50%, 73.52% and 62.72%, respectively), and enhance the antioxidant defense of nematodes. Among which, 100 μmol/L genistein exhibited the greatest antioxidant effect. In summary, genistein effectively scavenged free radicals, prolonged the healthy life of nematodes, and exerted good antioxidant capacities in vivo and in vitro. This research lays a foundation for studying the biological activity of genistein and provides a theoretical basis for its promotion and application as a natural antioxidant.

18 Enhancing the Immune Function of Mice Using Propolis Extract Mixtures

ZHAO Peipei , YIN Xin , XIA Xuekui , ZHANG Yu , LIU Changheng , SHI Yaping

2021, 37(11):144-150. DOI: 10.13982/j.mfst.1673-9078.2021.11.0493

[Abstract](168) [HTML](152) [PDF 435.50 K](442)

Abstract:
To study the effects of propolis extract mixtures on the immune function of immunocompromised mice models constructed using hydrocortisone (HY), experiments were conducted on six groups of mice models, namely, the negative control, model, propolis extract-treated (at a dose of 0.125 g/kg), and three propolis extract mixture-treated groups (at doses of 0.125 g/kg, 0.50 g/kg, and 1.25 g/kg, respectively). Oral administrations were continued for 30 days, and the immune indexes of the mice from the different groups were determined. Results showed that the propolis extract alone and the extract mixtures at different doses can resist HY damage to the spleen and thymus of mice, restoring the organ index from 2.80 to 3.89, 3.81, 3.92, and 4.11, respectively (p<0.01). For mice from all the treatment groups, the decrease in the peripheral white blood cell (PBWC) and lymphocyte (PBL) counts induced by HY was significantly improved (p<0.05). More specifically, for the high-dose group, the PBWC and PBL counts in the immunosuppressed mice increased from 3.62×109/L and 2.83×109/L to 5.35×109/L and 4.96×109/L, respectively (p<0.01). The carbon clearance indexes of the immunocompromised mice in the medium- and high-dose groups increased from 4.16 to 5.29 and 5.16, respectively (p<0.01); however, the effects on the low-dose group and the group treated with propolis extract were not as noticeable. The phagocytosis percentage of fluorescent microspheres by peritoneal macrophages in the medium-dose group increased from 18.70% to 28.60% (p<0.01). Furthermore, for the medium- and high-dose groups, the numbers of antibody-producing cells increased (p<0.05). These results demonstrate that the propolis extract mixtures can enhance the immunity of immunocompromised mice.

19 Recombinant Fusion Expression of Cell-penetrating Peptide and Human Epidermal Growth Factor in Escherichia coli

LI Feng , KE Bowen , SUN Zhongwei , HAN Shuangyan

2021, 37(11):151-158. DOI: 10.13982/j.mfst.1673-9078.2021.11.0232

[Abstract](195) [HTML](229) [PDF 3.69 M](564)

Abstract:
In this study, the recombinant expression plasmid PGEX-4T-1-epEGF containing the fusion genes of cell-penetrating peptide Pep-1 and human epidermal growth factor hEGF (epEGF) was constructed and successfully transformed into E. coli BL21 (DE3) to obtain a recombinant E coli BL21 (DE3)/ PGEX-4T1-epEGF. The recombinant fusion human epidermal growth factor was prepared through IPTG induced fermentation, the preliminary purification was established, and the soluble expression of human epidermal growth factor (hEGF) in E. coli was effectively achieved. Through optimization of fermentation conditions, it was found that temperature, inducer concentration, induction time and culture medium were the key factors affecting protein expression; Under the conditions of 20 ℃, IPTG concentration of 0.4 mmol/L, induction time of 8 h, and use of TB liquid medium, the target protein accounted for 21.58% of the total protein and the protein concentration was 0.13 mg/mL. The purities of the fusion protein after GST affinity chromatography and anion exchange chromatography were 66.82% and 92.57%, respectively. In this study, the soluble form of hEGF was successfully expressed in E. coli, and the purification process was relatively simple, which provided a reference for the further exploitation and utilization of hEGF.

20 Saccharomycete Fermenting Xylose to Ethanol and Its ARTP Mutation Breeding

ZHANG Lizhao , ZHANG Juan , JIANG Xuan , CHEN Lili , LU Changli

2021, 37(11):159-166. DOI: 10.13982/j.mfst.1673-9078.2021.11.0268

[Abstract](193) [HTML](217) [PDF 972.75 K](483)

Abstract:
In order to improve the ability of saccharomycete to produce ethanol by xylose fermentation, the wild strain of Wickerhamomyces anomalus A42 was mutated by normal temperature and atmospheric pressure plasma technology (ARTP), and a high ethanol producing mutant strain with excellent performance was selected. The results showed that the best mutation condition was 120 s, under this condition, the lethal rate of A42 was 97.53%. The results showed that the ethanol yield of A42-338 was 42.59% higher than that of the original strain, and the ethanol content was 20.78 g/L after 60 h of fermentation, and the change rate of ethanol production of each generation was not larger than 2.50% after 8 passages. The results showed that the content of ethanol and reducing sugar of A42-338 were 19.88 g/L, 9.06 g/L, 1.79 g/L, 7.27 g/L, 84.61%, 81.05% and 0.40 g ethanol/g sugar respectively. Therefore, ARTP mutation is an efficient and feasible method for yeast breeding.

21 Cloning and Bioinformatics Analysis of DDE Transposase Gene from Streptomyces

SU Aizhen , XUE Yongchang

2021, 37(11):167-174. DOI: 10.13982/j.mfst.1673-9078.2021.11.0274

[Abstract](351) [HTML](265) [PDF 1.67 M](479)

Abstract:
In this paper, a DDE transposase-producing strain was selected from the strains preserved in the laboratory and indentified as Streptomyces labedae sp. X1 by morphology, physi-biochemistry and 16S rDNA. One 401 bp DDE transposase gene was amplified from the Streptomyces labedae sp. X1 genomic DNA, Blast and ISfinder results showed that it had 88% similarity with ISAzo13 family transposase genes. Bioinformatics analysis showed that the gene encoded 133 amino acids with stable hydrophilic structure, and the conserved amino acid triplet of Asp43, Asp49, Glu91 were found in the amplified DDE transposase; Based on the results of its α-spiral and irregular crimp, absence of signal peptides and transmembrane domains, it was a non-secreting protein with 14 phosphorylation and only one glycosylation site; and α-helix was the main composition in its advanced structure; SDS-polyacrylamide gelelectrophoresis showed that the molecular weight of the proposed protein was 27 ku. The results provide important information for the study of the expression mechanism of Streptomyces DDE transposase gene, and lay a foundation for the identification of DDE transposase activity, its structure and function in the future.

22 A Multiple-enzyme Cascade Reaction Strategy in Vitro for Efficient Synthesis of Rebaudioside M

LIU Siying , WANG Bin , PAN Li

2021, 37(11):175-184. DOI: 10.13982/j.mfst.1673-9078.2021.11.0241

[Abstract](389) [HTML](282) [PDF 992.51 K](888)

Abstract:
To efficiently synthesize rebaudioside M (RM) by multiple-enzyme cascade reaction method, a recombinant E. coli containing UDP-glucosyltransferase UGT76G1 from Stevia rebaudiana, UDP-glucosyltransferase EUGT11 from Oryza sativa, and the sucrose synthase SUS1 from Arabidopsis thaliana was constructed respectively. To improve the catalytic efficiency of the rate-limiting enzyme, here, the EUGT11 single-promoter expression plasmid was modified by using multiple-promoter. When the triple-promoter initiated transcription, the enzyme activity of the recombinase EUGT11 was the highest, which was 2.13 times than that of single-promoter. When it participated in the in vitro multiple-enzyme cascade reaction system, under the condition that the enzyme ratio was SUS1: UGT76G1: EUGT11/3 copies of T7=1: 2: 6.39, the yield of RM was 3.79 mmol/L, which was 2.35 times higher than before. The in vitro multiple-enzyme cascade reaction system for the efficient synthesis of RM was successfully established. In summary, this study improved the strategy of enzymatic synthesis of RM and provided theoretical data support for industrial production.

23 Effect of Precise Temperature Control on Low-temperature Preservation of Blueberries

XUE Youlin , YUAN Xingling , ZHANG Peng , JIA Xiaoyu , LI Chunyuan , LI Jiangkuo

2021, 37(11):185-194. DOI: 10.13982/j.mfst.1673-9078.2021.11.0239

[Abstract](210) [HTML](252) [PDF 530.61 K](532)

Abstract:
In order to study the application potential of precision temperature control technology in the preservation of blueberries, blueberries were divided into a control group and three precision temperature control groups, which were put into a foam box (CK), a foam box + cool-storage agent (ice temperature 1), a precision temperature control box (ice temperature 2), and a precision temperature control box + cool-storage agent (phase temperature). The temperatures inside the boxes were recorded every day, and the quality changes of blueberries were measured during storage. Then the four groups of blueberries were comprehensively evaluated by the principal component analysis method, to obtain the most accurate temperature control processing method. The results showed that the inner temperature of the icestorage boxes was lower, and the inner temperature of the phase temperature storage boxes fluctuated to a lesser extent than that of the control. On the 60th day of storage, the good fruit rate, soft fruit rate, flavor index and fruit frost coverage index of blueberries of the phase temperature group were 79.54%, 17.87%, 72.22%, 76.00%, respectively, with their color changes less than 2, and their L values as 27.03. In addition, blueberries stored by the precision temperature control had higher hardness, and lower consumption rates for nutrients such as soluble solids, titratable acid, Vc and anthocyanins. Among which, the Vc content of blueberries of the CK group decreased by 5.01, 9.18 and 16.67 mg/100 g, respectively, compared with those of the ice temperature group 1, ice temperature group 2 and phase temperature group. After principal component analysis, the quality ranking of the four groups of blueberries was: phase temperature group> ice temperature group 2> ice temperature group 1> CK group. Moreover, the relative contents of the desirable aroma components (such as aldehydes, terpenoids and esters) of the blueberries stored by precision temperature control were higher. Therefore, precision temperature control technology is beneficial to the cold preservation of blueberries, with the effect of the phase temperature storage being better.

24 Application of Modified Atmosphere Fumigation Microporous Packaging Technology in the Storage and Transportation of Grapes

ZHANG Zhao , XU Yaohui , WEI Jia , ZHANG Zheng , WU Bin

2021, 37(11):195-203. DOI: 10.13982/j.mfst.1673-9078.2021.11.0068

[Abstract](283) [HTML](207) [PDF 853.12 K](491)

Abstract:
In order to solve the "individualized" demand for fresh-keeping packaging technology for Xinjiang's fresh grapes e-commerce logistics. Effects of modified atmosphere packaging (5% O2+8% CO2) combined with different concentrations of sulfur dioxide (SO2) (100 μL/L, 300 μL/L, 500 μL/L, 800 μL/L) fumigation on the postharvest physiological indicators of Xinjiang red globe grapes were examined. The effect of modified atmosphere fumigation packaging technology on the postharvest quality of red grapes was investigated. The results showed that compared with the control, the modified atmosphere fumigation microporous packaging could preserve better fruit hardness, soluble solids content (TSS), titratable acid (TA) content and vitamin C (Vc) content, slow down the rise of pH, and maintain the postharvest quality of the fruit. The 500 μL/L SO2+5% O2+8% CO2 treatment exhibited a better fresh-keeping effect. After 8 days of storage, the pH value was 4.26, which is lower than the control group; the grape fruit hardness was 10.76 N, the TSS content was 16.67%, the TA content was 0.52%, and the Vc content was 1.18 mg/100 g, which were all higher than those of the control group. These showed that the modified atmosphere fumigation microporous packaging method can effectively extend the organoleptic quality and commerciality of grapes, and slow down the loss of nutrition and flavor of red globe grapes. Therefore, the 500 μL/L SO2+5% O2+8% CO2 controlled atmosphere fumigation microporous packaging technology can provide theoretical and data support for the research on postharvest storage, transportation and preservation technology of fresh table grapes.

25 Effects of 60Co-γ-irradiation Combined with Cold Storage on Storage Quality of Different Packing Peanuts

ZHENG Xiuyan , LI Guolin , LIN Mao , HUANG Daomei , MENG Fanbo , CEHN Xi

2021, 37(11):204-213. DOI: 10.13982/j.mfst.1673-9078.2021.11.0261

[Abstract](205) [HTML](175) [PDF 1.44 M](355)

Abstract:
In order to prolong the storage period of peanut kernel, the effects of 60Co-γ-irradiation combined with cold storage on storage quality of different packing peanuts were studied. The peanut kernel samples were treated at the irradiation doses 1.5 kGy by 60Co-γ ray and were packed by polyethylene bag, vacuum polyethylene bag and vacuum fresco bag, respectively. To evaluate the storage effectiveness of 60Co-γ-irradiation combined with cold storage of peanuts, during the period, the main physic-chemistry indexes were determined including microorganism, nutrient content, moisture content, texture characteristics, lipoxygenase and volatile component. The results showed that the total bacterial count of un-irradiated group was 980 CFU/g in the 4th month of storage, which exceeded the standard of 750 CFU/g, while the total colonies of irradiated peanuts were all lower than 340 CFU/g in the 14th months of storage, which met the standard. During storage, irradiation treatment did not have obvious effects on the nutritional composition and texture characteristics of peanut kernels. It is beneficial to reduce water loss and maintain the activity of lipid oxidase in peanut kernels under low temperature storage. Different packages of irradiated peanut kernels showed certain differences during storage, the changes of nutritional quality, texture characteristics and odor of peanut kernels packed with vacuum tin foil bags were the smallest. In conclusion, the storage period of peanut kernel could be extended to 14 months by 60Co-γ-irradiation combined with cold storage. This methodis easy to realize the industrialization, which has important instruction significance for industrialized production of peanut.

26 Regulation of Near Freezing Temperature and Calcium Treatment on Apricot Fruit Shelf Life Quality

ZHANG Huanhuan , HE Huan , SUN Lina , ZHANG Yu , ZHANG Wenna , YE Yufei , ZHANG Yalin , ZHU Xuan , CUI Kuanbo

2021, 37(11):214-221. DOI: 10.13982/j.mfst.1673-9078.2021.11.0243

[Abstract](156) [HTML](215) [PDF 644.91 K](409)

Abstract:
In order to explore ways to extend the shelf life of apricot fruits, Xinjiang’s Saimati apricot fruits were used as experimental materials, the calcium treatment group and the near freezing temperature group were used as controls to study the effects of the near freezing temperature combined with calcium treatment on the shelf quality of apricot fruits. The apricots stored for 70 days were shipped out of the warehouse in a low-temperature cold chain and stored in an environment of 13~15 ℃. Samples were taken every 2 days to determine the quality indicators of apricot fruits. The results showed that at the end of shelf life, the commodity rate, hardness, titratable acid and ascorbic acid contents of apricot fruit in the near freezing temperature combined with calcium treatment group were 62.50%, 4.41 N, 0.46%, and 3.49 mg/100 g, respectively, which were 32.81%, 39%, 27.78% and 17.51%, respectively, higher than those in the near freezing temperature group alone. The respiration intensity of apricot fruits treated with near freezing temperature and calcium remained at a low level. The above results show that the combination of near freezing temperature and calcium treatment can maintain a higher hardness and commodity rate of apricot fruits, effectively delay the decline of SSC, TA, and Vc contents and the color change of apricot fruits, and keep the sensory quality of apricot fruits at a higher level.

27 Study on Storage Stability of Seaweed Sandwich Based on Adsorption Isotherm and Glass Transition

LI Xiaonan , NIE Meimei , WANG Chunyan , TAO Yang , LI Dajing , XIE Hong , ZHANG Zhongyuan

2021, 37(11):222-230. DOI: 10.13982/j.mfst.1673-9078.2021.11.0141

[Abstract](151) [HTML](190) [PDF 739.35 K](426)

Abstract:
In order to understand the relationship among the water activity, moisture content, glass transition temperature and storage temperature of sandwich seaweed during storage, the adsorption isotherm and glass transition curves of sandwich seaweed were studied and fitted with a mathematical model. The absolute safe moisture content and critical moisture content of sandwich seaweed, and the thermodynamic properties, were discussed. The results showed that the GAB model could better reflect the moisture adsorption characteristics of the sandwich seaweed, and the absolute safe moisture contents of the sandwich seaweed at 20, 30 and 40 ℃were 5.19%, 4.69% and 3.72%, respectively, which could be used as the basis for predicting the optimal moisture content during the processing and storage of sandwich seaweed; In the same way, the critical moisture contents at 20, 30 and 40 ℃were 0.98, 0.84 and 0.71 g/g, respectively, which could be used as a basis for assessing the storage stability. When the equilibrium moisture content of the sandwich seaweed was higher than 0.08%, the binding energy of water and the substance was small, and water loss occurred easily. The water adsorption process of sandwich seaweed had an isothermal rate of 0.62 K and a Gibbs free energy of 2.61 kJ/mol, which was an entropy-driven spontaneous endothermic process. Comprehensive analysis showed that as the temperature decreased, the safe moisture content of the sandwich seaweed increased, and the vitrified structure was easy to collapse, which provided certain significant reference for its processing technology and dry product storage. The research results can provide a scientific basis for the sandwich seaweed industry.

28 Mass Transfer Kinetics and Quality Analysis of Mango under Vacuum Pretreated and Ultrasound Assisted Osmotic Dehydration

SONG Luyao , LIU Donghong

2021, 37(11):231-238. DOI: 10.13982/j.mfst.1673-9078.2021.11.0296

[Abstract](189) [HTML](186) [PDF 2.38 M](366)

Abstract:
To improve mass transfer efficiency and reduce production duration, the effects of the pulsed vacuum pretreated and ultrasound assisted osmotic dehydration (VUOD) on the mass transfer kinetics, quality and microstructure of mangoes were investigated. In terms of mass transfer efficiency, the results showed that the water loss (54.43%) of the VUOD samples was the highest, which was 45.85%, 14.06%, 29.38% higher than that in the traditional osmotic dehydration (OD), ultrasound assisted osmotic dehydration (UOD) and pulsed vacuum pretreated osmotic dehydration (VOD) samples, respectively, and the solid gain (12.81%) of the VUOD samples was 90.03%, 53.43% and 32.06% higher than that in the OD, UOD and VOD groups, respectively. The high regression coefficient (R2>0.9) and low RMSE value represented the suitability of Azuara model for describing WL and SG of osmo dehydrated mangoes. The model predicted that the equilibrium value of WL and SG of VUOD were the highest, which were 65.06% and 23.35% respectively. The hardness of the mangoes in the UOD and VUOD groups were significantly lower than those in the OD and VOD groups (p<0.05), while the color of mangoes was well protected. The results of scanning electron microscope (SEM) showed that ultrasound treatment caused a significant collapse in cell wall, the decrease in cross-sectional area and the formation of the microscopic pores. Meanwhile, vacuum pretreatment had little effect on the hardness, color and microstructure of mangoes. Overall, VUOD improved the efficiency of osmotic dehydration by changing the cell structure, increasing the mass transfer microchannels which can better protect the color of mangoes but result in a decrease in hardness.

29 Effect of the Combination of Propionibacterium Fermented Extract and Nisin on the Quality of Smoked and Cooked Sausages

WANG Zhaoyu , WANG Xiangpo , ZHANG Wangang

2021, 37(11):239-249. DOI: 10.13982/j.mfst.1673-9078.2021.11.0313

[Abstract](175) [HTML](192) [PDF 1.51 M](379)

Abstract:
In order to extend the shelf life and maintain the eating quality of smoked and cooked sausages, the effects of propionibacterium fermented extract (PFE) combined with Nisin on quality (color, textural characteristics), oxidation level (thiobarbituric acid reactive substance, TBARS) and microorganism profiles (total viable counts and microbial diversity) of smoked and cooked sausages during storage (4 ℃) were investigated. Six treatment groups were set as following: adding PFE (0.3%) with 0.01%, 0.02% or 0.03% Nisin, and adding PFE (0.3%) or Nisin (0.03%) alone and adding neither PFE nor Nisin as control group. The results showed that PFE-Nisin combination could significantly increase the a* value and the L* value, decrease the b* value (p<0.05), and reduce the hardness, chewiness and spring (p<0.05). Compared with adding PFE or Nisin alone, the treatment of 0.01% or 0.02% Nisin with 0.3% PFE showed better inhibition on lipid oxidation (p<0.05). Meanwhile, the total viable counts of colonies in each combined treatment were significantly lower than that in other treatment groups during the whole storage period (p<0.05), especially the combined treatment with 0.01% Nisin exhibited better antibacterial effect in the final period of storage. By high-throughput sequencing, PFE-Nisin combination showed better inhibition on Staphylococcus, Acinetobacter, and Sporosarcina. PFE-Nisin combination could significantly inhibit lipid oxidation and microorganism, which maintained the quality of smoked sausage and extended the shelf life of the product. PFE combined with 0.01% Nisin showed better improving effect on the quality of smoked and cooked sausages.

30 Effects of NaCl Addition and pH on Quality Characteristics of Mashed Potatoes

WANG Xiangtian , MU Taihua , MA Mengmei

2021, 37(11):250-260. DOI: 10.13982/j.mfst.1673-9078.2021.11.0271

[Abstract](221) [HTML](338) [PDF 1.65 M](520)

Abstract:
The effects of NaCl addition (0%, 0.5%, 1.0%, m/m), and pH (6, 7, 8) on the color, rheological, textural, and microstructural properties of mashed potatoes were investigated by using an electronic eye, rheometer, texture analyzer, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR). The results showed that with the increase of NaCl addition, the springiness was decreased from 81.86% to 79.40%, the hardness was increased from 551.72 g to 784.28 g, while the network structure was destroyed. Furthermore, with the increase of pH, compared to pH6, the springiness was decreased from 81.44% to 75.96%, the hardness showed a trend of decreasing first and then increasing, while the stability was decreased. The highest springiness (81.44%) and lower hardness (528.84 g) were obtained for mashed potatoes at pH 6. Overall, the mashed potatoes exhibited the best processing characteristics at pH 6 without NaCl addition. Thus, the study can provide theoretical support for the preparation of high quality mashed potatoes suitable for processing staple and leisure food by NaCl and pH regulation.

31 B3 Subunit in Soy Globulin G4 Protein Leads to the Formation of Secondary Precipitation in Chinese-type High-salt and Diluted-state Soy Sauce

FENG Tuo , SHAN Pei , GAO Xianli , FU Jiangyan , HU Feng , LIN Hong , XU Ting , WANG Bo , ZHANG Yaqiong

2021, 37(11):261-269. DOI: 10.13982/j.mfst.1673-9078.2021.11.0352

[Abstract](145) [HTML](184) [PDF 679.80 K](420)

Abstract:
In this paper, Japanese-type soy sauce was used as control, the effects of pH, Fe3+/Fe2+, polyphenol, soybean polysaccharide, soybean protein hydrolysate, NaCl, ethanol and temperature on the secondary precipitation, and the free amino acid composition and sensitive proteins in Chinese-type high-salt and diluted-state soy sauce were systematically analyzed. The results showed that all the above factors except ethanol (<1.8%) had significant effects on the secondary precipitate formation of Chinese-type high-salt and diluted-state soy sauce (p<0.05), only pH (6.5), soy protein hydrolysate, NaCl and temperature (60 ℃) had markedly effects on the secondary precipitate formation of Japanese-type soy sauce (p<0.05); the contents of 15 free amino acids and their average hydrophobic value (HΦavg) in Chinese-type high-salt and diluted-state soy sauce were significantly lower than those in Japanese-type soy sauce; the content of soy globulin B3 subunit (sensitive protein) in Chinese-type high-salt and diluted-state soy sauce was significantly higher than that in Japanese-type soy sauce (not detected). Based on the above results, it was speculated that B3 subunit in soy globulin G4 protein was the key substance of secondary precipitate formation in Chinese-type high-salt and diluted-state soy sauce, the secondary precipitate in Chinese-type high-salt and diluted-state soy sauce may be formed through B3 subunit-Fe3+/Fe2+-polyphenol complex and B3 subunit-soybean polysaccharide-Na+-Cl- complex. The above results will provide a theoretical reference for solving the secondary precipitation problem in Chinese-type high-salt and diluted-state soy sauce.

32 Comparative Analysis of the Effects of Three Kinds of Improver on the Characteristics of Blended Flour and Dough Quality

HUANG Tingting , BAI Yujia , FU Wenqian , FENG Zuoshan

2021, 37(11):270-280. DOI: 10.13982/j.mfst.1673-9078.2021.11.0136

[Abstract](199) [HTML](382) [PDF 790.27 K](557)

Abstract:
In order to improve the dough characteristics and quality of soup noodle made from commercially available wheat flour (11% protein), different phosphates, edible gums and starches were added to the wheat flour to determine the gelatinization properties of the blended flour, dough characteristics and the quality of the noodle after rehydration. The results showed that phosphate increased the peak viscosity, minimum viscosity, final viscosity, breakdown value and setback value of flour within significant effects on the peak time and gelatinization temperature (p>0.05).Pyrophosphate and tripolyphosphate significantly increased the peak viscosity of flour (p>0.05); Sodium polyacrylate significantly decreased the setback and breakdown values of flour (767 cP and 593 cP, respectively) (p<0.05); Potato modified starch and cassava modified starch significantly decreased the setback of flour (p<0.05). Phosphate and edible gums significantly improved the farinose quality of dough, while starch decreased the farinose quality of dough. Sodium hexametaphosphate, sodium tripolyphosphate and sodium pyrophosphate exhibited the smallest weakening effect (all 4 BU). The minimum weakening degrees of sodium polyacrylate and xanthan gum in edible glue were1 BU and 4 BU, respectively. All three kinds of modifiers can improve the shear properties of noodle sheets. Except for sodium bicarbonate, the other experimental groups could effectively improve the rehydration capability and sensory properties of noodle sheets. Tripolyphosphate, xanthan gum and potato modified starch showed better hardness, ductility, rehydration capability, quality and palatability in the experimental group. Comprehensive evaluation showed that the addition of tripolyphosphate, xanthan gum and potato modified starch can better improve the characteristics of dough and the quality of noodle sheets, and can produce the instant noodle sheets suitable for making Xinjiang soup noodle.

33 Biological Activities and Structure Characterization of Perilla Essential Oil Microcapsule Powder

LI Huizhen , WANG Qinqin , ZHANG Zhijun

2021, 37(11):281-287. DOI: 10.13982/j.mfst.1673-9078.2021.11.0364

[Abstract](170) [HTML](216) [PDF 1.10 M](404)

Abstract:
Using Perilla essential oil as raw material, the antioxidant and antibacterial activities of Perilla essential oil microcapsule powder prepared by different treatment of two wall materials, gum Arabic and octenyl starch ester, were studied and compared. The structure of the microcapsule powder was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The results showed that with the increase of the amount of microcapsule powder, the antioxidant capacity was gradually enhanced. When the amount of microcapsule powder was 7 mg, the scavenging ability of DPPH radical, hydroxyl radical and ABTS radical prepared by octenyl succinate starch ester reached 89.19%, 84.58% and 97.93%, respectively. When the optimum dosage was 5 mg, the antibacterial effect of the octenyl succinate starch ester wall material Perilla essential oil microcapsule powder on B. subtilis and E. coli was the best; when the dosage was 4 mg, the bacteriostatic effect on S. aureus was the best; the antibacterial rates of tomato early disease bacteria and watermelon wilt bacteria reached 31.58% and 90.48% respectively. Scanning electron microscopy (SEM), infrared spectroscopy (IR) and thermogravimetric analysis (TG) showed that the octenyl succinate starch ester perilla essential oil microcapsules were spherical, with a complete surface and shallow depression, and the embedding process was only physical encapsulation. The results showed that the microcapsule powder of Perilla essential oil prepared by octenyl succinic acid starch ester had strong oxidation resistance and good antibacterial effect, and had broad application prospect.

34 High-efficiency Extraction Process of Anthocyanins from Mulberry Based on Choline Chloride/Acetic Acid

ZHANG Xiaohui , JI Qingxia , DING Chengxin , BI Yanhong , ZHAO Xiangjie , WANG Zhaoyu

2021, 37(11):288-294. DOI: 10.13982/j.mfst.1673-9078.2021.11.0153

[Abstract](162) [HTML](240) [PDF 2.22 M](412)

Abstract:
In order to establish a new green and efficient process for extracting anthocyanins from mulberry, mulberry was used as the raw material and deep eutectic solvents (DESs) was used as the extractant to explore the effects of the types of DESs, water content, solid-liquid ratio, as well as extraction temperature and extraction time on the extraction efficiency of anthocyanins. On the basis of single factor experiments, the extraction conditions were optimized by response surface methodology. The results revealed that the yield of anthocyanins was 6.35 mg/g when the choline chloride/acetic acid (1/3 n/n) -water (80/20 V/V) was selected as the suitable solvent, solid-liquid ratio was 1/10 (g/mL), extraction temperature was 60 ℃ and extraction time was40 min. The experimental result was close to the predicted value of the response surface model, indicating that the model is suitable. The extraction efficiency of this process for mulberry anthocyanins was much higher than that of traditional extractants, suggesting the strong hydrogen bonding between DESs and the target product (which was composed of a proper ratio of hydrogen bond donors and acceptors) was more conducive to the leaching and dissolution of anthocyanins. The results of this study provide a reference for high-efficiency preparation of natural products with green and designable DES solvents.

35 Analysis the Difference of Feng-flavour Vintage Base Liquor Based on the Derivatization-GC-MS Metabonomics Method

YANG Hui , LIU Lili , JING Xiong , ZHANG Yafang , XU Chen , YAN Zongke , QI Yaohua

2021, 37(11):295-303. DOI: 10.13982/j.mfst.1673-9078.2021.11.0231

[Abstract](253) [HTML](209) [PDF 1.28 M](554)

Abstract:
With the aid of derivatization and gas chromatography-mass spectrometry combined with metabolomics analysis, the differences in the compositions of different years-stored base liquors were examined. The results showed that there were 59 compounds in different years-stored base liquors, including 30 kinds of organic acids, 10 kinds of amino acids, 7 kinds of sugar substances, 7 kinds of sugar alcohol substances and 5 kinds of other compounds. Based on sample dendrogram, PCA and PLS-DA analysis, new liquors and liquors stored for 2 years could be classified as one category, liquors stored for 3 years and 5 years as one category, and liquors stored for 7 years and 9 years as one category. The classification was obvious, indicating that there were obvious differences in compound types and contents among different years-stored base liquors. According to the importance of VIP variables, 20 different compounds were screened out, including organic acids, amino acids, sugars and glycerol. The contents of these substances significantly increased during storage, which was related to the particularity of the inner wall materials during Jiuhai making. This is also the reason why the new liquor becomes mellow after being stored in the Jiuhai for a period of time. The storage of liquor- in Jiuhai plays an important role in the formation of liquor flavor.

36 Analysis of Flavor Difference of Macadamia Nuts Dried with Different Methods Based on Electronic Sensory Technology Combined with GC-MS

REN Erfang , LIU Gongde , AI Jingwen , NIU Debao , LUO Chaodan , LUO Xiaojie

2021, 37(11):304-316. DOI: 10.13982/j.mfst.1673-9078.2021.11.0167

[Abstract](325) [HTML](158) [PDF 788.52 K](514)

Abstract:
In order to evaluate scientifically the differences in the flavor of macadamia nuts dried with different methods, electronic tongue and electronic nose sensory technologies combined with gas chromatography-mass spectrometry（GC-MS）were used to analyze their flavor quality. The results showed that there were significant differences between fresh macadamia nuts and different dried macadamia nuts in umami, salty, sour and bitter tastes, and the cumulative contribution rate of the first two principal components of linear discriminant analysis (LDA) was 96.60%, which could distinguish completely macadamia nuts dried in different ways. The responses of the electronic nose to macadamia nuts processed differently differed significantly. The cumulative contribution rate of the first two principal components in principal component analysis (PCA) reached 98.79%, which could well distinguish the volatile flavor compounds of the macadamia nuts dried by different treatments. The sensors W1S, W3S and W3C played major roles in the principal component analysis. As a supplement to the electronic nose, GC-MS identified a total of 227 volatile components, with alkanes and aldehydes being dominant in types and contents. The relative contents of alkanes in the four different treatments of macadamia nuts were 26.29%, 40.76%, 23.64% and 39.46%, respectively, and the relative contents of aldehydes were 29.01%, 18.96%, 26.03% and 23.87%, respectively. Therefore, the combination of electronic tongue, electronic nose and GC-MS can better distinguish macadamia nuts dried with different methods, thereby providing a theoretical reference for postharvest primary processing of macadamia nuts in growing regions.

37 Enhancement of Umami Taste and Intensity of Retronasally Perceived Model Aroma of Chicken Soup by Pork Bone Essence Constituents

LIU He , ZHANG Bin , REN Zhen , PENG Shengjing , ZHANG Yuyu

2021, 37(11):317-327. DOI: 10.13982/j.mfst.1673-9078.2021.11.0097

[Abstract](256) [HTML](192) [PDF 1.53 M](460)

Abstract:
In this study, the molecular weight cut-off method was used to divide pork bone essence (PBE) into three fractions, and sensory analysis was performed to evaluate the enhancing effect of the constituents in PBE on umami and retronasal aroma. The molecular weight distribution and hydrophobicity of the peptide fractions from PBE were further analyzed to elucidate the relationship between hydrophobic aggregation of the peptide components and their umami-/aroma-enhancing abilities. The results showed that after the treatment with a denaturant, the content of the fraction >30 ku of PBE dropped from from 36.07% to 2.95%, indicating that there was aggregation of proteins in this PBE fraction. After the three fractions were freeze dried, sensory evaluation was performed. It was found that the PBE (10~30 ku) fraction in a NaCl-based solution had a score of 7.6 for saltiness, 8.6 for thickness, 7.6 for continuity and 8.0 for mouthfulness, which were all higher than those of the other two fractions. In addition, the intensity of retronasally perceived aroma of the PBE (10~30 ku) fraction scored 7.5, which was also higher than those of the other two fractions. Analyses of the three fractions revealed that the contents of umami and sweet amino acids of the PBE (10~30 ku) fraction were 14.7% and 44.19% respectively, which were insignificantly different from those of PBE (>30 ku), and the kokumi effect of the PBE (10~30 ku) fraction was significantly greater than that of PBE (>30 ku). After the hydrophobicity was analyzed, it was found that the hydrophobicity index of the PBE (10~30 ku) fraction was 60.00±1.33, which differed significantly from those of the other two fractions. It could be speculated that the high content of taste-active amino acids (umami and sweet) could increase the intensities of the umami taste and retronasally perceived aroma to some extents, but only when the overall hydrophobicity of proteins or peptides was within a certain range, the enhancement of the umami taste and retronasal aroma was the greatest. Finally, the relationship between hydrophobicity and the enhancement of umami taste and retronasally perceived aroma were confirmed by the heat treatment experiments at 40 ℃ and 70 ℃.

38 Changes of Nutrients and Flavor Substances in Lingnan Yellow Chicken Stewed Chicken Soup

ZOU Jinhao , LIN Yaosheng , YANG Huaigu , TANG Daobang , CHENG Jingrong , WANG Xuping , DENG Yongpeng

2021, 37(11):328-337. DOI: 10.13982/j.mfst.1673-9078.2021.11.0276

[Abstract](247) [HTML](327) [PDF 1.14 M](744)

Abstract:
Lingnan yellow-feather chickens of different feeding periods (90 d, 120 d, 150 d) were used as raw materials to explore the changes of nutritional components, physicochemical properties, free amino acids and volatile flavor compounds in different stewing time (1 h, 2 h, 3 h) chicken soups. The results showed that the contents of fat, protein, b* value, soluble solids and total free amino acids in chicken soups increased gradually with the prolongation of stewing time, while the yield of chicken soups decreased with the increase of time. The protein content of 120 d chicken soup was higher, which reached 6.17% after 3 h stewing. The maximum L* value of 120 d 2 h chicken soup was 50.91, and the color of chicken soup was relatively clear. The contents of glutamic acid and alanine in chicken soup were the highest, which were 380.59~2467.01 mg/kg and 240.34~1309.55 mg/kg, respectively. The contents of glutamic acid (1857.08 mg/kg, 2467.01 mg/kg) and alanine (1042.50 mg/kg, 1309.55 mg/kg) in chicken soups (120 d 2 h, 120 d 3 h) were higher than those in other seven groups, and the taste was more delicious. 85 kinds of volatile flavor compounds were identified, and the relative content of aldehydes was the highest, ranging from 63.99% to 85.44%. The relative content of hexanal in chicken soup was the highest (about 50%). There were 45 kinds of volatile flavor components in 90 d 2 h chicken soup, followed by 120 d 2 h chicken soup (42 kinds). This study revealed the effects of feeding period and stewing time on the quality of Lingnan yellow-feather chicken soups. The results showed that the comprehensive quality of Lingnan yellow-feather chicken soup with suitable stewing time (2 h) and feeding period (120 d) was the best.

39 Determination of Iron, Copper and Manganese in Wine by Tandem Solid Phase Extraction and Atomic Absorption Spectroscopy

LI Jinliang , PENG Jingjing , YANG Jie , LAN Huijing , ZHANG Mengyao , GUO Anque

2021, 37(11):338-347. DOI: 10.13982/j.mfst.1673-9078.2021.11.0270

[Abstract](218) [HTML](229) [PDF 1.60 M](445)

Abstract:
A rapid and accurate method for the speciation analysis of iron (Fe), copper (Cu) and manganese (Mn) in wine was developed using a tandem column solid phase extraction (SPE) and an atomic absorption spectrometry (AAS). The optimization of SPE conditions, and the effects of pH values (3.00~4.00) and organic acids (single or blend) on recovery rates of metal fraction were investigated in wine-like solutions. Under the optimized activation conditions and flow rate (1 mL/min) of Polyclean X-HLB column linking the column of Superclean SCX at a flow rate of 2 mL/min, these metals were efficiently fractionated into hydrophobic, cationic and residual forms, with a subsequent direct determination of metal ions by graphite furnace AAS. The limit of detection for Fe, Cu and Mn was from 0.39 to 1.56 μg/L, obtaining the recoveries from 90.53% to 112.18%, with the relative standard deviation between 0.89% and 7.12%, suggesting the assay is sensitive with good reproducibility. In aqueous alcoholic solutions, significant effects of pH and organic acids on the distribution of ferric and cupric ions were observed, while few effects were found for manganous (II) ion. In real wine samples, the distributions of Fe, Cu or Mn were different between white and red wines, and were affected by chemical components and the redox state of a wine, present with the predominant residual (Fe, Mn) or hydrophobic (Cu) form.

40 Preparation and Testing of Vibrio parahaemolyticus Reference Materials for Food Analysis

LIU Na , ZHAO Linna , WANG Xueshuo , CUI Shenghui

2021, 37(11):348-353. DOI: 10.13982/j.mfst.1673-9078.2021.11.0257

[Abstract](167) [HTML](158) [PDF 350.18 K](318)

Abstract:
In this study, Vibrio parahaemolyticus reference materials without matrix were prepared and detected. The standard strain CMCC20030 was identified by MALDI-TOF MS, biochemical reaction and 16S RNA gene sequencing. The Vibrio parahaemolyticus samples (800) with 103 CFU/sample (20 μL) were prepared by freeze-drying technology. 20 samples were selected randomly for uniformity test. The samples were stored at 25 ℃ and 37 ℃ for 1, 3, 5 and 7 days respectively for transportation stability test, stored at 4 ℃ for 7, 14 and 28 days respectively for short-term preservation stability test, and stored at -20 ℃ for 14, 28 and 60 days respectively for preservation stability test. Five laboratories were organized for collaborative calibration. 20 food products were chosen as the substrate, the applicability was tested according to GB4789.7-2013. The strain CMCC20030 was identified as Vibrio parahaemolyticus by MALDI-TOF MS, biochemical reaction and 16s RNA gene sequencing. The uniformity result was Fsample=1.930< FINV (0.05, 19, 20) by one-way anova. The samples were still 103 CFU/sample when storing 60 d at -20 ℃, 28 d at 4 ℃, 3 d at 37 ℃ and 7 d at 25 ℃. All the results of 5 laboratories were 103 CFU/sample. All 20 samples presented Vibrio parahaemolyticus positively when adding any substrate, only 20 substrates presented negatively. The Vibrio parahaemolyticus sample without matrix meets relevant standards of uniformity, stability, collaborative calibration and applicability, can be applied to different study as reference material according to different purposes.

41 Rapid Screening of 73 Pesticide Residues in Gleditsia Sinensis Seeds by Matrix Solid-phase Dispersion Extraction Combined with Gas Chromatography-mass Spectrometry

ZHANG Quan , ZHOU Yibing , LIN Ye , LI Lei , WU Yutian , LIU Wenzheng , LIU Liya , GUO Hua , CHEN Qingyuan

2021, 37(11):354-363. DOI: 10.13982/j.mfst.1673-9078.2021.11.0090

[Abstract](196) [HTML](151) [PDF 1006.04 K](414)

Abstract:
A rapid screening method for 73 pesticide residues of different polarities in Gleditsia sinensis was established by matrix solid-phase dispersion extraction (dSPE) combined with GC-MS/MS analysis. The Gleditsia sinensis seed samples were extracted with acidified acetonitrile by shaking and ultrasonic-assisted extraction, and then added to the extraction bag for high-speed centrifugation. The supernatant was added to the purification tube and then subjected to dispersive solid-phase extraction purification. Multi-reaction monitoring scanning mode (MRM) was used for monitoring, and the matrix matching solution internal standard method was used for quantification. Each target had a good linear correlation in different ranges, with the correlation coefficients (R2) not lower than 0.990, and limits of quantification (LOQs) in the range of 2.5 ~ 20. 0 μg/kg (S/N=10). In the spiked Gleditsia sinensis seed matrix, the average recovery rates were 68.6%~110.7% with the relative standard deviations (RSDs, n=6) between 2.1% and 9.7%. Compared with the traditional pretreatment method, QuEChERS, the dispersive solid-phase extraction technology has certain advantages in detection cost and processing speed, and can analyze 73 pesticides simultaneously by one injection with high accuracy and sensitivity. This method can provide technical support for future research on the screening and confirmation of pesticide residues in food, risk assessment, and quantitative arbitration in the field of food risk monitoring.

42 Volatile Profiles Fingerprint Construction and Adulteration Recognition of Qinghai Flaxseed Oil Based on SPME-GC-MS

HAN Yuze , WANG Xingrui , LI Yingxia , WANG Shuzhen , CHEN Yunyun , WANG Jinying

2021, 37(11):364-371. DOI: 10.13982/j.mfst.1673-9078.2021.11.0283

[Abstract](222) [HTML](191) [PDF 1.12 M](451)

Abstract:
Soxhlet extraction method was used to extract oil from flaxseed of different varieties and producing areas in Qinghai province. The volatile components of flaxseed oil were enriched by headspace solid phase microextraction (SPME) and determined by gas chromatography-mass spectrometry (GC-MS). The volatile components of 40 batches of samples were analyzed and a fingerprint was constructed to identify the flaxseed oil samples mixed with sixkinds of vegetable oil in different proportions. The results showed that Qinghai flaxseed oil samples contained 58 volatile components, among which aldehydes were the main flavor components. In addition, the chromatogram of six kinds of vegetable oil were less similar to the standard fingerprint of flaxseed oil, the difference provided the feasibility for the identification of adulterated flaxseed oil. The adulteration model established is suitable for theidentification of flaxseed oil adulterated with 10% peanut oil, sunflower oil, sesame oil, more than 20% corn oil, more than 30% rapeseed oil and more than 40% soybean oil. This study provided a theoretical basis for the adulteration identification and quality control of flaxseed oil.

43 Assessment of Dietary Exposure to Cadmium from Fresh Aquatic Products from the Gulf of Tonkin, Guangxi

TIAN Tian , WU Jian , WEN Jinhua , ZENG Xianglin

2021, 37(11):372-378. DOI: 10.13982/j.mfst.1673-9078.2021.11.0199

[Abstract](212) [HTML](202) [PDF 754.69 K](422)

Abstract:
The dietary exposure risk to cadmium was evaluated in aquatic products from the Gulf of Tonkin, Guangxi, China. Cadmium pollution in aquatic products in the region in the last 3 years was monitored, and the differences in the cadmium content in different aquatic products were analyzed. The exposure risk to cadmium was quantitatively analyzed separately by point and probability assessments. Cadmium was detected in 54.65% of the samples tested. The cadmium content exceeded the national standard in 0.66% of the samples. Chi-square testing revealed no significant differences in the failure rates of different aquatic products. The failure rates of crustaceans and shellfish tended to be higher than those of other products. The exposure risk assessment results suggested that cadmium intake would have minimal effects on the health for low-exposure but would pose health risks for greater exposure (middle- and high-exposure populations). The dietary hazard quotient (HQ) values for shellfish and mollusks (mainly squid) were one to three orders of magnitude higher than those for other aquatic products. The probability of health risks caused by cadmium intake from aquatic products from the Gulf of Tonkin was 21.10%. Key sensitive factors affecting the cadmium HQ were cadmium content in mollusks (r=0.71) and shellfish (r=0.51). The findings indicate that the residents of Guangxi should control their consumption of mollusks and shellfish. Authorities should strengthen efforts to monitor the cadmium levels in these aquatic products. Concurrently, water pollution by industrial and agricultural activities should be strictly controlled.

44 Research Progress on the Functional Activity of Flaxseed Oil Components

LIAO Zhenlin , LI Qianying , CHEN Junjie , DU Liyu , WANG Jie , FANG Xiang

2021, 37(11):379-389. DOI: 10.13982/j.mfst.1673-9078.2021.11.0005

[Abstract](269) [HTML](848) [PDF 2.53 M](924)

Abstract:
Flaxseed oil is a kind of natural health-promoting plant functional oil, containing large amounts of unsaturated fatty acids, with α-linolenic acid and linoleic acid having the highest contents. These two kinds of polyunsaturated fatty acids played an indispensable role in the metabolism, growth and development of the body. In addition, flaxseed oil also contained a variety of bioactive substances, for example, other unsaturated fatty acids (docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and prostaglandin (PG)), flaxseed cyclolinopeptides, vitamin E, secoisolariciresinol diglucoside, oleic acid and flavonoids also play active roles in the body. This article mainly discusses the various functions of linseed oil for the human body, such as the antioxidant effect of α-linolenic acid and vitamin E on the body, the hypolipidemic effect of α-linolenic acid on the body fluid and at the gene level, and hypoglycemic effect of α-linolenic acid through coordinating insulin. In addition, secoisolariciresinol diglucoside and cyclolinopeptide of flaxseed exhibited anti-inflammatory and anti-cancer effects. Polyunsaturated fatty acids play a role in preventing and treating cardiovascular diseases, anti-aging and anti-oxidation, regulating intestinal flora, enhancing eyesight and antibacterial actions.

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Volume 37,Issue 11,2021 Table of Contents