Volume 34,Issue 10,2018 Table of Contents

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  • 1  Protection against Isoproterenol-induced Hypertrophy in H9c2 Cardiomyocytes by Notoginsenoside R1
    ZHU Ting FENG Yu YIN Yue-zhang WANG Xiao-jing XIAO Jing SUN Bing
    2018, 34(10):1-7. DOI: 10.13982/j.mfst.1673-9078.2018.10.001
    [Abstract](678) [HTML](0) [PDF 586.05 K](844)
    Abstract:
    The protection of notoginsenoside R1 against isoproterenol-induced hypertrophy in rats H9c2 cardiomyocyte was investigated, and its therapeutic effect on cardiac hypertrophy was also verified. The H9c2 cardiomyocytes was induced by ISO 20 μg/mL to observe the effect of notoginsenoside R1 on cardiac hypertrophy. The viability of cardiomyocytes was detected by MTT assay, and the mRNA levels of ANP, β-MHC, TNF-α, IL-6 and IL-1β were detected by real-time RT-PCR. Western blot was used to detect the protein levels of p65, p-p65, I-κBα; Fluorometric assay kit was used to detect caspase-3 activity. The results showed that, notoginsenoside R1 is effective in inhibiting ISO-induced cardiomyocyte hypertrophy, which manifects increased cardiomyocyte viability, decreased ANP, β-MHC, TNF-α, IL-6 and IL-1β mRNA levels, actived I-κBα protein level, inhibited p65 phosphorylation and decreased Caspase-3 activity. Therefore, notoginsenoside R1 exhibits a protection against ISO-induced H9c2 cardiomyocyte hypertrophy and can effectively inhibit cardiac hypertrophy, and its underlying mechanism may be associated with attenuation of the NF-κB signaling pathway.
    2  Diosmetin Ameliorated Acetaminophen-induced Hepatotoxicity via Activating Nrf2 /ARE Signaling Pathway
    LIU Xing LI Xiao-na LIU Cui-ling HUANG Jin-long HUANG Wei-feng
    2018, 34(10):8-14. DOI: 10.13982/j.mfst.1673-9078.2018.10.002
    [Abstract](582) [HTML](0) [PDF 834.66 K](742)
    Abstract:
    In order to examine the protective effect of diosmetin against acetaminophen-induced hepatotoxicity in vitro and vivo, Human non-tumor hepatic cells LO2 were pretreated with either vehicle or Dios (15, 30 μM), for 6h, followed by incubation with or without APAP (10 mM) for 24 h. In an in vivo assay, male C57BL/6J mice were randomly divided into control group, APAP group, low dose Dios group (30 mg/kg) and high dose Dios group (60 mg/kg). Each group included 10 mice. The mice were treated with different doses of diosmetin once daily for consecutive 7 days. At the end of the experiment, acetaminophen (300 mg/kg) was given intragastrically to induce liver injury in all groups except for the control group. Twenty-four hours later, the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) were detected. The contents of glutathione (GSH) and malondiadehyde (MDA) in liver tissue homogenates were measured through commercial kits. HE staining was performed to observe pathologic changes of the liver. The protein expression of Nrf2 was detected by Western blotting and the mRNA expressions of Nqo1, G6pdx, SOD2 was tested by quantitative real-time PCR. The results showed that in LO2 cells, APAP exposure decreased the cell viability and glutathione (GSH) content, which were both greatly restored by Dios pretreatment. Compared with the model group, the serum activities of ALT and AST as well as MDA content remarkably decreased by the administration of diosmetin (60 mg/kg), while GSH contents were elevated in liver tissues; Nrf2 protein expression in the nucleus as well as mRNA expressions of Nqo1, G6pdx, SOD2 increased. High-dose diosmetin can inhibit acetaminophen-induced hepatotoxicity, and the mechanism may be associated with the activation of Nrf2 /ARE signaling pathway.
    3  Improvement Effect of Dietary Fiber from Chickpea on Lipid Metabolism in Hyperlipidemic Rats
    ZHANG Rui LYU Mei-xia WU bu li ka si mu•AI KE BAI ER PENG Bing-xin Di na•MU HE YA TI Fei luo na•PA ER HA TI HAN Jia
    2018, 34(10):15-21. DOI: 10.13982/j.mfst.1673-9078.2018.10.003
    [Abstract](605) [HTML](0) [PDF 525.27 K](738)
    Abstract:
    In this study, the effects of chickpea dietary fiber on blood lipid and antioxidant levels of hyperlipidemic rats were observed to provide a reference for the research of the health benefits of chickpeas. Forty male SD rats were fed with high-fat diet to establish hyperlipidemia model. Then the hyperlipidemia model of rats were randomly divided into hyperlipidemia model group, high chickpea fiber (30 g/kg high-fat diet), middle chickpea fiber (15 g/kg high-fat diet), and low chickpea fiber (5 g/kg high-fat diet) three intervention groups. The hyperlipidemia model group was fed with high-fat diet, and intervention groups were given high-fat diet containing different levels of chickpea dietary fiber. After 7 weeks of intervention, the animals were executed. The body weight, liver weight, epididymal fat weight, serum lipid levels and oxidative stress levels of rats were measured in each group. The results showed that: The weight gain, liver weight and epididymal lipid weight were decreased in chickpea dietary fiber group, compared with the hyperlipidemia model group. After five weeks the body weight was obviously decreased by 29.34%, the epididymal fat weight decreased 33.81%, 17.28% and 21.86% in the high, medium and low dose groups, respectively, but there was no significant difference in liver weight. In terms of blood lipids, triglyceride (TG) and low density lipoprotein (LDL-C) in high-dose group decreased by 51.52% and 40.45%, respectively. The total cholesterol (TC) value was optimal in the middle dose group, which was reduced by 34.31%. High density lipoprotein (HDL-C) in high-dose group increased by 42%. In terms of antioxidant capacity, the malondialdehyde (MDA) content in the middle-dose group was reduced by 40%, the total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) levels in the high-dose group were increased by 54% and 55%, respectively, the increases of T-SOD and GSH-Px levels were dose-dependent. It can be seen that the dietary fiber of chickpea can reduce body weight and regulate abnormal blood-lipids in hyperlipidemic rats, and this effect may be related to the improvement of antioxidation ability and reduction of oxidative stress injury in hyperlipidemic rats.
    4  Protection of Liver Injury Induced by Carbon Tetrachloride of Kunlun Chrysanthemun by Proanthocyanidon
    ZHAI Hong-yue JING Si-qun CHAI Wen-jie ZHAO Zheng-mei
    2018, 34(10):22-28. DOI: 10.13982/j.mfst.1673-9078.2018.10.004
    [Abstract](633) [HTML](0) [PDF 898.30 K](726)
    Abstract:
    The protective effect of Kunlun chrysanthemun proanthocyanidin (KCPC) against acute liver injury induced by carbon tetrachloride in mice was investigated. The effects of KCPC on liver appearance pathology and liver index in mice with acute liver injury were analyzed; alanine aminotransferase (ALT) and aspartate aminotransferase (AST) level in serum, as well as antioxidant enzymes SOD, GSH-Px and lipid peroxidase MDA activities in liver of mice were determined by biochemical methods. In addition, the protective effect of KCPC on mitochondria was analyzed by inhibiting mitochondrial membrane swelling induced by Fe2+-Vc and the activity of succinic dehydrogenase (SDH) was evaluated. The results showed that, in the KCPC groups, no distinct pathological changes occurred, while for the control group, the pathology of mice liver tissue dramatically changed, with the activity of ALT and AST in serum increasing remarkably. The activity of ALT and AST in the high-dose KCPC group (800 mg/kg) decreased by 82.5% and 69.4%, respectively. The activities of SOD and GSH-Px increased by 101.1% and 92.1%% (p<0.01), respectively, whereas the MDA content decreased 45.2% (p<0.01). In addition, KCPC has the ability to inhibit the swelling of mitochondria, and the activity of SDH in 400 mg/kg dose group was 1.22 times that of the control group. The results suggest that KCPC exerts a significant protective effect on CCl4 induced liver injury in mice, and its mechanism may be related to the upregulation of antioxidative enzyme activity.
    5  Importance of the S2P Protease Sll0528 of Synechocystis sp. PCC6803 to Ammonium Stress Tolerance
    LIU Xiao-fang CHEN Gu LIN Shi-qi XU Bai-xue
    2018, 34(10):29-37. DOI: 10.13982/j.mfst.1673-9078.2018.10.005
    [Abstract](589) [HTML](0) [PDF 1.13 M](751)
    Abstract:
    Sll0528 is one of the site-2-protease (S2P) in Synechocystis sp. PCC 6803. In the work, the growth of three mutants of Synechocystis (the mutant overexpressed with OE0528 of the sll0528 gene, the ∆sll0528- knockout mutant, and the wild type) was compared under different concentrations of ammonium chloride. The results indicated that the knockout mutant ∆sll0528 was more sensitive to 120 mM ammonium chloride than the wild type, with the photosynthetic system damaged more seriously; at 180 mM ammonium chloride, the growth of wild type was inhibited, while the sll0528-overexpressed mutant OE0528 grew well, which showed higher toleration to the high concentration of ammonium, and better protection for the photosystem pigment phycocyanin and chlorophyll than the wild type. All the results suggested that Sll0528 plays an important role in the acclimation to ammonium stress in Synechocystis sp. PCC6803, probably through protected or recovered the photosystems under ammonium stress directly or indirectly. This is the first report to unveil the importance of S2P protease in ammonium stress of cyanobacteria, thus provding the base for the research of acclimation to ammonium stress and improvement of ammonium tolerance and utilization in microalgae in the future.
    6  Effect of Saccharomyces Cerevisiae on the Metabolism of Ethyl Carbamate and Quality of Chinese Yellow Wine during Wine Fermentation
    SHU Qin JIAO Zhi-hua NIU Yong-wu CHEN Qi-he JIAO Ying-chun
    2018, 34(10):38-43. DOI: 10.13982/j.mfst.1673-9078.2018.10.006
    [Abstract](584) [HTML](0) [PDF 777.98 K](840)
    Abstract:
    Ethyl carbamate (EC) is a potential carcinogen commonly exists in Chinese yellow rice wine. In thisstudy, the effects of substituting Saccharomyces cerevisiae for Chinese starter on the quality of yellow rice wine was investigated, to provide the theoretical basis for the application of laboratory strains and exploration of the metabolic process of ethyl carbamate in the fermentation system of yellow rice wine. The wild-type Saccharomyces cerevisiae (Saccharomyces cerevisiae, SC) isolated in this laboratory and industrial pure Saccharomyces cerevisiae (BY4741) were used to replace Chinese starter, and brewing experiments were carried out according to the industrial brewing process of yellow rice wine. High performance liquid chromatographic analysis revealed that the concentrations of urea and ethyl carbamate in the fermentation broth of BY4741 and SC fermentation systems were not significantly different from those in the traditional Chinese starter fermentation system. Adding ammonium sulfate as a supplemental nitrogen source during late stage of fermenttiona could reduce the ethyl carbamate concentration to some extent. The finished product after fermentation and decoction was analyzed,there were little differences in alcohol content, flavor composition and amino acid composition. These results indicate that the use of BY4741 and SC in the place of Chinese starter and the addition of ammonium sulfate during fermentation would likely not affect the quality of yellow rice wine. The results of this study indicated that the use of laboratory S. cerevisiae to replace Chinese starter for fermentation had little effect on the quality of yellow wine, and can be applied to the simulation system as a regulator of ethyl carbamate formation in the future.
    7  Protective Effect of Natural Deep Eutectic Solvent on Green Fluorescent Protein
    LI Fei WANG Yong-hua LAN Dong-ming
    2018, 34(10):44-48. DOI: 10.13982/j.mfst.1673-9078.2018.10.007
    [Abstract](956) [HTML](0) [PDF 621.14 K](816)
    Abstract:
    Natural deep eutectic solvent (NADES) is a new kind of “green” solvent, which can be applied to the extraction and biocatalysis of natural bioactive substances. In this study, green fluorescent protein (GFP) was used as a model protein for investigations on the protective effects of different NADESs on the stability of GFP at 70 ℃. It was found that the hightest fluorescence retention rate of GFP was in choline chloride sorbital (CS) under heat treatment at 70 ℃. The effect of the water content in CS NADES on the stability of GFP was examined, and CS NADES with a water content of 40% had the highest stability. CS NADES with 40% water content also enhanced the tolerance of GFP against SDS, but didn’t improve significantly the tolerance of GFP. CS NADES also contributed to the improvement of the thermal stability of lipase AOL at 45 ℃. In summary, CS NADESs provided a good protective effect on proteins and have application prospects in the fields of food processing and biocatalysis.
    8  Research on Purification and Moisturization Effect of Polysaccharides from Auricularia heimuer under Submerged Fermentation
    FAN Xiu-zhi YIN Chao-min YAO Fen SHI De-fang GAO Hong
    2018, 34(10):49-57. DOI: 10.13982/j.mfst.1673-9078.2018.10.008
    [Abstract](551) [HTML](0) [PDF 869.06 K](840)
    Abstract:
    In order to shorten the production cycle and increase the yield of polysaccharides, the selected strain and the optimized fermentation medium were used for liquid fermentation of Auricularia heimuer. Under these conditions, the yields of crude extracellular (EPS) and intracellular (IPS) polysaccharide respectively were 10.49±0.27 g/L and 3.05±0.03 g/L. Furthermore, in order to realize the reasonable utilization of fermented polysaccharides, the enzyme-Sevag method was used to remove the protein from the EPS and IPS. And then the polysaccharides were separated and purified by DEAE-52 and Sephadex G-200 column chromatography. Subsequently, the functional group analysis of the purified polysaccharides was conducted by Fourier transform infrared spectroscopy (FT-IR), and the effects of the purified polysaccharides on antioxidant and moisturizing were evaluated in vitro. The results showed that the enzyme-Sevag method could nicely remove the protein from the fermented polysaccharides with the purity of the deproteinizing polysaccharides (DEPS and DIPS) more than 95%, after the column chromatography, two mono-component PEPS and PIPS were obtained, respectively. By the FT-IR functional group analysis, both PEPS and PIPS were presumed to be β-configuration pyranose. Finally, with the comparison of antioxidant activity and moisture retention, it was found that PEPS was superior to PIPS in reducing ability and scavenging ability of superoxide anion radical, while the PIPS possessed higher abilities in DPPH radical, hydroxyl radical scavenging and moisturizing than PEPS. In summary, these findings provide a basis for the rational use of different components of polysaccharides from the submerged fermentation of A. heimuer, and lay a theoretical foundation for their application in food and cosmetics.
    9  Raman Spectroscopic Characterization of the Structural Changes in Soybean Protein Isolate Induced by Low Pressure Homogenization
    LYU Bo LI Ming-da ZHANG Yi-fang NIU Xiang-chen WANG Zhong-jiang JIANG Lian-zhou LIU Jun
    2018, 34(10):58-63. DOI: 10.13982/j.mfst.1673-9078.2018.10.009
    [Abstract](633) [HTML](0) [PDF 656.91 K](751)
    Abstract:
    In this study, Raman spectroscopy and circular dichroism spectra of soy protein isolate solutions subjected to different homogenization conditions were acquired for investigations on the effects of low pressure homogenization on the structure of soy protein isolate. The results showed that the secondary structure of soybean protein isolate basically remained unchanged when the homogenization pressure was low (0~8 MPa). When the homogeneous pressure was 10~30 MPa, the α-helical and random coil structures increased significantly, β-sheet decreased significantly. Thetryptophan and tyrosine residues gradually changed from “buried state” to “exposed state”, and the protein molecule exhibited depolymerization behavior; Over the course of the increase of homogenization pressure to 40 MPa, the ratio of tyrosine - Fermi resonance line I850/I830 decreased slightly, and the tyrosine residue changed from “exposed state” to “buried state”, indicating that protein aggregates were produced, and low pressure homogenizatio did not significantly alter the configuration of disulfide bonds. In summary, the secondary structure and tertiary structure of protein molecules can be characterized by Raman spectroscopy, and obtained results revealed that low-pressure homogenization induced depolymerization and then polymerization of soy protein isolate. These results were confirmed by circular dichroism.
    10  CRISPR/Cas9 Mediated ADH2 Gene Disruptionin Saccharomyces Cerevisiae and Antisense RNA Interference in GPD1 Expression
    LIU Kui LIANG Li-min LI Zhen-hui YE Hao-ying PAN Yan-fei HE Wen-jing CHEN You-qiang XUE Ting
    2018, 34(10):64-71. DOI: 10.13982/j.mfst.1673-9078.2018.10.010
    [Abstract](780) [HTML](0) [PDF 1.05 M](721)
    Abstract:
    CRISPR/Cas9 is a simple and efficient tool for targeted and marker-free genome engineering. Here, we constructed the silencing component PGK-SGPD1-CYC1 of Saccharomyces cerevisiae to interfere the glycerol 3-phosphate dehydrogenase1 (GPD1) geneand express in the specific region of PGK promoter and CYC1 terminator. Using CRISPR/Cas9 technology, while interrupting the alcohol dehydrogenase II (ADH2) gene, the target site were knocked into the antisense interference component of the GPD1 gene, thus interfering with the expression of GPD1. Through high-efficiency yeast transformation, the components were transformed into Y1H, CRISPR/Cas9 mediated recombination efficiencies of 43.40% were achieved, thus mutant strains with ADH2 gene interruption and GPD1 antisense interference were obtained. Fermentation test shows that the ethanol yield of the mutant strain SG1-1 was 9.07% higher than the wild type, and the yield of glycerol and acetate were decreased by 12.05% and 12.30%, respectively. Results showed that the antisense interference of the GPD1 and interruption of the ADH2 can not only interrupt the function of ADH2 gene, and reduce the conversion of ethanol into acetaldehyde, but also effectively interfere with GPD1 expression in engineered yeast strains, thus improving the yield of ethanol.
    11  Inhibitory Effect of Complex Polysaccharides Degradation Products on Proliferation of HeLa Cells in vitro
    ZHONG Si-en LIU Yang CAO Chun-jie CHEN Mei-zhen
    2018, 34(10):72-80. DOI: 10.13982/j.mfst.1673-9078.2018.10.011
    [Abstract](465) [HTML](0) [PDF 830.59 K](623)
    Abstract:
    The synergistic inhibitory effect of complex polysaccharides degradation products from Coprinus comatus, Gracilaria Lemaneiformis and Porphyra haitanensis on HeLa cell proliferation in vitro and its mechanism were investigated. In the experiment, the complex polysaccharides degradation products were combined by three kinds of polysaccharides degradation products from Coprinus comatus, Gracilaria Lemaneiformis and Porphyra haitanensis. The influence of complex polysaccharides degradation products on HeLa cells proliferation was assayed by MTT test. The intracellular level of reactive oxygen species was determined by DCFH-DA and the change of mitochondrial membrane potential was measured by JC-1. Based on orthogonal experiment, when the quality ratio of three kinds of polysaccharides degradation products from Coprinus comatus, Gracilaria Lemaneiformis and Porphyra haitanensis was 4:4:5, the inhibition effect on proliferation of HeLa cells was the strongest. In a concentration of 100 μg/mL, the inhibition rate was 75.72%, which outclassed the maximum inhibition rate of 56.09% when the three kinds of single polysaccharides degradation product were used alone. The results indicated that treatments of complex polysaccharides degradation products could significantly improve the intracellular level of reactive oxygen species and decrease mitochondrial membrane potential by DCFH-DA and JC-1, respectively. Combination of polysaccharides degradation products from Coprinus comatus, Gracilaria Lemaneiformis and Porphyra haitanensis, exhibited syneigistic the inhibition on proliferation of HeLa cells. The effect of complex polysaccharides degradation products might be related to increasing reactive oxygen species and reducing mitochondrial membrane potential.
    12  Comparison on the Antioxidant Activity and Tyrosinase Inhibitory Effect of Five Natural Plant Extracts
    WU Ying CUI Bin-yu WANG Lu SHUI He-ruizhi LI Kai
    2018, 34(10):81-86. DOI: 10.13982/j.mfst.1673-9078.2018.10.012
    [Abstract](956) [HTML](0) [PDF 705.30 K](893)
    Abstract:
    This study examined the in vitro antioxidant activity and tyrosinase inhibitory effect of five natural plant extracts, analyzed the flavonoid and total phenolic contents, and explored the correlation between whitening effect and antioxidant activity of extracts. The results of ABTS+, DPPH+, hydroxyl and superoxide anion radical scavenging assays revealed that the five extracts all possessed some antioxidant activity but their potencies different. At the same time, tyrosinase inhibition assay showed that these extracts all had some inhibitory effects on enzyme activity. The antioxidant activities and tyrosinase y inhibitory capacities of the five plant extracts increased with elevated concentrations of the sample. These results suggest that the antioxidant capacity of the extract is related to its inhibitory effect on tyrosinase activity, which may be associated with flavonoids and total phenolics in the extracts. When ABTS+ and DPPH+ methods were used, the antioxidant activities of the five extracts were related closer to their corresponding tyrosinase inhibitory effects. This finding may be associated with the inhibitory functions of flavonoids and phenolics towards tyrosinase activity. The research results provide a theoretical basis and reference for the screening and development of natural whitening plant-based raw materials.
    13  High-performance Expression of Recombinant Pullulanase in Bacillus Subtilis
    WANG Hai YE Yan-rui LIU Xin WANG Bin PAN Li
    2018, 34(10):87-93. DOI: 10.13982/j.mfst.1673-9078.2018.10.013
    [Abstract](704) [HTML](0) [PDF 786.01 K](725)
    Abstract:
    Pullulanase can specifically hydrolyze amylopectin to get amylose, which is important in Starch industry applications. In this study, the pullulanase gene pul was cloned from the Bacillus naganoensis ATCC 53909 genome and inserted into the E.coli-Bacillus subtilis shuttle vector pBE to construct the expression vector pBE-pul. Based on these, seventeen strong promoters from Bacillus subtilis, Bacillus licheniformis and Bacillus amyloliquefaciens were respectively cloned into the expression vector pBE-pul and transformed into Bacillus subtilis ATCC6051∆10. Finally, Seventeen recombinant strains containing different strong promoters were constructed, the secretory expression of pullulanase was achieved and the activity of pullulanase was measured. The results indicated that the activity of pullulanase mediated by promoter P43 and PspovG was significantly higher than that mediated by the other promoters and the activity of pullulanase mediated by promoter PspovG was higher than that mediated by the promoter P43.Meanwhile, the pullulanase gene mutant pul324 which deleted N-terminal 108 amino acids was investigated, which was mediated by promoter PspovG. Through comparing seventeen promoters and two pullulanase genes, a recombinant strain that can efficiently overexpress pullulanase was constructed successfully. The highest pullulanase activity reached 389.85 U/mL, significantly higher than that reported in the literature.
    14  Antimicrobial Activity of Natural Antimicrobial Agents against Zygosaccharomyces Rouxii
    WANG Xuan HU Zhong-qiu YUAN Ya-hong REN Ting-ting YUE Tian-li
    2018, 34(10):94-102. DOI: 10.13982/j.mfst.1673-9078.2018.10.014
    [Abstract](700) [HTML](0) [PDF 836.09 K](791)
    Abstract:
    The antimicrobial activity of 20 natural antimicrobial agents from plant, animal and microbial sources against Zygosaccharomyces rouxii was investigated in this study. The antimicrobial activity of 20 natural antimicrobial agents was determined based on the diameter of the inhibition zone by the double-layer plate perforated method. The minimum inhibitory concentrations (MICs) of natural antimicrobial agents against Zygosaccharomyces rouxii were determined by the double dilution method. The spectrophotometric method was used to determine the growth of Zygosaccharomyces rouxii in YPD medium and juice, e.g. the effects of two natural antimicrobial agents and different proportions of the two natural antimicrobial agents into juice on the growth of Zygosaccharomyces rouxii, along with the effects of citric acid concentration, temperature and ultraviolet irradiation time on the stability of antimicrobial activity of the composite antimicrobial agents. The results showed that antimicrobial agents had the highest antimicrobial activities against Zygosaccharomyces rouxii. The growth of Zygosaccharomyces rouxii in YPD was better than in juice. Two kinds of microbial inhibitors, natamycin and ε-polylysine, were screened out, and they exhibited synergistic effect. Citric acid concentration, temperature, ultraviolet irradiation time affected the stability of antimicrobial activity of the composite antimicrobial agents.
    15  Sucrose Conversion and Fructo-oligosaccharide Synthesis in Longan Juice Promoted by Enzymatic Treatment
    CHENG Yong-xia WEI Xin-yu LAN Hai-bo WANG Kai ZHAO Lei HU Zhuo-yan
    2018, 34(10):103-110. DOI: 10.13982/j.mfst.1673-9078.2018.10.015
    [Abstract](672) [HTML](0) [PDF 933.01 K](658)
    Abstract:
    This study aimed to reduce the sucrose content in Longan (Dimocarpus longan Lour.) juice and to prepare a Longan juice rich in Fructo-oligosaccharides. Longan juice was used as the main raw material for the investigations on. the effect of a single factor, including substrate concentration (as total soluble solids, TSS), substrate pH, fructosyltransferase addition, enzyme treatment temperature and time, on the conversion of sucrose and oligo-fructose formation in fruit juice. The changes in the contents of sucrose, fructose, glucose and fructo-oligosaccharides in the juice before and after enzymatic conversion were tracked and analyzed by liquid chromatography. The obtained results showed that parameters like substrate concentration, pH, amount of enzyme, treatment temperature and treatment time had significant effects (p<0.05) on the conversion of sucrose to fructo-oligosaccharides in Longan juice. Under the enzymatic conditions of TSS 30 oBrix, pH 6.0, enzyme dosage 9 U/g sucrose, 55°C for 7 h, the sucrose decreased from 164.36 to 22.34 mg/mL, leading to the fructo-oligosaccharide content of 97.88 mg /mL which accounted for 38.21% of the total sugar in the juice. The treatment with fructosyltransferase can effectively reduce the sucrose content in the Longan juice, and facilitate a low-calorie functional juice rich in fructo-oligosaccharide.
    16  Molecular Mechanism Underlying Inclusion Complexation of Curcumin with Short-chain Glucan
    FENG Tao ZENG Xiao-lan ZHANG Yu Marcelo Carignano Osvaldo Campanella LI Xiao-xi
    2018, 34(10):111-116. DOI: 10.13982/j.mfst.1673-9078.2018.10.016
    [Abstract](610) [HTML](0) [PDF 616.30 K](573)
    Abstract:
    The short-chain glucan obtained via enzymatic hydrolysis of waxy corn starch with the pullulanase is used to encapsulate curcumin to improve greatly water solubility of curcumin. This study uses a novel computer simulation method to analyze the inclusion of curcumin into short-chain dextran, and simulate molecular inclusion behavior of short-chain dextran-curcumin inclusion complex within 600 ns. By means of a self-assembly snapshot taken from the simulated trajectory, the inclusion complexation is achieved through simultaneous dissociation and complexation until a final stable structure is formed. The conformational change of short-chain glucan during its inclusion with curcumin was reflected by the radius of gyration of the system, which was consistent with the snapshot. The solubility of the system is good, and the results obtained by the simulation are basically consistent with the experimental results. The solubility of short-chain dextran-curcumin was higher than that of curcumin alone, thus, inclusion complexation improved the bioavailability of curcumin. Inclusion complexation represents a new approach for developing a suitable wall material for medicines.
    17  Characterization of the Diversity of Starter and Non-starter Microorganism from Natural Cheeses by High-throughput Sequencing
    ZENG Chun-lin ZHU Lin GAO Feng YU Bing-qian XU Qin YANG Sai WEI Wei
    2018, 34(10):117-125. DOI: 10.13982/j.mfst.1673-9078.2018.10.017
    [Abstract](645) [HTML](0) [PDF 814.30 K](795)
    Abstract:
    To reveal the diversity characteristic of starter and non-starter microorganism from natural cheeses, the Illumina-HiSeq high-throughput sequencing technology was used to carry out sequencing of V4 regions of 16S rDNA gene in the microorganism from the rinds and cores of the five groups of natural cheeses. The number of valid sequences obtained from each sample was over 50,000, and these sequences were confirmed as 118 to 646 operational taxonomic units (OTUs) in each sample. Chao 1 index, Shannon's index, and Simpson's index were used to evaluate the diversity of the samples, the results showed the rinds of natural cheese have higher bacterial diversity than the cores. Principal co-ordinates analysis showed there was a great difference in the bacterial community structure between the rind and the core of the natural cheese. The starter microorganism groups were of the genus Lactococcus, Lactobacillus and Streptococcus, with a total relative abundance between 51% and 97%. The non-starter microorganism groups were of the phylum Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, Deinococcus-Thermus and Tenericutes, with a total relative abundance between 2% and 16%. Furthermore, the genus Thermus, which can screen thermostable lactase, was firstly reported and was a predominant non-starter microbial group in all the samples. This study contributed to the clarification of the effect of microorganisms on flavor in natural cheeses, as well as the exploration of microbial resources in natural cheeses.
    18  Efficient Expression of Candida rugosa Lipase CRL1 in Pichia pastoris and its Application for Synthesis of Vitamin E Acetate
    HAO Yue-chuo LIN Ying LIANG Shu-li
    2018, 34(10):126-132. DOI: 10.13982/j.mfst.1673-9078.2018.10.018
    [Abstract](891) [HTML](0) [PDF 885.08 K](1096)
    Abstract:
    In this study, the optimized gene encoding Candida rugosa lipase CRL1 was synthesized in vitro, cloned into the vector pHKA and expressed in Pichia pastoris, producing a lipase activity of 39.73 U/mL towards p-nitrophenyl butyrate (pNPB) after induction for 120 h in flask fermentation. A new gene encoding GS115/pHKA-AOX1m/αm-CRL1 was obtained by modifying the AOX1 promoter and α-factor signal peptide, which lipase activity achieved 63.63 U/mL. Then the purified CRL1 was isolated from the supernatant of the zymotic fluid, through sequential treatments of ultrafiltration, ammonium sulphate precipitation and anion exchange chromatography. The specific enzyme activity of this purified CRL1 was 984.5 U/mg. The recombined CRL1 was characterized by the optimal temperature and pH at 40 ℃ and 7.5, respectively. Besides, it retained 52.99% of its original activity after incubation at 40 ℃ for 6 h and it was relatively stable in a slightly acidic environment. Furthermore, the crude CRL1 was lyophilized and harvested as an effective biocatalyst to synthesize vitamin E acetate in the solvent-free system. The optimal synthesis was performed with 200 mg D-α-tocopherol, 1 mL acetic anhydride, and 100 mg crude CRL1, at 60 ℃ and a shearing rate of 200 r/min for 6 h, of which more than 97% of D-α-tocopherol was transformed.
    19  High-yield-of-protease Strain Treated by ARTP and Its Improvement of Fermentation of Soybean Meal
    QU Wen-juan ZHANG Tian MA Hai-le HE Rong-hai
    2018, 34(10):133-140. DOI: 10.13982/j.mfst.1673-9078.2018.10.019
    [Abstract](573) [HTML](0) [PDF 627.97 K](725)
    Abstract:
    Bacillus amyloliquefaciens 10160 was treated by the technology of atmospheric and room temperature plasma (ARTP). Under the optimum dose of of lethality 80% for ARTP-induced mutagenesis (10 s), two stable mutant strains of C5 and C12 were succefully screened. Compared with the original strain, the neutral protease activities of C5 and C12 strains were increased by 86.0% and 85.0%, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) observations indicated that, the composition of the proteins extracted from C5, C12, and the original strains was similar, while the treated samples exhibited higher protein concentrations. The liquid fermentation experiments of soybean meal showed that, as compared with the original strain, the yield and content of peptides in the fermentation broth of C5 and C12 strains increased by 14.2% and 15.6%, and 13.2% and 11.8%, respectively. Neutral protease activities in the fermentation broths of C5 and C12 strains increased by 26.00% and 29.84%, respectively. There was no significant difference in the molecular weight distribution and ACE inhibition rate between the strains. Therefore, ARTP treatment of Bacillus amyloliquefaciens 10160 can significantly increase the yield of peptides produced by liquid fermentation of soybean meal.
    20  Extrusion with Enzyme Pretreatment Improves Dispersibility of Whole Corn Flour
    LIU Lei QIU Ting-ting ZHAO Zhi-hao ZHU Xue-mei HAN Ya-meng ZHANG Ming-wei
    2018, 34(10):141-146. DOI: 10.13982/j.mfst.1673-9078.2018.10.020
    [Abstract](647) [HTML](0) [PDF 544.05 K](815)
    Abstract:
    The changes in physicochemical properties of whole corn flour extruded with α-amylase pretreatment under solid state at high temperature were investigated. The result showed that compared with the extruded corn samples, the water solubility index of samples extruded with enzyme pretreatment increased 12.26%, and the water absorption index decreased 26.40%. The dispersion time reduced 24.14%, while the agglomerate rate increased 75.32%, and the viscosity decreased, and the dispersibility increased significantly. Carr index and Hausner ratio of samples increased 8.39% and 3.60%, respectively. Angle of repose and slio angle increased 24.59% and 6.49%, respectively; while bulk density increased. In addition, L* value and b* value of samples increased significantly, a* value and ?E value decreased, compared to extruded samples. In addition, extrusion with enzyme pretreatment decreased starch content by 5.85%, and increased the content of reducing sugar, fat and solube protein by 139.43%, 7.87% and 243.52%, respectively. This research overcome the technical problems of limited enzymolysis, which is caused by the low water content, high processing temperature and short time during extrusion process, and provide guidance for application of extrusion with enzymatic pretreatment techniques in processing of grain-based nutrient instant food.
    21  Analysis of Changes of Physiological and Biochemical Parameters in Banana Ripening Process and Establishment of Banana Quality Evaluation Model
    CHEN Li-hua HAO De-lan XIA Bin WANG Qin
    2018, 34(10):147-155. DOI: 10.13982/j.mfst.1673-9078.2018.10.021
    [Abstract](595) [HTML](0) [PDF 1.04 M](1113)
    Abstract:
    In this work, the color, aroma, taste, injury, and detachment of banana were evaluated as sensory indices. The physiological and biochemical parameters of banana, such as the hardness, peroxidase activity, the amount of soluble solids, total soluble sugar, Vc, total titrated acids and tannins under different temperature and concentration of ethephon were measured. The best ripening conditions for banana were spraying 1% 1000 mg/L ethephon (V/W, ethephon diluent volume/banana weight) evenly on banana surface, and saved under 90% RH and 19 ℃ for 5d. The maturity and quality of banana reach the best state. The banana got the sensory attributes score of 96.00. The relationships between sensory attributes score and the seven physiological and biochemical parameters were evaluated by means of partial least squares (PLS) to establish a mature quality evaluation model of banana. The significant physiochemical factors were the content of total soluble sugar, total titratable acid, tannin, hardness, Vc content, peroxidase activity, soluble solids content.
    22  Preparation of Microemulsion of Cymbopogon citratus (DC) Stapf Essential Oil and Analysis of Antioxidant Activity
    TAO Zi ZHAO Zhen-gang
    2018, 34(10):156-164. DOI: 10.13982/j.mfst.1673-9078.2018.10.022
    [Abstract](729) [HTML](0) [PDF 1.08 M](800)
    Abstract:
    This study aimed to prepare a microemulsion system that could improve the application of Cymbopogon citratus (DC) Stapf essential oil in aqueous environments. The essential oil was extracted by hydrodistillation and the volatile compounds in the extract (CEO) were analyzed by GC-MS. Pseudo-ternary phase diagrams were constructed to select suitable ingredients for preparation of microemulsions. The effects of surfactants, co-surfactant, Km value, pH value, ionic strength and other factors on the microemulsion existing area in the pseudo ternary diagram were investigated, to prepare a C.EO O/W microemulsion using Tween 80 (surfactant), anhydrous ethanol (co-surfactant), and deionized water ( aqueous phase). Its physicochemical properties were as follows: pH 6.73 ± 0.02, viscosity 15.50 ± 0.11 mPa ? s-1, conductivity 108.90 ± 0.21 μs ? cm-1, and average particle diameter 16.50 ± 0.53 nm. Finally, the antioxidant activities of CEO and CEO microemulsion were determined by DPPH, ORAC and PSC assays. The obtained results showed the antioxidant activity of CEO microemulsion was significantly higher than that of CEO (p < 0.05).
    23  Changes in the Activity of Dextranase under Simulated Sugar Refining Conditions
    LI Zhi-de LIANG Da-feng HUANG Zeng-wei ZHANG Jiu-hua CHANG Guo-wei LIU Gui-yun
    2018, 34(10):165-170. DOI: 10.13982/j.mfst.1673-9078.2018.10.023
    [Abstract](626) [HTML](0) [PDF 699.56 K](691)
    Abstract:
    Dextranase (EC 3.2.1.11) has been used in the production of cane sugar, beet sugar and refined sugar. There were obvious differences between the conditions of using this enzyme and those normally used for studies on general enzymatic properties. In this study, we simulated sugar refining conditions by preheating, pH adjustment and adding sucrose to the reaction substrate solution according to the actual production conditions, and then measured the activity changes in the activity of dextranase under different conditions. The obtained results the data will be provided data to support for the sugar refining production. The experimental results showed that, it’s obvious that the effect of temperature and pH on enzyme in the inorganic salt buffer. In the inorganic salt buffer system, the increase in temperature and use of a neutral to alkaline pH had a significant effect on the activity of dextranase. At 85 ℃, pH 5.5~7.0, the enzyme activity remained between 20% to 40%. When sucrose was added after an incubation in the water bath at 55 ℃ and pH 5.5~7.0 for 15 min, the remaining enzyme activity was in the range of 20% to 40%. Upon the addition of sucrose to the reaction solution, the adaptability of the dextranase to temperature and pH was remarkably improved. So this dextranase can be used in manufacture. In the 60 °Brix sucrose solution, when the dextranase was at 85 ℃, pH 5.5~7.0 or 75 pH 5.5~8.0, the activity after 15 min could be maintained over 40%. When the sucrose concentration was at 60 °Brix, no less than 40% of the activity of dextranase was retained after a reaction for 15 min in the water bath at 65 ℃ and pH 5.5~8.0 or 75 ℃ and pH 5.5~7.0. These results indicate that dextranase has good thermal stability in a high-concentration sucrose solution and can be used in sugar refining.
    24  Effect of High Hydrostatic Pressure Combined with Freezing on the Shucking and Quality of Penaeus vannamei
    CUI Yan LIN Xu-dong KANG Meng-li XUAN Xiao-ting YAO Ling-qiao LING Jian-gang
    2018, 34(10):171-178. DOI: 10.13982/j.mfst.1673-9078.2018.10.024
    [Abstract](569) [HTML](0) [PDF 660.93 K](659)
    Abstract:
    In order to determine the effect of high hydrostatic pressure combined with freezing (FT-HHP) on the shucking and quality of Penaeus vannamei, the fresh shrimps were froze and subjected to high hydrostatic pressure processing (200, 300 and 400 MPa at ambient temperature for 1, 3 and 5 min). The effect of FT-HHP on the shucking of shrimps was determined by investigating shucking time, integrity and shrimp meatyield. The changes in drip loss, water binding capacity (WBC), pH, color and texture of peeled shrimps as afunction of shucking conditions were determined. The results showed that FT-HHP is an effective method for Penaeus vannamei shucking. Under the co-treatment of 300 MPa, 1 min with freezing, the integrity of shrimp meat improved significantly, the shucking time decreased by 59.80% and 13.54%respectively, and shrimp meatyield increased by 30.92% and 7.25%respectively compared to the untreated and freezing samples. FT-HHP treatment observably reduced the drip loss of shrimp caused by the freezing process, and remarkably increased the WBC, and had no significant change compared with control group. After FT-HHP treatment, the L*, WI and ?E values of shrimps were enhanced obviously, and showed the cooked appearance at pressure ≥300 MPa, holding time≥3 min. With the increasing of treatment pressure, the hardness and chewiness increased, while the springiness decreased. According to the shucking performance and effect of FT-HHP on the quality characteristics of shrimps, co-treatment of 300 MPa, 1 min with freezing was suitable to treat Penaeus vannamei. It can significantly improve shucking efficiency, and maintain the good quality of shrimps. These results suggest that FT-HHP is a potent strategy for the shucking of Penaeus vannamei.
    25  Effects of Different Conditions on the Biofilm Formation of Cronobacter Sakazakii
    HAO Xu-sheng ZHANG Xiao-rong GUO Du ZHENG Zhan-wen SUN Yi XIA Xiao-dong SHI Chao
    2018, 34(10):179-187. DOI: 10.13982/j.mfst.1673-9078.2018.10.025
    [Abstract](637) [HTML](0) [PDF 983.78 K](749)
    Abstract:
    The present study investigated biofilm formation of C. sakazakii ATCC 29004 at various growth temperatures (12 ℃, 25 ℃ and 37 ℃), incubation medium (tryptone soya broth and infant formula broth) and surface material (stainless steel, glass and silicone). Firstly, attachment and biofilm formation were evaluated by viable counting method. The micro-structure of biofilm formed by C. sakazakii were confirmed by field emission scanning electron microscope. In addition, the effects of growth temperature and surface type on the biofilm resistance to disinfectants were also determined. The results showed that higher temperatures (25 ℃ and 37 ℃) induced stronger attachment and biofilm formation than 12 ℃, the bacterial biofilm formed better in tryptone soy broth than in infant formula broth. The silicone surface had significantly stronger attachment than stainless steel and glass at 37 ℃, but there was no differences in attachment and biofilm formation on different materials at other conditions. C. sakazakii formed flat and thin biofilms when growing at 12 ℃, but C. sakazakii formed compact and thick biofilms at 25 ℃ and 37 ℃. The biofilm structure were different at three different surface materials. The biofilm resistance to disinfectants is affected by growth temperature, incubation medium and surface type. The results indicated that the growth temperature, incubation medium and surface material were important to control biofilm formed by C. sakazakii.
    26  Chemical Deacidification Technology of Blue Honeysuckle Wine and Its Effect on Anthocyanin Composition
    LIANG Min BAO Yi-hong XU Fu-cheng
    2018, 34(10):188-195. DOI: 10.13982/j.mfst.1673-9078.2018.10.026
    [Abstract](609) [HTML](0) [PDF 783.42 K](651)
    Abstract:
    The blue honeysuckle wine obtained by fermentation has high acidity and poor taste, which needs to be improved by increasing the acid-reducing process. In this experiment, six kinds of chemical acid-reducing agents with obvious acid-reducing effect and low cost were used to reduce the acidity of blue honeysuckle wine, and the changes of anthocyanin content and composition in blueberry wine before and after acid-reducing were studied by liquid-mass spectrometry. The results showed that the best acid-reducing effect was found in sodium carbonate, followed by calcium carbonate. The best combination of composite acid-reducing agent was 2 g/L calcium carbonate and 3 g/L sodium carbonate. Under this condition, the blueberry wine could be reduced to 7~9 g /L, and increase the content of organic calcium in fruit wine, and get a better sensory quality. The results of HPLC-MS/MS showed that the anthocyanin species in the wine samples before and after acid reduction did not change, the total peak area after acid reduction was reduced by 19.92%, and the peak area of each anthocyanin was changed. Among them, the content of cyanidin-3,5-dihexanol glycoside and peonidin-3,5-dihexanol glycoside increased, especially the peak area of peonidin-3,5-dihexanol glycoside was 10.42-fold that before acid reduction, and peak areas of the rest anthocyanins all decreased.
    27  Comparison of Different Packaging Methods on the Quality of Persimmon Chips Stored at Constant Temperature
    JIA Yang-yang ZHOU Shi-jing LI Chun-mei
    2018, 34(10):196-204. DOI: 10.13982/j.mfst.1673-9078.2018.10.027
    [Abstract](484) [HTML](0) [PDF 887.40 K](665)
    Abstract:
    The persimmon fruits were sliced and dried by combined hot-air-microwave drying technique to obtain persimmon chips. The preservation effects of polyethylene(PE) bag, polyamide (PA) bag, aluminum foil composites, the PA bag packing with nitrogen, the aluminum foil composite packaged with desiccant and deoxidizer on the persimmon chips were compared. The persimmon chips packaged in 6 different packaging forms were subjected to a thermostatic preservation test to select the best packaging method. The moisture content, color and texture of the products were measured and compared every 7 days. Besides, the persimmon chips were exposed to air for destructive testing to determine the end of shelf life, and the changes in L* values were measured by accelerated shelf test to predict the shelf life of products. The results showed that the nitrogen filling of the PA bag had the best preserve effect on the moisture content, chroma, firmness and crispness of the persimmon chips. It was proved by the destructive test that the end of shelf life of persimmon product finished when the L* value decreased to 64.56, and the prediction model for L* value change of persimmon chips at 37 ℃ and 47 ℃ was: y=73.30622e-0.00079x and y=73.05771e-0.0180x, respectively. The calculated Q10 was 2.28. It was predicted that the shelf life of the persimmon chips packed with nitrogen in the PA bag at the storage temperature of 25 ℃ was about 460 days.
    28  Rapid Determination of 36 Pesticide Residues in Fruits by Solid-phase Extraction-Gas Chromatography-Mass Spectrometry
    ZHOU Xue CHEN Ting-ting LI Wan-rong LIU Xue WU Lin-jing ZHANG Nen-ling
    2018, 34(10):205-213. DOI: 10.13982/j.mfst.1673-9078.2018.10.028
    [Abstract](517) [HTML](0) [PDF 860.24 K](619)
    Abstract:
    A gas chromatography-mass spectrometry (GC/MS) method for the determination of 36 pesticide residues in fruits was established on the basis of the selection of solid phase extraction column, extraction solvent and eluent volume. The fruit samples were extracted with acetonitrile, purified by graphitized carbon black/amino solid-phase column (PC/NH2) t, analyzed by GC/MS with the single ion monitoring scanning mode (SIM), and quantified by the matrix-matched method with external standards. All the targeted substances showed a good linear correlation in the range of 70.00 ng/mL~560.0 ng/mL, with the correlation coefficients (R2) not less than 0.990. The limit of detection (LOD) of the method ranged in 0.0001~0.0018 mg/kg when the signal/noise (S/N) ration =3, with the limit of quantification (LOQ) in the range of 0.0002~0.0060 mg/kg (S/N=10). The spiked recovery tests were carried out at low, medium and high levels of the extraction matrix. The average recovery of the method ranged in 60.6 %~116.5 % with the relative standard deviations (RSDs, n=6) in the range of 0.8%~9.5%.The results demonstrated that the method is simple and the outcome of purification of matrix by solid phase extraction was satisfactory. Owing to high specificity and broad range of application, this method is suitable for screening and verification of multicomponent pesticide residues in pome fruits and small climbing fruits.
    29  The Characteristic Flavor Compounds Analysis of Different Cultivars of Mango by Electronic Tongue and SPME-GC-MS
    ZHANG Hao AN Ke-jing XU Yu-juan YU Yuan-shan WU Ji-jun XIAO Geng-sheng
    2018, 34(10):214-224. DOI: 10.13982/j.mfst.1673-9078.2018.10.029
    [Abstract](847) [HTML](0) [PDF 1.07 M](850)
    Abstract:
    The flavor quality differences of four mango cultivars (Jin Mang, Qing Mang, Hongyu and Guifei) were studied electronic tongue and headspace solid phase microextraction combined with Gas Chromatography-Mass Spectrometry detection technology. The result of principal component analysis (PCA) of electronic tongue showed that four cultivars of mangos can be well distinguished into two groups by electronic tongue. Qing Mang and Hongyu have similar gustatory quality, to Jin Mang and Guifei. The physio-chemical indexes of water content, pH, (and colors) soluble solids also showed similarity in Jing Mang and Guifei, as well as in Qing Mang and Hongyu, which was consistent with the result of electronic tongue. HS-SPME/GC-MS results showed that there were 7 categories compounds detected in four cultivars of mangos, mainly including terpenes, esters and aldehydes. The terpenes were the dominant volatile compounds, whose relative content were more than 50% in all four cultivars of mangoes. The PCA results of volatile compounds showed that the characteristic volatile compounds of Jin Mang were (E,Z)-2, 6-nonadienal, isophenolene, 3-hexene-1-alcohol and palmitic acid, the characteristic volatile compounds of Guifei were 2-carene, (E) loreleene and 4-carene, the characteristic volatile compounds of Qing Mang were a-eucalyptus, hexanal and (E) -3- hexenal, the characteristic volatile compounds of Hongyu were 3- careen and limonene. The flavor of four mangos, which was shaped by the characteristic volatile compounds showed that the Qing Mang and the Hongyu were similar, the Jin Mang and the Guifei were similar, too. Comprehensive analysis of the above results showed that the Qing Mang and Hongyu have similar flavors, Jin Mang and Guifei have similar flavors.
    30  Preparation of Antibodies and Preliminary Establishment of Immunoassay Method against Allergen β-Lactoglobulin from Milk
    LI Ya-pu MA Yun-lian FAN Dan ZHANG Xiao-bing
    2018, 34(10):225-230. DOI: 10.13982/j.mfst.1673-9078.2018.10.030
    [Abstract](721) [HTML](0) [PDF 609.53 K](949)
    Abstract:
    The β-lactoglobulin antigen was used with injection to immunonize the New Zealand white rabbit and the BALB/c mice so as to get the rabbit polyclonal antibody serum (PcAb) and the monoclonal antibody (McAb), and the titers of antibodies were analyzed; The polyclonal antibody was purified by protein A affinity chromatography and the 3A7 monoclonal antibody was purified by Caprylic acid precipitation. The experiment was operated by the double-antibody sandwich procedure and some samples were detected. The results showed that the titer of polyclonal antibody was over 1:6.56×106, and the polyclonal antibody serum could bind to β-lactoglobulin specifically, and its specificity was low reactivity with casein. The titers of the three strains of monoclonal antibodies were above 106 and the 3A7 monoclonal antibody had almost no cross reactivities with other proteins in milk and other allergen proteins. The accuracy was 100% for the detection of samples.
    31  The Effect of Chlorina on the Aroma of Yinghong9 Black Tea
    CHEN Wei QI Dan-dan WANG Wen-wen MIAO Ai-qing PANG Shi MA Cheng-ying
    2018, 34(10):231-239. DOI: 10.13982/j.mfst.1673-9078.2018.10.031
    [Abstract](685) [HTML](0) [PDF 1021.81 K](635)
    Abstract:
    The chlorina Yinghong9 which occur in yellow young leaves during growing stage is a result of abnormal chloroplast development. The changes of photosynthesis and metabolite accumulation in chlorina Yinghong9 might potentially affect the quality of its processed tea. To reveal the possible tea aroma changes caused by chlorina, cut-tear-curl (CTC) black tea prepared from the chlorina and normal Yinghong9, marked as HY and CK (control) respectively, were selected to valuate sensory aroma quality and volatile organic compounds (VOCs). The result of sensory evaluation indicated that an overall aroma intensity of HY black tea (especially in attributes of sweetness and freshness) decreases in comparison to the CK. A total of 56 VOCs were identified by headspace-solid phase mircoextraction (HS-SPME) coupled with gas chromatography-triple quadrupole mass spectrometry (GC/MS/MS) among the samples. Forty-nine differential VOCs were obtained between the sample groups according to the frequency of occurrence as well as univariate analysis. These VOCs were applied to chemometrics analyses and pathway-based classification subsequently. Clear separation was achieved among HY and CK samples in score plot of principle component analysis (PCA). Ten differential VOCs demonstrated composition variation between sample groups where HY black teas presented VOC varieties in lesser amount. Thirty-nine differential VOCs showed content variation between sample groups, and 28 of them decreased in HY black teas while the other 11 ones increased. The differential VOCs were mainly related to the tea aroma derivation pathways of fatty acid and carotenoids oxidation as well as the terpenoid biosynthesis.
    32  Determination of Protein Amino Acids and Nonprotein Amino Acids in Two Edible Fungi by HPLC with OPA-FMOC Precolumn Derivatization
    XIE Zhi-ru CHENG Min TAN Li-rong XIAO Xue LI Sha-sha
    2018, 34(10):240-246. DOI: 10.13982/j.mfst.1673-9078.2018.10.032
    [Abstract](602) [HTML](0) [PDF 657.88 K](953)
    Abstract:
    To study composition and content of protein amino acids (PAA) and nonprotein amino acids (NPAA) in Letinous edodes and Flammulina velutipes, and to evaluation their nutrition and flavor, the composition and content of PAA and NPAA in Letinous edodes and Flammulina velutipes were determined by OPA-FMOC precolumn derivatization and HPLC. The results showed that Letinous edodes contains 15 kinds of PAA with the content of 10.99 mg/g, contains 2 kinds of NPAA with a content of 2.37 mg/g. The content of essential amino acids (EAA) is 4.39 mg/g and the content of flavor amino acid (FAA) is 5.40 mg/g. There are 14 kinds of PAA in the Flammulina velutipes with content of 16.79 mg/g and 2 kinds of NPAA with the content of 3.99 mg/g. The content of the EAA is 5.98 mg/g and FAA is 9.96 mg/g. The method is accurate and feasible. It can be used for the determination of PAA and NPAA in the fungi. There are more kinds of PAA in Letinous edodes than that in Flammulina velutipes, EAA in Letinous edodes was more than that in Flammulina velutipes, and PAA and NPAA contents in Flammulina velutipes were higher than those in letinous edodes. Flammulina velutipes occupy high nutritional value and delicious taste, while Letinous edodes possess a balance nutritional value. The results in this work were helpful for the re-development of Letinous edodes and Flammulina velutipes.
    33  Identification and Virulence Genes Detection of Bacillus Cereus Food Isolates
    BAI Feng-lan CHEN Song LUO Meng-you ZENG Bao-feng TANG Jun-ni
    2018, 34(10):247-252. DOI: 10.13982/j.mfst.1673-9078.2018.10.033
    [Abstract](795) [HTML](0) [PDF 578.73 K](849)
    Abstract:
    To identify the virulence genes of Bacillus cereus food isolates,a total of 130 food samples were collected in Chengdu city in this study. The isolation of Bacillus cereus strains was performed according to the colony morphology on MYP medium. Then 16S rRNA sequencing analysis and Bacillus cereus housekeeping genes (gyrB, rpoB, VrrA, groEL) were used to identify the isolates. Finally, the virulence genes of Bacillus cereus isolates were detected. The results showed that 23 Bacillus cereus isolates were identified from 130 collected food samples. The isolation rate was 17.7%. Twenty-three Bacillus cereus isolates carried all four housekeeping genes (gyrB, rpoB, VrrA, groEL). The virulence genes detection showed nheB and entFM were found in 16 isolates and the detection rates were relatively high (16/23, 69.6%); the nheA and nheC genes were detected in 14 isolated strains and the detection rates were 60.9%; the hblD gene was detected in 11 isolates and the detection rate was 47.8%; the cytK gene was detected in 10 isolates and the detection rate was 43.5%; the bceT gene was detected in 9 isolates and the detection rate was 39.1%; the hblA and hblC genes were detected in 8 strains and the detection rates were 34.8%; the cer and ces genes were detected in 2 isolated strains, and the detection rates were 8.7%; the hblB and Hly genes were not found in any isolates. This study indicated that the occurrence rates of virulence genesin Bacillus cereus food isolates were relatively high, which had a potential threat to food safety. The regulatory authority should pay attention to Bacillus cereus contamination.
    34  Study of the Rapid Identification Method of Coffee Adulteration Based on Near-infrared Spectroscopy
    CHEN Xiu-ming XI Xing-lin PAN Bing-zhen LIANG Rui-ting SHAO Shi-ping LI Shuang HE Ji-zi
    2018, 34(10):253-257. DOI: 10.13982/j.mfst.1673-9078.2018.10.034
    [Abstract](710) [HTML](0) [PDF 539.28 K](843)
    Abstract:
    The near infrared spectroscopy combined with adulterant screen algorithm was used to establish coffee fast identification method in this word. The near infrared spectrometer was used to collect coffee spectral data, the spectral database of standard samples (material spectrum), the spectral data of adulterants, and then to establish the spectral database of adulterants. The classification model and adulterant model of coffee were established. The Adulterant Screen was used to analyze the principal components of the model and composition of adulteration, and then to establish a coffee adulteration fast identification model. The method can be used to identify adulterated coffee containing 2, 5, 10, 15, 20, 30 and 40 percent of Brazil berry fruit power. It can be also used to identify adulterated coffee containing 5, 10, 15, 20, 30 and 40 percent of barley. The lowest identified concentrations of adulterated acai and barley in coffee were 2% and 5%, respectively. The near infrared spectroscopy combined with Adulterant Screen algorithm based fast identification model can identify coffee in adulteration, such as brazil berry fruit powder and barley. It provides a fast, reliable and nondestructive testing method for the adulteration identification of coffee samples. It can be used in routine testing of coffee sample adulteration.
    35  Detection and Quantification of Goose-derived Materials in Food and Feedstuffs by Droplet Digital PCR
    WANG Qiang CAI Yi-cun ZHANG Yang PAN Liang-wen
    2018, 34(10):258-263. DOI: 10.13982/j.mfst.1673-9078.2018.10.035
    [Abstract](540) [HTML](0) [PDF 592.27 K](647)
    Abstract:
    In this study, a highly precise, quantitative method based on the droplet digital polymerase chain reaction (ddPCR) technique was developed to identify and quantify the goose content in food and feedstuffs. The single-copy Anser cygnoides domesticus genomic scaffold gene was selected as the target gene, a formula for calculating raw meat weight based on target DNA copy number was established. Exclusive specificity was verified using samples from 21 different animal species, and inclusive specificity of goose was tested using nine different breeds. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were 1 and 5 copies/μL, respectively. The accuracy and applicability of the method were verified using mixed powder samples with known proportions and commercial products.The results confirmed that the developed ddPCR method is highly precise for identifying and quantifying the goose content in food and feedstuffs, indicating the potential applicability in future routine analyses.
    36  Automatic Recognition Method of Five-flowered Meat with Adaptive Threshold Based on Maximum Inter-class Variance
    HE Qiu-rong HE Zi-liang GU Wan-rong ZHONH Nan SUN Yuan-ming
    2018, 34(10):264-270. DOI: 10.13982/j.mfst.1673-9078.2018.10.036
    [Abstract](491) [HTML](0) [PDF 13.38 M](682)
    Abstract:
    Chemical or manual detection methods are often used in the detection of five-flowered meat. The both methods are costly and time-consuming, and the errors are large. In order to improve the accuracy of this research, reduce the cost and achieve automatic detection, we used maximum interval variance adaptive threshold approach to separate the background of R-based color layer and filtered the image by median filtering in this paper. Aiming at the non-strong contrast between fat and lean meat in the five-flower meat image, we used the adaptive histogram function with limited contrast to enhance the contrast between fatness and lean meat, and then use the maximum interval adaptive threshold method to separate the fat and lean meat regions. The experimental results on the actual image samples showed that the proposed method is more accurate than the traditional new method. It shows that our method based on automatic threshold filtering can distinguish the fat and lean meat areas effectively.
    37  Research Progress of Microencapsulation Technologies for Lipid Encapsulation
    WANG Hui-mei FAN Yan-min WANG Lian-yan
    2018, 34(10):271-280. DOI: 10.13982/j.mfst.1673-9078.2018.10.037
    [Abstract](938) [HTML](0) [PDF 1021.76 K](1213)
    Abstract:
    Lipids including oils widely exist in nature and are rich in nutrients, thus, they have high application value in the fields of medicine, food and cosmetics. However, they are easily oxidized and deteriorated owing to the presence of unsaturated fatty acids, which limits their applications. Microencapsulation is an advanced technology with high practical value and has been widely applied in many fields. This technology can encapsulate lipids into microcapsules, by which lipids can not only be separated from oxygen in air to prevent oxidation and mask bad flavors, but also improve their different properties. In addition, microencapsultion can convert lipids into solid powders to offer special functions, which further broaden the applications of lipids. This article will provide an overview, focusing on the structure, preparation and release mechanism of microcapsules, as well as the advantages and application of microencapsulation technologies for different lipids. This review provides some theoretical basis for the study of oil microencapsulation of lipids, and offers reference for further use and development of lipid products or other bioactive substances.
    38  Progress in Detection Technology of Veterinary Drug Content in Feed
    CHEN Qin FANG Ke-yan ZHAO Chao-min DENG Xiao-jun
    2018, 34(10):281-290. DOI: 10.13982/j.mfst.1673-9078.2018.10.038
    [Abstract](650) [HTML](0) [PDF 596.21 K](712)
    Abstract:
    The methods for the detection and analysis of veterinary drugs in feed in recent years were reviewed. A brief introduction on the relative laws and regulations regarding the usage of forage and medicine, as well as the advantages of using veterinary drugs and the harm of illegal uses of unsafe drugs in feed were summarized. Emphasis was laid on pretreatment technology and detection technology of feed matrices, including sample extraction and separation as well as purification and different detection methods, being in use for the determination of drugs. It is provided to illustrate common trends and method variability. The advantages and disadvantages of different detection techniques, as well as the application of different detection techniques in the detection of veterinary drugs were analyzed. Finally, the possibilities of novel analytical approaches were discussed. Due to the variety of the veterinary drug and the complex feed matrix, there are many differences in the detection methods of veterinary drugs. However, the exact, fast and high-throughput detection methods are relatively few. It is necessary to optimize the pretreatment technology, shorten pre-processing time and improve detection efficiency of veterinary drug detection, and intensify research and development of high-sensitivity and accuracy detection technology to provide a reliable basis for better supervision and regulation of the use of veterinary drugs in feed.

    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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