Volume 35,Issue 6,2019 Table of Contents

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  • 1  Protective Effect of Caffeic Acid Phenylethyl Ester on Pancreas of Diabetic Rats
    GONG Pin WANG Sheng-nan CHANG Xiang-na YANG Wen-juan CHEN Fu-xin
    2019, 35(6):1-6. DOI: 10.13982/j.mfst.1673-9078.2019.6.001
    [Abstract](476) [HTML](198) [PDF 38.14 M](709)
    Abstract:
    The protective effect of caffeic acid phenethylester (CAPE) on pancreas of type 2 diabetic rats and their mechanism were investigated. Thirty male SD rats were randomly divided into three groups: blank group, injury group and protection group. The rat model of type 2 diabetes mellitus was induced by high-fat and high-sugar diet combined with streptozocin (STZ). The protective group was protected by CAPE. The contents of malondialdehyde (MDA), protein carbonylation (PCO), nitric oxide (NO), glutathione (GSH) and activities of super oxide dismutase (super oxide dismutase), catalase (CAT) in pancreas were determined. The results showed that the contents of MDA, PCO and NO in the injured group were significantly increased, which were 2.52, 1.64 and 2.78 times higher than those in the blank group, respectively, while the contents of MDA, PCO and NO in the protective group were lower than those in the injured group, only 47%, 69% and 47% of the injured group, respectively. It indicated that diabetes can lead to oxidative stress of pancreas and destroy its structure and function. Protecting with CAPE could decrease the contents of MDA, PCO and NO and reduce the damage to pancreas. The activities of SOD, CAT, GSH and other antioxidants in the body were reduced by excessive free radicals produced by the body in response to oxidative stress. CAPE could enhance the activities of SOD, CAT and GSH and accelerate the speed of scavenging free radicals in the body. It had certain protective effect on diabetic pancreas.
    2  Synergistic Tumor Inhibition Effects of Vitamin B2 and 5-fuorouracil on Colon Cancer Cell C26 and Balb/c Mice
    CHEN Xi LI Hai-tao
    2019, 35(6):7-16. DOI: 10.13982/j.mfst.1673-9078.2019.6.002
    [Abstract](485) [HTML](431) [PDF 91.74 M](606)
    Abstract:
    The aim of this research is toexplore the synergistic effect of penta-fluorouracil (5-FU) combined with VB2 on anti-colon tumor activity in vivo and in vitro. In vitro, the combined index (CI) was quantitatively analyzed by MTT assay and Chou-Talalay Method (CI=1 additive effect; CI<1 synergistic effect; CI>1 antagonism); the influence of drug combination on the cleavage of apoptotic protein PARP and cell cyclewas studied through cell flow and Western blot experiments. In vivo, the animal experiments of colon cancer Balb/c tumor-bearing mice were used to explore the effect of combining two drugs on tumor growth and immune function. The results showed that 5-FU combined with VB2, the corresponding CI values to 50% and 90% of C26 cell inhibition were 0.52 and 0.13 respectively, so the effect of these two drugs combination was synergistic. The PARP protein band was observed using 5-FU or VB2 alone, but the band of the combined group was significantly enhanced. Besides, the percentage in the G1 phase for thecombing drugs group was 75.12%, while the 5-FU group was 64.02%, and the difference was statistically significant (p<0.05). In vivo, after combining two drugs, the tumor inhibition rate of mice increased from 51.53% to 76.18%, and the tumor body ratio index decreased from 0.16 to 0.07, and the difference was significant (p<0.001); spleen index of combination group was obviously lower than 5-FU single-use group; liver and kidney index and blood urea nitrogen and plasma creatinine levels were not statistically different; and compared with the 5-FU treatment group (its plasma uric acid content was 108.50 μmol/L), the uric acid content of the combination group was only 59.75 μmol/L, which was significantly decreased (p<0.001). Therefore, 5-FU combined with VB2 has synergistic antitumor activity in colon cancer C26 cells and Balb/c tumor-bearing mice, and is associated with cell G1 arrest.
    3  Changes in Protein, Saponin Content and Starch Profiles of Quinoa (Chenopodium quinoa Willd) Seeds during Germination
    HAN Ya-meng CHI Jian-wei MA Yong-xuan JIA Xu-chao FAN San-hong LIU Lei
    2019, 35(6):17-23. DOI: 10.13982/j.mfst.1673-9078.2019.6.003
    [Abstract](727) [HTML](367) [PDF 4.71 M](945)
    Abstract:
    Germination is an effective processing method to improve the texture and nutritional value of cereals. This study aimed to investigate changes in protein, saponin content and starch profiles of quinoa seeds during germination. Results showed that the crude and soluble protein content of quinoa seeds increased significantly by 5.38% and 17.55% during germination. As the germination time gradually increased, the total starch, amylose and amylopectin content decreased by 25.95%, 4.86% and 29.53%, respectively, while the reducing sugar content increased significantly by 26.60%. In addition, germination process significantly improved the in vitro starch digestibility of quinoa seeds. The percentage contents of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) were 38.45%, 43.64% and 17.90% in raw quinoa seeds, respectively. The RDS increased significantly to 53.46% after germination for 48h, while SDS and RS decreased to 40.42% and 6.11%, respectively. Moreover, the total saponin content of quinoa seeds increased significantly by 16.46% after germination. Therefore, germinated quinoa seeds have better nutritional value and digestibility, and can be used as functional food ingredient for human healthy.
    4  Protective Effect of Urtica fissa on Kidney Injury in Type 2 Diabetic Mice
    YANG Wen-juan MA Yang-min WANG Lan ZHANG Jia-yuan ZHENG Rui DONG Hong-yan
    2019, 35(6):24-29. DOI: 10.13982/j.mfst.1673-9078.2019.6.004
    [Abstract](469) [HTML](229) [PDF 85.09 M](776)
    Abstract:
    The study is about the protective effect of Urtica fissa on kidney injury in type 2 diabetic mice and its relationship with antioxidant activity. The model of type 2 diabetes mellitus in mice was established by intraperitoneal injection of streptozotocin (STZ). Diabetic mice were randomly divided into model group, metformin group (0.14 g/kg), low, medium and high dose group of Urtica fissa (0.25 g/kg, 0.50 g/kg, 1.00 g/kg). Mice were given saline for 4 weeks. The levels of serum urea nitrogen (BUN), creatinine (SCr) and malondialdehyde (MDA) and protein carbonyl (PCO) in kidney tissue were measured. The activity of superoxide dismutase (SOD) and catalase (CAT) were measured and the pathological changes of kidney were observed. The results showed that compared with the model group, serum BUN and SCr decreased by 6.15 mmol/L and 30.87 μmol/L (p<0.05), renal MDA decreased by 2.97 nmol/mg, PCO decreased by 23.43 nmoL/mg (p<0.05, p<0.01), SOD activity increased by 55.85 U/mg and CAT activity increased by 33.84 U/mg (p<0.01), and alleviate the pathological state of kidney tissue in a dose-dependent manner. It can be concluded that Urtica fissa has protective effect on STZ-induced kidney injury in type 2 diabetic mice, and the protective mechanism is related to antioxidant effect.
    5  Protective Effects of a Polysaccharide from Eurycoma longifolia against Oxidative Stress-induced Erythrocyte Hemolysis
    HE Ping WANG Qian ZHANG Meng-meng ZHAN Qi-ping LAI Fu-rao MIN Tian ZHANG Xiao-yuan WU Hui
    2019, 35(6):30-38. DOI: 10.13982/j.mfst.1673-9078.2019.6.005
    [Abstract](550) [HTML](208) [PDF 19.55 M](631)
    Abstract:
    A crude polysaccharide extract was obtained from Eurycoma longifolia via ultrasound-assisted water extraction, and the optimal extraction conditions were determined by the L9(34) orthogonal test. A novel polysaccharide component containing uronic acid, Ali-1, was obtained through purification by column chromatography. The basic structure of Ali-1 was determined through analyses of its molecular weight and monosaccharide composition. The antioxidant activity of Ali-1 was evaluated based on the oxygen radical absorption capacity (ORAC), as well as the changes in the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) of red blood cells in the human erythrocyte hemolysis model. The results showed that the optimal extraction conditions for the crude polysaccharide were: ratio of material to liquid 1:40, extraction temperature 95 oC, ultrasonic power 300 W, extraction time 2 h. The yield of the crude polysaccharide from Eurycoma longifolia was 10.09% under the optimum conditions. Ali-1 had an average molecular weight of 14.3 ku and was mainly composed of xylose, arabinose, glucuronic acid and galacturonic acid at a molar ratio of 4.43:1.10:1:1.14. The ORAC value of Ali-1 was 302.48±2.71 μmol Trolox equivalents/g. Pretreating with Ali-1 could effectively reduce the levels of MDA and ROS in the 2-2′-azo-bis- (2-amidinopropane) dihydrochloride (AAPH)-injured erythrocytes, restore the erythrocytes to the normal state, and protect the weak erythrocytes (even though their average SOD, GSH-Px and CAT activities decreased). In summary, the isolated and purified polysaccharide Ali-1 from Eurycoma longifolia can protect human red blood cells against AAPH-induced injury and exhibit good antioxidant activity.
    6  Antioxidant Activity of Mulberry Alkaloid in Mice on High-fat Diet
    HAO Qi-lin PENG Xiao-die YANG Min DING Xiao-wen HUANG Xian-zhi
    2019, 35(6):39-47. DOI: 10.13982/j.mfst.1673-9078.2019.6.006
    [Abstract](482) [HTML](200) [PDF 974.18 K](667)
    Abstract:
    To study the antioxidant capacity of mulberry alkaloid in mice on high fat-diet, the mice on high fat-diet were fed with alkaloid at different concentrations (20, 40, 80 mg/kg) by gastric gavage for 4, 8, 12, 16 weeks respectively, the content of malondialdehyde (MDA) and other indicators in liver and serum of the mice on high fat-diet were assessed by kit. The results showed that in the mice fed with a dose of 80 mg/kg by gastric gavage for 16 weeks, the content of MDA in liver decreased by 43.63% and in serum decreased by 50.91%, compared with the hyperlipidemic control group. The contents of T-AOC and GSH in liver were increased by 2.36 and 2.69 times respectively, and the contents in serum increased by 2.25 and 1.59 times respectively. The activity of glutathione (GSH), catalase (CAT), peroxidase (POD), glutathione peroxidase (GSH-Px) and superoxide dismutase(SOD) in liver increased by 1.82, 2.22, 1.90 and 1.22 times, and the activity in serum increased by 1.48, 2.19, 1.59 and 1.44 times, respectively. In conclusion, the alkaloids of mulberry leaves have strong antioxidant effects on high-fat diet mice.
    7  Comparative Analysis of Antioxidant Activity and Anti-proliferative Activity against Hep G2 Cells of Three Blueberry Varieties
    LIANG Ze-ming CHEN Chun WU Hui-yi HU Xin-yi WANG Rui-fei YU Yi-gang
    2019, 35(6):48-55. DOI: 10.13982/j.mfst.1673-9078.2019.6.007
    [Abstract](366) [HTML](308) [PDF 21.49 M](702)
    Abstract:
    Three common commercially available blueberries (Vaccinium uliginosum L., Vaccinium ashei Reade and Vaccinium corymbosum L.) were studied for their total contents of polyphenols, flavonoids and anthocyanins, as well as the antioxidant activity and anti-proliferative activity against Hep G2 cells. The correlation between the content of active components and the activities was also examined. The results showed that the contents of total polyphenols, total flavonoids and total anthocyanins and abilities to scavenge the DPPH and ABTS free radicals of the Vaccinium uliginosum L. (a wild blueberry from the Northeast China) were significantly (p<0.05) higher than those in Vaccinium ashei Reade (a blueberry from Guizhou China) and Vaccinium corymbosum L. (a blueberry from Chile). The results of cellular antioxidant experiments indicated that the wild blueberry from the Northeast China exhibited significantly (p<0.05) higher Cellular Antioxidant Activity (CAA) values [65.40±3.04 μmol QE/100 g fresh fruit for Phosphate Buffered Saline (PBS) cleaning; 202.40±6.33 μmol QE/100 g fresh fruit for non-PBS cleaning] than the blueberries from Guizhou and the Chilean blueberry. The three types of blueberries all exhibited strong inhibitory effects on Hep G2 cell proliferation, with the half maximal effective concentration (EC50 value) of the wild blueberry from the Northeast China (150.41±7.82 mg/mL) was significantly (p<0.05) lower than those of the Guizhou blueberry (212.87±13.10 mg/mL) and Chilean blueberry (223.53±12.53 mg/mL). The CAA values of the blueberries were significantly correlated with the total contents of polyphenols and flavonoids, while there was also a significant (p<0.05) correlation between the EC50 values of anti-Hep G2 cell proliferation and the total polyphenols, and between the total flavonoid content and the total anthocyanin content. The above results indicate that the wild blueberry from the Northeast China has great advantages in development and utilization.
    8  Mechanism of Antibacterial Peptide Met-Ala-Lys Affecting on the Cytomembrane of Pseudomonas aeruginosa
    LIU Ying-jun LI Su-fen WANG Qin LIU Hui-fan
    2019, 35(6):56-63. DOI: 10.13982/j.mfst.1673-9078.2019.6.008
    [Abstract](425) [HTML](343) [PDF 24.26 M](709)
    Abstract:
    The present study investigated the antibacterial effected of the peptide Met-Ala-Lys (MAK) on the structure of Pseudomonas aeruginosa based on the NPN fluorescence method, the circular dichroism spectroscopy analysis, and the level of potassium ions and protein were employed respectively to characterize the extracellular membrane permeability, the variation of secondary structure, and the cell surface hydrophobicity and its endometrial permeability induced by the MAK. The results showed that with the increase of time, the secondary-structure, specially the Random coil, of MAK changed, resulting in the leakage of potassium (getting rapidly from the first 10 min) and protein were significantly high (from 4.65 μg/mL to 10.25 μg/mL), indicating that the inner (from 54.03% to 27.33%) and outer (increase rapidly in the first 30 min and basically stable at around 45 after 30 min ) membrane permeability were changed, thus, MAK can change the surface characteristics of Pseudomonas aeruginosa and contribute to the inhibition of bacterial growth. These results may provide some information for further study of antibacterial peptide, especially in the aspect of the mechanism of antibacterial peptide Met-Ala-Lys.
    9  Effect of Stems and Buds of Alisma orientalis on Blood Lipid in Rats with Hyperlipemia
    HOU Shao-wei LUO Ying-ying YAN Xin WU Miao-Lin ZHANG Ai-ling LUO Xiao-jian YU Jun
    2019, 35(6):64-69. DOI: 10.13982/j.mfst.1673-9078.2019.6.009
    [Abstract](515) [HTML](243) [PDF 14.44 M](605)
    Abstract:
    The regulating effect of Stems and Buds of Alisma orientalis on blood lipid in hyperlipidemia rats was investigated. Sixty male SD rats were fed with high-fat diet for a certain period of time to establish a rat model of hyperlipidemia. At the same time, different doses of Stems and Buds of Alisma Orientalis were administered by intragastric administration. Biochemical tests were performed to observe total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein (LDL-C) in serum of rats in different groups at different times, and at the end of experiment HE staining was used to observe the histopathological changes of the liver of each group. The results showed that for the high and low dose groups of Stems and Buds of Alisma orientalis, the levels of TC and LDL-C in serum were significantly decreased on the 14th day of modeling. Compared with the model group, the TC decreased by 16.64% and 12.85%, respectively (p<0.05); The LDL-C decreased by 29.90% and 22.98%, respectively (p<0.05). On the 21st day of modeling, the levels of TC and LDL-C in the high and middle dose groups decreased. On the 28th day of modeling, there was no significant difference compared with the model group. Stems and Buds of Alisma orientalis has a certain effect of lowering blood lipids in the early stage of high fat formation. The results of HE staining showed that there was some cell degeneration in the hepatocyte tissue of the model group. Compared with the model group, the liver tissue of the rats in the drug-administered group had a certain degree of improvement. It can be seen that the Stems and Buds of Alisma orientalis has a certain effect on lowering blood lipids.
    10  Protective Effect of a Pueraria-Ampelopsis grossedentata-Corn Oligopeptides Composite against Chronic Alcohol-induced Liver Injury in Mice
    LUO An-ling CHEN Xin-xin ZHENG You-li TANG Xing-jun ZHOU Qin-li LIU Xiao-jie CONG Feng-song
    2019, 35(6):70-76. DOI: 10.13982/j.mfst.1673-9078.2019.6.010
    [Abstract](646) [HTML](255) [PDF 874.50 K](940)
    Abstract:
    The anti-alcohol and hepatoprotective effect of a composite of pueraria, Ampelopsis grossedentata (AG) and corn oligopeptides (COP) were investigated. The anti-alcohol effects of pueraria, AG and COP used alone or in combination on drunk mice were evaluated through animal behavior experiments. The results showed that the pueraria-AG-COP composite (PAC composite) could significantly (p < 0.05) extend the waking time for drunkenness (up to 55.14±20.97 min) and shorten the period of hangover (to 75.88±23.28 min) while improving significantly the behavioral indices of the drunk mice, as compared with the model group. In the established chronic alcohol-induced liver injury mouse model, the hepatoprotective effect of PAC composite was investigated through measuring the biochemical indices of serum and liver tissues in mice, observing the pathological changes in hepatic tissues and examining the protein expression in liver tissues. Compared with the model group, the PAC composite could alleviate alcohol-induced liver damage in liver-injured mice: reducing significantly (p < 0.05) the activities of ALT and AST (to 17.09±6.26 and 21.41±6.80 U/L, respectively) in serum and the content of malondialdehyde (MDA; 2.46±0.31 nmol/mg) in liver tissues, whilst increasing significantly (p < 0.05) the content of glutathione (GSH, to 8.80±2.14 nmol/mg) and activity of superoxide dismutase (SOD; to 241.99±35.60 U/mg) in liver tissues. The PAC composite could also combat the pathological changes in liver tissues while down-regulating the protein expression of hepatic NF-κB and TNF-α in the liver-injured mice. All these results indicated that the PAC composite exhibited anti-alcohol and hepatoprotective effects through working mechanisms associated with its antioxidant activity and inhibition of the inflammatory-related signaling.
    11  Comparison on the Structure-activity Relationship of the Antioxidant Activity of Casein-derived Heptapeptide AVPYPQR in Different Systems
    WANG Chen-yang ZHAO Mou-ming ZHENG Lin
    2019, 35(6):77-83. DOI: 10.13982/j.mfst.1673-9078.2019.6.011
    [Abstract](473) [HTML](198) [PDF 13.21 M](804)
    Abstract:
    In order to investigate the antioxidant activity and structure-activity relationship of casein-derived heptapeptide AVPYPQR in different systems, the antioxidant activity of AVPYPQR and its related fragments PYPQ, PYPQR, VPYPQ, VPYPQR and AVPYPQ were compared in this study using in vitro chemical assays and cellular models. The results showed that the six peptides exhibited higher ABTS free radical scavenging activity and oxygen radical absorbance capacity (ORAC) than the standard antioxidant, Trolox. The co-occurrence of Val, Ala and Arg residues led to a reduced ABTS radical scavenging activity of AVPYPQR, while the presence of Arg residue resulted in an enhanced ORAC. In the cell oxidative damage model, all the six peptides offered protection against AAPH-induced erythrocyte hemolysis. Among which, AVPYPQR exhibited the greatest protective effect, and the presence of Ala and Arg residues improved further such an effect. In H2O2-induced HepG2 cell oxidative damage model, all the peptides showed (p < 0.05) significant protective effect except for PYPQ, and the Ala, Val and Arg residues could enhance the protection but without an addictive effect. In summary, all the peptides, except for PYPQ, had strong antioxidant activity in both in vitro chemical assays and cellular models, but no significant correlation was found among the detected activities in different assays. The influence of Val, Ala and Arg residues on the antioxidant activity of AVPYPQR varied between analysis assays.
    12  Effects of Ultrasonic Treatment and Sucrose Addition on the Rheological Properties of Gelatin/Modified Starch Blends during Sol-Gel Transition
    ZHU Jian-hua ZOU Xiu-rong LIU Ri-bin SHAN Bin LI Chun-fen
    2019, 35(6):84-91. DOI: 10.13982/j.mfst.1673-9078.2019.6.012
    [Abstract](463) [HTML](247) [PDF 87.53 M](665)
    Abstract:
    The effects of sucrose addition as co-solute (0%~15%, W/W) without ultrasonic treatment and in the presence of 10% sucrose with ultrasonic treatment (475 W, 0~15 min) on the viscouselastic modulus (G′,G″), the gel structure formation instant gelation velocity (vg) of the gelatin/modified starch blends (4.5%/9.0%) as gel candy model system during sol-gel transition and gel properties such as microstructure were investigated. Results showed that, in the presence of relatively low concentration of sucrose (0%~10%), G′ and vg values increased significantly, while the activation energy (Ea) values of GL/MS blends reduced significantly. Formation of more uniform surface microstructure was found. Compared with the controls without ultrasonic treatment under 10% sucrose cosolute environment, G′, vg of GL/MS blends of sample with ultrasonic treatment 5 min decreased sharply from 6482.40 Pa, 7.01 Pa/min to1378.90 Pa and 2.94 Pa/min, corresponding the decreased amplitude as 78.73% and 58.06%, respectively, while the gelation Ea values significantly increased from 116.23 kJ/moL to 319.42 kJ/moL (p<0.05). The change trends of G', vg, and Ea were further exacerbated with the extension of ultrasonic treatment time, while the microstructure porosity and irregular degree increased, suggesting that ultrasonic treatment could suppress the improve effect of low concentration sucrose on the formation and performance of the blend gels. These results would apply to optimize the sol-gel process and product performance of gelatin type gel candy.
    13  Comparison of Volatile Flavor Components in Gonad of Male Chinese Mitten Crab (Eriocheir sinensis) Cultured with Four Different Eco-environment Modes
    WU Hao-ran LIN Lin GE Meng-tian CHENG Hua-feng JIANG Shao-tong LU Jian-feng
    2019, 35(6):92-101. DOI: 10.13982/j.mfst.1673-9078.2019.6.013
    [Abstract](427) [HTML](180) [PDF 10.18 M](558)
    Abstract:
    Both E-Nose and HS-SPME-GC-MS techniques were applied to identify volatile components from gonad of male Eriocheir sinensis cultured with four different eco-environment modes (pond, rice-field, lake, and Yangtze River). The results of E-Nose showed that the flavor profiles of gonad in male Eriocheir sinensis cultured in lake and rice-field were similar, while the flavor profiles of gonad from pond and Yangtze River were unique and could be distinguished well. GC-MS was used to analyze the type and content of volatile components in male gonad, and the main aroma compounds were selected according to their thresholds (OAV≥1). The results showed that the volatile components in the gonad of lake and rice-field male crab were similar in composition and content, but in the gonad of pond and Yangtze male crab, the composition of volatile components was more complicated, and the contents of hexanal (634.36 ng/g), benzaldehyde (1361.98 ng/g), and 2-pentylfuran (231.11 ng/g) in the gonad of male crab from the Yangtze River were significantly higher than those in the other three male gonad. In conclusion, this study showed that the flavors of gonad in male Eriocheir sinensis cultured in lake and rice-field were similar, while the flavors of gonad from pond and Yangtze River were unique, and among the four different modes, the gonad of Yangtze River has better flavor than others.
    14  Physicochemical Properties and in Vitro Bioactivity of Sulfated Pleurotus eryngii Polysaccharide
    BO Ji-fang MA Qi LIU Dong-ru LIU Yu-di NAI Yi-fan LI Mei XU Huai-de
    2019, 35(6):102-109. DOI: 10.13982/j.mfst.1673-9078.2019.6.014
    [Abstract](470) [HTML](178) [PDF 9.10 M](912)
    Abstract:
    In this work, Pleurotuseryngii polysaccharide (PEP) was chemically modified by chlorosulfonic acid-pyridine method, and three kinds of sulfated Pleurotuseryngiipolysaccharides (SPEP) were obtained. According to the volume ratio of chlorosulfonic acid to pyridine (1:2, 1:5 and 1:8), the three kinds of SPEP were recorded as SPEP-601:2, SPEP-601:5 and SPEP-601:8, respectively. The physicochemical properties of PEP and SPEP were detected by chemical methods, gas chromatography and gel permeation chromatography. In addition, the antioxidant activities (DPPH· scavenging ability and O2-· scavenging power) and the inhibitory effect on key enzymes (α-amylase and α-glucosidase) for carbohydrate digestion and absorption of PEP and SPEP were also determined. The results showed that the degree of substitution of SPEP-601:2, SPEP-601:5 and SPEP-601:8 were 0.26±0.00, 0.21±0.00 and 0.19±0.00, respectively. All the SPEP had less total sugar, uronic acid and lower molecular weight than the PEP. They had the same monosaccharide composition with different molar ratio. Moreover, SPEP-601:8 possessed the best scavenging capacity for DPPH compared with other SPEP. SPEP-601:2 showed the strongest scavenging effect on O2- ·. All the SPEP had higher α-amylase and α-glucosidase inhibitory activity than the PEP, increasing at least by 834.33% and 97.66%, respectively. In addition to DPPH radical scavenging capacity, SPEP exhibited stronger biological activity than PEP at the same dose. These results suggested that sulfation modification might be an effective way to enhance antioxidant and hypoglycemic activities of the polysaccharide.
    15  Synergistic Antioxidant Activity of Coptidis with Ginseng
    GAO Jia-min DENG Jian-ping WANG Yi-fei WANG Zhi-ping
    2019, 35(6):110-118. DOI: 10.13982/j.mfst.1673-9078.2019.6.015
    [Abstract](490) [HTML](166) [PDF 44.53 M](661)
    Abstract:
    The study compared the scavenging effects and synergies of the combinations of Coptis extract (CE) and Ginseng extract (GE) with different mass ratios on the ABTS and DPPH free radicals. The obtained data for the combinations were analyzed using the drug combined analysis software "CompuSyn" to achieve the related parameters. In the ABTS reaction system, the IC50 values of CE and GE were 170.18±5.20 and 1615.73±40.17 μg/mL, respectively, while the IC50 values of the CE-GE combinations with the mass ratios of 4:1, 2:1, 1:1, 1:2 and 1:4 were 88.86±9.31, 209.12±9.56, 329.42±10.29, 188.39±6.33 and 31.42±7.52 μg/mL, respectively. According to the combined index (CI) values, CE and GE at a ratio of 4:1, 2:1 or 1:4 exhibited synergistic effects. In the DPPH reaction system, the IC50 values of CE and GE were 67.57±9.68 and 1590.86±21.35 μg/mL, respectively, while the IC50 values of the CE-GE combinations with the mass ratios of 4:1, 2:1, 1:1, 1:2 and 1:4 were 49.48±12.56, 195.04±7.58, 129.27±15.14, 404.07±10.55 and 153.11±6.32 μg/mL, respectively. According to the combined index (CI) values, CE and GE at a ratio of 4:1 and 1:4 exhibited synergistic effects. CE and GE worked synergistically to scavenge the ABTS and DPPH free radicals.
    16  Evaluation of the Antioxidant Activity and Whitening Effect of a Resveratrol-Grape Polyphenol Composite Oral Solution
    LIU Hui-ping DENG Yu-di LIAO Wen-zhen KONG Jing-jing ZHOU Si-yun JIANG Liang
    2019, 35(6):119-128. DOI: 10.13982/j.mfst.1673-9078.2019.6.016
    [Abstract](560) [HTML](219) [PDF 35.37 M](1067)
    Abstract:
    This study developed a resveratrol-grape polyphenol composite whitening oral solution, evaluated its antioxidant activity and whitening effect, and discussed preliminarily the underlying mechanism. The results of the antioxidant activity experiments showed that the whitening oral solution exhibited strong antioxidant activity: not only reduced iron ions, but also exerted significant scavenging effects on the DPPH+ and ABTS+ free radicals and peroxides. The IC50 values for DPPH+ and ABTS+ radical scavenging activities were 10.32±1.20 μg/mL and 87.06±9.52 μg/mL, respectively. The peroxyl radical scavenging and absorption capacities were 1649.00±2.78 μmol Vit. C equivalents/g and 4251.30±566.71 μmol Trolox equivalents (TE)/g, respectively. In human hepatoma cell line HepG2 model, the intracellular antioxidant activity of the whitening oral solution reached 5570.10±312.09 μmol quercetin equivalents (QE)/100 g. The mouse melanoma B16 cells, which are physiologically relevant to the human melanocytes, were selected as the research models to evaluate in vitro the whitening effect. The results showed that at a certain dose, the whitening oral solution could inhibit the proliferation of B16 cells, cellular tyrosinase activity and protein expression of B16 cells, thereby reducing the production of melanin. This composite whitening oral solution exhibited good antioxidant activity and whitening effect, thus, will have great prospects for the functional foods and healthcare products industry.
    17  Optimization of the Combined Microwave-vacuum Freezing Drying Process and Quality Analysis of Pleurotus ostreatus
    ZHU Cai-ping SUN Jing-ru SUN Hong-xia CHEN Xin-ran LI Qian-nan
    2019, 35(6):129-138. DOI: 10.13982/j.mfst.1673-9078.2019.6.017
    [Abstract](576) [HTML](179) [PDF 34.51 M](833)
    Abstract:
    This paper aims to obtain the optimal drying process of Pleurotus ostreatus as well as to improve the quality of its drying products. Based on the methods of single factor and response surface method with the Box-Benhnken design (BBD), an experiment was conducted to analyze the effect of three factors including the microwave power, moisture content of switching point and vacuum freezing time on the 4 indicators of dry basis moisture content, drying rate, rehydration ratio and sensory score of the product correspondingly. The quadratic regression models of the 4 indicators were constructed and analyzed with the response surface method according to the experimental data, and the optimal drying process of Pleurotus ostreatus was obtained, which was microwave power 300 W, conversion point moisture content 37%, vacuum freezing time 11 h. In addition, the nutrients of the dried Pleurotus ostreatus (protein, crude fat and total sugar content) were measured under the optimal process conditions. From the experiment and data analysis, it can be concluded that under the proposed optimal processing, the dried Pleurotus ostreatus products have the advantages of good color, excellent quality and high retention of nutrients, which can guide the mass-production of dried Pleurotus ostreatus under industrial conditions.
    18  Effect of Pregelatinization on the Quality of Noodles with a High Oat Flour Content
    XU Bin SUN Yi-lin LIU Shu-yi CHEN Xiao-pei JIANG Song CHEN Zhong-wei SUN Jun
    2019, 35(6):139-144. DOI: 10.13982/j.mfst.1673-9078.2019.6.018
    [Abstract](661) [HTML](207) [PDF 13.79 M](627)
    Abstract:
    In order to investigate the effects of pregelatinized oat flour on the quality of noodles with a high oat flour content, the oat was pregelatinized by steaming, extrusion and drum drying, and then the mechanical properties, cooking quality and texture properties of oat noodles (70% oat flour) containing different types and addition levels of pregelatinized oat flour were analyzed. The results showed that the viscosity of the mixed flour under room temperature increased with the increase of the pregelatinized oat flour addition. The pasting viscosity of the mixed flour was positively correlated with the amount of steamed oat flour (SOF) and negatively correlated with the amount of extruded pregelatinized oat flour (EOF) and drum dried oat flour (DOF). When the addition of SOF was 70%, the noodle quality was high; when the addition of EOF and DOF was 8.75%, the noodle quality was high. In contrast, the elastic modulus, bending stress, fracture displacement and chewiness of the former were greater, and adhesiveness and cooking loss were smaller. In summary, adding pregelatinized oat flour can improve the oat noodles quality, and the oat noodles prepared by SOF have the best quality.
    19  Construction and Expression Analysis of 18S rDNA-mediated Expression Vector of Nuclease P1 from Penicillium citrinum
    CHEN Xiao-yi WANG Bin PAN Li
    2019, 35(6):145-153. DOI: 10.13982/j.mfst.1673-9078.2019.6.019
    [Abstract](466) [HTML](229) [PDF 32.43 M](625)
    Abstract:
    In this study, the Aspergillus niger Bdel4 strain was used as the host strain, and the four major extracellular secretion proteins, glaA, aamA, An05g02100 and An12g06930, were knocked out to provide a pathway for the expression and secretion of nuclease P1. The rDNA sequence of A. niger Bdel4 was amplified by PCR, and the recombinant plasmids, pRpT-nucP1-18S and pRpT-2A-nucP1-18S were constructed through using the rDNA sequence as integration sites. The constructed recombinant plasmids pRpT-nucP1-18S and pRpT-2A-nucP1-18S were then transferred into A. niger Bdel4. Prescreening of the transformants was carried out by semi-quantitative fluorescent PCR, and the activity of nuclease P1 was then measured to screen a strain with high activity for industrial production. The total genomic samples containing the exogenous target gene of nuc P1 were repeatedly detected by SYBR Green real-time fluorescent quantitative PCR, and the average value was taken as the copy number of the target gene nuc P1 to explore the relationship between the copy number and the expression level of the enzyme. The result showed that the enzymatic activity of the strain containing 9 nuc P1 gene copies reached 88.52 U/ml, which was 3.86 times higher than that of the nuclease P1 for the single copy strain, and 1.2-fold as high as that of the heterologous nuclease P1 reported in the previous studies. When the copy number of nuc P1 was increased to over 9, the enzyme activity decreased.
    20  Increasing the Concentrations of Soybean Isoflavone Aglycones in Soymilk by an Enzymatic Method
    GOU Yun ZHAO Shi-lei LIU Shi-sheng
    2019, 35(6):154-160. DOI: 10.13982/j.mfst.1673-9078.2019.6.020
    [Abstract](732) [HTML](207) [PDF 6.95 M](882)
    Abstract:
    The soybean was hydrolyzed by the Aspergillus niger β-glucosidase to convert the bound soy isoflavone glycosides into a free aglycone. Using soybean as the raw material, the influence of three factors (enzyme dose for addition, reaction time, reaction temperature) on the hydrolysis of soybean isoflavone glycosides in soy milk was first investigated in single factor experiments. According to the Box-Behnken center-united experimental design principles, three factors and three levels were adopted based on the combinations of different enzyme doses, reaction times and reaction temperatures to establish polynomial regression prediction models for the isoflavone aglycone content in soy milk and determine the optimal process parameters. The results showed that optimal hydrolysis conditions were as follows: the enzyme dose, 0.028 U/5 mL; reaction time, 1.64 h; reaction temperature, 53.82 ℃. Under these conditions, the content of isoflavone aglycone in soy milk was significantly improved, with the concentrations of daidzein (De), glycitein (Gle) and genistein (Ge) being 39.434±1.410, 4.626±0.462, 45.851±2.098 μg/mL, respectively. The response surface prediction values of De, Gle and Ge were 40.905, 4.263, and 48.441 μg/mL, respectively, indicating that the measured values were close to the predicted values. The optimized process conditions are reasonable and feasible, and can allow a significant increase in the contents of isoflavone aglycones in soy milk.
    21  Comparison of DNA Extraction Methods and Species Identification of Fish Meat
    YANG Jun-ru XIONG Xiong HUANG Man-hong YUAN Fang-ying LU Li-xia XIONG Xiao-hui
    2019, 35(6):161-170. DOI: 10.13982/j.mfst.1673-9078.2019.6.021
    [Abstract](604) [HTML](490) [PDF 36.72 M](739)
    Abstract:
    In this study, an improved boiling method (BP method) and traditional proteinase K method (TP method) were used to extract DNAs from 16 kinds of fish meat samples. Then, the concentration and purity of the extracted DNAs as well as the performance of the common polymerase chain reaction (PCR) and fluorescence PCR were compared. In the mean time, the total DNA was extracted from 70 commercially available fish products using the BP method and analyzed for species identification using DNA barcode technology. The results showed that the extraction of DNA by the BP method required a shorter time. For most fish samples, the concentration of the DNA extracted by the BP method was lower than that by the TP method, but the two methods led to insignificant difference in the A260/A280 ratio of the extracted DNAs, thus, met the requirements for common and fluorescent PCR amplification. Moreover, the DNA extracted by the BP method could be used for DNA barcode identification of commercially available fish products. By comparison, 81.43% of the fish products could be matched with a similarity degree ≥ 98%, and the identification success rates at the species and genus levels were 48.57% and 72.86%, respectively. The BP method can shorten the DNA extraction time, reduce the extraction cost, and facilitate the detection of large quantities of samples.
    22  Effect of BAT2 Deletion with Lg-ATF1 Overexpression on the Production of Higher Alcohols and Ester in Brewer’s Yeast
    GE Jun-ling GUO Ying LIU Xiao-er ZHANG Cui-ying XIAO Dong-guang
    2019, 35(6):171-176. DOI: 10.13982/j.mfst.1673-9078.2019.6.022
    [Abstract](606) [HTML](188) [PDF 7.52 M](0)
    Abstract:
    Ethyl acetate and higher alcohols are important flavor substances in beer. The effect of BAT2 gene and Lg-ATF1 gene in beer yeast on producing alcohol esters was explored to solve the problem of more higher alcohols and less ethyl acetate in beer. The expression vector pUC-PLABBK was constructed by using the method of enzyme digestion and connection. Saccharomyces cerevisiae multiploid S5 was used as the original strain and the KanMX gene was used as a selection marker in this study. Lithium acetate transformation and homologous recombination were employed to screen for a mutant strain S5-Lg that overexpressing Lg-ATF1 and at the same time deleting BAT2. The variation between the content of higher alcohols, ethyl acetate and expression of related genes in the engineered yeast strain S5-Lg was investigated by fermentation experiments and digital PCR. The results showed that compared with the original strain S5, the ethyl acetate production of the S5-Lg strain was increased by 26.81%, total higher alcohol production decreased by 45.72%, of which the contents of isobutanol and isoamyl alcohol were reduced by 10.63% and 9.55%, respectively. The expression of Lg-ATF1 gene was greatly increased, and the expression level of BAT2 gene was decreased by 45.72%. It effectively changed the ability of brewer's yeast to produce ethyl acetate and higher alcohols and has important significance for improving beer flavor.
    23  6-Benzylaminopurine Improves the Quality of Harvested Green Lotus Seed Storage at Refrigerated Temperature
    FAN Chuan-hui CHEN Xue-ling MEI Xin SHI Jian-bin SUI Yong CAI Sha HE Jian-jun
    2019, 35(6):177-183. DOI: 10.13982/j.mfst.1673-9078.2019.6.023
    [Abstract](431) [HTML](150) [PDF 86.91 M](0)
    Abstract:
    Space Lotus No. 36' green lotus seed was chosen as test materials. Their quality and physiological indices were measured after green lotus seed immersed in 75 mg/L and 175 mg/L 6-BA respectively and stored at 4 ℃. The results showed that 175 mg/L 6-BA can alleviate the weight loss rate of green lotus seed during storage and reduce the loss of total soluble solids (TTS) in green lotus seed nut. 175 mg/L 6-BA can delay the brown time of green lotus seed during storage. The brown time of green lotus seed and green lotus seed nut was delayed by 3 days and 6 days, respectively. In addition, 6-BA treatment can delay the increase of malondialdehyde (MDA) content and inhibit the activity of polyphenol oxidase (PPO) and respiration rate in green lotus seed peel. The peak of activities of PAL in green lotus seed peel was delayed by 3 days in 175 mg/L 6-BA treatment group. The 175 mg/L 6-BA treatment can inhibit the aging process of green lotus seed, which is beneficial to maintain fruit quality and improve storage.
    24  Study on Characteristics of Salt-Enhanced Peptides Prepared by Enzymatic Hydrolysis of Larimichthys crocea
    LI Wei SU Guo-wan SUN Wei-zheng
    2019, 35(6):184-190. DOI: 10.13982/j.mfst.1673-9078.2019.6.024
    [Abstract](526) [HTML](203) [PDF 86.91 M](0)
    Abstract:
    In this work, papain and trypsin were used to hydrolyze protein from Larimichthys crocea, and their hydrolysates were subjected to sensory salty taste evaluation. The taste sensing system-electronic tongue for numerical analysis of taste was also used. The protein recovery, hydrolysis degree and peptide nitrogen recovery were analyzed to investigate the changes of nitrogen forms during enzymatic hydrolysis. Trypsin hydrolysate was found to have the greatest salt-enhanced activity. The maximum of the sensory saltiness value and the electronic tongue salty electric signal value obtained at the enzyme to substrate ratio of 5‰ based protein content, the incubation time of 3 h, the incubation temperature of 55 ℃, the meat to water ratio of 1:1 (the protein content and sodium content of all samples were the same). The salty taste enhanced effect was the strongest, and the protein recovery rate reached 49.7%. Results of antioxidant activities showed that the salt-enhanced peptide prepared with trypsin for 3h had a reducing power of 0.149 mmol TE/mmol and DPPH radical scavenging activity of 0.057 mmol TE/mmol. The salt-enhanced peptide as a bioactive peptide has important nutritional value and biological activity. It can partially replace sodium chloride for the development of high-grade seasonings and as a functional food ingredient.
    25  Effect of Composite Preservatives on the Storage Quality of Sciaenops ocellatus Conditioned Fillets
    ZHENG Yu-xiu ZHOU Bin WANG Ming WEI Xu-qing HAN Ying SUN Tong XIE Jing LI Jian-rong
    2019, 35(6):191-199. DOI: 10.13982/j.mfst.1673-9078.2019.6.025
    [Abstract](565) [HTML](172) [PDF 754.74 K](625)
    Abstract:
    To improve the storage quality of conditioned Sciaenops ocellatus fillets, Nisin, ε-polylysine hydrochloride and their composite preservatives were used to treat fish fillets in this study. The influence of the preservatives on the freshness indices for fish fillets was evaluated. The results showed that the immersion of fish fillet in a solution for conditioning delayed significantly the changes of the total number of colonies, TVB-N value, TBA value and pH of the conditioned fish fillets, but increased the juice loss rate of the conditioned fish fillets. The application of Nisin or ε-polylysine hydrochloride could inhibit the microbial growth in the fish fillets and delay significantly the changes in TVB-N and TBA values of the conditioned fish fillets. Upon the treatment with the composite preservative, all the freshness indices were improved. During storage, the treatment with the composite preservative led to a decrease of 0.03~0.34 log CFU/g in the total number of colonies of the conditioned fish fillets (as compared with the treatment with either preservative alone), as well as a significant delay in protein decomposition and fat oxidation, and decrease in juice loss of the conditioned fillets. These results indicate that the performance of the composite preservative was better (prolonging more effectively the shelf life of conditioned fish fillets).
    26  Fermentation Process Optimization of Bacterial Cellulose via Acetic Acid Bacteria
    ZONG Dan WANG Yan-bin XIONG Qiang ZHU Ben-wei
    2019, 35(6):200-206. DOI: 10.13982/j.mfst.1673-9078.2019.6.026
    [Abstract](637) [HTML](321) [PDF 768.79 K](0)
    Abstract:
    In the production of bacterial cellulose (BC) by Gluconacetobacter hansenii via traditional Hestrin-Scharmm (HS) medium, there are still some problems that limit the production, such as low BC production and utilization rate of glucose. In this study, the results of BC production by fermentation of traditional HS medium and improved HS medium were first compared and the BC yield by improved HS medium was increased by 28% to 3.34 g/L. However, the fermentation waste still contained 41% residual sugar and 70% residual nitrogen. Afterwards, the primary fermentation waste was optimized and used for secondary fermentation. In consequence, 3.16 g/L of BC could be produced by adjusting the pH of fermentation waste to 5.9 and adding 2.5 g/L yeast extract and 1.8 g/L Na2HPO4, and the concentration of acetic acid was only half of that in primary fermentation. In conclusion, the yield of BC achieved 6.50 g/L, which was 2.5 times as much as before. Moreover, the utilization rate and conversion rate of glucose were increased from 56.74% to 88.02% and 22.86% to 36.87%, respectively.
    27  Effect of Cooking Methods on the Flavor and Microstructure of Salted-dried Fish
    ZENG Ping ZHANG Ye-hui ZHANG You-sheng NING Zheng-xiang CHEN Xiong QIN Ya-ru
    2019, 35(6):207-215. DOI: 10.13982/j.mfst.1673-9078.2019.6.027
    [Abstract](504) [HTML](339) [PDF 700.88 K](0)
    Abstract:
    The effects of microwave, air-frying, baking and steaming cooking method on the chewiness (texture), taste (free amino acids), flavor (volatile compounds) and microstructure of salted-dried fish were investigated. The results showed that the microwave, air-frying, baking and steaming cooking method could induce the textural changes of salted-dried fish by decreasing hardness and chewiness, and increasing springiness of samples. The microwave, air-frying and baking cooking method reduced the total of free amino acids in varying degrees. However, the content of the total of free amino acids increaded from 586.66 mg/100 g to 631.45 mg/100 g by the steaming cooking method. The contents of aldehydes, ketones and esters were significantly increased and the content of alkanes was declined in all cooked samples. The sample cooked by air-frying method had the highest contents (37.07%) of aldehydes and ketones. The cooking treatment could result in serious shrink of muscle fiber of salted-dried fish, and the space among muscle fiber bundles was filled with cooking oil. The space among muscle fiber bundles was obvious relatively in the samples cooked by air-frying and baking method.
    28  Process Optimization of Sweet Potato Chips by Microwave Puffing
    WEI Qiang ZHENG Li-jing WU Dong-xue
    2019, 35(6):216-222. DOI: 10.13982/j.mfst.1673-9078.2019.6.028
    [Abstract](576) [HTML](179) [PDF 17.44 M](0)
    Abstract:
    In order to optimize the process conditions of microwave puffed sweet potato chips, the orthogonal test design method was used, the main factors were sweet potato varieties, slice thickness, initial water content, blanching time, microwave intensity and puffing time, and the evaluation indexes were color, puffing rate, fracture strength and sensory score. The results showed that sweet potato varieties, slice thickness, initial water content, microwave intensity and puffing time were the main influencing factors. The optimum technological conditions for microwave puffing sweet potato chips were as follows: variety “Shandong purple potato”, longitudinal section thickness 2.0 mm, blanching 180 s with boiling water, water content 15%, microwave intensity 2.3 W/g, puffing time 50 s; variety "Fujian yellow heart", longitudinal section thickness 2.5 mm, blanching 180 s with boiling water, water content 15%, microwave intensity 2.3 W/g and the puffing time 50 s. The sweet potato chips obtained under the process conditions had good color, taste and texture, and puffing effect, which provided an effective reference for the development and utilization of sweet potato and the improvement of the quality of sweet potato chips.
    29  Effect of Microwave Cooking Method on Lipid Changes of Silky Fowl's Egg Yolk
    HU Wen-cai YANG Shuai CHEN Zu-ming
    2019, 35(6):223-229. DOI: 10.13982/j.mfst.1673-9078.2019.6.029
    [Abstract](465) [HTML](234) [PDF 18.88 M](0)
    Abstract:
    The effects of microwave cooking methods on the lipids of silky fowl's egg yolk were investigated. The results showed that the total lipid content of silky fowl's egg yolk increased first and then decreased under different heating modes of high fire, high medium fire and medium fire. Triglyceride and free fatty acids were the main ones. The content of lipid components increased, while the content of phospholipids increased first and then decreased; The variation trends of peak area of phosphatidylcholine, phosphatidylethanolamine phosphatidic acid phosphatidylhexyl alcoho, phosphatidylserine, lysolecithin phosphatidylglycerol and lysophosphatidylethanolamine in phospholipids were generally the same, which increased first and then decreased.. Under different heating treatment, the variation trends of C16:0, C18:0, C20:0, C24:0 and SFA in silky fowl's egg yolk were generally the same. Among them, the contents of fatty acid components C16:0 and C20:0 of silky fowl's egg yellow showed an upward trend in general, increasing by 2.2%, 14.77% and 17.65%, respectively. The content of C18:0 of silky fowl's egg yellow increased to 90.16% and then decreased to 66.80%.The content of C24:0 increased to 27.61% and then decreased to 27.33%. Under the three heat preservation points of high fire, middle fire and middle fire, the difference of retention rate of lipid nutrients of silky fowl's egg yellow was about 5%~10%. Through the analysis and research of the relevant content of this article, the food is heated scientifically and reasonably, and the nutrients of silky fowl's eggs are preserved as much as possible.
    30  Microwave Vacuum Drying Characteristics and Quality of Maca Slices (Lepidium meyenii)
    ZHANG Ming-yu REN Ya-min ZHANG Cai-fang
    2019, 35(6):230-236. DOI: 10.13982/j.mfst.1673-9078.2019.6.030
    [Abstract](563) [HTML](232) [PDF 10.19 M](0)
    Abstract:
    In order to shorten the drying process of maca slices and improve the quality of dried products, microwave vacuum drying technology was used to dehydrate maca slices. The drying characteristics and quality of maca slices obtained under different drying conditions were studied. Mathematical models were established to predict the relationship between the dry product quality and drying conditions of maca slices by stepwise regression. Comparisons were made on the microwave vacuum drying processes of maca under different conditions by weighted comprehensive evaluation. The results showed that the effect of microwave power density on the drying rate and product quality was more significant (p < 0.05). The Weibull distribution function can describe the changing pattern of moisture ratio in maca slices as a function of time during microwave vacuum drying with high accuracy (R2 > 0.99). The effective moisture diffusion coefficients of maca slices subjected to microwave vacuum drying ranged from 2.98×10-12 to 5.08 ×10-12 m2/s, and were influenced more remarkably by the microwave density. Stepwise regression analysis can accurately build a mathematical model between the dry product quality and drying condition of maca slices (R2 > 0.99). The maca slices gained the highest comprehensive assessment score when the microwave power density and drying pressure were 1.5 W/g and 300 Pa, respectively. Thus, among the selected conditions for drying, such a condition was the most suitable for microwave vacuum drying of maca slices.
    31  Analysis on the Use of Preservatives in 21 Categories of Food Matrices in Henan Province
    LIU Ying HUANG Yu-kun ZHOU Nan YUAN Li-jie
    2019, 35(6):237-244. DOI: 10.13982/j.mfst.1673-9078.2019.6.031
    [Abstract](562) [HTML](159) [PDF 820.72 K](0)
    Abstract:
    In this study, the national standard test method was used to measure six common preservatives in 21 categories of food matrices, and the results and reasons had been analyzed. The results were assessed in accordance with GB 2760-2014. The usages of preservatives were found to be in good condition. Some usages of parabens and their sodium salts, benzoic acid and its sodium salts, sorbic acid and its potassium salts, dehydroacetic acid and its sodium salts were inappropriate, the usage percentages of which were detected as 3.43%, 0.18%, 0.16%, and 0.14%, respectively. However, due to their special features, the rates of preservatives in pastry, condiments, pickles, beverages, convenience foods, meat products, etc. were high. The detection rate of dimethyl fumarate usage in pastry was 0.66%. Two or even more preservatives were determined in 327 samples at the same time. Besides, the sum of the maximum usages of preservatives was beyond 1, which was detected in 46 samples. Among 21 categories of food matrices, pastry and condiments were found that the usage rates, types and over-limit ratios of preservatives were high. This study can reveal overall usage of preservatives in a wide range of foods for the public, and provide some technical references for production enterprises, regulatory authorities and inspection agencies.
    32  Nutritional Analysis and Evaluation on Muscle of Spinibarbus caldwelli
    CHENG Xiao-fei SONG Rui XU Yuan-qin YUAN Xi-ping LI Cheng WU Yuan-an DENG Da-qing LI Hong LI Jin-long
    2019, 35(6):245-250. DOI: 10.13982/j.mfst.1673-9078.2019.6.032
    [Abstract](558) [HTML](203) [PDF 711.49 K](0)
    Abstract:
    In order to evaluate the nutritonal values of the muscle (fresh samples) of spinibarbus hollandi (Oshima) cultured in Zhijiang river reservoir cage in Hunan province, the composition and content of the nutrients were determined by conventional biochemical analysis methods. The results showed that the contents of moisture, crude protein, crude fat, and ash in fresh muscle of Spinibarbus caldwelli were 73.44%, 24.18%, 3.63%, 1.28%, respectively. There were 17 kinds of amino acids in Spinibarbus caldwelli muscle, with the content of total amino acids (TAA) of 18.08% and the content of essential amino acids (EAA) of 6.70%. The EAA /TAA was found to be 37.06% and EAA /NEAA 58.88%, which were completely met to the high-quality protein standard of the Food and Agriculture Organization /World Health Organization (FAO/WHO). The essential amino acid index (EAAI) was 58.39 and the delicious amino acids(DAA) accounted for 6.97% with the DAA/TAA was 38.55%.The muscle contained with 11 kinds of fatty acids, in which the saturated fatty acids (SFA) accounted for 20.56%, the monounsaturated fatty acids (MUFA) accounted for 54.71%, and the polyunsaturated fatty acids (PUFA) accounted for 24.72%, respectively. The total content of EPA and DHA accounted for 1.86%. The results showed that Spinibarbus caldwelli had edible nutritional value.
    33  Quantitative Determination of the Antifungal Activity of Polymyxin against Mold Fungi by Agar Infusion Method
    WANG Zhi-xin HONG Dan LIU Yang LU Lei-zhen ZHOU Jing-bo NING Ya-wei JIA Ying-min
    2019, 35(6):251-257. DOI: 10.13982/j.mfst.1673-9078.2019.6.033
    [Abstract](462) [HTML](181) [PDF 36.30 M](666)
    Abstract:
    The quantitative determination method of antimicrobial peptides against mold fungi was studied in this paper. The antifungal activity of polymyxin B against Penicillium chrysogenum was determined by agar infusion method, and the determination conditions of indicator concentration, peptide addition amount and culture time were then optimized. Furthermore, the quantitative determination method was verified with Aspergillus niger. The antifungal activity was calculated by establishing a linear equation between the antimicrobial peptide concentration and inhibition zone diameter. The results showed that the optimal conditions for quantitatively testing the activities of polymyxin B against mold fungi were as follows: The amount of PDA in 90 mm petri dish was 15 mL, the spore concentration was (1~5)×106 spores/mL, the addition of polymyxin B was 100 μL, the pre-diffusion time was 6~10 h at 4 ℃ and the culture time was 24 h at 28 ℃. The quantitative determination method was verified with Aspergillus niger, and the results indicated that this determination method had good repeatability and high precision. Under these conditions, the antifungal activities of polymyxin B against Penicillium chrysogenum and Aspergillus niger were 524.81 U/mg and 605.76 U/mg, respectively. This study could provide a reference and basis for the activity determination of antimicrobial peptides in the process of research and production.
    34  Discrimination of Plum Fruit Maturity Based on Hyperspectral Imaging Technology
    LI Li-li WANG Bin ZHANG Xue-hao ZHANG Shu-juan
    2019, 35(6):258-263. DOI: 10.13982/j.mfst.1673-9078.2019.6.034
    [Abstract](476) [HTML](214) [PDF 29.74 M](801)
    Abstract:
    In order to investigate an effective method for rapid discrimination of plum fruits at different maturity levels, plum fruits were used as the research object of this study, and spectral information (420~1000 nm) of plum fruits at different maturity levels (unripe, mid-ripe, ripe, over-ripe) was collected using hyperspectral imaging technology. A combination of smoothing and standard normalized variate (SNV) was applied to pretreat spectral data. Then, the partial least squares method(PLS) model was established for comparing the accuracy of different discriminant models, through using the pre-treated full spectrum (FS) data, the principal components extracted by the principal component analysis (PCA) method, and the feature wavelengths extracted by the successive projection algorithm (SPA) technique as input variables. The results revealed that the model established by FS-PLS had the highest discriminative accuracy and the accuracy rate reached 91.88%. However, considering the amount and complexity of the experimental calculations, the accuracy rate of the model established by SPA-PLS was the best with the comprehensive accuracy reaching 91.25%. This study provides a new theoretical basis for discriminative detection of plums maturity.
    35  Detection of Pseudomonas in Pork by Real-Time Fluorescence Loop-Mediated Isothermal Amplification Method
    LI Ning ZHANG You-xiong WU Qing-ping GU Qi-hui ZHANG Yin-zhi WANG Jia-sheng SUN Xiu-lan ZHANG Ju-mei
    2019, 35(6):264-272. DOI: 10.13982/j.mfst.1673-9078.2019.6.035
    [Abstract](643) [HTML](225) [PDF 23.01 M](717)
    Abstract:
    In this work, a real-time fluorescence loop-mediated isothermal amplification (LAMP) assay was established to detect Pseudomonas in pork. Based on the published 16S rDNA gene sequence, the 16S rDNA genes of 62 strains of Pseudomonas were sequenced by DNAMAN software to obtain the consensus fragment, which was used to design primers. The saturated nucleic acid dye Eva Green was added to the reaction system, which allowed amplification products to be measured by real-time fluorescence platforms. The amplification system was optimized and the optimization results were identified by electrophoresis. The specificity and sensitivity was compared with ordinary LAMP, and the detection limit of artificially contaminated pork was determined. The results showed that 12 strains of Pseudomonas are positive in the specific verification and 23 strains of non-Pseudomonas are negative. The sensitivity for Pseudomonas is 36 CFU/mL in pure cultures, which is 10 times more sensitive than the ordinary LAMP. The detection limit of artificially contaminated samples is 1.73×103 CFU/g. In this work, a method for detecting Pseudomonas in refrigerated pork was established, which can simultaneously detect Pseudomonas spp. and avoid the limitations of single species detection. The real-time fluorescent LAMP detection technology established in this work is less time-consuming, accurate and has high specificity and sensitivity. Pseudomonas in fresh pork could be detected within 2 hours by this method.
    36  Study on PMA-ddPCR Method for Quantitative Detection of Live Vibrio parahaemolyticus in Aquatic Products
    WENG Wen-chuan GUAN Jin-xiu XIE Hui LING Li CHEN Wen-rui XIAN Yu-yin XU Xi-lin
    2019, 35(6):273-279. DOI: 10.13982/j.mfst.1673-9078.2019.6.036
    [Abstract](623) [HTML](155) [PDF 28.33 M](752)
    Abstract:
    A rapid quantitative PCR detection method for live Vibrio parahaemolyticus in aquatic products was studied. As propidium monoazide (PMA) can inhibit the death of bacteria DNA amplification under at certain lighting condition, and the droplet digital PCR technology can extend detection accuracy to single molecule target genes and achieve absolute quantification, a new method called PMA-ddPCR (combined PMA and ddPCR ) was applied to detect live Vibrio parahaemolyticus. Specific primers and probes targeting the tlh gene of Vibrio parahaemolyticus were designed, and the PCR reaction system was optimized. The PMA concentration and exposure conditions of PMA-ddPCR for target gene were also tested. The results showed that the working concentration of PMA was 16 μg/mL and the exposure time was 8 min. The expansion of dead bacteria could be completely inhibited and the activity of live bacteria was not affected under this condition. The sensitivity of PMA-ddPCR method was higher than that of PMA-qPCR method by comparing the detection limits of PMA-ddPCR and PMA-qPCR (2×101 cfu/mL and 2×102 cfu/mL, respectively). The live Vibrio parahaemolyticus in artificially contaminated marine products (sea shrimp and small scallop) were detected by PMA-ddPCR quantitative method, and the lowest detectable Vibrio parahaemolyticus in sea shrimps was 1.9×101 cfu/g, and the lowest detectable of Vibrio parahaemolyticus in small sail was 0.89×101 cfu/g. This study provided the foundation for the application of PCR technology to the quantitative detection of low-level pollution of live Vibrio parahaemolyticus in aquatic products.
    37  Determination of 4 Kinds of Alternaria Toxins in Baked Food by QuEChERS and Ultra-high Performance Liquid Chromatography-tandem Mass Spectrometry
    LIANG Ming CHEN Jie-feng XIAN Yan-ping WANG Bin WANG Li HOU Xiang-chang WU Yu-luan
    2019, 35(6):280-286. DOI: 10.13982/j.mfst.1673-9078.2019.6.037
    [Abstract](430) [HTML](181) [PDF 30.03 M](664)
    Abstract:
    An analysis method using ultra-high performance liquid chromatography-tandem mass spectrometru (UPLC-MS/MS) was established for the determination of four alternaria toxins [Tenuazonic acid (TeA), Alternariol (AOH), Alternariol Monomethyl Ether (AME), Tentoxin (TEN)] in baked food. The samples were extracted with acetonitrile and 0.1 mol/L HCl, and the extracted solutions were purified using the QuEChERS approach. The target analytes were then separated on a RP18 column (2.1 mm×100 mm, 1.7 μm) using acetonitrile and 1 mmol/L NH4HCO3 as the mobile phase and detected by MS/MS under multiple reaction monitoring (MRM) mode. The mass spectrometry measurement was conducted using positive (ESI+) and negative (ESI-) electrospray ionization. Under the optimized conditions, the linearity of the four analytes were good in the corresponding concentration range with the correlation coefficients more than 0.999. The MLOQ was 0.03~0.3 μg/kg and the average recoveries (n=6) ranged from 83.2% to 105.3%, and relative standard deviation (RSD, n=6) in a range of 1.2%~6.4% when three levels of standard were spiked. This developed method was successfully applied for the detection of 45 baking food samples, and mycotoxins were detected in several samples. AME was detected in 24 samples with the concentrations ranged from 0.1 to 4.6 μg/kg; AOH was detected in 6 samples with the concentrations ranged from 0.47 to 1.5 μg/kg; TeA was detected in 27 samples with the concentrations ranged from 0.6 to 3.7 μg/kg; and TEN was detected in 9 samples with the concentrations ranged from 0.3 to 2.1 μg/kg.
    38  Analysis of Flavor Quality of Pre- and Post- Rigor Lamb
    XIAO Xiong ZHANG De-quan LI Zheng LI Xin REN Chi Hussain Zubair LIU Deng-yong HOU Cheng-li
    2019, 35(6):287-294. DOI: 10.13982/j.mfst.1673-9078.2019.6.038
    [Abstract](606) [HTML](201) [PDF 7.82 M](1205)
    Abstract:
    The aim of this study was to explore the changes of flavor quality in lamb during rigor moris and post-rigor periods at 4 ℃. Longissimus dorsi muscle was selected, ultra-rapid gas phase electronic nose instrument and gas chromatography mass spectrometry (GC-MS) were used to determine the difference of volatile flavor compounds among different storage time of lambs. The results showed that 51 kinds of volatile flavor compounds were detected, mainly include aldehyde and alcohol. The aldehyde content of chilled lamb increased first and then decreased with the prolongation of storage time, while the alcohol content first decreased and then increased. Hexaldehyde, heptanal, octanal, nonaldehyde, 1-pentanol, 1-octene-3-alcohol and 1-heptanol were the key flavor compounds as these compounds always existed in lamb during storage. The difference was not significant in the key flavor compounds between 1 d and 1 h of lamb after slaughtered (p>0.05), however, the kinds and contents of flavor compounds in 3 d and 5 d of lamb decreased. The results of principal component analysis carried out by ultra-rapid gas phase electron nose were consistent with the GC-MS. Therefore, there was no significant difference in the types and contents of the key flavor compounds between pre-rigor (1 h after slaughtered) and the initial stage of rigor (1 d after slaughtered), while decreased at post-rigor stage (3 d and 5 d after slaughtered) significantly.
    39  Comparison of the Volatile Components in Leaves, Flowers and Stems of Loquat by HS-SPME-GC-MS and Principal Component Analysis
    HUANG Jing-ling JIANG Han-mei DI Jiang-xue XIAO Huan XIAO Yu-shuo MENG Jia-min
    2019, 35(6):295-300. DOI: 10.13982/j.mfst.1673-9078.2019.6.039
    [Abstract](476) [HTML](242) [PDF 6.99 M](754)
    Abstract:
    The volatile components in the leaves, flowers and stems of loquat were analyzed and compared using headspace solid-phase microextraction and gas chromatography-mass spectrometry. The relative contents of individual components were calculated by the area normalization method while the principal components were also analyzed. Twenty nine compounds were identified in loquat leaves, accounting for 91.16% of the total volatile components; Twenty seven compounds were identified in loquat flowers, accounting for 99.99% of the total volatile components; Nineteen compounds were identified in the stems of loquat, accounting for 90.05% of the total volatile components. A total of 55 compounds were identified from the leaves, flowers and stems of loquat, among which 6 compounds were in common. The loquat leaves, flowers and stems had 23, 21 and 13, respectively, their own characteristic compounds. Two principal components were found to represent the 55 volatile components in the 3 types of samples. The Principal Component Analysis revealed a great difference in the comprehensive score among the samples, with the comprehensive score decreasing in this order: leaves > flowers > stems. The experimental results showed large differences in the species and contents of the volatile components among the leaves, flowers and stems of loquat.
    40  Determination of Eugenol Residues in Muscle Tissues of Spotted Catfish by High Performance Liquid Chromatography
    WANG Cai-xia XIONG Guang-quan BAI Chan WANG Ju-guang WANG Bing-xuan LI Ning WANG Jun ZU Xiao-yan LIAO Tao
    2019, 35(6):301-307. DOI: 10.13982/j.mfst.1673-9078.2019.6.040
    [Abstract](456) [HTML](196) [PDF 17.59 M](698)
    Abstract:
    In order to detect the metabolic residues of eugenol anesthetics during the transportation of fresh aquatic products, a high performance liquid chromatography (HPLC) method for the simultaneous determination of six eugenol compounds in the muscle tissue of catfish (Ietalurus punetaus) was developed. The freeze-dried fish muscle tissue was ultrasonically extracted with a mixture of 15 mL methanol and acetonitrile (V/V, 2:1), purified by 100 mg of hydrophobic gas phase nano-silica, and filtered. The mobile phase was a mixture of methanol and 0.1% acetic acid solution (V/V, 58:42) with a flow rate of 0.8 mL/min and ultraviolet detection wavelength at 272 nm, the column temperature was 35 ℃, the injection volume was 10 μL, and the external standard method was developed. The linear relationship of six eugenol compounds was good in the range of 0.02~100.0 ug/mL with a linear regression coefficient more than 0.999. The average intra-recovery was between 50.52% and 97.98% and the relative standard deviation was between 1.25 and 14.56% at three different addition levels. The stability and repeatability of the method were good. The detection limit of the method is 0.026~0.121 mg/kg, which is lower than the residue limit standard of eugenol in Japan. It can be used for the detection of various eugenol compounds in fish samples in batches.
    41  Bioaccessibility of Different Speciation of Chromium in Auricularia auricula during the in Vitro System
    LI Bing-ru ZUO Ji-min LI Yang LIU Jing WANG Bei-hong HE Zhao-ying MA Zhi-hong
    2019, 35(6):308-313. DOI: 10.13982/j.mfst.1673-9078.2019.6.041
    [Abstract](504) [HTML](282) [PDF 9.06 M](658)
    Abstract:
    The in vitro system was used to simulate the digestion of Auricularia auricula in stomach and intestine to analyze the bioaccessibility of chromium. The contents of chromium with different speciations were determined by HPLC-ICP-MS. The 29 samples were simulated the digestion by in vitro system. The bioaccessibilities of chromium in the stomach were ranged from 15.10% to 35.87%, and from 11.02% to 20.36% in the intestine. The contents of chromium in stomach were more than that in the intestine. The speciation of chromium mainly was trivalent, which proved that Auricularia auricula could absorb Cr(Ⅵ). The standard solutions of 0.5 μg/L Cr(Ⅲ) and Cr(Ⅵ) were mixed to determined for seven times, which RSD was 2.55%~4.98%. Six parallel experiments were repeated to verify the precision of the method, which relative deviation of the results was less than 9.5%. It was put forward that the bioaccessibility of chromium in Auricularia auricula was Cr (Ⅲ), which was benefit for the body. The Auricularia auricula could absorb Cr(Ⅵ) which do harm to the health. This experiment explored the change of the chromium speciation in Auricularia auricula during the process of digestion in stomach and intestine, which provided a reference for the study on the limit standard of the chromium in Auricularia auricula.
    42  Application and Research Progress of Pretreatment Technology for Drying of Fruits and Vegetables
    AN Ke-jing WEI Lai TANG Dao-bang YU Yuan-shan BU Zhi-bin ZHANG Yan XU Yu-juan
    2019, 35(6):314-321. DOI: 10.13982/j.mfst.1673-9078.2019.6.042
    [Abstract](693) [HTML](278) [PDF 931.38 K](1523)
    Abstract:
    At present, there are many problems associated with drying of fruits and vegetables such as high energy consumption, long drying time, and severe loss of nutrients. Those problems have commonly been solved via the innovation of drying technology and development of drying equipment. However, the growth of technologies for pre-drying is relatively slow. The pre-drying treatment technology refers to the treatment of materials through using methods such as physical, chemical or biological techniques prior to drying to accelerate the drying rate, improve product appearance and nutritional quality, and extend shelf life of fruits and vegetables. Currently, the commonly used pre-drying treatment technologies include blanching, freezing and thawing, osmotic treatment, chemical reagents, ultrasonic treatment, ultra-high pressure, high-voltage pulsed electric field, and carbonic maceration. In this research, the principles and characteristics of the above pretreatment technologies were reviewed, the mechanisms and application scopes for different fruits and vegetables were compared, and the prospects and development trends for pre-drying treatment technologies were also presented in order to provide guidance for research and development of new technologies for drying of fruits and vegetables.

    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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