Volume 35,Issue 1,2019 Table of Contents

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  • 1  Preprotective Effect of Actinidia arguta Proanthocyanidins on the Cell Injuried by Drogen Peroxide
    SHI Hao WANG Ren-cai PANG Li WANG Yan WANG Fang-fang
    2019, 35(1):1-8. DOI: 10.13982/j.mfst.1673-9078.2019.1.001
    [Abstract](713) [HTML](207) [PDF 68.17 M](929)
    Abstract:
    The protective effect of Actinidia arguta Proanthocyanidinss on the Human immortalized epidermal cells (HaCat) injuried by drogen peroxide was investigated. Actinidia arguta in Dawei Mountain of Liuyang was used as test material and HaCat cells cultured in vitro were used as the experimental objects. The experiment was divided into three groups: control group, hydrogen peroxide injury group and treatment group (pretreatment with 5~1000 μg/mL proanthocyanidins of Actinidia arguta), the cell survival rate (apoptosis rate), SOD (superoxide dismutase), GSH-PX (glutathione peroxidase), ROS (reactive oxygen species), Nrf2 gene and protein expression level were measured to evaluate their antioxidant activity. Results showed that when the proanthocyanidins were added to the cells to protect the cells, the survival rate of the injured cells was about 77% at the concentration of 5~500 μg/L proanthocyanidins, which was 2.88 times higher than that in the model group. The levels of SOD (10.46 U/mg prot) and GSH-PX (33.83 U/mg prot) in the treatment group were 108.28% and 137.48% higher than those in the model group (p<0.05), respectively. The level of ROS decreased significantly, and the average intracellular fluorescence intensity decreased by 48.60% compared with the model group (96.21). Meanwhile, the expression of Nrf2 and its protein were 1.40 and 35.11, respectively, which were 63.93% and 80.70% higher than that in the model group. These indicated that procyanidins in Actinidia chinensis have a preprotective effect on oxidative damage of HaCat cells induced by H2O2, and can be further developed into natural and effective antioxidant products to be used in the industry.
    2  Study on the Protective Effect of Zhige Oral Disintegration Tablets on Mice with Alcoholic Liver Injury
    YANG Wen-juan HE Ya-juan HU Yuan HOU Jing-long MAO Gen-nian MA Yang-min
    2019, 35(1):9-14. DOI: 10.13982/j.mfst.1673-9078.2019.1.002
    [Abstract](530) [HTML](257) [PDF 727.32 K](751)
    Abstract:
    Zhige oral disintegration tablets’ relieving effect on the hangover of drunken mice and hepatoprotective effect on mice with alcoholic liver injury were investigated. In anti-drunk study, after the model was established, 3 groups of mice were given intragastric intervention with high, medium and low dose of Zhige oral disintegration tablets, pure water was used as a control, and the time for the disappearance of righting reflex and recovery was recorded. In liver protection study, except the normal group was given pure water, the other groups were given 56-degree white spirits, and after 30 minutes, except thenormal group and the model group, the positive drug group and the high, medium and low dose groups were administered bifendate and Zhige oral disintegration tablets respectively for 10 consecutive days. The body weights of the mice were measured and their liver coefficients were calculated. The serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione (GSH content) in the liver tissues were measured. Compared with the model group, the drunken time and the hangover time of the mice in the high-dose group were prolonged by 6 min and 122.94 min (p<0.01), respectively. In the drug groups, the body weight of the mice increased and the liver mass indexes decreased to various degrees. Compared with the normal group, the model group’s serum ALT level increased by 99.8 IU/L, AST content increased by 48.03 IU/L, MDA of the liver tissue increased by 9.45 nmoL/L, and GSH content of the liver tissue decreased by 9.45 nmoL/mg, and SOD content was reduced by 51.13 U/mg (p<0.05). Compared with the model group, the high, medium and low dose groups’ serum MALT, AST and MDA content in liver tissue were reduced and liver GSH and SOD content (p<0.05) were increased, and the results were dose-dependent. It could be seen that Zhige oral disintegrating tablets were alcohol relieving and hepatoprotective.
    3  Interaction between Repressor Protein ArgR and Arginine Biosynthesis Pathway Related Genes in Corynebacterium glutamicum ATCC 14067
    AO Wan-qin ZHANG Hao ZHENG Sui-ping
    2019, 35(1):15-21. DOI: 10.13982/j.mfst.1673-9078.2019.1.003
    [Abstract](687) [HTML](248) [PDF 28.31 M](666)
    Abstract:
    In bacteria, the repressor protein inhibits the transcription of arginine biosynthesis related genes through binding to conserved sequences in these genes. In Corynebacterium glutamicum ATCC 14067, the genes involved in arginine biosynthesis are located in argCJBDFRGH and carAB gene clusters. The recombinant E.coli BL21 (DE3)/ pET22b-argR was constructed to induce the expression of ArgR derived from ATCC 14067 and subsequently achieve the target protein. The analysis of the ArgR protein using molecular sieve columns showed that the relative molecular mass of ArgR protein was about 108 ku, and the ArgR protein was hexamer in the active state. The argC, argJ, argB, argF, argG, argH, carA gene fragments were obtained from biotin-labeled Corynebacterium glutamicum ATCC 14067, and their in vitro interactions with the ArgR protein were examined by electrophoretic mobility shift assays (EMSA). The results showed that the ArgR protein could bind to argC gene at positions -26 ~+32 bp, argB gene at positions -86~-29 bp, argG gene at positions -161~-104 bp, and carA gene at positions -99~ -42 bp, and the degree of binding to the argB gene was the greatest whilst no binding between ArgR and the argJ, argF or argH gene fragment. For the first time, the target binding sites of ArgR protein in argC, argB, argG, and carA genes were located within 60 bp, which provided a theoretical basis for further study on the regulatory mechanism of arginine synthesis in Corynebacterium glutamicum ATCC 14067.
    4  Inhibitory Effect of Artemisia argyi Extracts on Xanthine Oxidase Activities and Their Uric Acid-lowering Effect on Hyperuricemia in Mice
    LI Mei-ping WANG Wei ZHANG Jie ZHANG Sheng-wan YANG Xi-hua YU Li-gang GUO Cai-xia
    2019, 35(1):22-30. DOI: 10.13982/j.mfst.1673-9078.2019.1.004
    [Abstract](741) [HTML](328) [PDF 11.23 M](956)
    Abstract:
    The total flavonoids, total phenols, the inhibitory effect on xanthine oxidase (XOD) activities and free radical scavenging capacity of the extracts from Artemisia argyi by distilled water, anhydrous ethanol assisted with ultrasonic and traditional decoction were measured. Alcohol extract was selected to investigate the effect on hyperuricemia. Potassium oxazidate was used as the inducer for hyperuricemia mice. The mice were continuously fed for 7 days, and serum uric acid (UA), creatinine (Scr), urea nitrogen (BUN) level and liver XOD activity were measured. Results showed that the order of total flavonoids and total phenolics content of Artemisia argyi extracts was anhydrous ethanol assisted with ultrasonic method > traditional decoction method distilled > water method; the order of free radical scavenging capacity and XOD inhibitory activity was anhydrous ethanol assisted with ultrasonic method > traditional decoction method distilled > water method.The inhibition mechanism of the three extracts showed irreversible inhibition. The inhibition type of traditional and alcohol extracts effect on XOD is anti-competitive inhibition. The water extract effect on XOD is mixed inhibition. The type of associated inhibition with allopurinol of traditional and water extracts is additive effect. The alcohol extract is weak synergies. The level of UA, Scr and BUN in hyperuricemia mice decreased and the XOD activity of liver was inhibited. The Artemisia argyi extracts have better potential for XOD inhibitory effect and antioxidation. The alcohol extract may be developed to prevent and treat hyperuricemia.
    5  Antibacterial Activity and Mechanism of Eugenol against Multidrug-resistant Escherichia coli
    QIAN Wei-dong LIU Chan-chan WANG Ting LI Yong-dong SHEN Lan-fang LIU Miao LU Jia-xing
    2019, 35(1):31-36. DOI: 10.13982/j.mfst.1673-9078.2019.1.005
    [Abstract](605) [HTML](239) [PDF 36.87 M](849)
    Abstract:
    In order to study the antibacterial activity of eugenol on multidrug-resistant Escherichia coli (MDR E.coli), the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of eugenol against MDR E.coli were determined by micro-diluted dilution method and agar diffusion method. UV spectrophotometry and the Coomassie blue method were used to analyze the antibacterial activity. The results showed that the MIC and MBC of eugenol for MDR E.coli were 2.50 mg/mL and 5.00 mg/mL, respectively. Eugenol can prolong the progression of MDR E.coli into the logarithmic growth phase, change the structure of the bacteria and increase the soluble protein content and the amount of extracellular nucleic acids of the strain. Eugenol also increased the conductivity in the culture medium. These may be attributed to the destruction effect of eugenol on cellular structure of the bacteria. The study provides a new way to overcome drug resistance, infection and mortality of MDR E.coli, and lay a theoretical foundation for the application of eugenol in medicine and food development.
    6  Study on the Relationship between Taste Profile and Microorganism of Naturally Fermented Soybean Paste based on Electronic Tongue Technology
    XIE Meng-xi WU Ri-na JIANG Jing AN Fei-yu QIU Bo-shu WU Jun-rui
    2019, 35(1):37-43. DOI: 10.13982/j.mfst.1673-9078.2019.1.006
    [Abstract](599) [HTML](301) [PDF 26.13 M](783)
    Abstract:
    Nine natural fermented soybean paste samples from Liaoning province were analyzed by using llumina Mi Seq high throughput sequencing and electronic tongue technology, and the relationship between microorganisms and taste characteristics of the samples were investigated. The correlation analysis showed that the bacteria had a greater impact on the taste of soybean paste than fungi. On the level of fungi, the Wickerhamomyces was negatively correlated with bitter taste. Mucor was negatively correlated with acidity and astringency, and positively correlated with after taste-A, umami, richness and saltiness. And Pichia pastoris was negatively correlated with richness (p<0.05). For the bacteria, Lactobacillus, Enterococcus, Leuconostoc, Pseudomonas and Wesella have very significant negative correlations with sourness and astringency, and showed highly significant positive correlations (p<0.01) with bitterness, aftertaste-A, aftertaste-B and umami. This study provides a basis for the industrialization of high-quality soybean paste and the development and utilization of microbial resources.
    7  Inhibitory Effects of 2 Kinds of Molybdenum Cluster Compounds on Tyrosinase and their Preservative Effects on Litopenaeus vannamei
    HU Jing-jing CHEN Bing-nian WANG Li DENG Yang-yang
    2019, 35(1):44-50. DOI: 10.13982/j.mfst.1673-9078.2019.1.007
    [Abstract](512) [HTML](209) [PDF 19.53 M](887)
    Abstract:
    Two kinds of high-nuclear molybdenum clusters (NH4)12[Mo36O108(NO)4(H2O)16]?33H2O and [Mo36O112(OH2)16 (H2bipy)4]?28H2O were synthesized. Inhibition mechanisms on diphenolase activity of tyrosianase, anti-melanosis effects of Litopenaeus vannamei and preservation of Mo36 and Mo36-bipy were investigated. The result showed that the IC50 values of tyrosine diphenolase respectively were 0.0358 mmol/L and 0.0601 mmol/L. The inhibitory effect of Mo36 on tyrosinase was reversible competitive inhibition, the inhibition of tyrosinase by Mo36-bipy was reversible mixed inhibition, and the inhibitory effect of Mo36 on tyrosinase activity was better than that of Mo36-bipy. Litopenaeus vannamei was stored under 4 ℃ environment for 10 days, and the sensory score, color, pH value, TVB-N and total number of colonies was detected. It was found that the high-nuclear molybdenum clusters had a certain preservation effect on Litopenaeus vannamei (p<0.05). Mo36 and Mo36-bipy can significantly improve the value of sensory score and L*, and reduce the pH value and the total number of colonies. This paper can provide experimental basis for the preservation of the Litopenaeus vannamei body and the application of polyoxometalates to new areas.
    8  Comparative Studies on the Properties of Starches from Different Waxy / Glutinous Cereals
    ZHANG Zheng-mao KAN Ling WANG Li
    2019, 35(1):51-57. DOI: 10.13982/j.mfst.1673-9078.2019.1.008
    [Abstract](895) [HTML](642) [PDF 22.92 M](785)
    Abstract:
    In this study, starches were extracted from different raw materials (round waxy rice, blood waxy rice, waxy wheat, waxy corn, waxy proso millet, waxy sorghum and waxy coix seed) for comparative studies to provide a reference for their applications. The results showed that the light transmittance of waxy corn starch and waxy sorghum starch was the greatest (about 20%). Waxy coix seed starch and waxy wheat starch tended to aggregate and precipitate. At 50 ℃, the swelling power of round waxy rice starch, blood waxy rice starch and waxy corn starch was greater. The round waxy rice starch had the worst freeze-thaw stability, while the waxy wheat starch, waxy cornstarch, waxy proso millet starch and waxy sorghum starch had better freeze-thaw stability. The gelatinization temperature of the waxy proso millet starch was the highest (67.8 ℃), with the round waxy rice starch, blood waxy rice starch and waxy corn starch having the lowest (60 ℃). Among the 7 waxy grain starches, the peak viscosity, hold viscosity and final viscosity were the highest for the waxy wheat starch, waxy sorghum starch and waxy coix seed starch but the lowest for the waxy corn starch. Based on the value of setback viscosity / peak viscosity, the waxy corn starch was the least susceptible to aging, whilst the waxy coix seed starch was the most susceptible to aging. The anti-shear capacity of waxy sorghum starch, waxy wheat starch and waxy coix seed starch was relatively weak, and the starch of blood waxy rice and waxy corn starch exhibited shear-thickening behaviors.
    9  L-phenylalanine-induced the Synthetic of Acetic Acid-2-phenyl Ethyl Ester in Apple Vinegar Fermentation
    SONG Juan ZHANG Ji-hong KANG San-jiang ZENG Chao-zhen ZHANG Hai-yan YUAN Jin ZHAGN Fang HUANG Yu-long
    2019, 35(1):58-64. DOI: 10.13982/j.mfst.1673-9078.2019.1.009
    [Abstract](554) [HTML](255) [PDF 17.44 M](624)
    Abstract:
    In order to study the effects of L-phenylalanine (a food additive) on the synthetic pathway and key enzyme activity related to acetic acid-2-phenyl ethyl ester in apple vinegar fermentation, HS-SPME-GC-MS and ELISA were employed to detect the changes of the matrix concentration and key enzyme activities in the synthesis of acetic acid-2-phenyl ethyl ester. It was shown that different amounts of L-phenylalanine can significantly promote the production of acetic acid-2-phenyl ethyl ester and the synthesis of the related matrix, and L-phenylalanine can increase the enzymatic activities of ADH and AAT, however, it suppressed the activity of Esterase enzyme. When 8 g/L of L-phenylalanine was added, the concentration of acetic acid-2-phenyl ethyl ester significantly increased from 43.76% to 86.59%;Therefore, the optimum additive amount of L-phenylalanine was 8 g/L, speculating that L-phenylalanine induced the synthesis of acetic acid-2-phenyl ethyl ester and its related matrix, and increased key enzyme activities through alcohol acyltransferase pathway, which increased the unique aroma and flavor of apple vinegar products and provided a reference for the production process.
    10  Effects of Vacuum Chopping and Calcium Ion Concentration on Gelling Properties of Silver Carp Surimi
    GUO Xiu-jin YIN Tao SHI Liu MA Yao-lan YOU Juan HU Yang XIONG Shan-bai
    2019, 35(1):65-71. DOI: 10.13982/j.mfst.1673-9078.2019.1.010
    [Abstract](680) [HTML](228) [PDF 17.71 M](687)
    Abstract:
    Gelling properties of silver carp surimi as influenced by vacuum and calcium ion concentration were investigated for the production high-quality surimi products. As concentration of calcium chloride increased, breaking forces of surimi gels prepared under atmospheric pressure fluctuated, which increased and then decreased twice (p<0.05).The calcium ion concentrations corresponding to the two peaks were 20 mmol/kg and 40 mmol/kg. Cross-linking degree of surimi gels increased from 18.08% to 30.98%, and then decreased gradually after 30mmol/kg and finally reached the minimum value of 14.54%. Microstructure was in irregular form firstly, and then changed to a continuous network followed by scattered aggregations. Under vacuum chopping, changes in characteristic values of surimi gel, including breaking force and cross-linking degree, were similar to those under atmospheric pressure. However, calcium ion concentrations corresponding to the peaks and turnover were lower by 10 mmol/kg. Under both chopping conditions, water holding capacities of surimi gels decreased from 80.74% and 82.27% to 62.09% and 67.23%, respectively. And their whiteness were increased from 79.11 and 79.10 to 83.80 and 83.15, respectively. Results indicated that vacuum changed the gelling properties of surimi by decreasing calcium ion concentrations.
    11  Physicochemical Properties of Potato Starch and Its Influence on the Quality of Potato Hot-and-dry Noodles
    CAI Sha SHI Jian-bin SUI Yong HE Jian-jun CHEN Xue-ling FAN Chuan-hui CAI Fang MEI Xin
    2019, 35(1):72-81. DOI: 10.13982/j.mfst.1673-9078.2019.1.011
    [Abstract](533) [HTML](171) [PDF 25.86 M](769)
    Abstract:
    In order to study the physicochemical characteristics of potato starch, the influence of potato starch mixed powder with different content of potato starch on the quality of fresh or dry potato hot-and-dry noodles was investigated using potato as raw materials. The results showed that the content of starch in the potato was 73.80%. The content of amylose and amylopectin in potato starch was 28.23% and 71.70% respectively. The content of RDS, SDS and RS in potato starch was 20.29%, 15.03% and 64.68% respectively. When the content of potato starch was 60%~70%, the water-holding capacity, water-absorbing expansibility and viscosity of the mixed powder were higher. The cooking characteristics and texture characteristics of fresh potato hot-and-dry noodles were improved when the content of potato starch was 70%~80%. For drying potato hot-and-dry noodles, the rehydration characteristics was the best when the content of potato starch was 70%. This study provided the theoretical basis for the application of potato starch to potato hot-and-dry noodles production. Hot-and-dry noodles were easier to digest with the increase of the potato starch content in potato hot-and-dry noodles. In conclusion, the suggested addition of potato starch was 70%.
    12  Study on the Antibacterial Activity of the Total Saponins Extract from the Stems and Leaves of Astragalus membranaceus
    GUO Li-li WANG Xiao-min QIN Nan FANG Xue
    2019, 35(1):82-88. DOI: 10.13982/j.mfst.1673-9078.2019.1.012
    [Abstract](738) [HTML](237) [PDF 16.05 M](762)
    Abstract:
    In this study, the antibacterial activity of the stems and leaves of Astragalus membranaceus (denoted as AMSL herein) was explored through testing the inhibition zone diameter and the minimum inhibitory concentration (MIC) of different components on six test bacteria by the filter paper method and double dilution method respectively. Besides, the antibacterial mechanism of AMSL was preliminarily described by measuring the growth curve of Escherichia coli and evaluating the influence of AMSL on the release of macromolecular substances in the suspension. The results showed that the total saponins of AMSL had obvious antibacterial activities against the six test bacteria, especially its effect on Escherichia coli with the MIC value of 12.5 μg/mL. The total flavonoids had significant antibacterial activities against only two test bacteria with the MIC values of 93.8 μg/mL, and the total polysaccharides had no activity. After the extract of AMSL saponins was added to the bacterial suspension, the growth of Escherichia coli was severely inhibited and the content of macromolecules such as nucleic acids in the bacterial suspension increased, indicating that the AMSL exerted bacteriostatic action mainly by destroying the integrity of the cell membrane which caused the macromolecular substances to overflow. This study provides a theoretical basis for the application of AMSL as a natural preservative in the field of food preservation and storage.
    13  Dynamic Model of Quality Change of Fresh Rice Noodle in Different Temperatures and the Prediction of Its Shelf Life
    HU Yun-feng WANG Xiao-bin ZHANG Li-ping
    2019, 35(1):89-96. DOI: 10.13982/j.mfst.1673-9078.2019.1.013
    [Abstract](635) [HTML](248) [PDF 47.34 M](667)
    Abstract:
    In order to study the correlation between the quality changes of fresh rice noodle and storage time, in this paper, iodine blue value, acidity, pH value and water absorption of fresh rice noodle stored at 4, 10, 20, 25 and 37 ℃ were fitted by statistical software. A dynamic model was established. A shelf-life prediction model was also established with iodine blue value of fresh rice noodle as the end of shelf life. The results showed that the iodine blue value and pH value could be fitted into a zero order kinetic model, and the water absorption could be fitted into a first-order kinetic model. The fitting coefficients R2 of the three models were 0.9901 (iodine blue value), 0.9524 (pH value) and 0.9785 (water absorption) respectively. The average relative error of W was 7.0%, 5.8% and 5.6%, respectively, both less than 10%. The model of shelf-life was established based on the change of iodine blue value of fresh rice noodle during storage. At the end of shelf life, the iodine blue value was 1.2389, and the average relative error was 1.06%, which was less than 10%. The model established in this paper could predict the storage time of fresh rice noodle.
    14  Antifungal Properties and Mechanism of Limonin from Lemon Peel against Aspergillus niger
    WANG Hui ZENG Xiao-fang FENG Wei-hua YU Li-mei ZHAI Wan-jing BAI Wei-dong ZENG Ling-gang
    2019, 35(1):97-102. DOI: 10.13982/j.mfst.1673-9078.2019.1.014
    [Abstract](526) [HTML](230) [PDF 18.62 M](623)
    Abstract:
    The antifungal activity, stability and mechanism of limonin from lemon peel against Aspergillus niger were investigated. The results showed that the minimal inhibitory concentration (MIC) and the minimal fungicidal concentration (MFC) of limonin from lemon peel on Aspergillus Niger were 625 μg/mL and 5000 μg/mL respectively, and the half-effective concentration (EC50) on spore germination and mycelium growth were 311.03 μg/mL and 291.63 μg/mL respectively. The antifungal activity of limonin on Aspergillus niger was weakened under UV light and pH 6~7. Fe3+ and Fe2+ could enhance the antifungal activity. The limonin from lemon peel could greatly change extracellular alkaline phosphatase (AKP) activity, soluble protein and total sugar content of mycelium of Aspergillus niger. Therefore, limonin destroyed the integrity of cell wall and cell membrane of Aspergillus niger, resulting in a large amount of content exudation, affecting the normal metabolism of cells, thereby inhibiting the growth and reproduction of cells.
    15  Analysis of Microbial Changes in Fermented Beverage of Pitaya during Low Temperature Fermentation
    HUANG Dao-mei MENG Fan-bo CHEN Xi BAN Qian ZHENG Xiu-yan LI Guo-lin LIN Mao
    2019, 35(1):103-108. DOI: 10.13982/j.mfst.1673-9078.2019.1.015
    [Abstract](569) [HTML](195) [PDF 11.27 M](728)
    Abstract:
    To explore the changes of main microorganisms and understand the effects of inoculated fermentation and natural fermentation on microorganisms in the fermentation process of pitaya beverage, the pH, soluble solids and main microbial species were assayed in the inoculated and natural fermentation processes of Hongxin pitaya beverage at low temperature (18 ℃). The results showed that lactic acid bacteria reached the maximum values of 5.20×108 cfu/mL using inoculated fermentation and 1.14×109 cfu/mL using natural fermentation on the 9th day. The decrease rate of lactic acid bacteria in natural fermentation was higher than that in inoculated fermentation during further fermentation period. Yeast maintained a growth trend during the whole fermentation process, while the number of inoculated yeasts was lower than that of natural fermentation. The number of mold and coliform group grew vigorously in the middle fermentation period, the mold reached the maximum values of 11.60 cfu/mL using inoculated fermentation and 602.00 cfu/mL using natural fermentation on the 13th day of fermentation, and coliform group reached the maximum values of 0.36 MPN/mL and 46 MPN/mL on the 9th day of fermentation. The study revealed that inoculated fermentation had dominant lactic acid bacteria compared with natural fermentation, which inhibited the growth and reproduction of some hybrids, and also effectively reduced the growth and reproduction of mold and coliform bacteria, and was more beneficial to the quality control of fermented pitaya beverage. This study provides a reference for further research on low temperature-fermented pitaya juice.
    16  Inhibition of Multi-drug Resistant Acinetobacter baumannii by Seven Essential Oils
    YUE Cong-cong LI Yu-le HAO Xiao-kang GUO Rui-lin
    2019, 35(1):109-113. DOI: 10.13982/j.mfst.1673-9078.2019.1.016
    [Abstract](635) [HTML](182) [PDF 5.10 M](1045)
    Abstract:
    To observe the antibacterial effect of essential oils on multidrug-resistant Acinetobacter baumannii (MDRAB) in vitro, the inhibitory zone diameter and the minimum inhibitory concentration (MIC) of seven essential oils on MDRAB were measured by disk diffusion method and micro-broth dilution method, the strongest antibacterial essential oil was found and then its dynamic germicidal curve against MDRAB was drawn. The combinatory effect of the two lowest MIC essential oils on MDRAB was studied by the checkerboard dilution method. The results showed that cinnamon essential oil has the strongest antibacterial effect on MDRAB. The inhibition zone diameter is 29.30±1.16 mm, the MIC value is 0.62 μL/mL, and the antibacterial activity against MDRAB is dependent on the drug concentration. A synergistic effect was observed with the combination of cinnamon oil with peppermint oil. Additive effect was observed with the combination of cinnamon oil and lavender oil. Furthermore, peppermint oil and lavender oil had stronger antibacterial effect, MIC value were 1.25 μL/mL and 2.50 μL/mL, respectively. Clove oil had moderate antibacterial activity on MDRAB, the MIC value was 10 μL/mL. The antibacterial effect of wintergreen oil and green tea oil on MDRAB were relatively weak, the MIC value was 20 μL/mL. The inhibitory effect of benzoin essential oil on MDRAB was weak or not detected. It was concluded that cinnamon oil had the strongest antibacterial effect on MDRAB and was concentration-dependent. In addition, cinnamon essential oil and lavender essential oil as well as cinnamon essential oil and peppermint essential oil had synergistic anti-MDRAB effect, providing effective guidance for clinical use.
    17  Optimization of Polysaccharide from Agaricus bitorquis mushroom by Ultrasonic-assisited Extraction method and its Anti-hypoxia Activity
    JIAO Ying-chun YU Mei ZHANG Yan WU Shan CHEN Qi-he
    2019, 35(1):114-120. DOI: 10.13982/j.mfst.1673-9078.2019.1.017
    [Abstract](930) [HTML](171) [PDF 12.35 M](722)
    Abstract:
    Ultrasonic-assisted extraction optimized by single factor experiment and response surface methodology (RSM) was implemented to extract polysacchrides from the fruiting body of Agaricus bitorquis (Quél.) Sacc. Results showed that the optimal condition was ultrasonic wave power 130 W, liquid /solid ratio 1:40, extracting time 15 min. The anti-hypoxia effect of crude polysacchrides extracted by the optimal condition was evaluated by national standard method. The death time, survival time and the gasp time of mice under atmospheric hypoxia, sodium nitrite poisoning and acute cerebral ischemic hypoxia were determined. Compared with the blank control and the positive control (Rhodiola rosea), variance analysis showed that the anti-hypoxia effect of polysacchrides prepared by the optimal extraction condition were significant (P<0.05). Three test results were determined to be positive. Compared to blank, crude polysaccharides significantly extended the death time, survival time and the gasp time by 76.60%, 50.33% and 144.96%, respectively. The death time, survival time and the gasp time of the crude polysaccharides treatment were also 19.20%, 34.20% and 43.07% longer than the positive control, respectively. In conclusion, this study revealed that the crude polysaccharides from the fruiting body of Agaricus bitorquis (Quél.) Sacc have potent anti-hypoxia effects.
    18  Preparation and Properties of Foam Emulsion Based on Corn Peptide-phytic Acid Complexes and Citrus Fiber
    ZENG Li-hua RUAN Qi-jun WANG Jin-mei GUO Jian WAN Zhi-li YANG Xiao-quan
    2019, 35(1):121-128. DOI: 10.13982/j.mfst.1673-9078.2019.1.018
    [Abstract](633) [HTML](229) [PDF 106.33 M](769)
    Abstract:
    Cow's milk is the main ingredient of whipped cream. However, its high cholesterol content is not conducive for cardiovascular health. Manufacturers often replace cow's milk with cheap hydrogenated oil (which contains a relatively high content of trans fatty acids that are harmful to human). In this study, a foam emulsion system based on a complex of raw materials corn peptides and phytic acid along with citrus fiber (as a thickener) is constructed. It was found that corn peptides interacted with phytic acid via non-covalent interactions (van der Waals force and hydrogen bonding), and the resultant complex had the ability to stabilize the oil-water interface. The citrus fiber effectively promoted the coalescence of oil droplets at the air-water interface and the formation of a foam emulsion containing stabilized oil droplets. Moreover, the addition of calcium chloride to the emulsion system could further enhance foam stability. In addition, with the increase of citrus fiber content, the viscosity of the emulsion and the stability of the foam increased; as the oil content increased, the foam had a reduced volume but enhanced stability. This study has successfully prepared a foam emulsion without trans fatty acid and cholesterol but rich in dietary fiber, and provides a new approach for the development of aerated dairy ingredients.
    19  Preparation of Tilapia Bone Collagen Calcium Chelating Peptides by Enzymatic Hydrolysis
    LIAO Wan-wen MIAO Jian-yin CHEN Yu-xing KANG Meng LIU Shan-xue YU Zhao-long CAO Yong
    2019, 35(1):129-136. DOI: 10.13982/j.mfst.1673-9078.2019.1.019
    [Abstract](909) [HTML](174) [PDF 11.15 M](748)
    Abstract:
    The purpose of this paper was to prepare collagen peptides with calcium-chelating ability from tilapia fish bone. Bone collagen was used as experimental material after pre-meat including removing meat from the skeleton and decalcification. With calcium chelation activity as the index, papain was selected as the acting enzyme. The single factor and orthogonal test were employed to optimize the enzymolysis process of preparation of tilapia bone collagen. The Tilapia calcium chelating peptide, obtained by enzymatic hydrolysis under optimal conditions, was used as the target for the determination of their molecular weight and amino acid composition. The results showed that the optimum enzymolysis process conditions were as follows: Enzymolysis time (4.5 h), pH (6.5), enzymolysis temperature (62 ℃), enzyme to substrate ratio (0.6%). Tilapia bone collagen calcium chelating peptide was a kind of function substance composed of small molecular peptides; By comparing the amino acid composition of tilapia bone collagen calcium chelating peptide and its calcium-peptide chelated, it is found that amino acids such as cystine, aspartic acid, serine, glutamic acid, glycine, histidine and lysine played an important role in the calcium chelating capacity of the active peptide.
    20  Preservative Effect of Different Monochromatic Light-emitting Diode (LED) Treatments on Broccoli (Brassica oleracea) in Low-temperature Storage
    LI Bian-sheng WEN Ya-xin RUAN Zheng ZHOU Wei CHEN Lin-yun
    2019, 35(1):137-143. DOI: 10.13982/j.mfst.1673-9078.2019.1.020
    [Abstract](585) [HTML](341) [PDF 24.10 M](1036)
    Abstract:
    In order to improve the post-harvest storage quality of broccoli (Brassica oleracea), and provide new approaches for preservation of fresh vegetables in practice, this research examined the preservative effects of different wavelengths of monochromatic light-emitting diode (LED) on the quality of broccoli stored at a low temperature: Red (642 nm), yellow (591 nm), green (519 nm), blue (464 nm), and purple (435 nm); treatment time 24 h/day ? 12 day dark conditions used as a control. A comprehensive evaluation was conducted based on sensory, physico-chemical, nutritional and microbial analyses (including color attributes, chlorophyll content, reducing sugar content, total soluble solid content, and total number of colonies),to assess the post-harvest storage quality of broccoli over the storage. Results showed that different monochromatic LED treatments could delay the decline of nutritional quality of broccoli during storage. After 12 days of storage, the green LED (519 nm) could maximally maintain the sensory quality of broccoli, inhibit the increase of brightness L*, delay the degradation of chlorophyll, reducing sugar and soluble solids, and in the meantime, suppress effectively the microbial growth, delay the decrease of hue angle (H-value) and maintain the content of vitamin C. Therefore, the green LED treatment was the most effective to maintain the storage quality of broccoli over the low-temperature storage and extend its shelf life.
    21  Response Surface Optimization of Proteolytic Process and Protein Peptide Composition Analysis of Antarctic Krill
    LIU Yun-jiao ZHANG Hai-yan LIU Shu-han WANG Yu HAN Feng KONG Cong WANG Yuan ZHANG Xuan SHEN Xiao-sheng
    2019, 35(1):144-151. DOI: 10.13982/j.mfst.1673-9078.2019.1.021
    [Abstract](567) [HTML](322) [PDF 49.89 M](700)
    Abstract:
    The amino nitrogen content in the antarctic krill hydrolysate was used as an indicator. The hydrolysis results of trypsin, papain, alkaline protease, pepsin, flavor protease and subtilisin were evaluated by formaldehyde potentiometric titration. The enzymatic hydrolysis of Antarctic krill protein was optimized for the enzymatic hydrolysis of Antarctic krill. On the basis of single factor experiment, the amino acid content in the enzymatic hydrolysate was used as the response value, and the enzymatic hydrolysis temperature, time and pH were selected as independent variables. The three-factor and three-level Box-Bohnken response surface analysis method was used to screen the bio-enzymatic solution. The process is optimized. Based on the optimized enzymatic hydrolysis process, the molecular weight distribution range of Antarctic krill enzymatic protein peptide and Antarctic krill protein was analyzed by SDS-PAGE gel electrophoresis. The results showed that trypsin was the ideal protease for enzymatic hydrolysis of Antarctic krill protein; the response surface analysis method was used to establish a quadratic multiple regression equation: Y=51.07-0.83A+1.72B-2.06C+0.25AC+1.15BC-3.06A2-2.77B2-3.69C2, the model p<0.0001, and the missing term p>0.05, indicating that the model is extremely significant and stable, the best condition obtained by model analysis is: Enzymatic hydrolysis temperature was 44.48 ℃, the enzymatic hydrolysis time was 8.52 h, and the pH was 7.88. Considering the practical application feasibility, the amino nitrogen content of the experiment was 50.96±1.07 mg/g under the conditions of enzymatic hydrolysis temperature of 45.0 ℃, hydrolysis time of 8.5 h and pH 7.9, which is basically consistent with the theoretical prediction value of 51.57 mg/g. The molecular weight of Antarctic krill protein was over 15 ku by electrophoresis analysis, and the main molecular weight range was 15 ku~45 ku. The molecular weight of trypsin peptide was below 25 ku, and the main molecular weight distribution was below 5 ku.
    22  Cultivation of Coccomyxa subellipsoidea C-169 using Different Carbon Sources to Purify Molasses Yeast Wastewater
    YU Zong-yi YAN Wen-jun LI Huan-kai WEI Dong
    2019, 35(1):152-156. DOI: 10.13982/j.mfst.1673-9078.2019.1.022
    [Abstract](654) [HTML](161) [PDF 7.21 M](782)
    Abstract:
    In this study, three carbon sources (CO2, acetic acid and glycerol) were added to the pretreated molasses wastewater, and then the growth of Coccomyxa subellipsoidea C-169 in a symbiotic algal-bacterial system cultured in such enhanced wastewater and the outcome of such an enhancement were examined. Compared with the results related to aeration with air, supplementation with 2% CO2 could significantly increase the average cell growth rate and biomass yield by 6.49 and 10.4 times, respectively, and remarkably increased the total nitrogen, total phosphorus and ammonia nitrogen (p<0.05) but reduced the removal rate of COD (chemical oxygen demand) of wastewater. It was found that Coccomyxa subellipsoidea C-169 could use glycerol as its carbon source. At a glycerol concentration within 0~20 g/L, an increase of glycerol concentration led to an increased cell growth rate, and total nitrogen and total phosphorus removal rates. At 20 g/L, the highest dry weight of biomass reached 8.80 g/L, the average specific growth rate was 2.07 times as high as that without glycerol (the biomass yield, 0.70 g/(L·d). When the glycerol concentration was above 15 g/L, the removal rates of total nitrogen and total phosphorus were over 85% and 95%, respectively, which significantly increased the wastewater COD (p<0.01). Addition of 1~4 g/L acetic acid would inhibit the growth of Coccomyxa subellipsoidea C-169 and reduce wastewater purification efficiency. Therefore, when C-169 is used to purify wastewater with a high COD, glycerin can be added as a carbon source for its growth.
    23  The Comparison and Analysis of the Patrinia villosa Tea Quality by Different Processing Technologies
    ZENG Xiang-ling WANG Dan ZOU Jing-jing YANG Jie SHI Yu-min ZHENG Li ZHONG Jun-qiong CHEN Hong-guo
    2019, 35(1):157-164. DOI: 10.13982/j.mfst.1673-9078.2019.1.023
    [Abstract](676) [HTML](210) [PDF 21.58 M](906)
    Abstract:
    To optimize the appropriate deep processing technique for P. villosa, four different techniques were adopted to make P. villosa. The sensory quality, nutritional quality, functional active components and flavonoid constituents were evaluated. Results showed that different processes could greatly affect the quality of P. villosa tea. Specifically, the control sample dried under 70 ℃ had the highest nutritional and pigment ingredient contents, and their water extract, free amino acid, chlorophyll and carotenoid content were 59.15%, 417.34 μg/g·DW, 7.63 mg/g·DW and 1.07 mg/g·DW, respectively. Compared to the other methods, the sensory quality of the sample with microwave blanching was the best and had a total points of 92.16. The saponin content was the highest, 13.08 mg/g·DW. The boiling water blanching led to the highest polysaccharide, total phenols and total flavonoid contents: 39.00 mg/g·DW, 29.39 mg/g·DW and 61.45 mg/g·DW, respectively. Unblanched products were poorer than those having undergone microwave and boiling water blanching in terms of the sensory quality and nutritional ingredient, which had the lowest functional active component contents. Compared to the control sample with the chlorogenic acid and isovitexin content of 12.77 mg/g·DW and 1.01 mg/g·DW, the flavonoid constituent analysis of the four products by HPLC showed that the boiling water blanching led to the highest chlorogenic acid and isovitexin contents (64.67 mg/g·DW and 3.50 mg/g·DW respectively); followed by the microwave blanching (34.62 mg/g·DW and 1.88 mg/g·DW respectively). The chlorogenic acid and isovitexin contents were the major factors causing the differences in the total flavonoid content in the four products. A theoretical basis for the follow-up development and utilization of P. villosa Juss was provided in this work.
    24  Study on Extraction and Antioxidant Activity of Flavonoids from Rosa davurica Pall. by Negative Pressure Ultrasound
    FU Qun WU Tong WANG Meng-li
    2019, 35(1):165-172. DOI: 10.13982/j.mfst.1673-9078.2019.1.024
    [Abstract](502) [HTML](207) [PDF 87.49 M](765)
    Abstract:
    Flavonoids from Rosa davurica Pall. were extracted with ethanol assisted by negative pressure ultrasonic technology. On the basis of single factor experiment, a three-level Box-Behnken experiment design was applied with ultrasonic time, ultrasonic temperature, ultrasonic power and material-liquid ratio as influencing factors. Using the yield of flavonoids from Rosa davurica Pall. as the response value, the extraction process was optimized by response surface methodology as follows: the ratio of material to liquid 1:30, the ultrasonic power 400 W, the ultrasonic time 33 min, and the ultrasonic temperature 56 ℃. Under these conditions, the yield of flavonoids reached (3.342±0.027) mg/g. In addition, a predictive quadratic mathematical model was established for extraction of flavonoids from Rosa davurica Pall. by ethanol solution. Antioxidant evaluation showed that Rosa davurica Pall. flavonoids had good reducibility and radical scavenging abilities towards OH·,DPPH·, and O2-·,with the IC50 values being of 0.021 mg/mL, 0.182 g/mL and 0.013 mg/mL, respectively. Their reducibility and radical scavenging abilities were higher than those of Vc at the same concentrations. The results showed that the flavonoids with good antioxidant activity could be extracted from Rosa davurica Pall. by negative pressure ultrasonic method.
    25  Optimization of Enzymatic Hydrolysis of Moringa oleifera Seed Protein by Response Surface Methodology and the Antibacterial Activity of Peptides of Protein Hydrolysate
    WANG Xue-feng CHEN Yue ZHAO Qiong ZHAO Cun-chao SHI Ya-nan HUANG Ai-xiang HE Rong
    2019, 35(1):173-181. DOI: 10.13982/j.mfst.1673-9078.2019.1.025
    [Abstract](674) [HTML](255) [PDF 56.71 M](908)
    Abstract:
    Moringa oleifera seed protein powder was used as raw material to prepare for peptides by enzymatic hydrolysis. Firstly, the protease with better proteolysis effect was screened as the optimal enzyme. Secondly, the effects of enzyme addition amount (enzyme-substrate mass percentage), material-liquid ratio, hydrolysis temperature and hydrolysis time on the degree of hydrolysis (DH) and peptide yield were investigated. The process for enzymatic preparation of Moringa oleifera seed peptides was optimized by response surface methodology (RSM). Finally, the antibacterial activity of the hydrolysates was evaluated. Results showed that alkaline protease was the optimal enzyme. The optimal process for enzymatic preparation of Moringa oleifera seed peptides was founded to be alkaline protease addition of 5.50%, pH of 9.0, solid-liquid ratio of 1:30 (g/mL), hydrolysis temperature of 62.50 ℃ and hydrolysis time of 143 min. Under these conditions, the actual peptide yield was (84.43±2.31)%, and the degree of hydrolysis was (20.69±0.46)%. The hydrolysates had inhibitory effects on Listeria monocytogenes, Escherichia coli, Staphylococcus aureus and Salmonella typhimurium, and the minimum inhibitory concentrations against these above four pathogens were 3.00 mg/mL, 0.75 mg/mL, 0.38 mg/mL and 0.75 mg/mL, respectively. The hydrolysates had better inhibitory effects on Staphylococcus aureus after incubation for 4.5 h.
    26  A Simple Calculation Method for the Sterilization Value of Canned Food
    MAO Wei-jie NISHIO Yo-sie FUKUOKA Mi-ka SAKAI Noboru
    2019, 35(1):182-188. DOI: 10.13982/j.mfst.1673-9078.2019.1.026
    [Abstract](577) [HTML](577) [PDF 53.16 M](806)
    Abstract:
    Flat-panel canned food was taken as the research object and a simple calculation method for the sterilization value of the central part of the heat sterilization process was proposed. Usually, calculating sterilization value needs either integrating the temperature value or using computer software for calculation, and both of the methods were difficult and complicated. In the proposed method, the central temperature was calculated first by mathematical analysis, then the sterilization value was calculated by integral method and finally a functional relationship between the central temperature and the sterilization value was established. It was relatively simple to calculate the sterilization value through the functional relationship. The expression used sterilization temperature and Z value as parameters to derive the expression relationship of the sterilization value for different sterilization temperatures and Z values. It could be expressed by a simple functional relation without integration. The sterilization value obtained by the functional expression was compared with the sterilization value obtained by the integration, and the error was within 1 min, and the simple calculation of the bactericidal value was realized. This method was simple and easy and beneficial to the optimization of the sterilization process and was of great significance to the quality management of canned food.
    27  Antioxidant Activity of Maillard Reaction Products Derived from Corbicula fluminea Hydrolysates
    XU Hao LIN Lin LIU Dong-xu LU Jian-feng JIANG Shao-tong
    2019, 35(1):189-197. DOI: 10.13982/j.mfst.1673-9078.2019.1.027
    [Abstract](633) [HTML](288) [PDF 17.66 M](767)
    Abstract:
    The hydrolysates were prepared from soft part of Corbicula fluminea, and three fractions of Corbicula fluminea hydrolysates (CFH) (>10 ku, 5 ku to 10 ku, <5 ku) were isolated with ultrafiltration. Then, the 3 fractions of CFH were reacted with D-xylose respectively to obtain the Maillard reaction products (CFH-MRP). The CFH-MRP’s antioxidant capacities, pH values, grafting degrees and browning degrees of CFH-MRP before and after the reaction were measured and the structure of CFH-MRP was analyzed. The results showed that the antioxidant capacity of CFH-MRP was enhanced through Maillard reaction. The CFH-MRP with the molecular weights range from 5 ku to 10 ku had the highest scavenging rate of hydroxyl (an increase of 31%), superoxide free radical scavenging capacity (an increase of 33%) and total reducibility (an increase of 152%), and the CFH-MRP with the molecular weights more than 10 ku had the highest DPPH scavenging ability (an increase of 106%). At the same time, Maillard reaction reduced the pH value and increased the browning degree of CFH. Fourier transform infrared spectra (FT-IR) indicated that covalent crosslinking between CFH and D-xylose occurred, and the amino content of reaction products reduced. GC-MS analysis showed that some new compounds generated from Maillard reaction including ketones, esters, alcohols, olefins, phenols and heterocyclic substances, which could increase the antioxidant activity of CFH-MRP in some cases.
    28  Optimization of Enzymatic Preparation of a Flavor Precursor with Mutton Characteristics by Response Surface Methodology
    MA Xue-ping ZHAN Ping TIAN Hong-lei WEI Zhi-sheng XI Jia-pei ZHANG Fang
    2019, 35(1):198-205. DOI: 10.13982/j.mfst.1673-9078.2019.1.028
    [Abstract](505) [HTML](198) [PDF 19.41 M](855)
    Abstract:
    Refined mutton was digested by lipases to obtain small molecular products. The substrate concentration, enzyme dosage and enzymatic hydrolysis time were selected as single factors, and the lipolysis rate was used as the response index. The Box-Behnken response surface method was used to optimize the lipolytic process based on the experiment of single factors. The characteristic volatile components with different degree of enzymatic hydrolysis were analyzed by a headspace solid phase microextraction / gas chromatography-mass spectrometry (SPME)/GC-MS), and the relationship between the degree of enzymatic hydrolysis and volatiles was determined. The optimum enzymatic hydrolysis conditions were determined as enzymatic temperature 50 ℃, pH 6.5, substrate mass fraction 60%, enzyme dosage 140 U/g substrate and hydrolysis time 6 h, under which the lipolysis rate was up to 29.76%. GC-MS analysis showed that with this lipolysis rate, the hydrolyzate was rich in characteristic volatiles such as aldehydes, ketones, acids and ethers, and aldehyde species contributed to the falvor, with the highest total content of 1.868±0.013 ng/g. This study laid the foundation for the subsequent preparation of mutton flavor by oxidation of mutton tallow and Maillard reaction.
    29  Production Process Optimization of Low-salt Chopped Capsicum by Inoculation and Fermentation of Multiple Strains
    LI Wen-qing LUO Feng-lian ZENG Xi-ke QING Quan JIANG Yi-lin LUO Yao-hua
    2019, 35(1):206-214. DOI: 10.13982/j.mfst.1673-9078.2019.1.029
    [Abstract](575) [HTML](259) [PDF 42.53 M](1092)
    Abstract:
    The experiments were carried out with a 1:1:1:1 ratio of Leuconostoc mesenteroides, Lactobacillus plantarum, Lactobacillus fermentum, and Lactobacillus acidophilus. With brittleness, total acid and sensory score as evaluation indexes, the effects of inoculation content, salt content and fermentation time on the quality of chopped capsicum were studied. The results showed that the brittleness of chopped capsicum first increased and then decreased with the increase of the amount of strains and salt, and the brittleness decreased gradually with the extension of fermentation time. The influencing order of brittleness Fmax was fermentation time>salt content>inoculation content. The influencing order of sensory score was inoculation content>fermentation time>salt content. The optimum conditions for producing low-salt chopped capsicum were inoculation content 6%, salt content 6%, fermentation time 5 d, and fermentation temperature 37 ℃. On the conditions, the Fmax of low salt chopped capsicum was 12316.3 g, the sensory score was 87.9, and the total acid content was 0.52%. The finished product has a strong aroma, bright red color and crispy taste, which meets the requirements of high quality chopped capsicum.
    30  Dry Mixing Process of Foods for Special Medical Purposes and Its Comparison with Wet Process and Dry-wet Process
    MA Kai-xiang ZHANG Mei-ping WU Shuai CHAI Cai-yun XU Xiao-xia GUAN Qin-hao
    2019, 35(1):215-220. DOI: 10.13982/j.mfst.1673-9078.2019.1.030
    [Abstract](1070) [HTML](438) [PDF 16.52 M](918)
    Abstract:
    In order to provide theoretical and practical basis of dry mixing technology for relevant manufacturers, the key steps of dry mixing process of formula food for special medical purposes and its comparison with wet and dry methods were evaluated. By analyzing the key control points of the dry mixing process, the material addition order, mixing time, mixing frequence and process stability were analyzed to investigate their influence on the uniformity of the mixed process. The final production process conditions were as follow: materials were added in the process of mixed process 1, a total mixing time was 20 min, a total mixing frequence was 20 Hz. Under these conditions, the relative standard deviation of vitamin A and vitamin B1 in different positions were 4.37% and 2.52%, respectively. It was close to the test results of the verification process, indicating that the product was mixed uniformly and the process was stable, and the test values were in accordance with the regulations and design requirements. Compared with the wet process and the dry and wet process, the dry mixing process also showed certain advantages. Therefore, this process can meet the requirements of the dry production of the special medical food formula.
    31  Separation and Purification of Polyphenols in Moringa Seeds
    CAO Xin-zhi XIAO Meng-yue ZHANG Chao YANG Jian-gang
    2019, 35(1):221-226. DOI: 10.13982/j.mfst.1673-9078.2019.1.031
    [Abstract](600) [HTML](174) [PDF 25.71 M](771)
    Abstract:
    Moringa seed polyphenols have been proven to possess excellent antioxidant properties. In order to study the bioactivity and physicochemical properties of Moringa seed polyphenols, it is necessary to further separate and remove impurities from the crude extract of Moringa seeds. In this study, the crude extract obtained via ultrasonic-assisted extraction was subjected to further purification. The adsorption rate and desorption rate of the polyphenols from Moringa seeds on different types of macroporous resins were determined, to screen the most suitable macroporous resin for separating and purifying polyphenols. The optimal conditions for the separation and purification of Moringa seed polyphenols were studied by static and dynamic adsorption and desorption experiments. The results showed that D-101 macroporous resin performed the best (which was used to determine the optimal adsorption and desorption conditions). The optimal conditions were: pH and concentration of the sample solution, 5 and 3 mg/mL; Eluent, 80% ethanol solution; olumn flow rate, 2 mL/min; Elution flow rate, 2 mL/min. The purity of the Moringa seed polyphenol extract increased from 10.37% to 32.29%, after the extract was treated under such conditions. The purification effect was significant, thus the findings of this study provided guidance for the separation and purification of Moringa seed polyphenols.
    32  Stability Analysis of Anthocyanin from Portulaca oleracea
    CHEN ling LUO Lu-jia CAO Qiao-qiao HE Wei-qiang ZHANG Jian-qun
    2019, 35(1):227-232. DOI: 10.13982/j.mfst.1673-9078.2019.1.032
    [Abstract](534) [HTML](301) [PDF 16.14 M](732)
    Abstract:
    The anthocyanin of purslane was extracted from wild purslane juice and its stability was studied. The results showed that the stability of purslane anthocyanin was improved by low temperature and light avoidance in acidic condition, and the stability of anthocyanin was decreased by oxidant and reductant. With the increase of xylitol concentration, anthocyanins of Portulaca oleracea showed a symmetrical normal distribution trend, reached the peak value at 10% of concentration, and then decreased with the increase of concentration. The anthocyanin of Portulaca oleracea decreased with the increase of mannitol concentration. With the increase of the amount of stevioside, the anthocyanin of Portulaca oleracea continually decreased to the bottom of the valley at 0.06% of concentration, increased to the peak value at 0.13% of concentration, and the color decreased beyond this concentration. However, when the concentration is 0.26%, it is still in the state of increasing color. When the concentration of citric acid and lactic acid was 0~3%, the effect of chromaticity increased with the increase of concentration, but the effect at concentration > 3% decreased with the increase of concentration until the decolorization. The effect of metal ion Na+, Mg2+, Zn2+and K+ on anthocyanin of Portulaca oleracea was relatively small, while that of Ca2+, Cu2+ and Fe3+ on anthocyanin of purslane was obvious. These results provide reference for the preparation of purslane juice healthy beverage.
    33  Development of Droplet Digital PCR for the Detection of Streptococcus suis
    SHI Lei WEN Wen CHEN Xun YE Lei CHANG Yan-lei LI Li-li
    2019, 35(1):233-238. DOI: 10.13982/j.mfst.1673-9078.2019.1.033
    [Abstract](680) [HTML](494) [PDF 38.23 M](766)
    Abstract:
    A droplet digital polymerase chain (ddPCR) detection method, based on gdh gene of Streptococcus suis was developed to improve the detection and quantification of S. suis. S. suis is an important pathogen, resulting in significant economic losses in pig farming. Prompt detection of S. suis in the field samples is important for effective control. ddPCR is a novel PCR technology, which offers good precision and direct quantification without using calibration curves. In this work, a ddPCR method for the sensitive and accurate quantification of S. suis was established. Under the optimized reaction conditions, results showed that ddPCR was specific to detect S. suis with detection limit of 2.692 copies/μL, and no cross-reactions with Actinobacillus pleuropneumoniae, Haemophilus parasuis, Bacillus subtilis, Escherichia coli, Salmonella, Staphylococcus aureu, Porcine circovirus type2 and Pseudorabies virus. The correlation coefficient (R2) obtained from linear regression analysis showed a good linearity of amplification for ddPCR (R2=0.991), and the repeatability test indicated that the coefficient of variation were 1.66%. The clinical application of ddPCR assay indicated that the sensitive and specific detection method could be useful to standardize quantitative detection of S. suis.
    34  Determination and Analysis of Different Morphology of Formaldehyde in Letinous edodes
    LI Bing-ru MA Zhi-hong HE Zhao-ying LI Yang PING Hua
    2019, 35(1):239-244. DOI: 10.13982/j.mfst.1673-9078.2019.1.034
    [Abstract](518) [HTML](201) [PDF 11.22 M](657)
    Abstract:
    In order to one-time and rapidly determine the dissociative formaldehyde and conjugate formaldehyde in Letinous edodes, the method of combining full automatic nitrogen analyzer and high performance liquid chromatography (HPLC) was established. According to the precipitation conditions with different morphology of formaldehyde in Letinous edodes, the 2 steps were set to distill with the automatic nitrogen analyzer. The first step was distilled dissociative formaldehyde and the second step was adding-acid to distill the conjugate formaldehyde. The conditions of experiment were that distilling-time 4 min, 10% phosphoric acid 40 mL, water-bathing temperature 60 ℃, and water-bathing time 60 min. When formaldehyde concentration is 0.0~10.0 mg/L, the standard curve has good linear relationship, the correlation coefficient r is 0.9995. The recoveries of dissociative formaldehyde were 87.8%~105.9%, the relative standard deviation (RSD) was 3.5%~7.0%; the recovery of conjugate formaldehyde was 89.5%~105.8%, and RSD was 2.5%~6.7%. The automatic nitrogen analyzer could improve the extraction efficiency of different morphology of formaldehyde in Letinous edodes. The content of conjugate formaldehyde in Lentinus edodes accounted for 62.6%~71.8%. The contents of dissociative formaldehyde and conjugate formaldehyde in the umbrella part were higher than that in the stalk part. The method combined with high performance liquid chromatography and the automatic nitrogen analyzer was suitable for the batch detection of formaldehyde in Letinous edodes.
    35  Prediction of Nutritional Compositions of Korla Pear Flesh Based on Rheological Properties
    WANG Jia-ping WU Jie YANG Xue-mei YU Li-juan
    2019, 35(1):245-251. DOI: 10.13982/j.mfst.1673-9078.2019.1.035
    [Abstract](589) [HTML](159) [PDF 45.82 M](711)
    Abstract:
    To achieve efficient and accurate detection of various nutritional composition indexes of Korla pear flesh, creep-recovery and stress relaxation tests were performed on pear flesh with using a TA-XT plus Texture Analyzer. Rheological models which were the fittest for describing Korla pear flesh’s creep-recovery and stress relaxation properties were determined, and the rheological parameters of Korla pear flesh were obtained with the models. Then, the correlations between the rheological parameters and soluble solid content (SSC), titratable acidity (TA), solid acid ratio (RTT) of pear flesh were analyzed, and the three nutritional composition indexes were predicted through stepwise multi-linear regression analyses. The results showed that creep-recovery and stress relaxation properties of Korla pear flesh can be best characterized by a generalized Kelvin-Voigt model with six elements and a generalized Maxwell model with five elements respectively, and the coefficients of determination R2 were higher than 0.95. Partial rheological parameters of the two models were significantly correlated with the SSC, TA and RTT (p<0.05), hence, the constructed stepwise multi-linear regression models could also effectively predict the three nutritional composition indexes. The correlation coefficient r of the prediction models were higher than 0.7, and there was no significant difference between the measured values and the predicted values. The RMSE values of the models for predicating the three nutritional compositions based on creep parameters were smaller than those of the models based on stress-relaxation parameters. Therefore, the models constructed on the basis of creep parameters were more stable and reliable for predicting nutritional compositions of Korla pear flesh.
    36  Determination of Taurine Content in Milk Powder and Liquid Milk by High Performance Liquid Chromatography
    ZHAO Chao-min JIANG Ying-jie ZENG Jing GU Shu-qing DENG Xiao-jun FANG Ke-yan YUE Zhen-feng LAI Fu-rao MIN Tian
    2019, 35(1):252-256. DOI: 10.13982/j.mfst.1673-9078.2019.1.036
    [Abstract](748) [HTML](429) [PDF 13.24 M](703)
    Abstract:
    A high performance liquid chromatography (HPLC) method was developed for the determination of taurine in milk powder and liquid milk. The milk samples were dissolved in water, subjected to ultrasonic-assisted extraction for 10 min, precipitated with zinc acetate and potassium ferrocyanide, and centrifuged. The resultant supernatant was derivatized with phenyl isothiocyanate and triethylamine at room temperature for 1 h, before addition of n-hexane (to terminate derivatization) and standing (to allow phase separation). The lower layer solution was diluted with water and the obtained solution was filtered through a 0.22 μm microporous membrane. The filtrate was further separated using an amino acid analysis column (Diamonsil AAA, 4.6 × 250 mm, 5 μm) and a mobile phase for gradient elution with an aqueous sodium acetate solution (0.05 mol/L, pH=6.50) and acetonitrile / methanol (1/1, V/V). Quantification was performed using external standards. Good linearity was obtained in the concentration range of 5.0~40 μg/mL with correlation coefficients greater than 0.999, the limit of quantification as 5 mg/100 g (S/N≥10). At spiking levels of 5, 10 and 25 mg taurine /100 g r, the average recovery was in the range of 90%~108% with the relative standard deviation within 1.16%~2.24%. The results show that the analysis method established in this study is accurate and reliable, and meet the requirements for efficient analysis of taurine in milk powder and liquid milk. Compared with the GB method, this method is more suitable for effective detection of taurine in special diet milk powder.
    37  Determination of Four Plant Growth Regulators in Bean Sprouts by Liquid Chromatography-tandem Mass Spectrometry
    LI Jian ZHENG Lei
    2019, 35(1):257-263. DOI: 10.13982/j.mfst.1673-9078.2019.1.037
    [Abstract](504) [HTML](209) [PDF 15.48 M](598)
    Abstract:
    The abuse of plant growth regulator (s) in bean sprouts is a major factor that affects the safety of bean sprouts for consumption. In this study, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) method was developed for the determination of 3-indoleacetic acid, 4-chlorphenoxyacetic acid, 6-benzyl adenine and gibberellin in bean sprouts, in which multiple-reaction monitoring mode was employed for simultaneous detection of target analytes and external standards were used for quantification. Test samples were obtained for HPLC-MS analysis, through ultrasonic-assisted extraction, NaCl-induced salting-out, and purification by dispersive solid-phase extraction (to yield organic phase). The detection limit of the 4 plant growth regulators was 5 μg/kg, and the limit of quantitation (LOQ) was 10 μg/kg. The recovery was in range of 65.1%~109.8% and the relative standard deviation (RSD) was in range of 1.49%~10.08% for soybean sprouts and mung bean sprouts when the spiking experiments were performed at the levels of LOQ, 2 LOQ and 10 LOQ with six replicates at each level. The recovery was. Enhanced product ion scan was performed along with the multiple-reaction monitoring in order to reduce false positive results during analysis. This method can be used to monitor the contents of 3-indole acetic acid, 4-chlorphenoxyacetic acid, 6-benzyl adenine and gibberellin in the commercial bean sprouts, and provides technical support for ensuring consumer safety.
    38  Effects of Different Extraction and GC-MS Injection Methods on the Volatile Composition of Pomelo Peel Essential Oil
    ZHANG Hao AN Ke-jing FU Man-qing YU Yuan-shan WU Ji-jun XU Yu-juan
    2019, 35(1):264-273. DOI: 10.13982/j.mfst.1673-9078.2019.1.038
    [Abstract](671) [HTML](241) [PDF 24.94 M](736)
    Abstract:
    In this study, pomelo peel essential oil was prepared by cold pressing, steam distillation and mechanical dermabrasion. The effects of direct injection and solid phase microextraction (SPME) on the type and amount of volatile components of pomelo peel essential oil were compared. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied to analyze the volatile components in essential oils extracted from the three methods and identify the characteristic volatile compounds. The results showed that totally 69 compounds were identified by the approach involving direct injection combined with GC-MS, and 51 compounds by SPME combined with GC-MS, with the direct injection approach showing the volatile profile of essential oil more comprehensively than SPME. For the volatile profiles obtained by the direct injection method, PCA analysis can distinguish the three kinds of pomelo peel essential oils with those derived from cold pressing and mechanical dermabrasion being more similar. PLS-DA analysis revealed that the characteristic volatile components in the three essential oils can be distinguished: Sabinene, D-limonene, α-terpineol, β-myrcene, α-pinene,and 4-terpineol in cold pressed oil; Linalool, (R)-limonene oxide and 8,9-dihydroneisoxylene in steam distillation oil; Nootkatone, n-palmitic acid, and (Z,Z)-9,12-octadienoic acid in dermabrasion oil. Among them, the characteristic volatile compound limonene oxide (5.19%) in steam distillation oil exhibited an irritating odor. The volatile components with a retention index greater than 2000 was higher (4.61%) in dermabrasion oil, which affected the clarity and stability of essential oils. Based on the above analyses, the quality of the pomelo peel oil prepared by cold pressing was better.
    39  Determination of the Residues of Fipronil and Its Metabolites in Eggs by Liquid Chromatography-tandem Mass Spectrometry
    LI Jing MA Qin-chuan WANG Zhuo SUN Li-ping YUAN Ke-bo CHEN Jun-ren
    2019, 35(1):274-280. DOI: 10.13982/j.mfst.1673-9078.2019.1.039
    [Abstract](549) [HTML](157) [PDF 11.24 M](746)
    Abstract:
    A rapid screening method was developed for the determination of the residues of fipronil and its metabolites (fipronil-desulfinyl, fipronil sulfone and fiproil sulfide) in eggs by liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS). Egg samples were extracted with acetonitrile and n-hexane. The obtained extract was purified by a C18 solid phase extraction (SPE) column and further separated using a Shim-pack XR-ODS Ⅲ column (2.0 mm I.D. × 150 mm L., 2.1 μm particle size) with a mobile phase in gradient elution (acetonitrile -5 mmol/L ammonium acetate (0.02% formic acid ). Qualitative screening and quantitative analysis were performed by LC-MS/MS with dynamic multiple reaction monitoring (DMRM) mode and in negative ion mode, and quantification was carried out by the external standard method. The results showed that good linearity was detected for fipronil and its metabolites in the range of 0~50 μg/L, with the correlation coefficient R2 greater than 0.999. The limit of quantification (LOQ) of fipronil and its metabolites was 0.3~0.6 μg/kg at the signal-to-noise ratio of 10. The average recovery of fipronil and its metabolites at the spiking levels of 0.5, 5.0 and 10.0 μg/kg ranged from 92.3% to 105.1%, with the relative standard deviation (RSD, n=6) in the range of 1.2%~8.6% The method was proven to be simple, rapid andsensitive, and suitable for rapid screening and quantitative detection of fipronil and metabolite residues in eggs.
    40  Research Progress on Heat Stress of Lactic Acid Bacteria
    MAN Li-li XIANG Dian-jun BU Ri-e WANG Si-zhen ZHANG Chun-lan GONG Xiao-xu
    2019, 35(1):281-287. DOI: 10.13982/j.mfst.1673-9078.2019.1.040
    [Abstract](945) [HTML](362) [PDF 718.85 K](1098)
    Abstract:
    Lactic acid bacteria (LAB), like other free-living microorganisms, are usually exposed to various environmental stress conditions in the course of microbial fermentation, food processing and storage, which include starvation stress, osmotic stress, and heat stress. Enhancement of stress resistance is considered an effective strategy for better cell growth and increased the yield of metabolites. Heat stress is probably the most common stress, which bacteria and other organisms are confronted in the natural world and industrial applications. Some studies had demonstrated that LAB from different habitats responded to a sudden increase in temperature by rapid changes in gene expression resulting in elevated levels of heat-shock proteins (HSPs). Under normal conditions, HSPs assist in receptor regulation, cytoskeleton stabilization, and protein folding, assembly, transport, degradation, and under heat stress these functions become especially important. In this paper, the tolerance mechanism of heat stress in LAB and heat stress reaction of different LAB were discussed in order to provide a theoretical reference for the study of the heat stress response mechanism in LAB and to facilitate the industrial application of LAB.

    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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