Volume 37,Issue 9,2021 Table of Contents

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  • 1  Milk-derived Sleep-inducing Peptides with Extracts of Semen ziziphi spinosae and Bulbus lilii Improve Sleep in Rat Models of Insomnia
    LIANG Cao-wen CAO Yong LI Jun LIU Guo ZHU Xiao-ai FENG Kong-long CHEN Yuan-yuan LI Yun LUO Zhen
    2021, 37(9):1-7. DOI: 10.13982/j.mfst.1673-9078.2021.9.0429
    [Abstract](422) [HTML](243) [PDF 945.28 K](763)
    Abstract:
    The effect and mechanism of action of a mixture of sleep-inducing peptides isolated from cow milk and Semen ziziphi spinosae and Bulbus lilii extracts on para-chlorophenylalanine-induced (PCPA-induced) insomnia in rat models were investigated. The sleep-inducing effect of the mixture was evaluated by studying the behavioral changes of the ratsusingopen-field tests. By measuring the levels of neurotransmitters and metabolites in the rat brains, the reaction pathway and sleep-inducing mechanism of the mixture were analyzed. There were significant differences between rats treated with the mixture and those in which insomnia had been induced (p<0.05) but no significant differences between the treatment and control groups (p>0.05). The number of stays in the central zone, the duration of the stays, and the total distances movedby the rats treated with the mixture were 11.00, 15.01 s, and 3309.71 cm, respectively. The concentrations of γ-aminobutyric acid (GABA), glutamic acid (Glu), glycine (Gly), noradrenaline (NE), dopamine (DA), and 5-hydroxytryptamine (5-HT) in the brains of the mixture-treated group were 94.96 μg/mL, 1508.42 μg/L, 74.59 μg/L, 37.36 μg/L, 1.76 μg/L, and 1.61 μg/L, respectively. In addition, the mixture-treated rats had significantly higher levels of hypothalamic inhibitory neurotransmitters, namely GABA, than the rats with insomnia (p<0.05) but significantly lower levels of excitatory neurotransmitters, namely NE and DA (p<0.05). The results suggest that the mixture of cow-milk-derived sleep-inducing peptides and Semen ziziphi spinosae and Bulbus lilii extracts can regulate the release of hypothalamic neurotransmittersand improve the behavior and sleep of rat models of insomnia.
    2  Sinapic Acid Ameliorated Lipid Metabolism and Oxidative Stress in High Fat Diet Fed Syrian Hamsters
    LIANG Chan-hua WANG Ke-ying CAO Wen-jing LUO Gao HE Wen ZENG Zhen SONG Jia-le
    2021, 37(9):8-16. DOI: 10.13982/j.mfst.1673-9078.2021.9.0096
    [Abstract](224) [HTML](307) [PDF 1.42 M](533)
    Abstract:
    To investigate the effect of sinapic acid on lipid metabolism and oxidative stress in a high-fat diet (HFD) fed Syrian hamsters, the serum and hepatic levels of total cholesterol (TC), triglycerides (TG), high density lipoprotein (HDL-c), low densitylipoprotein (LDL-c), nonesterified free fatty acids (NEFA) and malondialdehyde (MDA) and total antioxidant capacity (T-AOC) were determined by colorimetric method. The hepatic levels of lipid metabolism related proteins, which including peroxisome proliferator-activated receptor gamma (PPAR-γ) carnitine palmitoyltransferase-1 (CPT-1), acetyl-CoA carboxylase1 (ACC1), fatty acid synthase (FAS), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), sterol regulatory element binding protein-2 (SREBP2) and cytochrome P450 family 7 subfamily A member 1 (CYP7A1) were determined using a Western Blotassay. Administrated with sinapic acid can significantly reduce the weight of HFD hamsters (23.86%), epididymal fat (20.38%) and perirenal fat (27.91%) (p<0.05) compared with HFD fed hamsters. Sinapic acid treatment also attenuated the serum lipid levels (TG: 183.51 μmol/L, TC: 1481.67 μmol/L, HDL-c: 507.81 μmol/L, LDL-c: 272.50 μmol/L and NEFA: 1.16 ng/L). The MDA levels were reduced to 7.85 nmol/L and 5.47 nmol/L, and T-AOC levels were increased to 12.63 U/mL and 113.72 U/mL in serum and liver of the model hamsters, respectively, by the intervention of sinapic acid. In addition, sinapic acid can promote the protein expression of PPAR-γ (2.00 times), CPT-1 (2.61 times), CYP7A1 (1.65 times) and inhibit the protein expression of FAS (34.38%), ACC1 (52.73%), SREBP2 (53.49%) and HMGCR (32.68%) compared with HFD hamsters. Our results suggested that sinapic acid can significantly improve lipid metabolism disorders induced by HFD in hamsters, which is related to the regulation of lipid metabolism-related proteins and the reduction of oxidative stress levels.
    3  Liver Injury and Activation of CD8+T Cells Induced by Lectin of Agrocybe aegerita in C57BL/6 Mice
    LI Yue-liang CHEN Li-qiong WEN Yu-di HUANG Zhuang-lin ZENG Shu-xian LIANG Yi
    2021, 37(9):17-24. DOI: 10.13982/j.mfst.1673-9078.2021.9.0031
    [Abstract](214) [HTML](181) [PDF 1.24 M](444)
    Abstract:
    The mechanism of the lectin in edible mushroom Agrocybe aegerita (Agrocybe aegerita lectin, AAL) underlying its action on the liver injury in C57BL/6 mice was investigated. C57BL/6 mice were injected by AAL through the tail vein. According to different times of treatment, the mice were divided into three groups: 0 h, 6 h and 9 h, and the serum ALT (Alanine aminotransferase ) and AST (Aspartate aminotransferase) were measured, and the liver tissue sections were stained with HE, and the expression of liver cytokines were detected by RT-PCR, and he liver cells were analyzed by flow cytometry. At 6 h and 9 h groups, the 6 h and 9 h injection of AAL into the tail vein of mice significantly increased the serum ALT and AST (p<0.001); HE staining of liver tissue sections showed obvious liver damage, with necrotic areas and lymphocyte infiltration. Compared with the 0 h group, the serum ALT and AST of mice were significantly increased (p<0.001); the mRNA expression of cytokines IL-10, IL-33, IL-27, IFN-γ and TNF-α in the liver of the 6 h mouse group significantly increased by 25.14 times, 4.62 times, 5.14 times, 16.51 times and 28.10 times, respectively. The proportions of T cells, NKT cells, and CD8+T cells in the liver of the 6 h group significantly increased from 27.92% to 45.95% (p<0.05), 2.46% to 6.36% (p<0.05), and 17% to 27.15% (p<0.05), respectively. The proportions of activated CD69+T cells and CD69+CD8+T cells in the liver of the 6 h group significantly increased from 10.02% to 18.28% (p<0.01), and 5.96% to 16.20% (p<0.01), respectively. These results showed that AAL induced liver injury in mice, activated CD8+T cells, and significantly upregulated the mRNA expression of the liver cytokines IL-10, IL-33, IL-27, IFN-γ and TNF-α, suggesting that there is a need to consider the dose of the fungal lectin for safe use.
    4  Quercetin Attenuates High-fat Diet-induced Colon Inflammation in Mice
    ZENG Yu-peng LU Xiao-dan LI Guo-kun DONG Jia-hua CHEN Xiao-yi SU Li-jie
    2021, 37(9):25-30. DOI: 10.13982/j.mfst.1673-9078.2021.9.0074
    [Abstract](281) [HTML](192) [PDF 1.16 M](578)
    Abstract:
    The effects of quercetin on colonic inflammation in a mouse model of high-fat diet-induced obesity were investigated in this study. Thirty male C57BL/6J mice were randomly divided into three groups, including low-fat diet group (LF), high-fat diet group (HF), and high-fat diet feeding with quercetin group (50 mg/kg·BW, HF+Q). Quercetin was administered orally once a day for 20 weeks. The morphology of colon was observed by hematoxylin-eosin staining. The concentration of LPS was detected by ELISA. The levels of cytokines, including IL-6、IL-1β and TNF-α were measured by Real-time PCR and western blotting. The activation of the TLR4/NF-kβ signaling pathway was determined by western blotting. The HFD-induced body weight gain was significantly reduced by quercetin in obese mice (p<0.05). Besides, the colonic morphological damage was ameliorated, and the concentration of LPS was reduced to 5.04 ng/mL (compared with HF group: 7.01 ng/mL, p<0.05) by quercetin. Compared with the HF group, the protein expressions of TNF-α (39.04%), IL-1β (17.73%) and IL-6 (25.47%) were inhibited by quercetin, and the activation of TLR4/NF-kβ signaling pathway was inhibited by quercetin. In conclusion, tissue inflammation in colon of obese mice can be improved and the expression of inflammatory factors can be reduced by quercetin. The mechanism may be associated with the reducing the activation of TLR4/NF-kβ signaling pathway.
    5  Protective Effects of Total Triterpenoids in Inonotus obliquus against Liver Injury in Mice
    JU Chun-mei DU Yan-jia LIANG Xin-he WU Meng-ya ZHANG Hui LI Yan-jie
    2021, 37(9):31-36. DOI: 10.13982/j.mfst.1673-9078.2021.9.1149
    [Abstract](279) [HTML](205) [PDF 1.37 M](590)
    Abstract:
    To study the action mechanisms of total triterpenoids (TIO) in Inonotus obliquus on acetaminophen (APAP)-induced liver injury in mice, a total of 48 SPF-grade ICR male mice were divided into six groups with seven-day administration as follows: blank control; model; silymarin-treated (50 mg/kg); and TIO-treated low , medium, and high dose (15 mg/kg, 30 mg/kg, and 60 mg/kg, respectively). After the last administration, all groups, except the blank group, were subjected to a one-time abdominal injection of 300 mg/kg APAP to establish the liver injury models. Subsequently, the activities of alanine aminotransferase, aspartate aminotransferase, and superoxide dismutase were determined, and the contents of reduced glutathione and malondialdehyde were measured. Furthermore, the liver was processed for hematoxylin–eosin and Hoechst 33258 staining to observe pathological changes. The high dose of TIO reduced the aspartate aminotransferase and alanine aminotransferase contents to 8.38 U/L and 11.13 U/L, respectively, and that of malondialdehyde to 20.71 pmol/(mg pro). The superoxide dismutase and reduced glutathione levels were increased to 628.39 U/(mg pro) and 126.28 U/(mg pro), respectively Hematoxylin-eosin staining revealed the structure of the liver lobules in the TIO-treated medium- and high-dose and the silymarin-treated groups to be complete and clear, and the liver cell injury to be effectively repaired. Hoechst 33258 staining showed that the numbers of apoptotic liver cells in the TIO-treated groups were significantly reduced, and the fluorophore color was weakened. The above results indicate that the total triterpenoids in Inonotus obliquus provide marked protection against APAP-induced liver injury in mice. The mechanism may be related to reduction in oxidative stress and inhibition of apoptosis.
    6  Functional Analysis of Squalene Monooxygenase Gene for the Carotenoid Biosynthesis in Cordyceps militaris
    ZHAO Yi CHEN Hai-ying LI Shu-li XU Wei-jun GUO Li-qiong LIN Jun-fang YE Zhi-wei
    2021, 37(9):37-42. DOI: 10.13982/j.mfst.1673-9078.2021.9.0086
    [Abstract](286) [HTML](257) [PDF 1.77 M](544)
    Abstract:
    Based on transcriptome data, it was speculated that erg1 gene may be involved in carotenoid synthesis in Cordyceps militaris. Under the stress factors of KMnO4 and NaCl, the mRNA relative expression level of erg1 gene was further detected and analyzed to explore its regulatory role in carotenoid synthesis pathway. In order to verify erg1 gene function, an over-expressing vector pCambia0390- blpR-Pcmgpd-erg1of the erg1 gene was constructed. Subsequently, the expression cassette was introduced into the C. militaris by Agrobacterium tumefaciens. Finally, the expression level of erg1 gene and the amount of carotenoid biosynthesis were determined. The results indicated that the carotenoid production of recombinant strain Cmerg1 under KMnO4 (oxidative) and NaCl (osmotic) stress reached 6757.17 μg/g and 6363.93 μg/g respectively, which were 1.22 and 1.20 times of the control strain CM10, respectively. In conclusion, the overexpression of erg1gene caused the increase of carotenoid production of Cmerg1 strain. In other words, the squalene monoxygenase gene is involved in the carotenoid synthesis of C. militaris. The results laid the experimental foundation for the research and utilization of carotenoid biosynthesis in C. militaris.
    7  Difference Analysis of the Extracellular Metabolites of Saccharomyces cerevisiae Mutagenized by Low-energy Ion Implantation
    BAI Qiao-xiu OU Ke WANG Ting YANG Qian-qian LIU Jing LI Kan-she CHEN Fu-xin MAO Pei-hong
    2021, 37(9):43-49. DOI: 10.13982/j.mfst.1673-9078.2021.9.1102
    [Abstract](236) [HTML](211) [PDF 1.49 M](527)
    Abstract:
    Differences between extracellular metabolites of recombinant strain N6076 mutagenized by low-energy ion beams and original strain Kh08 at different fermentation stages were studied by metabolomic methods. The related metabolic pathways were discussed based on network pharmacology. The results show significant differences between the extracellular metabolites of the two strains at different stages. Fifteen metabolites with VIP>1 were identified including indole-3-propionate (IPA), a common metabolite showing the most significant difference. The pathways of metabolites showing differences were examined based on network pharmacology. It has been found that four metabolic pathways of the recombinant strain show significant differences, namely lipid metabolism, phosphatidylinositol (GPI)-anchoring, pantothenic acid and CoA biosynthesis, and the glycerophospholipid metabolism. This study provides scientific evidence and understanding of the metabolic differences of recombinant yeast and a possible direction for future strain improvement.
    8  Antibacterial Mechanism of Cinnamon Essential Oil Vapor Fumigation against Staphylococcus aureus
    DUAN Xue-juan HAN Ya-li LIU Ze-xuan ZHANG Tong XU Yu-tan HUANG Yu-qiang WU Ke-gang
    2021, 37(9):50-58. DOI: 10.13982/j.mfst.1673-9078.2021.9.1210
    [Abstract](258) [HTML](268) [PDF 1.59 M](486)
    Abstract:
    The antibacterial function of the vapor-phase of the essential oil from Cinnamomum cassia (EOL) against Staphylococcus aureus (S. aureus) and the underlying mechanisms were investigated. Gas phase fumigation was used in the experiments to examine the antibacterial mechanism of gas-phase cinnamon essential oils by TEM, conductivity test, FT-IR spectroscopy, fluorescence spectroscopy and other methods were used to characterize the change of cellular membrane after treated by essential oil through gas phase fumigation method. The results showed that EOL had significant vapor-phase antibacterial activity with a MIC and MBC against S. aureus being 0.25 μL/mL and 0.5 μL/mL, respectively. TEM observations showed that the cell membrane of S. aureus was damaged and dissolved after being fumigated by Cinnamomum essential oil, and the cells shrank, causing the contents to leak out. The conductivity experiments further confirmed that the cell membrane permeability of S. aureus was improved, and apositive correlation between nucleic acid leakage and the changes in the concentration of essential oil was found by measuring OD260. The FT-IR and fluorescence spectra showed the changes in protein conformation of S. aureus caused by the treatment with cinnamon essential oil. On the analysis of the amide I band, it was speculated that the secondary structure of bacterial proteins became more disordered in the process of fumigation. Based on the changes in fluorescence intensity and spectralpeak position, one could speculate that the bacterial proteins had changed after the cinnamon essential oil fumigation, leading to more exposed chromophores. Accordingly, the possible antibacterial mechanism of cinnamon essential oil fumigation against S. aureus was related to the changes in the cell membrane permeability and morphology, and secondary and tertiary structures of bacterial proteins.
    9  Application of Liquid Wastes from Enzyme Production to Enhance Cassava-based Alcohol Production
    YIN Ming
    2021, 37(9):59-66. DOI: 10.13982/j.mfst.1673-9078.2021.9.0674
    [Abstract](220) [HTML](218) [PDF 539.10 K](601)
    Abstract:
    To reduce the cost and increase the efficiency of raw material utilization in the production of alcohol from cassava, various conditions in the alcoholic fermentation of this starchy tuber were examined. The optimal fermentation conditions were determined to be a liquefaction temperature of 95.0℃ and a liquefaction time of 70.0 min. Additionally, at the saccharification temperature of 60.0℃, the saccharification time was 40.0 min. Under these conditions, the highest alcohol yield reached 54.01%, with a cassava starch utilization rate of 89.25%. On the basis of these findings, the application of liquid wastes generated from the production of various enzymes (viz., glucoamylase and amylase) in cassava-based alcohol production was studied for the first time. Following the addition of liquid waste from glucoamylase production to the alcoholic fermentation process, 1320 mL of amylase and 316.8 mL of glucoamylase were saved per ton of alcohol produced, and the addition of nutrient salts, such as urea and magnesium sulfate, was no longer required. Meanwhile, the alcohol yield had increased by 54.64%. Therefore, the utilization of fresh glucoamylase and amylase in the alcoholic fermentation of cassava can be greatly reduced by using the waste liquids from enzyme production, and the need for nutrient salts can be reduced. Furthermore, given the same quantity of raw materials, the alcohol yield can also be effectively enhanced. This study not only highlights the effective utilization of waste resources from the enzyme production industry but also provides theoretical support for new ways in which efficiency in the cassava-based alcohol production industry can be developed.
    10  Safety Evaluation and Fermentation Process Optimization of a High-yield Phenyllactic Acid Strain
    HOU Nan-nan XIE Quan-xi WANG Mei WANG Qian LU Xiao-hui ZHOU Hong GU Wei
    2021, 37(9):67-75. DOI: 10.13982/j.mfst.1673-9078.2021.9.1213
    [Abstract](348) [HTML](261) [PDF 787.74 K](514)
    Abstract:
    In this study, traditional bio-fermentation technology was used to produce phenyllactic acid, and the species, safety and fermentation process of high-yielding phenyllactic acid strains were studied. A high-yielding phenyllactic acid strain BLCC2-0069 was obtained through screening by reversed-phase high performance liquid chromatography. The content of phenyllactic acid in the fermentation broth of this strain was 1.26 g/L after 24 h of fermentation; By observations on the morphology of the strain and identification of 16S rDNA sequence of the strain, the strain was preliminarily determined as Lactobacillus plantarum; the strain entered the logarithmic growth phase after 4 hours of culture, and entered the stable phase after 10 hours, with the number of viable bacteria reaching 1.78×109 cfu/mL. Through an in vivo safety evaluation in mice, this strain was preliminarily determined safe in vivo. In the meantime, the fermentation process using Lactobacillus plantarum BLCC2-0069 was also studied, and that the yield of phenyllactic acid in the fermentation broth reached the highest (3.96 g/L) when 3.00 g/L of phenylpyruvate was added to the medium as a substrate. In summary, Lactobacillus plantarum BLCC2-0069 is non-toxic to mice and has a high level of biological safety. The yield of phenyllactic acid reached 1.26 g/L through direct fermentation, and 3.96 g/L through fermentation with a substrate addition. The results can provide a theoretical basis for the safe application of the strain.
    11  Variations in the Physicochemical Properties and Bacterial Community Compositions during Culture of Yellow Water with Addition of Calcium Carbonate Powder
    WANG Yan-li ZHANG Hui-min LI An-jun MENG Ya-jing LIU Guo-ying WANG Lu DING Feng ZHOU Qing-wu LIANG Jin-hui
    2021, 37(9):76-85. DOI: 10.13982/j.mfst.1673-9078.2021.9.1189
    [Abstract](190) [HTML](181) [PDF 1.77 M](411)
    Abstract:
    The bacterial community compositions and physicochemical properties of yellow water from young and old fermentation pits of strongly flavored liquors during two-month static culture after adding appropriate and excess amounts of calcium carbonate powder were invistigated. During the two-month culture, the pH value (from 4.20 to 4.60 → 5.00 to 5.30 for yellow water from the young pit; from 5.00 to 5.30 → 4.00 to 4.50 for that form the old pit) and the butyric and caproic acid contents increased and then decreased. Furthermore, the pH value dropped more significantly for yellow water with the addition of an appropriate amount of calcium carbonate powder. The starch and reducing sugar contents declined continuously. The calcium ion contents (from 4.82 to 6.32 g/L → 5.53 to 8.89 g/L), ammonium nitrogen (from 1.28 to 1.69 g/L → 1.53 to 2.18 g/L), and acetic acid (from 4.74 to 5.44 g/L → 5.74 to 9.61 g/L) increased. Moreover, the calcium ion concentration increased more remarkably for yellow water with excessive calcium carbonate, whereas the increases in the ammonium nitrogen and acetic acid contents were more considerable for yellow water from the old pit. The lactic acid content reduced first (from 62.21 to 64.57 g/L → 54.67 to 57.74 g/L) but then increased (from 54.67 to 57.74 g/L → 67.89 to 75.30 g/L); its increase is more noticeable for yellow water with an appropriate amount of calcium carbonate powder. The bacterial community diversity indices, including operational taxonomic units (from 125 to 169 → 83 to 90), Chao1 (from 133.08 to 174.44 → 88.08 to 95.52), and Shannon (from 1.43 to 2.24 → 0.57 to 0.83), decreased continuously during two-month culture for all yellow water samples. Meanwhile, the abundance of the predominant genus Lactobacillus grew continuously (from 94.48% → 99.99%), but the bacteria of other dominant and unknown genera died out gradually (from 5.52% to almost 0). The results demonstrate the environment is modified when calcium carbonate is added to yellow water, becoming more favorable for Lactobacillus. As a result, Lactobacillus becomes more dominant, while the growth of bacteria of other genera is inhibited. The findings of this study provide some theoretical explanation for the dominance of Lactobacillus in the mud of aging pits.
    12  Inhibitory Effects of Phenolic Acid Monomers in Sugarcane Molasses on PhIP in a Phenylalanine-creatinine Model Reaction System
    YU Di LONG Juan HUANG Yuan HUANG Jia-jia ZHAO Li-chun KONG Fan-lei
    2021, 37(9):86-92. DOI: 10.13982/j.mfst.1673-9078.2021.9.0014
    [Abstract](259) [HTML](173) [PDF 1.03 M](479)
    Abstract:
    The inhibitory effect of ferulic acid and vanillic acid in sugarcane molasses on PhIP was studied in a model reaction system. The colloid, ash and heavy metals in the molasses were removed through the molasses purification treatment method to yield a crude molasses extract. A gallic acid standard curve was established to determine the polyphenol content in molasses extract. The type of phenolic acids in the molasses extract was determined by UPLC-MS analysis. The phenolic acid standard was added to the model reaction system (phenylalanine and creatinine), and changes in PhIP in the model reaction system was analyzed by the UPLC-MS/MS system. The results showed that the polyphenol content in the molasses extract was as high as 3.58 mg/g. Compared with the phenolic acid standard, the molasses extract was found to contain ferulic acid and vanillic acid. In the model reaction system, withthe increase of the concentration of vanillic acid or ferulic acid, both the phenylalanine content and the amount of PhIP produced in the model reaction first decreased gradually and then leveled off. When the concentration of ferulic acid reached 2.33×10-7 g/mL, the inhibitory effect on PhIP was the best, and the overall inhibitory rate was 76.67%. When the concentration of vanillic acid reached 2.02×10-7 g/mL, the inhibitory effect on PhIP was the greatest, and the overall inhibitory rate reached 77.43%. In summary, the ferulic acid and vanillic acid monomers contained in sugarcane molasses had strong inhibitory effects on PhIP in the model reaction system, which provides a basis for subsequent research on the inhibitors of PhIP.
    13  Study on the Chemical Compositions and Emulsification Stability of Water-soluble Dietary Fibers from Wine Grape Skin
    QUAN Di-hong YANG Hua-feng ZOU Ji-yun LIU Xiao-hua WANG Yu-tao YU Shu-juan
    2021, 37(9):93-101. DOI: 10.13982/j.mfst.1673-9078.2021.9.0861
    [Abstract](208) [HTML](184) [PDF 5.16 M](564)
    Abstract:
    Soluble dietary fiber (SDF) was obtained from wine grape skin by two different methods, viz. hot acid and enzymatic methods, and the chemical compositions of the two types of water-soluble dietary fiber, viz. SDF1 (extracted via hot acid method) and SDF2 (obtained using enzyme method), were determined. Subsequently, SDF1 and SDF2 were used to prepare oil-in-water emulsions. The emulsion uniformity was examined using the particle size distribution, while the emulsifying stability was determined using the volume-weighted mean diameter (D4,3). The protein, galacturonic acid, and neutral sugar contents, degrees of methylation and acetylation, and molecular weight of SDF2 are lower than those of SDF1. The emulsions were stored separately for 15 d at 4, 20, and 60 ℃. After storage, the D4,3 value of SDF1 emulsion increases from 1.10 μm to 4.29 μm (4 ℃), 5.72 μm (20 ℃), and 7.57 μm (60 ℃), indicating the higher stability of SDF1 emulsion at low temperatures. After storage, the D4,3 value of SDF2 emulsion increases from 3.73 μm to 17.7 μm (4 ℃), 15.30 μm (20 ℃), and 12.47 μm (60 ℃). Eventually, the values of SDF2 emulsions stored at different temperatures reach ≥12 μm, indicating an unsatisfactory overall stability of SDF2 emulsions. The span of SDF1 ranges from 3.37 to 4.18, which is significantly higher than that of SDF2 (2.84~3.52); therefore, SDF2 is more homogeneous than SDF1. After enzyme treatment, the emulsifying activity of SDF decreases significantly. Hence, the emulsifying stability of SDF can be considerably improved by ensuring the integrity of components such as proteins and neutral sugars in SDF.
    14  Molecular Identification and Nutrients Composition Analyses of Two Wild Boletaceae
    WU Yan WANG Wei WANG Yan SHEN Li-qun
    2021, 37(9):102-108. DOI: 10.13982/j.mfst.1673-9078.2021.9.0017
    [Abstract](212) [HTML](290) [PDF 445.77 K](724)
    Abstract:
    The fruiting bodies of two wild Boletaceae Baicong and Hongcong grown in Xingyi were subjected identification by molecular biology tools. Based on the international general protein assessment model, the protein nutrition value of the two wild Boletaceaes was examined and compared with the data of Xerocomus spadiceus, Leccinum aurantiacum, and Boletus griseusin literature. The results showed that the scientific name of Baicongis Boletus roseoflavus, and the scientific name of Hongcong is Lanmaoa asiatica. The main nutritional components (g/100 g) of the Boletus roseoflavus fruiting body were: crude protein 46.20, crude fat 2.0, crude fiber 15.0, crude polysaccharide 4.70, soluble sugar 9.60; total essential amino acids 11.27, total amino acids 27.80, and total flavor amino acids 10.84. The main nutritional components of the Lanmaoa asiatica fruiting body were: crude protein 56.0, crude fat 2.0, crude fiber 17.0, crude polysaccharide 7.20, soluble sugar 7.60; total essential amino acids 13.76, total amino acids 33.40, and total flavor amino acids 13.04. The E/N ratios of Boletus roseoflavus and Lanmaoa asiatica were 0.68 and 0.70, respectively, with their E/E+N ratios being 40.58% and 41.20%, respectively. Both the total amounts of essential amino acids meet the FAO/WHO standard model, with a balanced nutritional composition and abundant amounts of amino acids. Both fungi had an essential amino acid index (EAAI) of 1.33, indicating high-quality protein sources.
    15  Analysis of the Degree of Polymerization and Antioxidant Activity of Procyanidins Degraded by Sodium Hydroxide
    YANG Yang ZHANG Lei LI Xue-wen
    2021, 37(9):109-118. DOI: 10.13982/j.mfst.1673-9078.2021.9.0054
    [Abstract](219) [HTML](268) [PDF 2.23 M](536)
    Abstract:
    The grape seed of Cabernet Sauvignon was studied, sodium hydroxide was used to degrade polymeric proanthocyanidins, and the degradation process was optimized through single factor experiment and response surface methodology. The mean degree of polymerization, proanthocyanidin content, changes in different components, and DPPH and ABTS free radical scavenging capabilities of the samples under different treatments and optimal degradation process conditions were analyzed. The results showed that the optimal degradation process conditions were 4.40% of sodium hydroxide concentration, 31 min of treatment time, and 59 ℃ of treatment temperature. Under these conditions, the average degree of polymerization of polymeric proanthocyanidins decreased from 5.71 to 2.37; the content of proanthocyanidins increased by 1.68 times; The peak areas of monomer, ECG and dimer increased by 14267.50, 28304.00, 52998.33 respectively, and the total peak area increased by 1.80 times. The free radical scavenging capacity of DPPH and ABTS increased by 2.41 times and 2.19 times, respectively. In summary, grape seed proanthocyanidins are degraded by sodium hydroxide to obtain oligomeric proanthocyanidins with strong antioxidant activity, which provides a theoretical basis for the development and utilization of polymeric proanthocyanidins in grape seeds, which is a byproduct of winemaking, and has certain practical application value and significance.
    16  Migration of Chitosan-cinnamaldehyde-β-cyclodextrin Inclusion Complex in Antibacterial Paper and Its Application for Preservation of Xiaoxiang Chicken
    WEI Yao DENG Li LI Jing-peng ZENG Xue-feng LI Shuang-yan LI Li-dan ZHAO Ting-xia
    2021, 37(9):119-127. DOI: 10.13982/j.mfst.1673-9078.2021.9.0076
    [Abstract](191) [HTML](209) [PDF 1.00 M](475)
    Abstract:
    The migration behavior of chitosan-cinnamaldehyde-β-cyclodextrin (β-cyclodextrin, β-CD) inclusion complex in antibacterial paper and its effect on preservation of xiaoxiang chicken were studied. The migration amount of cinnamaldehyde to food simulants was determined by UV spectrophotometry. The effects of food simulants on the migration of cinnamaldehyde were analyzed. The model for cinnamaldehyde migration was established by the Fick’s law, which provided a relatively standardized quantitative reference for this research. The control group and the packaging group in preserving the quality of xiaoxiang chicken were evaluated by total bacterial count, pH, TBA, TVB-N and sensory features. Theresults showed that the migration of cinnamaldehyde to four food simulants was in the decreasing order of 50% ethanol>10% ethanol >60% glycerin> n-hexane, which indicated that the chitosan-cinnamaldehyde-β-CD inclusion complex antibacterial paper had a long-term antibacterial effect on foods with medium and high water activity. When applied on xiaoxiang chicken, TVB-N≥20 mg/100 g was used as the standard to judge meat spoilage and storage end point, the TVB-N value of the control group was 19.48 mg/100 g at day 18, and the TVB-N value of the packaging group was 20 mg/ 100 g at day 25. Compared with the control group,the packaging group could prolong the storage period of Xiaoxiang chicken for 7 days. According to the above results, the migration rate of cinnamaldehyde was affected by the controlled release of β-CD and the properties of the food simulant, and the shelf life of xiaoxiang chicken could be effectively extended by antibacterial paper.
    17  Relationship between Antioxidant Systemand Browning of Postharvest Grape Rachis
    ZHANG Qiong-qiong WEI Jia LI Jie ZHANG Jian WEN Chun MA Xian-hua WU Bin
    2021, 37(9):128-137. DOI: 10.13982/j.mfst.1673-9078.2021.9.0061
    [Abstract](299) [HTML](201) [PDF 1.56 M](552)
    Abstract:
    Xinjiang Red Globe grape and Munage grape were used as test materials, which stored at a temperature of 10±0.5 ℃. The differences between fruit rachis were analyzed in storage. The correlation between the browning of fruit rachis and the changes of antioxidant systems were studied. The results showed that after storage to the 6th day, the total phenol content of Red Globe grape rachis and Munage grape rachis were respectively 5.37 and 5.41 A280 nm/g. The activities of PPO and POD were respectively 0.21, 1.09 and 0.82, 0.11 U/g. The activity of SOD, CAT and APX in Red Globe grape rachis were respectively 26.98 U/g, 64.44 U/g, 30.89 U/g, which were respectively 1.03 times, 2.19 times and 1.85 times of those in Munage grape rachis. The browning index, superoxide anion (O2-·), relative conductivity of H2O2 content, MDA content and flavonoid content of Red Globe Grape rachis were significantly lower than those of Munage grape rachis (p<0.05), which were 4.04%, 43.17%, 11.55%, 43.32%, 13.78% and 30.94% lower respectively. Through correlation analysis, the browning index of the Red Globe grape and the Munage grape rachis were significantly positively correlated with the relative conductivity, malondialdehyde content, total phenols, flavonoids and H2O2 content (p<0.05), and PPO activity is positively correlated (p>0.05). Red Globe grape rachis browning index has a good correlation with POD activity and CAT activity (p<0.05). However, Munage grape rachis browning index has a good correlation with PAL activity and SOD activity (p<0.05). Therefore, grape varieties are closely related to the antioxidant system, leading to different browning process of fruit rachis.
    18  Comparison of the Fruit Pulp Quality Characteristics and Antioxidant Capacity of Rambutan Fruits with Different Maturity Levels
    ZHU Wen-jing ZHANG Rong-hu DENG Hao LIN Yu-qin FENG Jian-cheng
    2021, 37(9):138-144. DOI: 10.13982/j.mfst.1673-9078.2021.9.0026
    [Abstract](205) [HTML](206) [PDF 700.99 K](611)
    Abstract:
    Hainan "Baoyan-7" rambutan fruit were used as the experimental raw materials, which were collected at different maturity stages (30 %, 50 %, 70 % and 100 % maturity levels). The fruit pulp quality and antioxidant capacity indices of the above-mentioned rambutan fruits including soluble solid substance (TSS), titratable acid (TA), reducing sugar, reduced ascorbic acid (AsA), total antioxidant capacity, hydroxyl radical (·OH) scavenging ability, and the activities of ascorbic acid peroxidase (APX), catalase (CAT), peroxidase (POD) and polyphenol oxidase (PPO) were determined, in order to evaluate the effects of maturity level on the quality and antioxidant capacity of rambutan fruit. The results showed that at the 70 % maturity level, the TSS content (17.01%), AsA content (278.13 μg/g), total antioxidant capacity (151.04 U/g), ·OH scavenging capacity (79.16%), APX activity [1.31×104 (nmol/min.g)] and CAT activity (99.86 U/g) were all the highest, with the TA content (0.53%) and reducing sugar content (57.44 mg/g) being the lowest; At the 50% maturity level, the POD activity reached the highest (12.22 U/g) and the PPO activity reached the lowest (7.33 U/g). In summary, there are significant differences in the pulp quality and antioxidant capacity of rambutan fruits with different maturity levels. The Hainan "Baoyan-7" rambutan fruit at the 70% maturity level was suitable for harvesting. The results of this research provide theoretical and technical bases for the improvement of post-harvest commercial processing of rambutan fruit and the quality maintenance during storage and transportation.
    19  Lateral Relaxation Analysis of Walnut Drying Process by Low Field Nuclear Magnetic Resonance
    QU Wen-juan FAN Wei XIONG Ting GUO Tian-tian SHI Jun-ling MA Hai-le PAN Zhong-li
    2021, 37(9):145-154. DOI: 10.13982/j.mfst.1673-9078.2021.9.0377
    [Abstract](162) [HTML](207) [PDF 2.02 M](580)
    Abstract:
    In order to quickly monitor the changes of moisture and oil in the drying process, low field-nuclear magnetic resonance (LF-NMR) technology was used to determine the free water, weakly and strongly bound water and oil of walnuts under the constant temperature and variable temperature drum catalytic infrared-hot air drying, and compared with the single hot air drying. Moreover, a mathematical model between the proportion of the moisture lateral relaxation peak area and the actual moisture content was established. The results showed that the changing trend of the drying curve under the three drying methods was the same. Compared with the single hot air drying [duration 20 h, maximum drying rate 0.11 g/(g·min)], the variable temperature and constant temperature drum catalytic infrared-hot air drying efficiencies [drying times of 14.38 h and 16.16 h, maximum drying rates of 0.28 g/(g·min) and 0.48 g/(g·min)] were significantly increased, the drying times were shortened by 28.10% and 19.20% respectively, and the maximum drying rates were increased by 2.55 and 4.36 times respectively, indicating that the catalytic infrared drying treatment significantly improved drying effectiveness. The LF-NMR transverse relaxation map showed that the free water peak area decreased significantly during the drying process until it disappeared, the weakly bound water peak area was significantly reduced, and the strongly bound water and oil peak areas remained basically unchanged, indicating that the drying process removed almost all the free water and most of the weakly bound water and had no obvious effects on the strongly bound water and oil contents. A mathematical model between the proportion of the moisture relaxation peak area and the actual moisture content was established. R2 was greater than 0.90, and the prediction effect was good. In general, compared with the national standard method, LF-NMR can detect the change of moisture and oil during the drying process very well, and it was a new method for efficient and rapid detection of moisture content.
    20  Thermal Insulation Performance Test of the Temperature Control System above Grain Bulk in a Single-storey Warehouse under Different Operating Conditions
    CHEN Yan WANG Yu-bo DING Yong-gang CUI Wei-hua
    2021, 37(9):155-161. DOI: 10.13982/j.mfst.1673-9078.2021.9.0010
    [Abstract](120) [HTML](227) [PDF 2.52 M](535)
    Abstract:
    A single-storey grain bulk warehouse was used as the research object, and a temperature control test system above the grain bulk was set up for a variety of thermal insulation experiments under different working conditions, to investigate the factors affecting the insulating effect of the system in hot climates. The results showed that the temperature rise of the grain bulk caused by external heat mainly occurred to the grains on the grain bulk surface 10 cm below the grain loading line. The surface temperature control system of grain bulk reduced effectively the impact of sudden high external temperature on the surface grain temperature. Under the optimal conditions, the surface temperature of the grain bulk was reduced by 1.67 ℃. Among the influencing factors such as inlet air temperature, inlet air speed, and interlayer height, the inlet air temperature exhibited a greater impact on the surface temperature rise of grain bulk, compared with inlet air speed and interlayer height. In the actual projects, low air speed and temperature were used to decrease the unit cost to 5.6 yuan/ton grain while reducing energy consumption. The Nusselt number (Nu=hl/λ) Nu was used to define the heat transfer performance of the system, with the dimensionless temperature θ in the range of 0.4~1. Nu increased (between 45 and 85) with Θ, but was not affected greatly by H (Nu in the range of 82~89 when H increased from 0.05 to 0.09). During the tests with an inlet air temperature of 22 ℃, the air humidity close to the upper surface of the system inside the warehouse was reduced by 13% compared to the initial value, which was 5% higher than the humidity outside, with no condensation occurring in the grain bulk.
    21  Rheological Properties of Whole Chestnut Powder-Wheat Flour Doughs
    SHI Jian-bin SUI Yong CAI Sha HE Jian-jun XIONG Tian FAN Chuan-hui CHEN Xue-ling JIA Zhi-wen WANG Shao-hua CAI Fang MEI Xin
    2021, 37(9):162-168. DOI: 10.13982/j.mfst.1673-9078.2021.9.0015
    [Abstract](158) [HTML](184) [PDF 1.59 M](456)
    Abstract:
    The whole chestnut powder was produced by different drying methods using defective and secondary products of chestnut processing as the raw materials. The physicochemical properties of the whole chestnut powder and rheological properties of the whole chestnut powder-wheat flour dough were investigated. The results showed that the degree of gelatinization of the obtained whole chestnut powder is over 50%, and the degree of gelatinization of the cooked chestnut powder was as high as 70.69%, whilst the degree of gelatinization of raw chestnut powder was only 3.28%. With an increase in the addition amount of the raw chestnut powder, the water absorption rate and setback value decreased, and the degree of softening increased, which were 50%, 0.65 N·m and 0.81 N·m, respectively when the addition amount was30%. However, the development time, stabilization time, pasting properties, paste stability decrease first and then increased. The water absorption rate increased, but the stabilization time, pasting properties, paste stability, degree of softening, and setback value decreased as the addition amount of cooked chestnut powder increased. The development time showed a slight upward trend with the addition of ZR and SH-20, whilst development time of dough with other gelatinized chestnut powders showed a small increase and then a sharp decrease. Cross-section analysis of doughs indicated that the addition of raw chestnut powder mainly reduced water absorption rate and mixing and gluten indices. The water absorption rate and gluten index were increased after the addition of gelatinized chestnut powder. In short, raw whole chestnut powder and gelatinized whole chestnut powder had different effects on the characteristics of resulting doughs, which will provide a vital theoretical basis for the processing and comprehensive utilization of defective and secondary chestnut products.
    22  Comparative Comprehensive Quality Analysis of Rosa roxburghii Fruit from Different Regions in Guizhou Province
    YU Lu ZHAO Zhi ZHANG Wen-xin REN Ting-yuan
    2021, 37(9):169-178. DOI: 10.13982/j.mfst.1673-9078.2021.7.0041
    [Abstract](339) [HTML](379) [PDF 486.25 K](648)
    Abstract:
    To identify superior Rosa roxburghii cultivars in Guizhou and provide a scientific basis for large-scale planting, cultivation, and processing of medicinal Rosa roxburghii products, this study examined Rosa roxburghii fruits from 22 regions of Guizhou by determining their basic nutritional content. Measured values include soluble solids, titratable acids, soluble proteins, vitamin C, and superoxide dismutase (SOD) activity. Overall quality of Rosa roxburghii fruit from different regions was analyzed and compared. Correlation analyses, principal component analyses, and cluster analyses were performed, and a scoring model was constructed to comprehensively evaluate Rosa roxburghii fruit quality. Significant differences were identified in the comprehensive quality indices of Rosa roxburghii fruits from different regions (p<0.05). In particular, vitamin C content varied greatly. Except for SOD activity index, a significant correlation was observed between all other indices (p<0.05). Soluble solid, total sugar, soluble protein, and vitamin C contents were the highest in fruit from the Renhuai region, whereas reducing sugar content and SOD activity were the highest in those from the Yinjiang region. Amino acid content was the highest in fruit grown in the Wangmo region. All comprehensive quality indices were relatively high in fruit from the Dejiang region. Three principal components (eigenvalue>1) were identified, and the cumulative variance contribution rate reached 75.162%. According to the comprehensive scoring model, the Rosa roxburghii fruit-growing regions are ranked in descending order of overall fruit quality as follows: RH>YJ>DJ>WM>LD>ZA>DZ> PD>HZ>LD>CS>LL>DF>BJ>ZN>KL>FG>AS>MJ>SN>SC>LZ>PZ. When the Euclidean distance is 20, Rosa roxburghii fruits from different regions can be divided into three categories according to their overall quality, and the results of cluster analysis are basically consistent with those of principal component analysis. Rosa roxburghii fruits in Dejiang, Renhuai, Yinjiang, and Wangmo were found to be of better overall quality. Fruit quality is thus closely correlated with altitude. Therefore, good-quality Rosa roxburghii fruits from high-altitude regions should be considered for exploitation and utilization.
    23  Synthetic Optimization of Ferulic Acid/Curdlan Graft Copolymers
    WANG Zi-wei CAI Wu-dan YAN Jing-kun
    2021, 37(9):179-185. DOI: 10.13982/j.mfst.1673-9078.2021.9.1100
    [Abstract](212) [HTML](178) [PDF 920.41 K](542)
    Abstract:
    A free-radical-mediated grafting method was used to prepare ferulic acid (FA)/curdlan graft copolymers. The effects of FA and vitamin C (Vc) addition, hydrogen peroxide (H2O2) concentration, and reaction time on the grafting ratio and yield of FA/curdlan graft copolymers were investigated using single factor experiments. Accordingly, the synthetic parameters of FA/curdlan graft copolymers were further optimized through orthogonal experiments. The results demonstrated that the optimal process conditions for the preparation of FA/curdlan graft copolymers included 25 mL of 5 mg/mL curdlan solution, 250 mg of FA, 50 mg of Vc, 5 mol/L H2O2, and a reaction time of 12 h. Under these conditions, the highest grafting rate and yield of the FA/curdlan graft copolymers of 98.62 mg FA/g and 40.84%, respectively, were obtained. Grafting was also confirmed by ultraviolet and infrared spectroscopy analyses. Therefore, the proposed preparation technique not only improved the physicochemical properties of curdlan, but also increased the grafting ratio of the graft copolymers. The findings of this study provide a theoretical foundation for the practical applications of curdlan in food industry.
    24  Comparative Analysis of Simiao Rice Quality under Different Degree of Milling
    LIU Jing-jing ZHANG Ming-wei WEI Zhen-cheng LIU Guang PENG Jun-jian TANG Xiao-jun ZHANG Yan ZHAO Zhi-hao ZHOU Peng-fei LI Ping WANG Jia-jia ZHONG Li-huang WANG Zhi-ming LIAO Na DENG Yuan-yuan
    2021, 37(9):186-192. DOI: 10.13982/j.mfst.1673-9078.2021.9.0161
    [Abstract](201) [HTML](187) [PDF 543.53 K](521)
    Abstract:
    In order to explore the changing law of the taste quality of the southern high-quality Simiao rice during the milling process, Meixiangzhan 2 was used as raw material in the milling experiment for different milling degree (2%, 4%, 6%, 8%, 10%, 12%) in this study. Then, the effects of different milling degree on processing characteristics, cooking and sensory properties were analyzed. The results showed that with the improvement of processing accuracy, the cooking properties and sensory qualities of rice were improved, but the energy consumption and broken kernel yield of rice were significantly increased. When the degree of milling reached 2%, compared with brown rice, the husk retention decreased from 99.8% to 52.83%, the broken kernel yield of rice increased to 2.74%, the energy consumption increased to 87.50 kJ/kg, and cooking properties and sensory qualities significantly improved. When the degree of milling reached 8%, the husk retention was 3.43%. There is no significant difference between milling degree 8% and 12% in sensory qualities. When the degree of milling reached 12%, the husk retention was 1.10%, the broken kernel yield of rice increased to 28.97%, the energy consumption increased to 1090.00 kJ/kg, the optimum cooking time was shortened from 32.67 min to 18.33 min, and the total score of sensory evaluation was 79.00. Choosing the suitable degree of milling according to different needs is more conducive to saving energy and improving the utilization of food resources.
    25  Effects of Different Modifiers on the Quality of Highland Barley Steamed Sponge Cakes
    RAO Chen-lu CHEN Ling ZHANG Cheng-zhi ZHENG Bo
    2021, 37(9):193-199. DOI: 10.13982/j.mfst.1673-9078.2021.9.0072
    [Abstract](240) [HTML](185) [PDF 1.61 M](582)
    Abstract:
    Traditional highland barley steamed sponge cakes contain the shortcomings of rough texture and high hardness, which seriously affect their sensory characteristics. In this study, therefore, the established sensory evaluation system of highland barley steamed sponge cake combined with modern analysis techniques were used to study the improvement effects of three modifiers, xanthan gum (Xan), guar gum (Guar), and modified tapioca starch (Cas), on the quality of highland barley steamed sponge cakes. The results showed that the optimal additive amount of Xan, Guar, and Cas were 0.2%, 0.4%, and 4%, respectively, and highland barley steamed sponge cake improved with 0.4% of Guar had the highest sensory score (94.00). The starting gelatinization temperature of the highland barley flour slurry was significantly increased, while the stability of hot paste and cold paste was reduced (p<0.05), because of the addition of these three modifiers. Furthermore, all three modifiers could increase the water holding capacity of the slurry. Among them, the content of strongly bound water of the highland barley flour slurry was increased by 16.68% after introducing Xan, while the content of weakly bound water was increased by 2.47% after introducing Guar. The stomatal surface fraction and stomatal density of the highland barley steamed sponge cake by adding 0.2% of Xan were reduced to 1.38% and 0.07 mm-2, respectively, while those of the highland barley steamed sponge cake by adding 0.4% of Guar could be increased to 24.26% and 0.50 mm-2, respectively. Also, the texture characteristics of the highland barley steamed sponge cake were improved by the three modifiers. Among them, the hardness of the highland barley steamed sponge cake could be reduced to 695.78 g by adding 0.4% of Guar. All three modifiers could improve the sensory quality of the highland barley steamed sponge cakes by reducing the hardness, adhesiveness, stringiness, chewiness and enhancing the resilience. The results can provide a theoretical reference for the quality improvement of the highland barley steamed sponge cakes.
    26  Comparative Analysis of Ultra-high Hydrostatic Pressure and Thermal Sterilization of Wampee Puree
    ZHANG Li-juan ZOU Bo XIAO Geng-sheng XU Yu-juan YU Yuan-shan WU Ji-jun LI Lu ZOU Ying
    2021, 37(9):200-206. DOI: 10.13982/j.mfst.1673-9078.2021.9.0028
    [Abstract](297) [HTML](271) [PDF 752.02 K](488)
    Abstract:
    Wampee puree was used as the research object, and sterilized by ultra-high hydrostatic pressure (HHP) and heat treatment (HT), respectively. The changes in the physico-chemical indexes of wampee pulp before and after the treatment as well as during the storage at 4 ℃ were compared. At the end of the storage, the total numbers of bacterial colonies for the HPP group and HT group were 67.36 and 43.49 CFU/mL, respectively, indicating that the sterilization ability of the treatments at ultra-high pressure of 600 Mpa/5 min towards wampee puree was equivalent to that of heat treatment at 85 ℃/30 min; The changes in pH, titratable acid (TA) and total soluble solid (TSS) content were insignificant before and after the two treatments and during storage; The total phenolics, ascorbic acid and antioxidant capacity of the wampee puree treated with HPP or HT decreased during storage. During storage, the total phenolics and ascorbic acid decreased by 11.71% and 9.45%, respectively, in the HPP group, and 19.61% and 18.92%, respectively, in the HT group. These results showed that HPP could retain better the contents of total phenolics and ascorbic acid in wampee puree and reduce the loss of antioxidant capacity; HT increased the pectin content of wampee puree by 23.15%, while HHP treatment had insignificant effect on pectin content but could retain better the pectin content during storage. The organic acids in wampee puree were mainly tartaric acid, malic acid and citric acid, with the content of tartaric acid being the highest (13.95 mg/g). The impact of HT on the organic acids in wampee puree was less than that of HPP treatment. The results provides a theoretical basis for the application of HHP and HT treatments to wampee puree processing. Key words: ultra-high hydrostatic pressure; wampee puree; storage; quality
    27  Comparison of Physicochemical Properties of Spinach Powder Using Different Drying Methods
    SONG Juan ZHANG Hai-yan YUAN Jing ZENG Chao-zhen MU Yu-wen KANG San-jiang LI Yu-xin GOU Li-na
    2021, 37(9):207-215. DOI: 10.13982/j.mfst.1673-9078.2021.9.0127
    [Abstract](341) [HTML](226) [PDF 5.83 M](697)
    Abstract:
    Spinach powder was prepared by hot air drying, solar drying, vacuum freeze drying and spray drying. The effects of different drying methods on the color, antioxidant activity, microstructure and other physicochemical properties of spinach powder were investigated. The results showed that the L* value of spray drying was 33.28 and the a* value was -5.86, which had little effect on the color of spinach powder. Compared with the fresh control, the contents of chlorophyll ascorbic acid total phenols and total flavonoids and antioxidant activity of spinach powder prepared by four drying methods were decreased, and the four drying methods had a greater effect on the antioxidant activity of spinach powder, spray drying had the highest antioxidant activity, and hot air drying had the lowest antioxidant activity. Correlation analysis showed that the total phenols, flavonoids and ascorbic acid of spinach powder were significantly positively correlated with their antioxidant activity (p<0.05). Through particle size distribution analyzer and SEM analysis, the median particle size DX(50) of spinach powder prepared by spray drying decreased to 17.76 μm, the specific surface area increased to 228.3 m2/kg, and the span value decreased to 2.87. Spinach powder was a short round rod-shaped or spherical, the particles were small and evenly distributed, part of the surface was round, the cell structure was better maintained compared with the other three drying methods. Based on the comprehensive analysis, spray drying was the best drying method for preparing spinach powder, which was more suitable for industrial production of spinach powder with high antioxidant activity, and provided scientific basis for the deep processing of spinach powder products.
    28  Optimization of the Purification Process for the Polysaccharides from Tetradium ruticarpum Fruit Using Macroporous Adsorption Resins
    PAN Feng RUAN Guo-yong YANG Jian-bo ZHU Xin-ting LIU Yun
    2021, 37(9):216-225. DOI: 10.13982/j.mfst.1673-9078.2021.9.0047
    [Abstract](253) [HTML](199) [PDF 4.10 M](582)
    Abstract:
    In order to obtain the best purification process using macroporous resin for the polysaccharides from Tetradium ruticarpum fruit (TrPs), water extraction and alcohol precipitation were applied to extract the polysaccharides. The purification performance of seven different types of macroporous adsorption resins was examined by used static and dynamic single factor experiments, and the purification process was optimized by the response surface method. Finally, the polysaccharide structure before and after adsorption was characterized. The results show that the S-8 resin had the highest comprehensive purification efficiency for the crude TrPs, and the optimal purification conditions were: sample concentration, 4.41 mg/mL; initial pH 5; adsorption environment temperature, 24.30 ℃; flow rate 2.0 BV/h. Under these conditions, the decolorization rate was 49.21%, deproteinization rate was 68.97% and polysaccharide retention rate was 55.05%. The structural characterization results revealed the molecular weight (Mw) distribution of the polysaccharide before and after adsorption (Mw of peak 1 higher than 2.00×105 u; Mw of peak 2, approximately 2.35×104 u), the infrared absorption characteristics and the sugar chain anomeric hydrogen absorption signal of TrPs (δ 5.04×10-6 and δ 4.42×10-6) did not change significantly before and after adsorption. In summary, S-8 macroporous adsorption resin can be used for the high-efficiency purification of TrPs, under mild and environmentally friendly conditions, without causing polysaccharide chain scission and polysaccharide structural changes.
    29  Optimization of Extraction Process of Russula virescens Polysaccharide
    ZHOU Li-hong WANG Guo-liang
    2021, 37(9):226-233. DOI: 10.13982/j.mfst.1673-9078.2021.9.0436
    [Abstract](277) [HTML](188) [PDF 2.84 M](426)
    Abstract:
    The ultrasonic-assisted extraction method of Russula virescens polysaccharide was studied. Several steps were used to extract Russula virescens polysaccharides including ultrasonic-assisted extraction, ethanol precipitation, Sevage deproteinization, then polysaccharide content was determined by phenol-sulfuric acid method. In this paper, single factor experiments were used to investigate the influence of four factors, including ultrasonic power, temperature, ultrasonic time and water-to-material ratio, on the yield of polysaccharides. On this basis, Box-Benhnken response surface method was used to design a four-factor three-level experiment, and a regression equation was established to study the degree of influence of each factor on the yield of Russula virescens polysaccharides. The extraction process was further optimized and the optimal extraction conditions for Russula virescens polysaccharides were obtained. The optimal extraction conditions were ultrasonic power 500 W, temperature 76 ℃, ultrasonic time 40 min, and water-to-material ratio 31 mL/g. The yield rate of polysaccharide was 6.50%. Therefore, the ultrasonic-assisted method is helpful to improve the extraction rate of Russula virescens polysaccharide. The regression model established by response surface method and the correlation between the actual value and the predicted value of related parameters are better, which can be used to analyze and predict the ultrasonic extraction of Russula virescens polysaccharides.
    30  Analysis of the Causes of the "Black Circles" in the Vacuum Cooked Salted Duck Eggs
    LI Qiu-yu LIU Hong-mei LI Yan DAI You LI Hui-zhong LIU Yan
    2021, 37(9):234-241. DOI: 10.13982/j.mfst.1673-9078.2021.9.0032
    [Abstract](668) [HTML](390) [PDF 1.61 M](623)
    Abstract:
    In order to determine the cause of the “black circle” phenomenon in the yolk of vacuum cooked salted duck eggs, the physico-chemical analyses were carried out on the black circle parts of the eggs with black circles and the corresponding parts of the non-black circle in the yolk of vacuum-cooked salted duck eggs in. The changes in the substances related to the formation of black circle were further studied after a preliminary determination. The results showed that the protein content of the black circle in the eggs with black circles decreased, the protein electrophoresis band at the molecular mass of 36 kDa became lighter, the microstructure of the egg yolk particles was in a mess, and the change of protein altered the pH value of the black circle region from 6.20 to 7.90, causing the change of the pigment color from yellow to yellow-green; The sulfur content is evenly distributed in the yolk of the non-black circled egg, while the sulfur content of the black circle part in the black circled egg was 5.17 mg/100 g, which is higher than that of the non-colored part (2.31 mg/100 g); The color reaction of S2- with egg yolk components indicated that it only led to a color reaction with metal ion-containing phosvitin, which can make the color of normal egg yolk turn black, darkening the egg yolk color, and promoting the formation of dark circles; The contents of Fe, Zn, and Cu in the black circled egg all increased to a certain extent, and all exhibited a color reaction with S2-, although only the color resulting from the reaction between Fe and S2- was in accordance with the characteristic color of the black circle. Further studies revealed the positive correlation between the Fe content and the degree of yolk black circle. In summary, the formation of black circle was caused by the combined action of protein, Fe, S2- and pigment.
    31  Changes in Aromatic and Functional Components of Finished Yunnan Black Tea Roasted under Different Conditions
    YANG Cai-xia WANG Yao WANG Yan-jiao YIN Jian-zhong WANG Song-mei PAN Hong-mei WU Zhi-shuang FENG Yue-mei WU Shao-xiong
    2021, 37(9):242-251. DOI: 10.13982/j.mfst.1673-9078.2021.9.1145
    [Abstract](231) [HTML](368) [PDF 428.18 K](595)
    Abstract:
    To improve Yunnan black tea quality, finished Yunnan black tea was roasted at different temperatures for varying durations. The aromatic components of the Yunnan black tea were detected using simultaneous steam distillation extraction-gas chromatography-mass spectrometry, whereas other functional components were determined using high-performance liquid chromatography. Changes in the primary aromatic and functional components of the Yunnan black tea roasted under different conditions were also studied. A total of 65 kinds of volatile substances were detected in the roasted Yunnan black tea. The contents of the primary aromatic components benzyl alcohol and geraniol increased significantly when the tea was roasted at 70 ℃ and 90 ℃ for 1~4 h. Similarly, the contents of indole and pyridine reached their maxima when the tea was roasted at 110 ℃ for 4 h. The content of pyrazine increased rapidly with time at 130 ℃. In contrast, tea polyphenol content decreased as the roasting temperature and time increased. Regardless of the roasting temperature, the gallic acid content increased gradually with time. The content of catechin peaked when the tea was roasted at 130 ℃ for 2.5 h. Furthermore, the contents of epigallocatechin gallate and three other substances increased after the tea was roasted at 70 ℃ and 90 ℃ for 1~2.5 h. In summary, roasting at 70 ℃ and 90 ℃ for 1~2.5 h enhanced the aroma of the finished tea and induced conversion of tea polyphenol to gallic acid and catechin. This method can enhance the effectiveness of Yunnan black tea as a health product.
    32  Determination and Comparation of the Volatile Components in Three Kinds of Characteristic Honeys of Yunnan Province
    WANG Tao-hong ZHANG Yun-shuang JIANG Xiao-lin GUAN Zhi-bin JIA Guang-qun ZHANG Jin-jie CUI Zong-yan
    2021, 37(9):252-262. DOI: 10.13982/j.mfst.1673-9078.2021.9.1222
    [Abstract](257) [HTML](210) [PDF 1.06 M](542)
    Abstract:
    In order to explore the composition and difference of the volatile components in three characteristic honeys from Yunnan province, headspace solid phase microextraction coupled to gas chromatography-mass spectrometry was used to determine the volatile components of the three honeys (Vicia villosa Roth honey, Macadamia integrifolia honey, and Hevea brasiliensis honey), combined with principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The results showed that a total of one hundred and five volatile compounds were detected in the three honeys, with 61 in Vicia villosa Roth honey, 55 in Macadamia integrifolia honey, and 62 in Hevea brasiliensis honey. Aldehydes, acids and alcohols were the main volatile compounds in Vicia villosa Roth honey (n-nonanal and acetic acid had higher contents). Alcohols terpenes and aldehydes were the main volatile compounds in Macadamia integrifolia honey (cis-linalool oxide and furanoid linalool oxide had higher contents, with trans- linalool 3,7-oxide as the characteristic volatile component). Aldehydes, alcohols and acids were the main volatile compounds in Hevea brasiliensis honey (nonaldehyde and trans-linalool oxide were of higher contents). The results of PCA and PLS-DA analysis showed that there were significant differences in volatile components among Vicia villosa Roth honey, Macadamia integrifolia honey, and Hevea brasiliensis honey, and the three kinds of honey were well classified with a 100% accuracy. The research showed that Vicia villosa Roth honey, Macadamia integrifolia honey and Hevea brasiliensis honey have their own unique volatile components, and the PCA and PLS-DA models established based on these volatile compounds can realize the effective classification and identification of the three honeys in Yunan.
    33  Toxicology Evaluation of Pandanus amaryllifolius Roxb Powder
    YU Huan ZHANG Ang MA Yong-zhong ZONG Ying FENG Ding-Shan JI Xun-zhi QIN Xiao-wei
    2021, 37(9):263-270. DOI: 10.13982/j.mfst.1673-9078.2021.9.0051
    [Abstract](333) [HTML](248) [PDF 406.98 K](485)
    Abstract:
    The subchronic toxicity of Pandanus amaryllifolius Roxb. powder on rats was evaluated, which was expected to provide toxicological safety basis for the development of food additions. The rats were randomly divided into the control group and Pandanus amaryllifolius Roxb. powder samples of low dose group (2.00 g/kg BW), middle dose group (4.00 g/kg BW), high dose group (8.00 g/kg BW), using the oral toxicity test method according to GB 15193.13-2015 in this study. There were 20 rats in each group, half male and half female. Oral toxicity of Pandanus amaryllifolius Roxb. powder was assessed by general clinical observation, weight and feeding, eye examination, hematology and biochemistry, urine examination, gross anatomy and histopathology. During the experiment, the rats’ growth was good. There were no significant differences in body weight, weight gain, food utilization rate, blood routine indexes, blood biochemical indexes, blood coagulation function indexes, organ weight and organ/body weight ratio among each Pandanus amaryllifolius Roxb. powder dose group and the control group (p>0.05). No abnormal changes were observed in routine urine, ophthalmoscopics, gross anatomy and histopathology. The no observed adverse effect levels (NOAEL) of Pandanus amaryllifolius Roxb. powder dose were 8.89 g/kg BW in male and 9.76 g/kg BW in female. There was no subchronic toxicity of Pandanus amaryllifolius Roxb. powdersamplesto rats in this study.
    34  Rapid Analysis of 13 Kinds of Plant Hormones in Rice by Ultra-performance Liquid Chromatography-tandem Mass Spectrometry
    ZHANG Qing LI Cheng-zhi LIN Yu-juan YU Xiao-zhang
    2021, 37(9):271-278. DOI: 10.13982/j.mfst.1673-9078.2021.9.1190
    [Abstract](359) [HTML](408) [PDF 644.49 K](908)
    Abstract:
    A rapid and efficient method based on ultra-performance liquid chromatography-tandem mass spectrometry was established for the analysis of 13 plant hormones in rice. The conditions for chromatographic separation and mass spectrometry detection were optimized. The target compounds were separated by ACQUITY UPLC BEH C18 (2.1 mm × 100 mm, id 1.7 μm) with gradient elution using acetonitrile (0.04% V/V formic acid) and water (0.04% V/V formic acid) solutions as the mobile phase; baseline separation was achieved within 11 min. The 13 plant hormones were determined in the electrospray positive ionization (ESI+) and multiple reactions monitoring (MRM) modes. Analysis of the results indicated that the 13 plant hormones had good linearity in the concentration range from 1 to 500 ng/mL, and the correlation coefficients were all greater than 0.9980; the recoveries ranged between 81.9% and 118.8%, and the relative standard deviations (RSD, n=3) were between 2.45% and 8.12%. The method is simple, sensitive, accurate, and reliable; therefore, it is suitable for determining the contents of 13 kinds of plant hormones in rice. Furthermore, it can provide technical support for detailed examination of the growth and development process of rice and the identification of plant hormone residue limits.
    35  Detection of Eggplant External Defects Using Hyperspectral Technology
    CHI Jiang-tao ZHANG Shu-juan REN Rui LIAN Meng-ru SUN Shuang-shuang MU Bing-yu
    2021, 37(9):279-284. DOI: 10.13982/j.mfst.1673-9078.2021.9.0034
    [Abstract](252) [HTML](183) [PDF 2.21 M](434)
    Abstract:
    Hyperspectral technology (in the range of 900~1700 nm) was employed to distinguish sound, suberized and rotten eggplants. A total of 252 eggplant samples were collected, including 170 sound eggplants, 60 suberized eggplants and 22 rotten eggplants. The hyperspectral imaging system was used to acquire hyperspectral images of 252 eggplant samples in the three types of areas (sound, suberized and rotten fruit regions), and a reasonable region of interest (ROI) was extracted to obtain the spectral data. A variety of preprocessing methods were used for spectral pretreatment and a partial least squares (PLS) discriminant analysis model was established. The results show that the prediction was the best after the model was subjected to normalization pretreatment. Therefore, normalization was selected as the pretreatment method, based on the pre-treated spectral data, the characteristic wavelengths were extracted by successive projections algorithm (SPA), regression coefficient (RC) and competitive adaptive reweighted sampling (CRAS) methods, and partial least squares (PLS) and multiple linear regression (MLR) discriminant models were established for analysis. The results showed that the CRAS-MLR model discriminate most effectively the 3 types of samples, with the coefficient of determination for the calibration set (Rc2) as 0.944, the coefficient of determination for prediction set (Rp2) as 0.901, and the RMSEC and RMSEP as 0.199 and 0.213, respectively. The discriminant accuracy of the prediction set was 96.8%. In this study, hyperspectral technology can be used to distinguish effectively the sound, suberized and rotten eggplants, which provides a theoretical reference for the nondestructive detection of eggplant defects.
    36  Establishment of Insulated Isothermal PCR Detection Method for Salmonella in Food
    YANG Ruo-xuan TONG Yao ZHAO Yan-ying TANG Cheng LIU Ji ZHU Cheng-lin ZENG Ying-jie YU Ji-cheng TANG Jun-ni
    2021, 37(9):285-293. DOI: 10.13982/j.mfst.1673-9078.2021.9.0080
    [Abstract](203) [HTML](232) [PDF 1.84 M](532)
    Abstract:
    In order to make up for the shortcomings of traditional culture method such as long time-consuming and cumbersome on-site detection steps, an insulated isothermal PCR (iiPCR) rapid detection method for Salmonella in food was established. Specific primers and probes were designed according to the invA gene of Salmonella; bacterial DNA was quickly extracted by the water bath method; the amount of primers, probes and templates was also optimized. Then, a method for rapid detection of Salmonella based on iiPCR was established. The specificity, sensitivity and stability of the established method were evaluated. At the same time, the established method was compared with the traditional PCR method and the traditional culture method for detecting Salmonella contamination in actual food samples. The established iiPCR detection method had good specificity, high sensitivity, and no cross-reaction with other bacteria. The lowest detection limit could reach 75 CFU/mL. The established iiPCR method could detect Salmonella contaminated in actual food samples within 6 hours, while the same detection effect was achieved by traditional PCR methods at least 12 hours. The accuracy of iiPCR method was verified by the traditional culture method. The established iiPCR method for detecting Salmonella contaminated in food is suitable for field detection, more quickly and simpler.
    37  Analysis and Identification of Angelica Quality Based on Three-dimensional Fluorescence Spectroscopy and Pattern Recognition Technology
    GUO Qing-ru LIU Hong SHI Zhen-ping YANG Fu-de SHI Xiao-feng SHAO Shi-jun
    2021, 37(9):294-304. DOI: 10.13982/j.mfst.1673-9078.2021.9.0106
    [Abstract](245) [HTML](228) [PDF 5.87 M](550)
    Abstract:
    The fluorescence spectral analysis technology was used to screen the preparation and test conditions of the sample solution, and the three-dimensional (3D) fluorescence spectrum quality analysis and discrimination method of Angelica sinensis extracts were established. The results showed that the 3D fluorescence spectral features of the water extracts were similar to those of the 50% methanol-water extracts, which mainly exhibited three characteristic excitation/emission peaks with different relative emission intensities at 270 nm/345 nm, 270 nm/475 nm and 330 nm/475 nm (λex/λem), respectively. The 3D fluorescence spectra of ethyl acetate extracts showed two characteristic fluorescence peaks of 265 nm/295 nm and 325 nm/425 nm. The established 3D fluorescence spectra of Angelica sinensis extracts also showed good specificities, which can realize the rapid and effective identification of several Chinese herbs from the same category of Angelica sinensis, i.e., Chuanxiong rhizoma, Angelicae pubescentis Radix, Glehniae Radix, Cnidii Fructus and Foeniculi Fructus. Combined with the computer pattern recognition method, the 3D fluorescence spectral information of the water extracts of Angelica sinensis samples from different producing areas and varieties were analyzed and discriminated by SPSS 22 software, and the results showed that the Angelica sinensis samples could be distinguished effectively, which were completely consistent with the actual results. The 3D fluorescence spectra of Angelica sinensis extracts showed the characteristic spectral morphology, which can reflect the information on composition and content of fluorescent substances. Combined with the computer pattern recognition method, the 3D fluorescence spectrum of the water extract of Angelica sinensis can realize the classification and discrimination of Angelica sinensis from different producing areas and varieties. The method is simple, fast and accurate, and can be used for quality consistency evaluation and authenticity identification of Angelica sinensis medicinal materials, which also provides a reference for further research and establishment of the quality control technology of 3D fluorescence spectrum fingerprint of Angelica sinensis.
    38  Pesticide Residue Analysis and Chronic Dietary Exposure Assessment of Highland Barley from Different Regions
    JIA Pai-pai LI Jia-mei LI Ji-rong LIAN Qian XIAO Ming
    2021, 37(9):305-312. DOI: 10.13982/j.mfst.1673-9078.2021.9.0389
    [Abstract](280) [HTML](155) [PDF 908.77 K](509)
    Abstract:
    In this study, highland barley samples from Qinghai and Tibet regions were examined, and 13 pesticides were quantified to determine the levels of pesticide residues in the samples. The risks of chronic dietary exposure to pesticide residues in highland barley from the two places were evaluated by comparison to the relevant standards. The results showed that the pesticide residue detection rate in Qinghai samples equaled 13.4%. Six pesticides were detected, namely carbendazim, difenoconazole, thiophanate-methyl, chlorpyrifos, triallate, and trifluralin, with the corresponding detection rates of 8.94%, 1.63%, 1.63%, 0.81%, 2.44%, and 0.81%. Two or more pesticide residues were found in 2.41% of the samples. The pesticide residue detection rate in the samples from Tibet was 8.55%. Four types of pesticides were detected: carbendazim, difenoconazole, thiophanate-methyl, and trifluralin, with detection rates of 3.42%, 3.42%, 0.85%, and 1.71%, respectively. Two pesticide residues were found in 0.86% of the samples. The chronic dietary exposure risk values for different age groups in China and of all pesticides detected in the highland barley samples from the two areas follow the order: (2~7 years) > (8~12 years) > (13~19 years) ≥ (> 65 years) ≥ (20~50 years) ≥ (51~65 years). The risk values for most female groups are higher than those of the corresponding male groups. The %ADI values range from 0.0004% to 0.14%, indicating that the contribution of pesticide residues from highland barley to the chronic dietary exposure risk is extremely low. The pesticide residue types, residual levels, and risk values of the highland barley samples from the two regions are different but the levels of pesticide residues in the highland barley samples from both regions are within the safety limit.
    39  QuEChERS-Gas Chromatography Tandem Mass Spectrometry for the Determination of Vinclozolin and Its Metabolite Residues in Fruits and Vegetables
    XIE Jian-jun HOU Ying-ye ZENG Guang-feng WANG Lu LI Ju
    2021, 37(9):313-318. DOI: 10.13982/j.mfst.1673-9078.2021.9.0012
    [Abstract](176) [HTML](203) [PDF 487.24 K](448)
    Abstract:
    An improved QuEChERS method combined with gas chromatography/mass spectrometry (GC/MS) method was established for the rapid determination of vinclozolin and its metabolite, 3,5-dichloroaniline residue, in fruits and vegetables. This research improved the type and amount of adsorbent in QuEChERS method. Vinclozolin and its metabolite residues in tomatoes, cucumbers, lettuce, celery, citrus and grapes were extracted with ethyl acetate. The extract was purified using 80 mg of PSA and 50 mg of GCB to remove impurities via adsorption, before quantification by GC/MS with external standards. The results showed that vinclozolin and its metabolite 3,5-dichloroaniline showed a linear relationship in the mass concentration range of 0.02~0.25 mg/mL, with the correlation coefficients as 0.997 and 0.998 respectively. The average recovery range of vinclozolin and its metabolite in tomatoes, cucumbers, lettuce, celery, citrus and grapes was between 81.67% and 113.33% at the spiked level of 0.05~3.0 mg/kg, with the relative standard deviations (RSDs) less than 9.47%. The limits of detection (LOD, S/N=3) were between 4.2 and 15.5 μg/kg for vinclozolin, and between 6.3 and 17.6 μg/kg for 3,5-dichloroaniline. This method is rapid, simple and sensitive, and can meet the detection requirements of residual vinclozolin and its metabolites in fruits and vegetables.
    40  Determination of Clothianidin and Sulfoxaflor Residues in Pumpkin by QuEChERS-liquid Chromatography-tandem Mass Spectrometry
    YANG Jin-qing YU Suo-yin GE Yu
    2021, 37(9):319-324. DOI: 10.13982/j.mfst.1673-9078.2021.9.1224
    [Abstract](201) [HTML](202) [PDF 681.59 K](552)
    Abstract:
    A QuEChERS-liquid chromatography-tandem mass spectrometry method was established for the simultaneous determination of clothianidin and sulfoxaflor residues in pumpkin. The clothianidin and sulfoxaflor were extracted with acetonitrile from the samples subjected to homogenization, purified by the matrix solid-phase dispersion method, filtered through a 0.22 μm filter membrane and analyzed by LC-MS /MS. The detection was performed after separation using a C18 chromatographic column, electrospray ionization, positive ion scanning mode and dynamic multi-reaction monitoring mode, and quantification was conducted by the matrix-matched external standard calibration. A linear relationship was found within the range of 2.5~100 μg/L for clothianidin and 0.5~20 μg/L for sulfoxaflor, with their correlation coefficients as 0.9994 and 0.9988, respectively. The average recoveries were 88.5%~111.2% at the three spiking levels of 5, 10 and 50 μg/kg for clothianidin, and 1, 2 and 10 μg/kg for sulfoxaflor, with the relative standard deviations in the range of 1.12%~6.92%. The limits of quantification (LOQs) were 1.0 and 5.0 μg/kg for clothianidin and sulfoxaflor respectively. The method is rapid, simple, sensitive, and reproducible, and can meet the requirements for the determination of clothianidin and sulfoxaflor residues in pumpkin.
    41  Salmonella Contamination Rate in Food based on A Hierarchical Bayesian Model
    WU Xian YANG Yong-heng BAO Yong-ming
    2021, 37(9):325-332. DOI: 10.13982/j.mfst.1673-9078.2021.9.1204
    [Abstract](268) [HTML](155) [PDF 1.04 M](487)
    Abstract:
    To systematically investigate the prevalence of Salmonella in food in mainland China, a hierarchical Bayesian model based on data obtained from literature mining was established to reliably estimate the Salmonella contamination rate of commercially available food. The average Salmonella contamination rate of the examined food was 5.91% in 2004~2018 (95% confidence interval, 4.69%~7.27%). The contamination rate fluctuated from 2.02% to 8.29%. The highest contamination rate of 8.45% was found in raw meat and meat products. In Sichuan province, Shanghai city, and Heilongjiang province, food contamination by Salmonella was high (12.05%, 11.53%, and 10.68%, respectively). The main pathogenic types were S. enterica serotype 1 and Salmonella infecting animals and humans. The main species of contaminating Salmonella were S. enteritidis, S. derby, and S. typhimurium, with contamination rates of 22.10%, 15.23%, and 12.54%, respectively. Health and market regulators should strengthen the monitoring of meat and meat products according to local conditions and formulate preventive strategies for the main pathogenic types and dominant species of Salmonella to ensure food hygiene and safety.
    42  Tumor Cell Apoptosis Induced by EGCG in Green Tea and Its Mechanism: A Research Review
    XIE Jing ZHAO Hong-ye TIAN Yang
    2021, 37(9):333-339. DOI: 10.13982/j.mfst.1673-9078.2021.9.1018
    [Abstract](206) [HTML](197) [PDF 349.86 K](575)
    Abstract:
    Green tea is one of the most popular drinks in Asia and the Middle East. It is a cancer-fighting, anti-inflammatory, antibacterial, and antioxidant drink, and it can help treat cardiovascular and cerebrovascular diseases. Moreover, it improves obesity and diabetes. Epigallocatechin-3-gallate (EGCG) is found in the highest amount in green tea compared to other polyphenols and demonstrates noticeable antitumor activity. It is well known that apoptosis is the main way for various anticancer drugs to induce cell death. Therefore, inducing apoptosis of cancer cells is a clear goal in cancer treatment. At present, a large number of studies have reported the antitumor activity of EGCG and revealed the effectiveness and mechanism of EGCG-induced tumor cell apoptosis. This study summarizes recently reported studies on the effects and mechanisms of EGCG in inducing tumor cell apoptosis. The pathways discussed include p53, STAT3, Akt, p38 MAPK, Wnt/β-catenin, and TRAIL. This study also discusses the mechanisms by which EGCG and natural products, antitumor drugs, and other compounds act synergistically to induce tumor cell apoptosis. Future research on the bioavailability, in vivo experiments, and clinical trials of EGCG is considered, offering a theoretical basis for clinical applications of EGCG.

    Editor in chief:李琳

    Inauguration:现代食品科技

    International standard number:ISSN 1673-9078

    Unified domestic issue:CN 44-1620/TS

    Domestic postal code:46-349

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