Volume 39,Issue 9,2023 Table of Contents

1 Anti-parkinsonism Effect of Laver Combined with Madopar and Its Effect on the Intestinal Flora

JIANG Jiali , ZHOU Sainan , DONG Xiaoli , ZHANG Wei , WANG Yuming , TANG Qingjuan

2023, 39(9):1-9. DOI: 10.13982/j.mfst.1673-9078.2023.9.1246

[Abstract](202) [HTML](386) [PDF 65.67 M](447)

Abstract:
This study aimed to investigate the anti-parkinsonism effect of laver combined with madopar and its influence on the intestinal flora of model mice. Forty-eight C57BL/6J mice were randomly divided into four groups: normal control, Parkinson’s disease (PD) model, madopar treatment, and laver combined with madopar treatment. Mice in the laver combined with madopar treatment group were fed a diet supplemented with 5% laver for 2 weeks. Subsequently, behavioral tests, immunohistochemistry, western blotting, and inflammatory factor level determination were performed to evaluate the brain function of the experimental mice. Paired-end sequencing of intestinal bacterial DNA was conducted on an Illumina platform to monitor changes in the intestinal flora. The results showed that, compared with madopar alone, laver combined with madopar significantly improved the brain function of PD model mice. The number of neurons and expression level of tyrosine hydroxylase in the substantia nigra were 46.95% and 52.91% higher, respectively, while the expression of α-synapse nucleoprotein was 34.56% lower. Serum IL-1β content was significantly lower, and inflammation was lower. Additionally, 16S rRNA sequencing showed that the richness and diversity of the intestinal flora were higher in the laver combined with madopar treatment group than in the madopar alone group. The ratio of Firmicutes/Bacteroidota was 71.59% lower. The relative abundance of Muribaculaceae and Akkermansia, which are related to anti-inflammation, were significantly enriched, whereas the relative abundances of Blautia, Helicobacter, and other inflammatory bacteria were significantly decreased. Compared with madopar alone, combined treatment with laver had more positive effects on the composition of the intestinal flora, reduced inflammation, and exerted stronger anti-parkinsonism effects.

2 Comparison of Sleep Improvement Effects of Three Common Functional Formulations

HUANG Pimiao , SU Aihua , CUI Chun

2023, 39(9):10-14. DOI: 10.13982/j.mfst.1673-9078.2023.9.1309

[Abstract](196) [HTML](135) [PDF 692.18 K](683)

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Sleep improvement effect of Semen Ziziphi Spinosae extract, longan aril extract, and γ-aminobutyric acid. were compared through direct sleep, sodium pentobarbital-induced sleep extension, subthreshold dose sodium pentobarbital-induced hypnosis, and sodium barbital-induced sleep latency experiments were carried out. The results showed that all three functional formulations had no significant effect on the direct sleep and body weight of mice. However, the high (33.3 mg/kg•d), medium (16.7 mg/kg•d), and low dose (8.3 mg/kg•d) of γ-aminobutyric acid, the high (110 mg/kg•d) and medium (55 mg/kg•d dose of Semen Ziziphi Spinosae extract, as well as the low dose (66.5 mg/kg•d) of longan aril extract could significantly prolong the sodium pentobarbital-induced sleep time of mice. Further, γ-aminobutyric acid had the greatest hypnotic effect on mice treated with the subthreshold dose of sodium pentobarbital. Among the 12 mice tested, 2 fell asleep at high, medium, and low doses of γ-aminobutyric acid. Thus, the incidence of sleep reached 16.67%. The high, medium, and low dose of Semen Ziziphi Spinosae extract could shorten the sleep latency of mice hypnotized by sodium barbital, whereas only the high- and medium-dose groups were significantly different from the control group (P<0.05).

3 Protective Effect of Cuminaldehyde on Indomethacin-induced Gastric Ulcers in Rats

DENG Hongyu , ZHOU Huiying , KANG Ruiping , AIFEIRE Abuduaini , HUANG Luodong , SUO Feiya

2023, 39(9):15-22. DOI: 10.13982/j.mfst.1673-9078.2023.9.1082

[Abstract](123) [HTML](265) [PDF 48.15 M](470)

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The protective effect and mechanism of cuminaldehyde, the active ingredient of cumin, was investigated in the indomethacin-induced gastric ulcer rat model. To this end, a control group (CK), indomethacin model group (Model), omeprazole positive control group (Positive), as well as cuminaldehyde low (CUM2), medium (CUM4), and high (CUM6) dose groups were employed, with six mice per group. Indomethacin was continuously administered over 7 days in order to establish the gastric ulcer rat model. The morphology, gastric ulcer index, pepsin activity, and antioxidant properties of gastric tissue were evaluated. Higher cuminaldehyde doses decreased the number of stripe-like ulcers and bleeding spots in gastric tissue. Further, edema and erosion were alleviated, the arrangement of glands tended to be orderly, and inflammatory cell infiltration was suppressed. The ulcer index and pepsin activity gradually decreased in a dose-dependent manner (P<0.01), whereas the ulcer inhibition rate increased. The highest ulcer inhibition rate was observed in the CUM6 group (58.48%). SOD and CAT activity as well as the GSH and NO content in gastric tissue increased to varying degrees, whereas MDA levels decreased under cuminaldehyde treatment (P<0.05 or P<0.01). Serum TNF-α and IL-1β levels, as well as MPO activity decreased, whereas IL-10 and PGE2 levels increased. In conclusion, cuminaldehyde could significantly reduce the size of ulcers and suppress pepsin activity while improving antioxidant and anti-inflammatory activities, thereby protecting gastric tissue against indomethacin. These findings highlight the potential of cuminaldehyde as a treatment for gastric ulcers.

4 Digestion, Absorption, and Utilization of Sialic Acid from Edible Bird’s Nests in Rats

XU Yuhan , XIE Qiaoling , ZHANG Wei , ZHU Meizhen , CHEN Xiaoxuan , GUO Dongbei , LI Yongzhong , GUO Jianrong , LI Hongwei

2023, 39(9):23-32. DOI: 10.13982/j.mfst.1673-9078.2023.9.1230

[Abstract](129) [HTML](262) [PDF 26.93 M](446)

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The digestion, absorption, and utilization of sialic acid (SA) in the ready-to-eat peptide-containing and the traditional stewed edible bird’s nest products were compared. Male SD rats aged 8 weeks (n=32) were divided into four groups randomly, including blank control group (BC), peptide-containing edible bird’s nest group (PB), traditional edible bird’s nest group (TB), and sialic acid standard control group (SC). After oral gavage, the feces and urine were collected over 2 days to evaluate the absorption and retention of SA by calculating its digestion and absorption rates. Blood was collected intermittently during 60-day consecutive gavage to monitor the content alteration of the free and protein-bound SA in plasma and the erythrocyte membrane-bound SA, and the degree of sialyation was adopted to evaluate exogenous SA utilization. The results of the 2-day feces and urine monitoring did not reveal any significant statistical differences in SA digestion and absorption among all groups. The results of 60-day consecutive gavage revealed that the free SA concentration (P<0.005) and protein-bound SA content (P<0.005) in plasma and the erythrocyte membrane-bound SA content (P<0.001) were significantly higher in each intervention group compared to the BC group. After 10 days of intervention, the protein-bound SA content in the PB group was 36.36% higher than that in the 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), respectively. In conclusion, the sialylation of blood can reflect exogenous SA utilization and peptides can promote the utilization of SA. Long-term consumption of all types of edible bird’s nests can effectively improve the sialylation level of the body, surpassing the benefits derived from the intake of free SA.

5 Preliminary Toxicity Evaluation of Anthocyanins Extract from Lycium ruthenicum

YAN Shuping , WANG Shuo , CHEN Tao , SHEN Cheng , ZHANG Yonglan , ZHAO Jingyang , FENG Bin , LUO Fang , LI Yulin

2023, 39(9):33-41. DOI: 10.13982/j.mfst.1673-9078.2023.9.0721

[Abstract](144) [HTML](281) [PDF 11.27 M](399)

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The acute toxicity and subacute toxicity of an anthocyanins extract of Lycium ruthenicum (AEL) were evaluated. Acute oral toxicity test was performed in mice via intragastric administration of AEL 8 000 mg/kg once by a fixed dose method, and the toxicity responses of the mice were observed while their general states within 14 days were recorded. SD rats were selected for a 30-day feeding experiment, the changes of body weight and physical signs of rats were recorded during theadministration. At the end of the experiment, the biochemical indexes of urine, hematological indexes, and serum biochemical indexes were examined, the morphological changes in organs were observed, and the visceral body coefficient and visceral brain coefficient were calculated. The study revealed that in the acute toxicity test, no side effects was observed in mice, and their body weights increased normally with no obvious abnormalities detected in the anatomical organs. After continuous intragastric administration for 30 days, the rats in each experimental group showed no obvious toxic reaction, and their weights increased normally; Compared with the control group, the percentage of monocytes (M%) in the female high-dose group increased significantly (P<0.05) while their AST/ALT ratios decreased significantly (P<0.05); The serum Cl- and spleen coefficients of the male high-dose group were higher than those of the control group (P<0.05). The other urine biochemical indexes, hematological indexes, serum biochemical indexes, visceral coefficient and visceral brain coefficient of the rats in the experimental group did not show significant abnormalities. The results showed that the maximum tolerable dose for single intragastric administration of AEL to mice was not lower than 8 000 mg/kg, and no toxicity reaction was found in the rats after continuous intragastric administration for 30 days. AEL had no acute and subacute toxicities under the experimental conditions, exhibiting relatively high safety.

6 Bioinformatics Analysis of the VP2 Protein of GII.4 Norovirus

LIN Peng , HUANG Yuwen , LI Xuepeng , LI Jianrong

2023, 39(9):42-51. DOI: 10.13982/j.mfst.1673-9078.2023.9.1140

[Abstract](118) [HTML](408) [PDF 71.37 M](386)

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In order to understand the biological characteristics of the VP2 protein of norovirus (NoV), the VP2 protein of current NoV epidemic strains was used as the research object in this study. Bioinformatics softwares were used to predict and analyze the physico-chemical properties, phosphorylation sites, glycosylation sites, transmembrane regions, signal peptides, secondary structures, tertiary structure, antigenic determinants and B cell epitopes of NoV VP2 protein. The results showed that the VP2 protein of epidemic NoV strain was a stable hydrophilic protein with an average isoelectric point of 10.47, a water absorption coefficient of -0.47, and an instability coefficient of 47.91, with basic amino acids accounting for about 11.60%. The VP2 protein contains about 43 potential phosphorylation modification sites and 2 potential glycosylation modification sites. Most strains do not contain transmembrane domains and signal peptides, however, the GI.3 VP2 protein has the transmembrane domain and signal peptide. The average proportion of α-helix, extended chain, β-fold and irregular coil were 38.17%, 7.45%, 6.25% and 48.13%, respectively. The protein coverage of the tertiary structure prediction model was 56.70%. There were 8 potential protein antigenic determinants and 25 B cell epitopes on average. In this study, bioinformatics analysis methods were used to predict the physicochemical properties and structures of the VP2 protein of the currently epidemic NoV GII.4 strains, which has laid a theoretical foundation for further research on the function of the NoV VP2 protein.

7 Analysis of Quality Changes of Dry-cured American Red Fish Induced by Inoculating Complex Bacteria during Processing

LIU Jiayue , MAI Ruijie , YANG Juan , LI Xiangluan , ZHAO Wenhong , BAI Weidong , OU Baiqiao

2023, 39(9):52-61. DOI: 10.13982/j.mfst.1673-9078.2023.9.1161

[Abstract](112) [HTML](217) [PDF 9.33 M](376)

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In this study, Lactobacillus plantarum and yeast were used as a composite starter to replace partially sodium salt to prepare low-salt dry-cured red fish. The inhibition of the composite bacteria on the oxidation of red fish during dry-curing was studied through measuring its water activity, water content, color difference, texture, pH, and protein oxidation. The results showed that the water activity and pH of the samples with simultaneously added Lactobacillus plantarum and yeast exogenous microorganisms were insignificantly different from those of the control group (P>0.05), though their water contents differed significantly (P<0.05; 35.21% m/m and 35.35% m/m, respectively, for the control group and the composite bacteria group). These results indicated that replacing partially sodium salt with composite bacteria did not affect the preservation of dry-cured red fish. The composite bacteria made the dry-cured red fish having a lower brightness (L*) (P<0.05) and a higher yellowness (b*) compared with the control group (P<0.05). These results showed that the composite bacteria helped maintain the stability of the color of dry-cured red fish. In addition, adding composite bacteria improved the texture characteristics of dry-cured red fish. The results showed that the protein oxidation in dry-cured red fish caused the increase of carbonyl content and decrease in the content of sulfhydryl group. Thus, replacing partially the sodium salt with the composimte bacteria could significantly reduce protein oxidation during processing. Furthermore, compared with the red fish added with yeast alone, the inhibitory effect of protein oxidation in the red fish induced by inoculating Lactobacillus plantarum alone was better.

8 Process Optimization and Microbial Diversity Analysis of Guizhou Loose Fu-tea

ZHANG Zhouqiong , CAO Xia , REN Xiyi , HUANG Yonghui , LIU Yongxiang , TAN Yumei

2023, 39(9):62-71. DOI: 10.13982/j.mfst.1673-9078.2023.9.0691

[Abstract](122) [HTML](273) [PDF 22.69 M](441)

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Guizhou is one of the provinces with the most abundant tea variety resources in China. The tea garden area is large, but the economic output value is low. The summer and autumn tea resources are seriously wasted and the variety structure is single. The dark tea Maocha was used as the raw material, and the Fuzhuan Brick tea golden flower fermentation agent was artificially inoculated to optimize the flowering process conditions of loose tea, and the changes of physical and chemical indexes and fungal diversity were studied. The effects of different factors on the flowering of dark tea loose tea were analyzed by monofactorial experiments and orthogonal optimization test. The results showed that the optimum conditions were as follows: moisture content was 30 %, temperature was 28 ℃, fermentation time was 9 d, inoculation amount 1:100 (m/m). Under these condition, the number of Aspergillus cristatum was 3×108 CFU/mL, the water content, total ash content, tea polyphenol content, free amino acid content, water extract content was respectively are 3.0%, 6.8%, 12.0%, 2.4%, 42.6%. After the above optimization, Jinhua lush, plump, soup was yellow and bright, taste of alcohol. High-throughput sequencing technology was used to analyze the fungal diversity at different fermentation time. The results showed that the relative abundance of Aspergillus reached 98.8 % after 3 days of fermentation. This study optimizes the process conditions of Guizhou loose tea, which is of great significance to improve the quality of Fuzhuan brick tea, and provides reference for the study of other loose tea flowering process.

9 Preparation Process Optimization and Taste Evaluation of Lanmaoa asiatica Enzymatic Hydrolysate

ZHANG Shasha , YANG Ning , ZHANG Weisi , LUO Xiaoli , ZHOU Pei , CAO Jingjing , SUN Dafeng

2023, 39(9):72-80. DOI: 10.13982/j.mfst.1673-9078.2023.9.1113

[Abstract](109) [HTML](132) [PDF 11.48 M](374)

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In order to improve the utilization rate and added value of Lanmaoa asiatica, the enzymatic hydrolysis conditions and compound ratio of neutral protease, papain and flavor protease were optimized by using amino acid nitrogen as the indicator and by the orthogonal test on the basis of single factor experiments. Then, amino acid automatic analyzer and high performance liquid chromatography were used to analyze the tasting subtances such as free amino acids, organic acids and flavor-active nucleotides in the the hydrolysate, in comabination with the evaluation of taste activity value (TAV) and equivalent umami concentration (EUC). The results showed that the optimal enzymatic hydrolysis process was: material-liquid ratio, 1:20 (m/m); pH, 7.0; temperature, 50 ℃; time, 1.5 h; addition amounts of neutral protease, flavor protease and papain (by weight ratio), 0.60%, 0.90% and 4.70%, respectively. Under such conditions, 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, total amount of flavor-active nucleotides was 96.48 μg/g, total amount of organic acids was 4 511.59 μg/g, and EUC value was 2.46 g MSG/100 g. Therefore, the Lanmaoa asiatica enzymatic hydrolysate prepared through the optimal process was delicious and nutritious, which meets people's needs. This study provides a theoretical basis for the further processing of Lanmaoa asiatica.

10 Changes in Microbial Community Structure of Chilled Chicken during A Partially Frozen Storage

TANG Mengjun , ZHOU Qian , ZHANG Xiaoyan , TANG Xiujun , LU Junxian , FAN Yanfeng , YANG Xingxing , CHEN Wei , GAO Yushi

2023, 39(9):81-87. DOI: 10.13982/j.mfst.1673-9078.2023.9.1162

[Abstract](92) [HTML](374) [PDF 27.82 M](400)

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In order to reveal the changing trend of the microbial communities in chilled chicken during a partially frozen storage, and to provide a theoretical basis for partially frozen preservation, 16S RNA high-throughput sequencing technology was used to analyze the changes of microbial community structure of the chilled chicken during a partially frozen storage at -3 ℃. The results showed that Shannon index decreased, Simpson index increased, and microbial diversity decreased; The Ace index and Chao1 index first decreased, then increased with the storage time, and reached the peak value at the 4th day of storage then gradually decreased. At the phylum level, the dominant microorganisms of the chilled chicken during the storage were Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteriota and Chloroflexi. The relative abundance of Proteobacteria increased with the extension of storage time, whilst the other Phyla decreased. At the genus level, the dominant taxa of chilled chickens were Pseudomonas, Acinetobacter, Shewanella and Psychrobactera. With the extension of storage time, the relative abundance of Pseudomonas increased, and the relative abundance of Acinetobacter, Shewanella or Psychrophilic decreased. At the 28 th day of the storage, Pseudomonas was the most abundant, with The relative abundance of other bacteria accounting for less than 1%, respectively. Accordingly, Pseudomonas is the dominant spoilage bacteria of chilled chickens during the partially frozen storage.

11 Cloning and Bioinformatics Analysis of RiPAL1 Gene of Raspberry

SUN Huajun , LIU Ying , LI Xuejing , YANG Siqi , QIAN Lili , LI Yue

2023, 39(9):88-95. DOI: 10.13982/j.mfst.1673-9078.2023.9.1190

[Abstract](105) [HTML](252) [PDF 70.80 M](336)

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Phenylalanine ammonia-lyase (PAL) is a key enzyme in the metabolism of phenylpropane that regulates the biosynthesis of flavonoids in raspberry. To elucidate the function and regulation mechanism of the RiPAL1 gene in raspberry, total RNA was extracted from raspberry fruits to synthesize first-strand cDNA. The gene was successfully cloned, and related bioinformatics analyses were carried out. Our results showed that the coding sequence (CDS) of the RiPAL1 gene was 2 133 bp in length, encoding 710 amino acids, with a molecular weight of 77.5 ku and an isoelectric point of 6.21. The maximum hydrophobicity of RiPAL1 protein was 4.50, its minimum hydrophobicity was -4.50, and its average hydrophobicity index was -0.49. Based on these, it was determined that it is a hydrophilic protein with no transmembrane structure and no signal peptide. The RiPAL1 protein contained 4 N-glycosylation sites and 67 specific kinase sites. Its secondary structure was mainly composed of α-helices, while its tertiary structure was a homotetramer. Multiple sequence alignment showed that the RiPAL1 protein has a typical conserved domain of phenylalanine ammonia-lyase. Phylogenetic analysis indicated that the RiPAL1 protein is closely related to that of strawberry. This study provides a reference for further research on the molecular mechanism of the RiPAL1 gene in the biosynthesis of flavonoids in raspberry fruit.

12 Screening and Identification of High Acid-producing Lactic Acid Bacteria in Traditional Kimchi

ZHENG Qikai , CAI Changyu , WANG Linhao , LIAO Zhenlin

2023, 39(9):96-105. DOI: 10.13982/j.mfst.1673-9078.2023.9.1092

[Abstract](148) [HTML](543) [PDF 63.51 M](389)

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Hunan homemade kimchi water that had been stored for more than 50 years was used for screening and isolating strains of lactic acid bacteria using the culture-dependent method. The isolated strains were examined for their hemolytic activity and acid generation ability, whereas the high acid-producing strains were assessed for their tolerance to acid and bile salts, self-aggregation and hydrophobicity, antioxidant properties, nitrite degradation ability, growth properties, and biosafety. In total, 70 lactic acid bacterial strains were isolated from the kimchi samples, of which 42 did no exhibit hemolytic activity. Additionally, 16S rDNA sequence was used to screen and identify nine high acid-producing strains, which were designated JT1-31, JT1-21, JT1-12, JT1-25, JT1-6, JT1-16, JT1-34, JT3-23, and JT3-10. They all belonged to Lactiplantibacillus plantarum; strain JT1-12 showed the best acid resistance, with a survival rate of 156.85% at pH 3.0; strain JT3-10 exhibited the best bile salt tolerance, with a survival rate of 145.04% at 0.3% bile salt concentration; strain JT1-16 showed the highest self-aggregation and hydrophobicity at 66.13% and 44.19%, respectively; and strain JT1-21 exhibited the highest DPPH scavenging rate at 51.93%. The α-glucosidase inhibition rate of strain JT1-25 was the highest at 20.36%. The nitrite degradation rate of all nine strains was >90%, with JT1-12 exhibiting the highest removal rate at 94.98%. Evaluation of biogenic amine production indicated that none of the nine strains produced biogenic amines. This study identified nine strains of lactic acid bacteria isolated from traditional kimchi that exhibited good probiotic potential, providing a valuable reference and foundation for further inviestigation into lactic acid bacteria derived from food sources.

13 Screening and Optimization of Lactic Acid Bacteria for Fermentation of Seabuckthorn Juice

MAO Xinliang , WANG Jing , ZHOU Ming , LU Lu , ZHANG Xinxue , FU Shaowei

2023, 39(9):106-112. DOI: 10.13982/j.mfst.1673-9078.2023.9.1318

[Abstract](149) [HTML](281) [PDF 1.94 M](330)

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A total of 26 strains of lactic acid bacteria were screened with the aim of achieving a high flavonoid aglycone conversion rate in fermented seabuckthorn juice. The fermentation was optimized through single strain selection, followed by mixed inoculation. Lactobacillus plantarum L23, Pediococcus pentosaceus P27, and Lactobacillus plantarum L21 emerged as the most efficient conversion strains used for mixed inoculation. Subsequently, the orthogonal test was conducted to optimize pH value, temperature, and carbon source addition. The flavonoid aglycone content (calculated by isorhamnetin) was measured as a primer value for optimization. After screening, the highest flavonoid aglycone content was obtained under the following conditions: pH value of 4, temperature of 30 ℃, carbon source of 6% (m/V), and inoculation ratio of 1:2:1. The contents of total flavonoids, total phenolic acid, organic acid, and crude polysaccharides were measured before and after fermentation of seabuckthorn raw juice. The flavonoid aglycone content increased by approximately 90%, whereas the total flavonoid content increased by approximately 108%. In this formula, the contents of crude polysaccharide, organic acid, and total phenolic acid were also significantly different from those of the original seabuckthorn juice before fermentation. This study serves as a valuable reference for investigating the conversion mechanism of flavonoid aglycones using lactic acid bacteria, providing guidance for further industrial processing of seabuckthorn in China.

14 HPLC-ECD Fingerprint of Phenolic Compounds in Cichorium intybus L. and Spectrum-effect Relationship of Their Antioxidant Activity

SHAO Qiju , LI Yuqin , CAO Li , YANG Yuyao , REN Fanyu , CHEN Rongxiang , YUAN Xiaoyan

2023, 39(9):113-122. DOI: 10.13982/j.mfst.1673-9078.2023.9.1179

[Abstract](128) [HTML](239) [PDF 19.47 M](428)

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High performance liquid chromatography-electrochemical detection (HPLC-ECD) fingerprints of Cichorium intybus L. (chicory) of different origins were established. The antioxidant activities of chicory were evaluated in vitro by 1,1-diphenyl-2-picrylhydrazyl (DPPH), [2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS+) radical scavenging assays and ferric reducing antioxidant power (FRAP) assays. The "spectrum-effect" relationship between the fingerprint and antioxidant activities of chicory was analyzed using Pearson correlation analysis, partial least squares regression (PLSR) analysis, and gray correlation analysis (GRA) to identify the active antioxidant compounds. In total, 13 phenolic compounds were identified from the fingerprint of 21 batches of chicory from different regions. The total phenol content of chicory extract was up to 30.76 mg GAE/g, and the correlation coefficient between peak areas and antioxidant activity was >0.92. According to "spectrum-effect" relationship analyses, chicoric acid, caftaric acid, isochlorogenic acid B, isochlorogenic acid A, 1,5-dicaffeoylquinic acid, and isochlorogenic acid C comprised the components primarily contributing to the antioxidant activity of chicory, indicating significant correlations between these chemical compounds and antioxidant activity (P<0.01). The HPLC-ECD fingerprint of chicory established in this study combined with the statistical analysis method exploring the "spectrum-effect"not only indicate the differences in chemical compounds between samples but also directly demonstrate the antioxidant activity of samples. This method is simple and reliable, providing a reference for improving the quality evaluation and product development of chicory.

15 The Structure-activity Relationship between Pro-Glu Dipeptides and Umami Receptor Based on Sensory Evaluation and Molecular Docking

ZHAO Mengbin , GU Huarong , MU Hongtao , GAO Xiangyang

2023, 39(9):123-136. DOI: 10.13982/j.mfst.1673-9078.2023.9.0996

[Abstract](211) [HTML](158) [PDF 326.76 M](344)

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Twelve proline (Pro)/glutamic acid (Glu) dipeptides were synthesized to explore the molecular interaction mechanism between Pro/Glu dipeptides and umami receptors. Based on sensory evaluation, the homology modeling and molecular docking technique were used to assess the structure-activity relationship between Pro/Glu dipeptides and umami receptors, including taste receptor type 1 member 1 (T1R1), taste receptor type 3 member 3 (T1R3) and calcium-sensitive receptor (CaSR). Our results indicated that except for proline-serine (Pro-Ser), valine-proline (Val-Pro), and leucine-glutamic acid (Leu-Glu), the umami threshold of other dipeptides was lower than that of sodium glutamate (0.3 mg/mL). The umami threshold of γ-glutamic acid-methionine (γ-Glu-Met) and glycine-glutamic acid (Gly-Glu) was the lowest (0.07 mg/mL). Notably, Asp147, Thr149, Ser172, and Arg277 were the key binding sites of Pro-Glu dipeptides to T1R1, the key umami receptor of Glu dipeptides. Similarly, Glu45, Ser147, Val277, and His278 were the key binding sites to T1R3, whereas Ser147 was the key binding site between N-γ-Glu dipeptides and the T1R3 receptor. Leu173, Asn176, Gln179, Arg220, Ser244, and Asp275 were the key binding sites to CaSR, with Glu dipeptides had a higher affinity for binding to the CaSR receptor compared to Pro dipeptides. Binding of Pro/Glu dipeptides to receptors was mainly achieved through hydrogen bonds and hydrophobic interaction. During molecular docking, dipeptides with strong umami interactions were predominantly embedded in the depth of the receptor binding pocket, whereas dipeptides with weak umami interactions were located in the shallow position of the binding pocket, with some of their hydrophobic or hydrophilic regions being exposed to the surface of the receptors. This study aided in clarifying the interaction mechanism between Pro-Glu dipeptides and umami receptors, establishing a foundation for further study on the mechanism of action of umami peptides.

16 Metabolomics-based Comparison of Color Difference Components in the Stems of Hong Caitai and Caixin

TANG Kang , LI Guihua , GUO Juxian , LUO Wenlong , LUO Shanwei , JIANG Shizheng , FU Mei

2023, 39(9):137-143. DOI: 10.13982/j.mfst.1673-9078.2023.9.0998

[Abstract](146) [HTML](240) [PDF 50.37 M](381)

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This study aimed to comparatively analyze the flavonoid contents of the purple-colored cultivar Xianghongtai No. 1 (XHT1H, R) and the green-colored cultivar Yinong 50 tian Caixin (YN50T, G). The flavonoid compounds were separated and identified by ultra-performance liquid chromatography-tandem mass spectrometry. Principal component analysis (PCA), hierarchical cluster analysis, and orthogonal partial least partial-least squares discrimination analysis (OPLS-DA) were used to analyze metabolomics data and screen for differential metabolites in Hong Caitai and Caixin. PCA revealed significant differences in the flavonoid compound contents between the two varieties. OPLS-DA identified 170 different flavonoid metabolites, including 56 flavonols, 38 anthocyanidins, and 32 flavones. The anthocyanins included 25 cyanidin glycosides, six delphinidin glycosides, three peonidin glycosides, and three petunidin glycosides. Additionally, six of the top ten metabolites with higher content in Hong Caitai than in Caixin were cyanidins. Based on the differential flavonoids profiles of the two varieties, cyanidin, delphinidin, peonidin, and petunidin were associated with the pigmentation in Hong Caitai. These results provide a reference for further study of the mechanism of stem color formation and pigment utilization in Caitai.

17 Changes in Glucosinolate Metabolism in Postharvest Pakchoi (Brassica rapa L subsp. chinensis) under Red Light-emitting Diode Irradiation

SUN Ying , GUO Feng , HAN Ying , HU Huali , LUO Shufen , LI Pengxia

2023, 39(9):144-154. DOI: 10.13982/j.mfst.1673-9078.2023.9.1293

[Abstract](96) [HTML](131) [PDF 201.19 M](323)

Abstract:
Light-emitting diode (LED) irradiation with different colors and densities was employed for investigating the effect of red light on glucosinolate metabolism in postharvest pakchoi (Brassica rapa L subsp. chinensis). The results showed that both chlorophyll degradation and pakchoi yellowing were inhibited by red LED irradiation at a density of 6.5 μmol/(m2•s). Subsequently, the changes in glucosinolate content and relative expression level of genes involved in the glucosinolate metabolism of pakchoi after red LED irradiation (6.5 μmol/m2•s) were analyzed to explore the underlying regulatory mechanism. The results indicated that the contents of total glucosinolate and isothiocyanate in pakchoi petiole were 2.72 and 1.32 times higher than those in leaves, respectively. Additionally, the expression of key aliphatic synthesis genes, including MYB28, CYP83A1, and GSTF11, was significantly upregulated by red LED irradiation, thus promoting the synthesis of glucosinolate such as 3-butenyl glucosinolate. Consequently, the total glucosinolate content in treated pakchoi petiole was 1.62~1.99 times higher than that in the control during 4~8 d of storage. The myrosinase activity was promoted, and consequently, the accumulation of total isothiocyanate was increased in pakchoi petiole following red LED irradiation. Notably, the total isothiocyanate content in the control group was 77.43%~91.98% lower than that in the irradiated group during 4~8 d. In conclusion, red LED light treatment delayed the loss of glucosinolates and isothiocyanates in pakchoi, as indicated by the upregulated relative gene expression levels involved in the synthesis of aliphatic glucosinolate and increased myrosinase activity.

18 Effects of Ethylene Removers Combined with 1-MCP Treatment on Chilling Injury and Active Oxygen Metabolism of Hanging Dried Apricot during Storage

LI Ziqin , ZHAO Zhiyong , PAN Yanfang , LI Wenqi , JIA Xiaoyu

2023, 39(9):155-161. DOI: 10.13982/j.mfst.1673-9078.2023.9.1199

[Abstract](115) [HTML](265) [PDF 53.09 M](390)

Abstract:
The effects of ethylene remover (EA) combined with 1-methylcyclopropene (1-MCP) on chilling injury and active oxygen metabolism of hanging dried apricots during storage were investigated. To screen suitable preservatives for storage and provide a theoretical and scientific basis for the freshness preservation of hanging dried apricots in production, hanging dried apricots from 4th Tuan of Xinjiang First Division was used as test material, whereas ethylene removal agent (EA) and 1-methylcyclopropene (1-MCP) were used to treat hanging dried apricots before storage, with no treatment as control (CK). Fruits were stored in a fresh storage room at 0 ℃ and 90%~95% humidity, and all physiological indexes were measured every 7 days. Our results showed that treatment with EA and 1-MCP alone or in combination positively inhibited the occurrence of chilling injury and maintained the metabolism of reactive oxygen species during storage of hanging dried apricots. Interestingly, EA combined with 1-MCP treatment was better than CK. The occurrence of chilling injury was delayed for 14 d, its incidence was reduced by 42.59%, whereas the production rate of superoxide anion radicals (O-2) was reduced by 24.52%. In addition, the content of hydrogen peroxide (H2O2) was reduced by 65.03 μmol/g, whereas the activity of SOD, CAT, and POD enzymes was increased by 0.11 U/g, 0.20 U/g, and 1.06 U/g, respectively. These results indicated that EA combined with 1-MCP treatment can inhibit the incidence of chilling injury, production rate of O-2•, and accumulation of intracellular H2O2 in hanging apricots during storage. This combined treatment delayed the decreasing rate of the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), prevented the excessive oxidative damage of fruits, maintained the balance of reactive oxygen species metabolism, and retained the quality and flavor of hanging dried apricots during storage.

19 Changes in Storage Quality of Ready-to-eat Crayfish after Electron Beam Irradiation

SHEN Lingwei , DU Liu , ZHAN Zhimin , LIU Dongyin , XIONG Guangquan , QIAO Yu , WANG Chao , WANG Lan

2023, 39(9):162-167. DOI: 10.13982/j.mfst.1673-9078.2023.9.0892

[Abstract](124) [HTML](353) [PDF 45.87 M](381)

Abstract:
In this study, the effects of 4 kGy electron beam irradiation (EBI4) and 8 kGy electron beam irradiation (EBI8) on the quality of ready-to-eat crayfish tail during the storage under cold conditions were studied. The changes in total colony count, TVB-N, TBA, pH and sensory quality, as well as the changes detected by electronic nose before and after storage, were determined. The results showed that the growth and reproduction of microorganisms were effectively inhibited by 4 kGy and 8 kGy electron beam irradiation, with the number of microorganisms still not exceeding the limit values at the end of the storage period (which were 4.64 and 4.26 lg CFU/g, respectively). During the storage period, TVB-N value was effectively inhibited, and the shrimp meat was prevented from spoilage. Compared with 8 kGy, 4 kGy irradiation could better maintain the quality of ready-to-eat crayfish and reduce the degree of fat oxidation, with the change of pH value resembling more the change of non-irradiated crayfish, and the sensory acceptance was higher during the storage period. After 4 kGy electron beam irradiation, the smell of crayfish resembled more that of the untreated ready-to-eat crayfish, with its flavor being retained better. Therefore, in actual production, 4 kGy electron beam irradiation treatment combined with refrigeration is more beneficial to maintaining the quality of ready-to-eat crayfish tail.

20 Changes in the Processing Properties of A Whole Chestnut Flour-Guar Gum-Ferulic Acid Complex System during Extrusion

LI Rui , ZHENG Bo , RAO Chenlu , CHEN Ling

2023, 39(9):168-174. DOI: 10.13982/j.mfst.1673-9078.2023.9.1152

[Abstract](118) [HTML](261) [PDF 40.32 M](364)

Abstract:
The nutritional value and quality of chestnut products can be determined by the processing and digestion properties of the whole chestnut flour. In this study, the properties of the whole chestnut flour was modified via extrusion combined with the addition of the common food additive, guar gum, and ferulic acid. The freeze-thaw stability, water absorption, oil absorption, rheological properties and in vitro digestibility were systematically investigated. The results showed that extrusion combined with the use of guar gum enhanced the freeze-thaw stability, water absorption and water solubility of the whole chestnut powder, decreased its oil absorption, gelatinization temperature, increased breakdown value, while redulating its paste stability. As for the rheological properties, extrusion along with guar gum helped improve the rigidity of gel during the storage of whole chestnut flour, but with the increase of addition amount, the gel rigidity decreased. Further introduction of ferulic acid into the system increased the peak viscosity, pasting temperature and breakdown value, though having relatively small impacts on freeze-thaw stability, water absorption, water solubility and oil absorption. Meanwhile, extrusion along with addition of 3 wt.% guar gum and 3 wt.% ferulic acid increased the anti-digestibility components of the whole chestnut flour by 27.00%~32.10%. The results of this study showed that extrusion combined with the addition of guar gum and ferulic acid can effectively influence the processing properties of whole chestnut flour, and provide basic data for the creation of novel chestnut foods.

21 Process Optimization and Quality Analysis of Jasmine Flavor Syrup Preparation by Ultrasonic-assisted Low-temperature Solid Osmotic Dehydration

HOU Liran , ZHANG Zhiming , HU Na , YU Junzhe , XIE Caifeng

2023, 39(9):175-186. DOI: 10.13982/j.mfst.1673-9078.2023.9.1136

[Abstract](103) [HTML](136) [PDF 24.30 M](454)

Abstract:
With the development of the market for flavoured foods and functional beverages in China, flavoured syrup with specific nutrition and health benefits are being used to meet the demand for flavored beverages. However, at present, flavored syrups are mainly produced by thermal concentration technologies, which can easily lead to the loss of heat-sensitive aromatic substances. Accordingly, in this study, jasmine flowers and yellow rock sugar were used as the raw materials to prepare jasmine flower flavor syrup via ultrasonic-assisted low-temperature solid osmotic dehydration (USOD). The optimum conditions obtained by single-factor experiments were: the amount of yellow rock sugar was 120% of that of jasmine (m/m), sugar size as 6~20 mesh, osmosis time as 168 h and ultrasonic time as 120 min. Under these conditions, the yield of the flavoured syrup was 41.40%, the contents of total phenolics and total flavonoids were 175.18 mg GAE/kg dw and 187.92 mg RE/kg dw, respectively, and the DPPH radical scavenging capacity of the flavored syrup was 313.55 mg Trolox/kg dw；Most flavour compounds of jasmine flower were effectively extracted, especially the alcohols, with linalool being 37.94%~46.06%, followed by benzyl alcohol (20.80%~23.90%), indicating that the SOD process had a significant effect on the extraction of flavor compounds. Therefore, the yield of flavored syrup was effectively improved and the flavor components and nutrients of jasmine flowers were retained in this study. This study lays a theoretical foundation for the development and utilization of flavored syrup.

22 Effect of Microwave Treatment on the Browning and Characteristics of Fresh and Wet Noodles

WANG Rui , LIN Jiangtao , YUE Qinghua , SONG Anqi , SONG Xiya , SU Dongmin

2023, 39(9):187-195. DOI: 10.13982/j.mfst.1673-9078.2023.9.1143

[Abstract](120) [HTML](207) [PDF 55.10 M](488)

Abstract:
The effects of microwave treatment of wheat flour on the browning and properties of fresh wet noodle were investigated in the present study. Wheat flour was microwaved, before the color of fresh wet dough sheet and polyphenol oxidase (PPO) activity were determined. Also, the effects of microwave treatment on the browning and its characteristics of fresh-wet noodle were studied through analyzing the changes in moisture distribution, free polyphenol content and rheological characteristics of dough sheet, as well as changes in the secondary structure of protein, sulfhydryl group and disulfide bond of wheat flour. The results showed that the whiteness of the fresh wet dough sheet increased with the increasea of microwaving time and microwave power. There was no significant difference in color at a low microwave power, but the whiteness of dough sheet decreased due to gelatinization of wheat flour at a high power of 700 W for 100 s. The PPO activity decreased by 42.78%, and the content of free phenolics decreased by 54.78% within 24 hours compared with the untreated group. The relaxation times T22 and T23 of the dough sheet increased first then decreased, and reached the maximum when a medium-intensity treatment was applied. The free thiol group showed a downward trend, whilst the content of disulfide bond increased, which were 1.29 and 4.38 μmol/g, respectively, for a 100-s treatment at 700 W. As for protein’s secondary structure, the content of α-helices decreased significantly, whilst the content of random coils increased significantly. In terms of the rheological properties of fresh wet dough sheet, both the G' and G" increased first then decreased, and Tanδ also decreased first then increased. In summary, the treatment with a microwave power of 700 W and treatment time of 80 s leads to the best outcome. This study provides a theoretical basis for the noodle industry.

23 Adsorption of Copper (II) Ions in Water by Low-methoxy Pectin from Sunflower Heads

PENG Xiaoxia , LU Xiaoqing , GAO Ruirui , GONG Qiang , ZHANG Yuan , BAO Ruowen , ZHANG Cuixia , DOU Zhifang

2023, 39(9):196-204. DOI: 10.13982/j.mfst.1673-9078.2023.9.1254

[Abstract](142) [HTML](261) [PDF 33.78 M](343)

Abstract:
The adsorption capacity of natural low-methoxy pectin from sunflower heads on heavy metal copper ions (Cu2+) in aqueous solution was studied, and the effects of dosage, pH, adsorption temperature and time, and coexisting ions were investigated. Our results indicated that with increasing the pectin dosage, the removal rate of Cu2+ was continuously increased, whereas the adsorption capacity was initially increased and then decreased. Both adsorption capacity and removal rate increased initially and then remained unchanged with the increase in adsorption temperature or time. Similarly, both increased initially and then decreased with the increase in pH of pectin, whereas they decreased with the increase in concentration of divalent metal ions (coexisting ions) owing to the effect of coexisting ions. When the initial concentration of Cu2+ was in the range of 0~200 mg/L, the Langmuir isothermal equation was used to obtain the maximum Cu2+ adsorption capacity of pectin, which was 29.94 mg/g. Thermodynamic analysis showed that the adsorption process was a spontaneous and endothermic reaction with increasing entropy. Kinetics analysis revealed that the adsorption process followed the pseudo-second-order kinetic equation with electrostatic attraction and complexation as the main driving force. Thus, pectin derived from sunflower heads exhibits a strong Cu2+ sption capacity, making it a viable option as a safe, effective, and eco-friendly biosorption material for the treatment of Cu2+-contaminated wastewater.

24 Computer Simulation-based Investigation of the Anti-exercise-fatigue Effect of Active Peptides from Fish NADH Dehydrogenases

ZENG Qiaohui , LIN Miaoluan , DING Yao , PENG Mingjun , WANG Jingjing

2023, 39(9):205-214. DOI: 10.13982/j.mfst.1673-9078.2023.9.1225

[Abstract](117) [HTML](99) [PDF 25.07 M](457)

Abstract:
The anti-exercise-fatigue effect of active peptides derived from fish nicotinamide adenine dinucleotide Dehydrogenase (NADH) was investigated by simulating the hydrolysis of NADH Dehydrogenase protein subunits in five common fish species in China using computer simulations. The oligopeptides obtained through simulated hydrolysis were docked with lactate Dehydrogenase (LDH) and creatine kinase (CK) to identify the oligopeptides with ultra-high affinity for both enzymes (docking fraction ≤ -160), whereas Pymol and Ligplot+ software were used to display and analyze the mechanisms of interaction for molecular docking. The results showed that a total of 72 oligopeptides with ultra-high affinity were obtained from seven different NADH Dehydrogenase protein subunits of five fish species after computer-simulated hydrolysis and molecular docking. There were 36 oligopeptides with ultra-high affinity for LDH and CK, among which the oligopeptide with the highest docking score and the most frequent occurrence was PTIW (-198.762, -204.400). These results establish a theoretical foundation for improving the high-value utilization of fish protein and developing functional foods for anti-exercise-fatigue.

25 Comparative Analysis of Nutrient Release during in Vitro Digestion of Morchella esculenta with Different Cooking Methods

XUE Shujing , LU Qi , WANG Yi , YAO Fen , SHI Defang , YANG De

2023, 39(9):215-222. DOI: 10.13982/j.mfst.1673-9078.2023.9.1013

[Abstract](109) [HTML](118) [PDF 37.55 M](385)

Abstract:
An in vitro digestion model was constructed to explore the digestion of Morchella esculenta after cooking with different methods (boiling, baking, and steaming) and in terms of particle size (coarse powder and ultrafine powder). The microscopic morphology of digested Morchella esculenta powder was compared, and the contents of reducing sugars, proteins, free amino acids, and total phenolics in gastric and intestinal digestive fluids, as well as the DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging capacity, ferric reducing antioxidant power (FRAP), and 2-azinobis- (3-ethylbenzthiazoline-6-sulfphonate) (ABTS) cation radical scavenging capacity were simulated. Following in vitro gastrointestinal digestion, baking treatment yielded the highest dissolution rate (followed by steaming then boiling) for reducing sugars, protein, and total phenolic contents at 62.87%, 58.58%, and four times higher than boiled samples, respectively. The mean free amino acids dissolution rate of the boiled samples was 40.40 mg/g and was higher than that of the baked and steamed samples by 18.77% and 19.81%, respectively. Superfine grinding did not cause a significant increase (P<0.05) in the dissolution rates of reducing sugar and total phenolics, whereas it caused a significant decrease in the dissolution rates of protein and free amino acids (P<0.05). No significant difference in DPPH values was observed, but the FRAP and ABTS values varied significantly among the three cooking methods. The baking method yielded the highest values, followed by the steaming and boiling methods. Superfine grinding did not cause a significant increase in the antioxidant activity also. This study provides a scientific framework for the selection of appropriate cooking methods for Morchella esculenta, both for industrial or household purposes.

26 Optimization of the Process Design for Germinated Quinoa Milk Drink by Fuzzy Mathematical Model Combined with Response Surface Methodology

ZHOU Yiming , LU Haoyu , CHEN Jiesheng , ZHOU Xiaoli

2023, 39(9):223-232. DOI: 10.13982/j.mfst.1673-9078.2023.9.0798

[Abstract](106) [HTML](201) [PDF 4.41 M](352)

Abstract:
The Fuzzy mathematics comprehensive evaluation method is an ideal evaluation model based on fuzzy mathematics. In this study, the black quinoa from the Jingle town, Shanxi Province was used as the raw material for studying the changes of its key nutrients at different germination stages of quinoa. A germinated quinoa-based milk drink was prepared after the optimization of quinoa germination and milk drink formulation and processing by the single factor experiments and response surface tests combined with fuzzy mathematics comprehensive evaluation method. The experimental results showed that compared with ungerminated quinoa, the protein content of the germinated quinoa increased by 11.65% after germination for 36 h (up to 16.2 g/100 g), whilst the ash content decreased by 24.78%, and the fat and starch contents decrease steadily (by 26.16% and 27.9%, respectively). The flavonoid content increased continuously, reaching 3.83 mg/g after 36 h (which was 2.5 times that of the ungerminated quinoa). The comprehensive analysis revealed that the optimal germination time for black quinoa was 36 h, and the optimized formula of quinoa milk was: germinated quinoa juice, 50.50%; stevioside, 0.10%; composite emulsion stabilizer (gellan gum: sucrose ester = 2 : 1), 0.20%. The sensory score of such drink was 87.26, and the germinated quinoa milk had a uniform color, moderate sweetness and natural quinoa fragrance.

27 Effects of Mild Heat Combined with Dimethyl Dicarbonate on the Quality of Litchi Juice

LI Jinghao , XIAO Gengsheng , XU Yujuan , WU Jijun , YU Yuanshan , LI Jun , ZOU Bo , XU Qing

2023, 39(9):233-243. DOI: 10.13982/j.mfst.1673-9078.2023.9.1052

[Abstract](132) [HTML](247) [PDF 1.52 M](334)

Abstract:
The effects of dimethyl dicarbonate (DMDC), mild heat and their combination on the microorganisms and physicochemical indices of litchi juice were compared. The results showed that the sterilization effect of DMDC alone or mild heat alone was poor, whilst the number of residual microorganisms in the litchi juice treated by the combination was the lowest, with the total number of colonies and lactic acid bacteria being 0.41 and 0.36 lg CFU/mL, respectively, and no yeast and mold being detected. Compared to fresh litchi juice, DMDC treatment had no effect on the quality of Litchi juice, and the changes in ascorbic acid content and color of the mild heat alone group and the combined treatment group were insignificant, causing the increases in the total phenolics (total flavonoids) by 40.16% (7.16%) and 38.01% (4.35%), respectively, and increases in the ferric ion reducing antioxidant power (DPPH free radical scavenging ability) by 15.55% (11.85%) and 7.61% (3.71%), respectively. These results indicated that mild heat could promote the release of phenolics and improve the antioxidant activity. Correlation analysis showed that the △E of litchi juice was negatively correlated with Vc content, and the antioxidant activity was positively correlated with the contents of total phenolics and total flavonoids. Cluster heat map analysis and sensory evaluation revealed that the combined treatment could promote the release of flavor substances without causing a pronounced cooking flavor. The total number of colonies in the combined treatment group stored at 4 ℃ for 21 days was less than 100 CFU/mL. In conclusion, the combination of mild heat and DMDC treatment led to a good sterilization effect on the microorganisms in the litchi juice without causing adverse effects, and the shelf life of the juice was up to 21 d. This study provides a scientific basis for the industrialization of high-quality litchi juice.

28 Effect of Hydroxybenzoic Acid with Varying Numbers of Phenolic Hydroxyl Groups on Chitosan Film Properties

YANG Linjie , ZHOU Chuang , YANG Ziming , WANG Chao , HE Zuyu , LIU Yunhao , YU Lijuan , QU Yunhui , LI Puwang

2023, 39(9):244-251. DOI: 10.13982/j.mfst.1673-9078.2023.9.1182

[Abstract](125) [HTML](263) [PDF 61.96 M](376)

Abstract:
Chitosan, a natural macromolecular material, was used as the matrix, and each of four types of hydroxybenzoic acid with different numbers of phenolic hydroxyl groups, that is, salicylic acid (SA), protocatechuic acid (PA), gentisic acid (GTA), and gallic acid (GA), were added to prepare composite films using the solvent casting method. The rheological properties of the composite film solutions were investigated. The structure and properties of the composite films were characterized using thermogravimetry (TG), Fourier-transform infrared spectroscopy (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 a strong interaction between chitosan and hydroxybenzoic acid containing more phenolic hydroxyl groups, leading to a more compact network structure, and thus forming uniform and stable composite films. The composite film based on gallic acid with three phenol hydroxyl groups, which had the best comprehensive performance, exhibited good ultraviolet barrier function, vapor transmission rate of 1.5010-9 g/(m•h•Pa), tensile strength of 23.22 MPa, and DPPH radical scavenging rate of 71.85%. This study showed that the performance of hydroxybenzoic acid and chitosan composite films was influenced by the number of phenolic hydroxyl groups; the higher the number, the better the overall performance of the composite film.

29 Structural Features and Activity Analyses of Polysaccharides from Different Parts of Hovenia dulcis

WANG Jie , BI Jinfeng , WU Qunjun , GOU Min , ZHOU Runsheng , CHEN Qinqin

2023, 39(9):252-260. DOI: 10.13982/j.mfst.1673-9078.2023.9.1233

[Abstract](108) [HTML](103) [PDF 15.51 M](304)

Abstract:
To identify structures and differences in physiological activity of polysaccharides from different Hovenia dulcis tissues, three populations of H. dulcis polysaccharides (HDP), including whole fruit polysaccharides (HDPW), seed polysaccharides (HDPS) and peduncle polysaccharides (HDPP), were prepared using water extraction and alcohol precipitation. Their structures were analyzed using UV-Vis spectroscopy, high-performance size exclusion chromatography, ion exchange chromatography, Fourier transform infrared spectrometry, and scanning electron microscopy. All three HDP preparations comprised the acidic polysaccharides fucose, rhamnose, arabinose, galactose, glucose, mannose, galacturonic acid, and glucuronic acid in different molar ratios. HDPW, HDPS, and HDPP each eluted in size exclusion chromatography with three chromatographic peaks, and the low and medium molecular weight HDPS peaks (45.72×104~165.75×104 u) displayed higher molecular weights than those of 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 bonds, while HDPS contained β-glycosidic linked polysaccharides. The respective median inhibitory concentrations of HDP for DPPH free radicals, ABTS free radicals, and α-glucosidase were 0.015~0.043, 0.47~1.21, and 0.13~9.99 mg/mL. When the mass/volume concentrations of HDPW and HDPP were 0.1 mg/mL or above, the glucose consumption rate of insulin-resistant HepG2 cells (IR-HepG2) was significantly increased, with the highest increase compared with the model group being 7.66%. Compared with HDPS, HDPW was similar to HDPP in structure, and both showed better antioxidant and α-glucosidase inhibitory activity and stronger IR-HepG2 glucose uptake promotion ability. This study provides a theoretical basis and data supporting the comprehensive utilization of H. dulcis.

30 Extraction, Identification, and Analysis of Morchella Polyphenols via Response Surface Methodology and HPLC

LU Huimin , LI Yongfu , QIU Ju

2023, 39(9):261-269. DOI: 10.13982/j.mfst.1673-9078.2023.9.1255

[Abstract](94) [HTML](235) [PDF 47.36 M](343)

Abstract:
The extraction process of Morchella polyphenols was optimized via response surface methodology. In addition, single-factor optimization of solvent type, ethanol concentration, solid-liquid ratio, ultrasonic time, ultrasonic temperature, and ultrasonic power were optimized. A three-factor and three-level Box-Behnken design was then implemented based on the factors of greater influence. The optimal process was verified as follows: ethanol concentration of 10%, liquid-to-material ratio of 1:67 (g/mL), ultrasonic extraction time of 90 min, ultrasonic extraction temperature of 33 ℃, and ultrasonic power of 300 W. The polyphenol content extracted from morels under these process conditions was 22.39 mg/g. According to the analysis of response surface experimental data, the model was significant (P<0.000 1), the lack of fit was not significant (P>0.05), and the fitting degree was high (96.2%). The order of the three major factors affecting extraction rate was as follows: ultrasonic temperature > material-to-liquid ratio > ultrasonic power. The polyphenol contents in Morchella esculenta obtained through various extraction conditions were analyzed via HPLC. Ten phenolic compounds were detected. The content curves of these ten phenolic compounds extracted under various single-factor conditions were basically consistent with the data determined via Folin-Ciocalteu colorimetry.

31 Application of Electronic Nose and Electronic Tongue Technology in Flavor Identification of Rhus chinensis Honey

DENG Mengqing , YUAN Yang , ZHAO Tian , WANG Yinchen , ZHANG Dinghong , ZHANG Jinhua

2023, 39(9):270-278. DOI: 10.13982/j.mfst.1673-9078.2023.9.1519

[Abstract](100) [HTML](259) [PDF 165.27 M](453)

Abstract:
In order to realize rapid identification of Rhuschinensis honey from different regions, the Rhuschinensis honey from 12 different regions in Guizhou province was tested by the PEN3 electronic nose system of AIRSENSE in Germany and the taste analysis system of INSENT in Japan. Principal component analysis (PCA), linear discriminant analysis (LDA) and Loadings analysis were used to identify Rhuschinensis honey from different producing areas in terms of smell and taste. In the electronic nose PCA analysis and LDA analysis, the contribution rates of the first and second main components of Rhuschinensis honey from different regions were 99.90% and 87.05%, respectively. Loadings analysis found that the odor differences were mainly from inorganic sulfides, nitrogen oxides, organic sulfides, alcohols, ethers, aldehydes, ketones, etc. The sum of contribution rates of the first and second principal components was 99.35% in electronic tongue PCA analysis. According to the dispersion degree of radar map, there were significant differences in sour, sweet and bitter taste of Rhuschinensis honey in different regions. Both the electronic nose and the electronic tongue technology can distinguish Rhuschinensis honey from different origin, which can be used in the identification analysis of honey in the future.

32 Comparison between Metabolomics and Transcriptomics for Revealing the Composition and Formation Pathway of Aroma Compounds in "19 Xiang" Rice

LIU Zhitao , LIANG Jiayan , KONG Leilei , HU XiaoDan , ZHENG Yixiong , BAI Song

2023, 39(9):279-295. DOI: 10.13982/j.mfst.1673-9078.2023.9.0768

[Abstract](103) [HTML](249) [PDF 97.07 M](401)

Abstract:
Using gas chromatography-mass spectrometry (GC-MS), a metabolomic analysis of volatile metabolites of "19 Xiang" milk-ripe stage endosperm grains grown in Longchuan City and Lianshan City, Guangdong Province was conducted. The effect of origin on the formation of aroma compounds in aromatic rice was also explored by identifying the genes related to the formation of aroma compounds using transcriptome technology. Multivariate statistical analysis was performed on the original data using principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The results showed that the content of volatile substances in "19 Xiang" varied among grains planted in different places, exhibiting significant differences in the relative contents of 14 aroma substances. KEGG enrichment analysis revealed that the biosynthetic pathways of secondary metabolites significantly affected on the content of aroma substances. At the transcriptional level, taking the Lianshan group as the control, the samples of the Longchuan group had 56 significantly upregulated genes and 89 downregulated genes, which were mainly associated with biological processes such as catabolism of organic matter and polysaccharide metabolism. In conclusion, different planting environments greatly influence the content of aroma substances in aromatic rice, and carbohydrate metabolism activities and stress response-related mechanisms at the milking stage may be crucial factors regulating the content of aroma substances in the planting environment.

33 Changes in Aroma Characteristics of Sunshine Muscat Grape during Storage Evaluated by GC-MS and Aroma Analysis

XIE Linjun , WANG Haijun , ZHANG Jin , ZHOU Sihong , ZHOU Yongmei , PANG Liting , CHENG Guo

2023, 39(9):296-306. DOI: 10.13982/j.mfst.1673-9078.2023.9.1156

[Abstract](118) [HTML](276) [PDF 10.92 M](333)

Abstract:
In order to study the effect of temperature on the aroma characteristics of sunshine Muscat grape during storage, headspace-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were used to for qualitative and quantitative analyses of 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 profiling and aroma analysis. The results showed that 55 volatile components were identified by GC-MS, including 20 aldehydes, 6 alcohols, 6 esters, 16 terpenes and 7 other compoundss. Among them, 16 compounds were identified as active aroma components (OAV>1). The characteristic aroma components of sunshine Muscat grape were terpenes and aldehydes. The changes in characteristic aroma profile of sunshine Muscat grape stored at ice temperatures (0 ℃ and 4 ℃) and low temperatures (10 ℃ and 15 ℃) tended to be consistent, respectively. The characteristic aromas exhibiting differences during storage were mainly floral characteristics, especially the aroma notes of bell, jasmine, orchid, rose and mandarin duck. The storage at 0 ℃ could keep the fresh fruit aroma of grapes, whilst the loss of floral characteristics was significant. The characteristic aroma deteriorated after 8 weeks of storage at 4 ℃ and 10 ℃ or after 6 weeks of storage at 15 ℃. In summary, the storage at ice temperatures easily caused a decrease or loss of flower aroma characteristics at the early stage of storage, whilst the storage at a low temperature was unable to maintain the characteristic aroma quality of the fruit during a relatively long storage.

34 Comparative Study of Campylobacter Contamination of Poultry and Risk Modeling in China and the European Union

LIU Qian , NIU Hongmei , ZHANG Xibin , DONG Qingli

2023, 39(9):307-314. DOI: 10.13982/j.mfst.1673-9078.2023.9.1232

[Abstract](94) [HTML](298) [PDF 943.19 K](353)

Abstract:
The food safety risks caused by food-borne pathogens are severe in developed and developing countries. Poultry is susceptible to contamination with Campylobacter during breeding, slaughtering, and consumption, which may lead to food-borne illness in consumers. Attention should thus be paid to the food safety of poultry products. With the gradual development of a close trade relationship between China and the European Union (EU) and the EU opening quotas for Chinese poultry products, strengthening the safety of the poultry supply chain necessitates safety evaluations of poultry products to ensure safe consumption of domestic and foreign poultry products while maintaining robust trade between China and the EU. This paper systematically compared differences between China and the EU in contamination assessment, prediction models, and risk assessment analysis methods relevant to the contamination of poultry with Campylobacter and summarized existing problems in risk assessment for Campylobacter in poultry. Future development prospects of China and the EU in the field of food safety risk assessment are presented, providing a reference for better microbial risk assessment.

35 Comparison of Counting Standard Microsphere Dispersion and Concentration for enumerating Saccharomyces cerevisiae

XU Juan , CHEN Xiangyu , LI Mengmeng , LIN Lijun , LU Lixia , LIU Yuanjian , XIONG Xiaohui

2023, 39(9):315-322. DOI: 10.13982/j.mfst.1673-9078.2023.9.1129

[Abstract](97) [HTML](337) [PDF 49.94 M](364)

Abstract:
The concentration and statistical numbers of counting standard microspheres used for cell counting of the Saccharomyces cerevisiae strain (ATCC9080) were selected for analyzing the effects of microsphere aggregation. The dispersion, concentration, and statistical numbers of microspheres in Tween 20 or Tween 80 suspension for S. cerevisiae counting were evaluated. In addition, we determined the linearity between standard microsphere counting and plate counting. Our study showed that the dispersion of microspheres in 0.08% Tween 20 or 0.06% Tween 80 suspension was suitable, with a dispersion index of 3.30. For counting 105, 106, and 107 cells/mL of S. cerevisiae, the total statistical numbers of standard microspheres should not be less than 2 000, 1 500, and 1 000, respectively. In addition, the total statistical numbers of cells should not be fewer than 200, 400, and 2 600. At 105 to 107 cells/mL of S. cerevisiae, the counting results by standard microspheres were consistent with those of the plate counting (R2=0.996 9), with 106 beads/mL of standard microsphere being the most suitable concentration. Our results indicated the standard microspheres could be effectively dispersed by Tween 20 or Tween 80. Hence, microbial cells in suspension can be accurately counted by using an appropriate concentration of dispersed standard microspheres. The suitable parameters of the standard microspheres for microbial counting were identified to provide the application conditions of standard microspheres in GB/T 39730-2020.

36 Efficacy of Plasma Activated Lactic Acid Solution in Killing Common Foodborne Pathogens

LI Jiahong , YAN Longfei , DAI Fanwei , CHEN Minhui , WANG Ling , CHEN Feiping , LUO Zheng , YE Mingqiang

2023, 39(9):323-329. DOI: 10.13982/j.mfst.1673-9078.2023.9.1126

[Abstract](134) [HTML](121) [PDF 25.80 M](321)

Abstract:
Foodborne pathogenic bacteria have long been one of the food safety hazards in China. How to control effectively the proliferation of foodborne pathogenic bacteria in food has always been a hot topic. Based on the single factor experiments of plasma activated lactic acid (PALA) volume concentration, activation time and reaction time, taking Escherichia coli, Salmonella Enteritidis, Staphylococcus aureus and Listeria monocytogenes as the model strains, and the total number of colonies as the response value, the effects of the PALA on four foodborne pathogens were investigated in this study. The results showed that the killing rates of four foodborne pathogens increased with an increase of the PALA volume concentration, extension of activation time and prolongation of reaction time in certain ranges. When the PALA was activated for 120 seconds, the volume concentration was 0.2%, and the reaction between PALA and the four foodborne pathogens lasted for 10 minutes, about 7.71 lg CFU/mL of Escherichia coli, 4.52 lg CFU/mL of Salmonella, 4.03 lg CFU/mL of Staphylococcus aureus and 3.90 lg CFU/mL of Listeria monocytogenes in pure culture were killed. The killing rates of 4 kinds of the pure culture foodborne pathogens reached 99.9% (P<0.05), and more than 3.9 logarithm of the total number of colonies of pathogenic bacteria were killed. In summary, PALA can rapidly and efficiently kill common foodborne pathogens.

37 Magnetic Separation Combined with qPCR for the Rapid Detection of Salmonella in Sauce Meat

PAN Hui , XU Yin , WANG Xiaohong , DING Yifeng , WANG Shishuang , GONG Fang , ZHONG Shengyang

2023, 39(9):330-336. DOI: 10.13982/j.mfst.1673-9078.2023.9.0235

[Abstract](81) [HTML](221) [PDF 22.76 M](356)

Abstract:
The efficacy of phage magnetic separation combined with fluorescent quantitative polymerase chain reaction (qPCR) for rapid detection of Salmonella in the food matrix was verified. The specific phage of Salmonella typhimurium (ATCC14028), T102, was used as a molecular recognition element and was first coupled with carboxylated magnetic beads to prepare a phage T102-magnetic beads complex. Salmonella was specifically isolated and enriched by the phage T102-magnetic beads complex from the food matrix and then quantified by qPCR. The detection limit of this rapid detection method for Salmonella was 100 colony-forming units CFU/mL (0.1 CFU/PCR). The method had high specificity, with a linear range of 1×102~1×109 CFU/mL and a coefficient of variation of 2.1%. The overall detection procedure takes 6 h. Three hundred batches of food safety samples were tested and compared with the “National Standard for Food Safety, Food Microbiology Inspection, Salmonella Inspection” (GB 4789.4-2016). No positive samples were detected, and the results were consistent with the results of the GB 4789.4-2016 standard method. This method provides a reference for the application of phage-coupled magnetic nanoparticles in the detection of foodborne pathogens.

38 Research Progress on the Flavor of Black Pork in China

LIU Haoyue , LI Cong , WANG Ying , LIAO Xianyan , HUANG Junyi , YANG Han , XU Baocai

2023, 39(9):337-352. DOI: 10.13982/j.mfst.1673-9078.2023.9.1095

[Abstract](113) [HTML](222) [PDF 43.03 M](406)

Abstract:
Black pork is a very popular pork product in the market. Differing from ordinary large white pigs, black pork has high nutritional value, abundant unsaturated fatty acids, and high contents of inosinic acid and proteins, etc., exhibiting advantages such as rich mouthfeel and unique flavor thereby gaining high consumer popularity. There are many black pig breeds in China, and the flavors of pig breeds vary with different regions. On the basis of summarizing the general procedure for analyzing the flavor substances of meat products, the volatile flavor substances and tasting substances of the black pigs from seven regions, Dingyuan, Hebei (Baoxu), Laiwu, Yunnan, Beijing, Shanxi and Qinghai (Bamei), were analyzed and summarized in this paper, with the white pig as a reference. The key flavor substances of the black pork samples from different regions were determined. Based on the formation pathways of aroma-active and taste-active substances of the black pork, the main reasons responsible for the flavor differences among the black pigs from different regions were analyzed. Future research directions were put forward, so as to provide a theoretical reference for selective development of specific black pork processed products and value exploration of specific black pork varieties in certain regions.

39 Improvement of Polyphenol Properties of Nanoemulsion System and Its Application in Food

WANG Siyu , CAI Yinan , WANG Yujia , WANG Tingting , ZHANG Di , FAN Ziluan

2023, 39(9):353-363. DOI: 10.13982/j.mfst.1673-9078.2023.9.1163

[Abstract](137) [HTML](313) [PDF 2.23 M](628)

Abstract:
Researchers have been focusing on the potential of using plant polyphenols for promoting human health and have identified that the problems of poor stability, poor solubility, and low bioavailability of polyphenols in practical applications need to be urgently solved. The nanoemulsion delivery system has a small droplet size and good stability, thus is an excellent polyphenol delivery system with promising applications. Nanoemulsion-encapsulated polyphenols show improved stability, in vivo bioavailability, bioaccessibility, and antioxidant and antitumor activities, making it more suitable for application in the food industry. This paper reviews the current research on the classification and role of polyphenols, novel technologies for the preparation of polyphenol nanoemulsions, and the mechanism of nanoemulsion encapsulation and its effects on various properties of polyphenols. Based on the current problems posed when using polyphenol nanoemulsions, emulsion optimization scheme is proposed. Overall, the application status and potential use of polyphenol nanoemulsions in the food industry were explored. The findings of this study provide insights into future application directions of polyphenol nanoemulsions.

40 Research Progress in Delivery Systems for Astaxanthin

XIANG Huan , LIU Yuhang , LI Laihao , HUANG Hui , YANG Xianqing , CEN Jianwei , WEI Ya , HAO Shuxian

2023, 39(9):364-370. DOI: 10.13982/j.mfst.1673-9078.2023.9.0937

[Abstract](105) [HTML](413) [PDF 62.63 M](332)

Abstract:
Astaxanthin is a powerful antioxidant with a wide array of biological efficacies, such as strong antioxidant properties and blood-sugar-lowering, anti-inflammatory, and anti-cancer properties. Many companies produce and extract astaxanthin locally and abroad. Their products are widely used in aquatic feed, healthcare products, and pharmaceutical industries, which have high requirements for raw materials. However, astaxanthin has low water solubility, poor stability, and high extraction and synthesis costs, which considerably affect its industrial application. Therefore, exploring embedding technology for astaxanthin preservation is gaining considerable research attention. Several types of astaxanthin delivery systems have been shown to improve the stability and bioavailability of astaxanthin. Here, recent advances in astaxanthin delivery systems based on liposomes, microcapsules, and emulsions-based methods are reviewed and discussed. Comparisons of the encapsulation efficiency, bioaccessibility, and advantages and disadvantages of these three delivery systems are expected to provide a reference for research and application of astaxanthin delivery systems and establish a solid scientific foundation for the commercial application of astaxanthin.

41 Research Progress on the Metabolic Network of Cordycepin in Cordyceps militaris and Its Key Nodes

ZENG Jiapeng , LYU Mengdi , ZHENG Qianwang , LIN Junfang , YE Zhiwei , WEI Tao

2023, 39(9):371-379. DOI: 10.13982/j.mfst.1673-9078.2023.9.1165

[Abstract](133) [HTML](405) [PDF 35.96 M](360)

Abstract:
Cordycepin is one of the core high-value-added secondary metabolites produced by fungi belonging to the genus Cordyceps. Compared with other industrial strains, Cordyceps militaris benefits from the innate metabolic flux in the synthesis of adenosine analogs such as cordycepin. In recent years, with the development of omic analysis technology and Cordyceps militaris gene-editing technology, the metabolic network of cordycepin synthesis, particularly the key substrate synthesis pathway, has been completely analyzed. Therefore, this review, the known metabolic network of cordycepin is modularized, dividing it into the central carbon metabolic pathway, inosinate (IMP) pathway, and substrate biosynthesis pathway, completely describing its metabolic network. The composition of cordycepin precursor and the influence of multiple dispersion pathways and key nodes on the synthesis of cordycepin have been analyzed, and the synthesis and flow direction of IMP substances have been systematically elaborated. This shows that the synthesis and metabolism of IMP is the essential node in cordycepin synthesis. These discoveries provide a comprehensive foundation for optimizing the metabolism network of Cordyceps militaris through metabolic engineering and synthetic biology strategies, for developing a stable and high-yielding Cordyceps militaris strain in the future.

42 Osteogenic Mechanism of Action of Strontium and Research and Development Status of Strontium-rich Foods

XI Xueyao , GAO Yanan , WANG Jiaqi , ZHENG Nan

2023, 39(9):380-392. DOI: 10.13982/j.mfst.1673-9078.2023.9.1209

[Abstract](116) [HTML](327) [PDF 12.71 M](292)

Abstract:
Strontium is an essential trace element widely distributed in human tissues, with bone being its largest "reservoir", in which approximately 99% of strontium is present in the ionic form. Strontium has a considerable impact on bone health, and hence there is wide research consensus that the clinical drug strontium ranelate can protect bone health by influencing bone metabolism. However, as it is a synthetic chemical that is less safe than natural strontium salts, the development of strontium-rich foods which will aid individuals to care for their bone health through their daily dietary routine, has garnered increasing research attention. This paper reviews the types of common orthopedic diseases, the mechanism of action of strontium on bone metabolism, and the current status 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. The findings of this study providea theoretical basis for the application of strontium in orthopedic diseases and the improved development of strontium-rich foods.

43 Research Progress on the Safety Risk of Compound Seasonings in China

OUYANG Can , ZENG Zhen , JIANG Chunping , YANG Yujing , LIU Yuyan , LIU Yuntao

2023, 39(9):393-401. DOI: 10.13982/j.mfst.1673-9078.2023.9.1153

[Abstract](170) [HTML](299) [PDF 1.15 M](548)

Abstract:
In recent years, with the rise of the prepared food market in China, compound seasonings are becoming more and more important in the food industry, catering industry and home cooking. The market size of compound seasonings is increasing rapidly, exhibiting a trend of mraket diversification. However, the existing safety risks are becoming more and more prominent: not only the health of consumers is threatened, but also the development of the prepared food industry is restricted. This paper introduces the existing safety risk of compound seasonings from the aspects of raw materials, production technology, packaging materials, storage and sales, etc. In order to ensure the healthy development of compound seasoning industry and propel the quality improvement and effectivenss enhancement of the prepared vegetable industry in China, enterprises are suggested to strengthen the management of supply chain, establish flexible and efficient HACCP system, and innovatively develop the production processes and technologies, while the regulatory authorities need to improve the principles for the uses of additives, conduct safety assessments of compound seasonings and organize trainings for practitioners.

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Volume 39,Issue 9,2023 Table of Contents