Volume 35,Issue 10,2019 Table of Contents

1 Protective Effect of Caffeic Acid Phenylethyl Ester on Heart of Diabetic Mice

GONG Pin , CUI Dan-dan , CHANG Xiang-na , YANG Wen-juan , CHEN Fu-xin

2019, 35(10):1-5. DOI: 10.13982/j.mfst.1673-9078.2019.10.001

[Abstract](479) [HTML](222) [PDF 532.83 K](617)

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The protective effect of caffeic acid phenylethyl ester (CAPE) on the heart of diabetic mice and its mechanism were investigated. Diabetes mellitus model was established in mice by subcutaneous intraperitoneal injection of streptozotocin and feeding high-fat and high-sugar diet. The mice were randomly divided into blank group, injury group and protection group. The protective group was given CAPE by gastric perfusion, the other two groups were given 0.9% saline by gastric perfusion. The changes of oxidative indexes in heart tissue of mice were detected to evaluate the protective effect of CAPE. After successful modeling, the contents of superoxide dismutase (SOD), glutathione (GSH), catalase (CAT) in the injured group decreased by 0.00058 U/mg protein, 0.0033 mg/mL tissue and 20.95 U/mg protein in turn, respectively. The contents of malondialdehyde (MDA), protein carbonylation (PCO), nitric oxide (NO) in the protected group decreased by 0.126 mmol/mg protein, 3.205 mmol/mg protein and 0.5469 μmol/mg protein in turn after CAPE protection, respectively. Results indicated that high glucose environment could aggravate oxidative stress and induce oxidative damage in the heart, while CAPE could reduce the content of various indicators and the degree of injury. Increased oxidative stress might lead to diabetes mellitus. After CAPE treatment, the degree of injury in mice decreased, the antioxidant activity and the free radical scavenging ability were improved, resulting in their hearts potection.

2 Effect of Lactobacillus plantarum ER135 on the Improvement of Depression Induced by Reserpine in Mice

BI Yun-feng , LI Lu , ZHAO Yu-juan , ZHAO Zi-jian , YANG Ge , WANG Chao , DUAN Cui-cui , LI Sheng-yu

2019, 35(10):6-11. DOI: 10.13982/j.mfst.1673-9078.2019.10.002

[Abstract](405) [HTML](266) [PDF 600.41 K](540)

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The improvement effect of Lactobacillus plantarum ER135 on depression induced by reserpine in mice was investigated. Male ICR mice (n=40, 6-week) were administered with L. plantarum ER135 strain suspension (2.0×1010 cfu/mL) by gavage for continuous 21 days, then all mice were injected with reserpine (4 mg/kg) at 22th day to establish depression model. The improvement effect of L. plantarum ER135 on the mice was evaluated by observing the changes of behavioristics phenomena of mice, detecting serum and tissue biochemical indicator as well as relevant protein expression changes in hippocampal tissue. Compared with the control group, after administration of L. plantarum ER135, the symptoms of hypothermia, blepharoptosis and decreased motor ability of these mice were significantly improved. Compared with the model group, the concentration of 5-hydroxytryptamine, dopamine and norepinephrine in brain tissue increased by 2.06 ng/L, 1.42 pg/L and 10.12 ng/L, respectively. The level of serum inflammatory factors decreased. Tumor necrosis factor and interleukin-1 beta decreased by 9.40 ng/l and 10.63 ng/L, respectively. It also reduced the level of oxidative stress (p<0.05, p<0.01). Western-blot results showed that L. plantarum ER135 significantly could incuce an increases of the expression of cAMP, CREB, BDNF and other key proteins in the hippocampal neurotrophic pathway of depressed mice. L. plantarum ER135 can relieve depression of mice induced by reserpine.

3 Protective Effect of Gardenia jasminoides Extract on Dopaminergic Neurons in Mice with Parkinson's Disease Induced by MPTP

ZHANG Qi-chang , WANG Ze , CHEN Yang , WANG Ya-rong

2019, 35(10):12-18. DOI: 10.13982/j.mfst.1673-9078.2019.10.003

[Abstract](410) [HTML](310) [PDF 682.75 K](496)

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In this study, mice with Parkinson's disease (PD) caused by MPTP were used as a model to systematically study the protective effects of Gardenia jasminoides extract from the medicinal and edible resources on the dopaminergic neurons in PD mice. The PD mice were administrated with Gardenia jasminoides extract (25, 50, 100 mg/kg) to detect the behavior. Detection of substantia nigra dopamine in mice by immunohistochemistry, to study the protective effect of Gardenia jasminoides extracts on dopaminergic neurons in PD mice. Compared with the model group, the climbing time of the low, medium and high dose groups decreased by 24.03% (p>0.05), 26.43% and 26.99% (both p<0.05) respectively; the rotational time increased by 64.16% (p<0.05), 77.46% (p<0.05) and 86.76% (p<0.05), respectively. The tensile strength increased by 16.95% (p>0.05), 22.56% (p<0.05) and 31.84% (p<0.05), respectively. The behavior of PD mice was significantly improved after Gardenia jasminoides extract treatments. The number of TH-positive cells in the Gardenia jasminoides extracts group was significantly higher than that in the model group. Compared with the model group, the DA of the low, medium and high dose groups increased by 100% (p<0.05), 138.46% (p<0.05) and 187.18% (p<0.05), respectively. The DOPAC increased by 52.63% (p<0.05), 89.47% (p<0.05) and 110.53% (p<0.05), respectively; In addition, compared with the model group, the serum levels of TNF-α, IL-1β, IL-6 in the low-dose group were reduced by 18.30% (p<0.05), 23.86% (p<0.05) and 26.03% (p<0.05), respectively. The data show that the Gardenia jasminoides extracts can significantly improve MPTP-induced behavioral changes in PD mice, protect dopaminergic neurons, and have good potential in the development of PD drugs.

4 Effects of Water Extract of Poria on Helicobacter pylori Inhibition and GES-1 Cells Proliferation

LI Liang , YUAN Er-dong , GOU Na , GAO Li , YANG Yi-ting , REN Jiao-yan

2019, 35(10):19-24. DOI: 10.13982/j.mfst.1673-9078.2019.10.004

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Inhibitory activity on Helicobacter pylori (Hp) of different water extracts of Chinese herb (Atractylodes rhizome, Poria, dried orange peel, Yam and polysaccharide complex (mixed water extracts of Atractylodes rhizome, Poria, dried orange peel and yam) was studied. The antibacterial experiment results showed that the water extract of Poria, polysaccharide complex and Atractylodes rhizome demonstrated a certain inhibitory activity on Hp. The inhibition rates were 93.29%, 62.85% and 47.14% at the concentration of 1000.00 μg/mL, respectively. The water extract of Poria showed the most significant effect. The water extract of Herb had different inhibitory effects on urease activity, and the water extract of Poria had the best effect (IC50=618.90 μg/mL). The water extract of Poria showed a dose-dependent effect on the inhibition of Hp. The inhibition rate was over 80% when the concentration reached 15.62 μg/mL or more. The survival rate of human gastric epithelial cells (GES-1) was significantly increased to 128.35% after treatment with 125.00 μg/mL of the water extract from Poria for 24 h. Therefore, the water extract of Poria might repair the Hp-injured stomach by inhibiting Hp proliferation and urease activity and promoting the proliferation of GES-1 cells.

5 Protective Effect of Saponins from Panax japonicus on Brain Apoptosis in Mice with High-fat and High-fructose Diet

WANG Rui , WANG Ting , ZHANG Xu-lan , WANG Jin-xin , LIU Chao-qi , YUAN Ding , HE Yu-min , ZHOU Zhi-yong

2019, 35(10):25-31. DOI: 10.13982/j.mfst.1673-9078.2019.10.005

[Abstract](353) [HTML](274) [PDF 94.19 M](759)

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The objective in this work was to investigate the effect of saponins from Panax japonicus (SPJ) on high-fat and high-fructose diet (HFFD) induced apoptosis in mice. KM mice were divided into normal control, high-fat and high-fructose-diet group, low-dose SPJ group (100 mg/kg) and high-dose SPJ group (300 mg/kg) and were fed with normal diet, high-fat and high-fructose diet (HFFD) and HFFD followed by SPJ at different doses (100 and 300 mg/kg) for one month, respectively. The protein levels of Bcl-2, Bax, Cytochrome C, Caspase-3, Caspase-12, COX-2, iNOS, IL-1β, NLRP3, Caspase-1, ASC, SIRT1 and p-AMPK were detected by western blot. The results showed that the protein levels of Bcl-2, SIRT1 and p-AMPK of high-dose SPJ group increased by 1.31, 1.05 and 1.33 times, respectively. The protein levels of Bax、Caspase 3、Caspase 12、Cytochrome C、COX-2、iNOS、IL-1β、NLRP3、Caspase 1 and ASC decreased by 34%、39%、60%、37%、41%、25%、43%、49%、31%、52%, respectively. In conclusion, SPJ have strong anti-apoptosis effect on mice with high-fat and high-fructose diet, and its mechanism is related with inhibition of NLRP3 inflammasome activitation, resulting in a reduction of expression of inflammatory factors, or the upregulation of the proteins associated with oxidative stress.

6 Inhibitory Effect of Astragalus Polysaccharide on Uterine Leiomyoma Model Rats

LIU Mei-ping

2019, 35(10):32-37. DOI: 10.13982/j.mfst.1673-9078.2019.10.006

[Abstract](364) [HTML](283) [PDF 22.39 M](642)

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The inhibitory effect of Astragalus Polysaccharide on uterine leiomyoma model rats was investigated in this work. Fifty SD healthy female rats were selected, of which 10 were normal group, and the rest 40 were established uterine leiomyoma model and divided into model group and low, medium and high concentration group. The rats of each group were intervened to observe the apoptosis and cell cycle distribution of cancer tissue. The levels of estradiol (E2), progesterone (P), follicle stimulating hormone (FSH), luteinizing hormone (LH) and the expression of p53 gene, B lymphoma-2 (bcl-2), Bcl-2 related X protein (BAX) were detected. The results indicated that: the levels of E2, P, FSH and LH of high concentration group were 305.22 pg/mL, 44.21 ng/mL, 4.02 IU/L and 7.20 IU/L, respectively, which were significantly lower than those of model group, low and medium concentration group (p<0.05).The uterine weight and uterine coefficient of rats of high concentration group were 1.21 g and 5.44, respectively, which were significantly lower than those of model group, low and medium concentration group (p<0.05).The apoptotic rate of rats of high concentration group was 50.24%, and the percentage of cells in G1 phase was 62.41%, which was higher than the other three groups. The expression of p53 and Bcl-2 of high concentration group was 1.35 and 1.40, respectively, which was lower than that of model group, low and medium concentration group. The expression of Bax was 0.73, which was higher than that of model group, low and medium concentration group. The results showed that Astragalus polysaccharides could regulate the level of sex hormones, promote apoptosis of tumor cells, block cell cycle, and also regulate the expression of p53, Bcl-2 and Bax proteins in uterine leiomyoma model rats. Astragalus polysaccharides have a certain anti-tumor effect, and its ability showed a certain concentration-dependent.

7 Study on Ability of Maca Alkaloids to Inhibit Tumor Formation in Colon Cancer by Regulatating Mouse Immunity

WANG Ying-jiao , HU Qi , QIAO Wang , HUANG Meng-jiao , RAO Yong , LIU Zu-ping , LIU Yun , GUO Qing-xi

2019, 35(10):38-43. DOI: 10.13982/j.mfst.1673-9078.2019.10.007

[Abstract](406) [HTML](169) [PDF 66.54 M](613)

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The effect of maca alkaloids on the tumorigenic ability of mouse colon cancer CT-26 cells was investigated and its possible mechanism was explored. The animal model of colon cancer CT-26 cell transplantation in BALB/c mice was established and randomly divided into high dose maca alkaloid group, low dose maca alkaloid group and saline control group. The drug was continuously administered for 27 days. The weight gain curve of the mice and the volume growth curve of the transplanted tumor were drawn. The mice were sacrificed on the 28th day. The tumor inhibition rate, relative tumor proliferation rate and spleen index were calculated. The levels of serum IL-2 and IFN-γ were detected by ELISA. The histological changes of transplanted tumor, spleen, liver and kidney were observed by HE section. The results showed that, compared with the control group, the weight of the transplanted tumor in the experimental groups was significantly reduced (p<0.05).The tumor inhibition rates of the experimental groups were 43.37% and 45.26%, respectively. Histological observation showed that the necrotic area of transplanted tumor in the experimental group was significantly increased compared with the control group. The spleen index of the experimental group was significantly higher than that of the control group (p<0.05), and the white pulp proliferation of the spleen of the tumor-bearing mice in the experimental group was significantly larger than that in the control group. The serum IL-2 and IFN-γ levels in the experimental group were significantly higher than that in the control group (p<0.05). Results indicated that maca alkaloids could inhibit the tumor formation of mouse colon cancer CT-26 cells by increasing mouse immunity.

8 The Protective Effect of Nobiletin on Lipopolysaccharides (LPS)-induced RAW 264.7 Cell Injury

CHEN Jun

2019, 35(10):44-49. DOI: 10.13982/j.mfst.1673-9078.2019.10.008

[Abstract](357) [HTML](201) [PDF 18.60 M](651)

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To investigate the protective effects of nobiletin on LPS-induced RAW 264.7 macrophage cell injury. The MTT method was used to detect the safe dosage of nobiletin. The release level of lactate dehydrogenase (LDH) was measured by the LDH assay kit. The level of nitric oxide (NO) released in the cell supernatant was evaluated by the NO assay kit. The mRNA expression levels of TNF-α, IL-1β, iNOS, TLR4 and CD14 were evaluated by real-time PCR analysis. The expression level of NF-κB nuclear protein was determined by the western blot method. Compared to the normal control group, the LDH activity and amount of released NO in the LPS-stimulated group increased by 4.12 times and 3.21 times, respectively (p<0.01), and the mRNA expression levels of iNOS, IL-1β, TNF-α, TLR4 and CD14 increased by 2.73 times, 4.91 times, 10 times, 1.84 times and 3.53 times, respectively (p<0.01). Meanwhile, the nuclear expression level of NF-κB in the LPS-stimulated group increased by 2.50 times (p<0.01). However, the treatment with nobiletin at different doses decreased the activity of LDH and amount of the released NO, while reducing the mRNA expression levels of TNF-α, IL-1β, iNOS, TLR4 and CD14 as well as the nuclear expression level of NF-κB, compared with the LPS-stimulated group (p<0.05 or p<0.01). Nobiletin attenuates LPS-induced injury in RAW 264.7 cells through mechanisms probably associated with the inhibition of TLR4-NF-κB signaling pathway.

9 Effect of Chitosan/CMC Composite Coating Treatment on Quality of Postharvest Citrus Fruit

ZHANG Jing-lin , WANG Yong-jiang , LIU Hai-dong , FEI Li-feng , CHEN Cun-kun , BAN Zhao-jun

2019, 35(10):50-57. DOI: 10.13982/j.mfst.1673-9078.2019.10.009

[Abstract](550) [HTML](170) [PDF 70.49 M](774)

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The single-layer chitosan film and the Na-carboxymethyl cellulose/chitosan double-layer film were prepared by casting method, and the mechanical properties, microstructure and water vapor transmission rate were investigated. Two Citrus varieties of Chunxiang and lemon were used as test materials. The effects on the postharvest quality of two Citrus fruits (Chunxiang, lemon) during shelf life by chitosan monolayer coating and Na-carboxymethyl cellulose/chitosan self-assembled coating were studied. Results showed that the water vapor permeability of the composite film significant (p<0.05）higher than single-layer film and it was 1.74 times that of the chitosan film. What’s more, it could maintain good mechanical properties and microstructure. Applied to the Citrus preservation, the film could improve the lightness of Citrus, inhibit the oxidation of ascorbic acid (Vc) and reduce the decline of firmness. By reducing the number of stomata on the surface of Citrus fruit, coating can effectively reduce weightlessness rate which controlled in 7.5% during storage and delay the decline on titratable acid content of Citrus fruit. Compared with single-layer coating, Na-carboxymethyl cellulose/chitosan self-assembled coating can significantly (p<0.05) improve the postharvest quality of Chunxiang and lemon, maintain high firmness and Vc content, and prolong the storage period. After 20 d of storage, the firmness of Chunxiang and lemon were 1.15 and 1.23 times that of the control group, respectively. This work confirmed that the polysaccharide film formed by electrostatic adsorption and self-assembly had the potential to maintain postharvest quality of Citrus fruits and provided reference for the study on the preservation of biological coating film on different Citrus varieties.

10 Expression and Purification of ladR Gene of Listeria monocytogenes in Two Prokaryotic Vectors

CHEN Yue-tao , CHEN Mou-tong , WU Qing-ping , ZHANG Ju-mei , CHENG Jian-heng , SUN Qi-fan , WANG Juan

2019, 35(10):58-65. DOI: 10.13982/j.mfst.1673-9078.2019.10.010

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The ladR genes was amplified using the specific primers, and then two prokaryotic expression vectors pET-28a-ladR (carried six His-tag) and pGEX-4T-ladR (carried a GST-tag) were constructed. The protein expression conditions of the two expression vectors were optimized, including induction time, temperature and concentration. The soluble expression levels of LadR protein in these two expression vectors were compared. The pET-28a-ladR and pGEX-4T-ladR expression vectors were successfully constructed and expressed the His-LadR and GST-LadR fusion proteins in E. coli BL21. The GST-LadR fusion protein was excised by thrombin and purified to obtain a LadR protein. Under the optimal expression conditions of 0.5 mmol/L isopropyl-β-D-thiogalactoside (IPTG) and induction at 22 ℃ for 12 h, the expression level of LadR protein in pGEX-4T-ladR expression vector was 4.48-fold higher than that of His-LadR protein in pET-28a-ladR (IPTG of 1.0 mmol/L, and induction at 22 ℃ for 12 h). The results of this study indicated that the GST-tag was beneficial for the soluble expression of the ladR gene, which could provide a good foundation for functional analysis and transcriptional regulation mechanism of the LadR protein in L. monocytogenes.

11 Theoretical and Kinetic Study of the Hydrogen Atom Abstraction Reactions of Neu5Gc with Hydroxyl Radical

CHANG Rui , HE Jiang , LUO Xian-kun , HUANG Yun-an , ZHU Qiu-jin

2019, 35(10):66-75. DOI: 10.13982/j.mfst.1673-9078.2019.10.011

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The new red meat and it’s products risk factor N-glycolylneuraminic acid (Neu5Gc) can induced inflammation, but the interaction mechanism with the hydroxyl radicals (OH·) that related to the food consumption, metabolism process and inflammation is unclear. The OH· simulation test showed that the optimal rate of Neu5Gc content decrease was 76.23%±2.17% at the conditions bellow, the amount of hydrogen peroxide (H2O2) was 2% and the 254 nm UV lamp was treated for 15 minutes. To explore the reaction mechanism, the density functional theory was used to optimize the station points and enthalpy correction of all one-step hydrogen abstraction channels of OH· on Neu5Gc hydroxyl hydrogen and non-hydroxy hydrogen at the theoretical level of M062X/6-31+G(d, p) in the gas phase, aqueous phase and benzene phase. The energy barrier was calculated at the level M062X/def2TZVP. Reaction rates and kinetic parameters were obtained in the 298 K~453 K range by the transition state theory and the three-parameter Arrhenius equation. Theoretical calculations showed that the minimum hydrogen extraction energy barrier occurred at the H 24 position of Neu5Gc under the gas and benzene phase with 13.20 kJ/mol and 19.54 kJ/mol, respectively, the lowest energy barrier in the aqueous phase was 6.25 kJ/mol at H 29 position. For the lowest activation energy, in the gas phase was 8.09 kJ/mol at the H 39 position, in the benzene phase was 1.78 kJ/mol at the H 38 position, in the aqueous phase was 14.3 kJ/mol at the H 24 position. In the range of 273 to 453 K, the hydrogen extraction rate of the non-hydroxyl hydrogen in the Neu5Gc molecule can be up to 108 times higher than that of the hydroxyl hydrogen. In summary, the interaction mechanism of OH· with Neu5Gc was mainly through the hydrogen extraction of Neu5Gc non-hydroxyl hydrogen atoms.

12 Effects of Cereal Protein Peptides on the Physicochemical Properties and in Vitro Digestion Characteristics of Rice Starch

FU Tian-tian , SHU Lan-ping , XU Li-hong , NIU Li-ya , TU Jin , XIAO Jian-hui

2019, 35(10):76-84. DOI: 10.13982/j.mfst.1673-9078.2019.10.012

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In this study, rice starch was used as the raw material to investigate the effects of addition of cereal protein peptides on the physicochemical properties and in vitro digestion of rice starch. The results showed that the addition of 10% wheat peptides led to the greatest reduction of the peak viscosity and disintegration value of starch paste (which were respectively reduced by 300 MPa·s); On the contrary, the addition of 5% corn peptide caused the greatest decreases in the final viscosity and recovery value (which were reduced by 256?MPa·s and 200 MPa·s). The cereal protein peptides could increase the enthalpy and improve the thermal stability of the starch paste. The solubility of the starch was positively correlated with the amount of the added cereal protein peptides, although these peptide had no effect on starch swelling. The rice peptide could obviously change the freeze-thaw stability of starch, with its addition at 5% or 10% enhancing the freeze-thaw stability of starch while reducing the syneresis rate by 3%. The three kinds of peptides could reduce the content of the rapidly digestible starch in the rice starch. On the basis of comparisons, the rice peptide lowered the in vitro digestibility of starch the most. Adding 5% corn peptide could cause the greatest decrease (by 25%) in the content of rapidly digestible starch, followed by adding 1% rice peptide. According the analysis of the main amino acid components in the cereal protein peptides, the content of basic amino acids in the rice peptide was significantly higher than those of the other two kinds of peptides, and the contents of amino acids in the corn peptides were correspondingly higher than those of wheat peptides. Thus, the main factors associated with the impact of the cereal peptides on the starch were related to their respective amino acid contents and molecular weights.

13 Quality Changes during the Fermentation of of Blueberry and Blackberry Juice Mixture by Composite Lactic Acid Bacteria

ZHANG Hong-zhi , MA Yan-hong , LIU Xiao-li , LI Ya-hui , GAO Hai-yan , CHEN Hang-jun , ZHOU Jian-zhong

2019, 35(10):85-91. DOI: 10.13982/j.mfst.1673-9078.2019.10.013

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Freshly squeezed and sterilized blueberry and blackberry juice mixture was used as the raw material for the fermentation with three different lactic acid bacteria (Lactobacillus plantarum, Lactobacillus lactis and Leuconostoc mesenteroides). The changes in the number of live lactic acid bacterium colonies, pH value, total acid, total sugar, reducing sugar and total phenolic content, in vitro antioxidant activity and bacteriostatic effect during fermentation were studied. The results showed that the lactic acid bacteria grew well in the juice mixture, with the highest colony number of viable bacteria (1.23×108 cfu/mL) occurring at the 24th h. During the fermentation, the pH value decreased constantly (from initial 5.50 to 3.75) while the total acid content increased continuously (from 0.15 to 2.15 g/100 mL). The reducing sugar content increased briefly and then decreased with the peak value (2.63 g/L) at 6 h, while the concentration of total sugar decreased steadily, due to the consumption by microorganisms, till almost 0 g/L after 42 h of fermentation. The content of phenolic compounds changed from 2.32 to 3.26 mg/mL (increase by 40.52% after fermentation). The DPPH·, hydroxyl and superoxide anion free radical scavenging rates increased by 18.17%, 30.67% and 34.55%, respectively, after fermentation. The fermented juice mixture significantly inhibited Escherichia coli, Aspergillus niger, Saccharomyces cerevisiae and Staphylococcus aureus, and the inhibitory activities increased gradually with fermentation time. Therefore, the use of fermentation by composite lactic acid bacteria is of high significance in terms of improving the quality of the blueberry and blackberry juice mixture and developing functional food products.

14 Quality Characteristics and Differences of Wild and Cultured Large Yellow Croakers (Larimichthys crocea)

GUO Quan-you , XING Xiao-liang , JIANG Chao-jun , YANG Xu

2019, 35(10):92-101. DOI: 10.13982/j.mfst.1673-9078.2019.10.014

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In order to explore the difference in the quality of cultured and wild large yellow croakers, comparison was made among the large yellow croakers raised using the current farming modes (deep-water cage S1, seine S2, multi-pass cage S3, pond S4, and small raft cage S5) in terms of appearance, texture, basic nutrients, fatty acids, amino acids, flavor substances and mineral elements. The results showed that cultured and wild large yellow croaker scales were firm and intact, with a shiny surface, clear mucus, and full eyeballs. The cohesiveness, elasticity, chewiness and shearing force of wild fish were significantly higher than those of cultured fish (p<0.05), but insignificant difference was found in cohesiveness and shear force among the cultured fish (p>0.05); the crude fat content of wild fish (9.76%) was significantly lower than those of the cultured fish (10.74%~14.00%) (p<0.05), with the crude protein content (21.02%) significantly higher than those of cultured fish(17.05%~17.35%), (p<0.05). In terms of the fatty acid composition of the wild and cultured large yellow croakers, the decreasing order was: ΣSFA>ΣMUFA>ΣPUFA. Σ(EPA+DHA) (12.84%), ΣPUFA(n-6) (2.15%) and ΣPUFA(n-3) (14.22%) of wild fish were lower than those of the cultured fish; TAA(14.64%), The contents of the non-essential amino acid (NEAA, 7.40%), semi-essential amino acid (SEAA, 1.31%) and essential amino acid (EAA, 5.93%) of the wild fish were significant higher than those of cultured fish (p<0.05); The inosine monophosphate (IMP) content of the wild fish (0.80 μmol/g) and cultured fish (0.98~1.03 μmol/g) was the highest among all the flavor nucleotides. The contents of macroelements in the wild fish and cultured fish decreased in order of Ca>K>Na>Mg, and the microelement with the lowest content was Cu. The ratio of Zn: Cu for the wild and cultured fish, and the ratio of Zn: Fe for the wild fish and the S1 or S2 cultured fish, were all within reasonable limits. This study can provide a basis for improving the quality of cultured large yellow croakers and optimizing its culturing mode.

15 Molecular Identification of Fungi Carried by Lycium barbarum from Ningxia

YUE Yuan , XU Juan , ZHAO Fei , ZHOU Meng-shi , HE Li-hua , ZHANG Jian-zhong , GONG Jie

2019, 35(10):102-109. DOI: 10.13982/j.mfst.1673-9078.2019.10.015

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Ningxia is the main planting area of Lycium barbarum. Due to improper storage conditions, L. barbarum is very prone to mildew. It has caused significant economic losses. This study mainly analyzed the main fungal species causing mold and mildew of L. barbarum in Ningxia, and discussed the relevant consequences. The fungal strains were isolated from the mildewed fruits of L. barbarum collected from five villages in Ningxia. The strains were identified based on biobarcode technology and phylogenetic analysis was performed. The 45 isolated strains were identified as 10 genus, including: Alternaria spp.、Fusarium spp.、Rhizoctonia solani、Trichoderma longibrachiatum、Filobasidium magnum、Penicillium chrysogenum、Curvularia spicifera、Mucor fragilis、Aspergillus niger、Rhodotorula mucilaginosa. At least four fungi might produce mycotoxins, causing food safety problems. Therefore, the relevant laws and regulations should be revised to manage the quality of L. barbarum.

16 Antioxidant and Anti-aging Activity of the Flavonoids and Saponins from Rosa davurica Pall

SONG De-xing , JIANG Jian-guo

2019, 35(10):110-115. DOI: 10.13982/j.mfst.1673-9078.2019.10.016

[Abstract](389) [HTML](181) [PDF 591.59 K](544)

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In this study, the flavonoids and saponins from Rosa davurica Pall were found to have strong antioxidant capacity and exhibit dose-dependence to some extent in DPPH free radical scavenging assay, ABTS free radical scavenging assay, ferric-reducing antioxidant power (FRAP) assay, and total reducing power assays. The test samples at all the examined concentrations exhibited higher ABTS free radical scavenging rate than Vc, among which the saponin components in the 30% ethanol-eluted fraction (at 200 μg/mL) had an ABTS scavenging rate of 98.78%; At 800 μg/mL, the saponins in the 50% ethanol-eluted fraction had a DPPH free radical scavenging rate of 91.88% (which was very close to that for Vc). In FRAP assay, the reducing power of the flavonoids and saponins was higher than 1.50 which was very close to that for Vc (1.72). The total reducing power of the saponin components in the 30% ethanol-eluted fraction was 2.07 (which was close to that for Vc 2.28). In the aging model based on HaCaT cell repair, the flavonoids and saponins from Rosa davurica Pall were found having good anti-aging activity, and could repair the morphology of damaged cells, increased their survival rate, and showed dose-dependence to some extent. At 800 μg/mL, the repair rate of the four test samples (the 30% ethanol-eluted flavonoids, 50% ethanol-eluted flavonoids, 30% ethanol-eluted saponins, and 50% ethanol-eluted saponins) were 371.94%, 394.39%, 392.35%, and 399.83%, respectively, which were all close to that for Vc (404.25%).

17 Effect of Non-cold Chain Transport on Refrigerator Storage Quality of Chilled Pork

YUE Qi-qi , LIU Wen , KONG Ping , HOU Wen-fu , Wang Li-mei , WANG Hong-xun

2019, 35(10):116-124. DOI: 10.13982/j.mfst.1673-9078.2019.10.017

[Abstract](330) [HTML](217) [PDF 933.05 K](677)

Abstract:
以采用保鲜处理的冷鲜猪肉为研究对象，研究了不同因素对非冷链运输的冷鲜猪肉冰箱贮藏品质特性的影响，并在实际物流中进行了初步验证。结果表明：吸水垫纸添加能有效延缓品质劣变，2层吸水垫纸可达到良好效果，冰箱贮藏12 d时，菌落总数为5.56±0.06 lg(cfu/g)；8 ℃、18 ℃、28 ℃和38 ℃下放置24 h后的冷鲜猪肉冰箱贮藏品质随环境温度升高劣变速度加快，冰袋放置可缓解18 ℃、28 ℃和38 ℃环境温度条件的影响，普通泡沫箱中放置2个冰袋，可以有效减缓18 ℃和28 ℃环境温度条件下冷鲜猪肉冰箱贮藏品质的劣变，延长2~3 d的保质期。随着物流运输时间延长，冷鲜猪肉冰箱贮藏品质劣变加快，模拟物流振动12 h内，冷鲜猪肉冰箱贮藏7 d品质保持良好，菌落总数为5.96±0.04 lg(cfu/g)，挥发性盐基氮为15.03±0.65 mg/100 g。优化相关控制因素条件下，在秋季经同城及同省异城实际非冷链物流条件下运输的冷鲜猪肉品质分别可在8 d及6 d冰箱贮藏期内保持良好的状态。

18 Changes in Active Components in Stauntonia chinensis Ferment during Fermentation

WANG Yu , LI Li-lang , ZHANG Jie , LI Xue , YANG Li-shou , LIN Ling , ZHOU Mei , YANG Xiao-sheng

2019, 35(10):125-130. DOI: 10.13982/j.mfst.1673-9078.2019.10.018

[Abstract](412) [HTML](280) [PDF 473.15 K](648)

Abstract:
In this study, Stauntonia chinensis ferment was prepared through using wild Stauntonia chinensis grown in Guizhou province as the raw material, and three different dominant microflora as the starter cultures. The loss of the major active substances (total triterpenes, total flavonoids, catechins and superoxide dismutase (SOD) were analyzed. The results showed that after efficient fermentation with starter cultures, the total triterpenes decreased from 6.79 mg/100 mL to 5.71 mg/100 mL (decrease by 15.91%), with the total flavonoid content, catechin content and SOD activity decreasing by 40.00%, 37.78% and 56.32%, respectively. After the fermentation with king starter cultures, the contents of total triterpenoids, total flavonoids and catechins, and SOD activity decreased by 38.73%, 58.82%, 35.56% and 42.27% (p<0.05) , respectively. After the fermentation with sweet starter cultures, the content of total triterpenoids increased by 0.74%, whilst the total flavonoid content, content of catechins, and SOD activity decreased by 15.89%, 0.11% and 48.73%, respectively. In conclusion, the fermentation using different starter cultures led to a loss of active components in Stauntonia chinensis ferments, with different dominant microflora causing different extents of loss. Among which, the decreases of the active components in the ferments were the lowest when the composite sweet starter cultures (consisting of yeast, acetic acid bacteria and lactic acid bacteria) was used. Therefore, the composite starter culture composed of yeast, acetic acid bacteria and lactic acid bacteria can be applied in the industrial production of Stauntonia chinensis ferments.

19 Comparison of Pretreatment Methods for Corn Gluten Meal and the Study of Decolorization Process of Corn Enzymatic Hydrolysate

ZHAO Mou-ming , MA Mei , SU Guo-wan , ZHENG Lin , LIU Yang

2019, 35(10):131-138. DOI: 10.13982/j.mfst.1673-9078.2019.10.019

[Abstract](556) [HTML](214) [PDF 704.79 K](736)

Abstract:
Corn enzymatic hydrolysate was prepared via enzymatic hydrolysis of corn gluten meal using commercial enzymes. The sites for cleavage by a protease are coated, causing low efficiency of enzymatic hydrolysis, and brownish yellow colour in the corn enzymatic hydrolysate, (which is not conducive to the separation and purification of peptides and affects product sensory effect). This research compared the pretreatment methods of corn gluten meal, and it was determined that the corn gluten meal was pretreated by heating and α-amylase to improve the efficiency of subsequent enzymatic hydrolysis. The corn enzymatic hydrolysate was decolorized by activated carbon, and the optimum decolorization conditions were determined based on the decolorization rate and protein loss rate: decolorization pH was 5, decolorization temperature was 40 ℃, and activated carbon dosage was 2%. Through the investigation on the antioxidant activities of decolorized corn peptides, it was found that the DPPH, ABTS and ORAC radical scavenging rates decreased: they were 93.11%, 1318.97 μmol TE/g, and 1192.39 μmol TE/g, respectively, before decolorization, but were 33.19%, 858.36 μmol TE/g and 582.62 μmol TE/g, respectively, after decolorization (i.e. the decolorized corn peptides still retained significant antioxidant activity). The determination of the ADH activation rate and hydrolyzed amino acids of the decolorized corn peptide showed that the ADH activation rate was 48.74%, and the decolorized corn peptide contained high levels of leucine and alanine, indicating its sobering activity.

20 Optimization of Technological Conditions of Fermented Suanyu and Their Quality Analysis

ZHANG Da-wei , ZHANG Jie , TIAN Yong-hang

2019, 35(10):139-147. DOI: 10.13982/j.mfst.1673-9078.2019.10.020

[Abstract](423) [HTML](193) [PDF 632.09 K](765)

Abstract:
Suanyu using golden pomfret as raw material was prepared by natural solid-state fermentation. The fermentation conditions of Suanyu were optimized by single factor and response surface experiments. The optimum fermentation conditions were obtained by using total acid and sensory score as the indice. The optimum fermentation conditions were as follows: salt addition of 4%, cornmeal addition of 55%, fermentation temperature of 38.9 ℃, fermentation time of 21.8 days. Under these conditions, the total acid and the sensory score of fermented golden Pomfret were 4.19‰ and 92, respectively. The pH, water content, water activity, fat and protein content were all decreased after fermentation. The protein content decreased from 19.43% to 17.76%. The hardness of the product decreased from 24.70 N to 24.40 N. The adhesion, elasticity and stickiness of the product increased from 0.57 mj to 0.89 mj, from 1.43 mm to 1.41 mm, from 5.60 N to 6.20 N, respectively. The chewiness increased from 7.42 mj to 7.58 mj. The electronic nose analysis indicated that the flavor of the fermented golden Pomfret changed obviously compared with fresh material. A large number of aroma compounds were produced after fermentation, which could provide a foundation for the analysis of aroma compounds and aroma formation mechanism of the fermented Suanyu.

21 Preparation of Pomelo Peel Nanocrystalline Cellulose and Its Application in Improving the Properties of Carboxymethyl Starch Film

TU Xiao-li , HE Ping , PAN Si-yi , WANG Lu-feng

2019, 35(10):148-154. DOI: 10.13982/j.mfst.1673-9078.2019.10.021

[Abstract](562) [HTML](239) [PDF 632.18 K](774)

Abstract:
Nanocrystalline cellulose (NCC) was prepared by sulfuric acid hydrolysis method using pomelo peel as the raw materials. The microstructure and crystal structure of the NCC were investigated. The effects of different NCC additions to carboxymethyl starch films on surface topography, water vapor permeability, light transmittance and mechanical properties of the composite films were investigated. It is revealed that the NCC consisted of rods with lengths ranging from 60 to 180 nm and diameters ranging from 3 to 15 nm. The X-ray diffraction indicates that the crystal structure of NCC is still type I. Scanning electron micrograph shows that the surface of the composite film is smooth and flat. It was found that the tensile strength of the nanocomposite films with 5% (W/W) NCC addition was optimum with an improvement of 52.22%. While the elongation at break of the composite films decreased with the addition of NCC. Water vapor permeability of the nanocomposite films decreased by 23% for the optimum 7% (W/W) NCC content. Although the addition of NCC has reduced the light transmittance of the composite films, it did not change the transmittance of the control films at different wavelengths. Therefore, the additions of NCC to carboxymethyl starch films can effectively improve the performance of the composite films and thus contribute to prepare films with good comprehensive properties.

22 Screening Endogenous Signal Peptides in Pichia pastoris for Promoting the Secretion of Lipase from Rhizomucor Miehei

MIAO Yang-li , LI Zhan-sheng , HAN Shuang-yan

2019, 35(10):155-163. DOI: 10.13982/j.mfst.1673-9078.2019.10.022

[Abstract](529) [HTML](405) [PDF 759.61 K](720)

Abstract:
Rhizomucor miehei Lipase (RML) is widely used in the paper, food, cosmetics, pharmaceutical industries. In this study, nine potential endogenous signal peptide-like sequences with a secretory potential from Pichia pastoris were predicted by a SignalP 4.1 online software: FLO10, CPR5, PRY2, DSE4, NUP145, MSB2, SSP120, FRE2 and FLO9. Using the widely used α-mating factor (α-MF) signal peptide of Saccharomyces cerevisiae as the control, the effects of the nine endogenous signal peptides on the secretion of the enhanced green fluorescent protein (EGFP) and RML in a protease-deficient PichiaPinkTM expression system were investigated. The results showed that FLO10, PRY2, DSE4, MSB2, SSP120 and FRE2 could effectively mediate the secretion of EGFP. Moreover, the secretion level of EGFP mediated by PRY2, DSE4, MSB2 and FRE2 were 2.15, 1.15, 1.33, 1.30 folds, respectively, that of α-MF. FLO10, PRY2, DSE4 and FRE2 could effectively mediate RML secretion, with the highest secretion level of RML with FLO10 (which was 1.50 folds that of α-MF). This study laid a foundation for improving the expression of RML in protease-deficient Pichia pastoris.

23 Degradation of Sugars in Fruit Processing Wastewater by Low Temperature Plasma

XU Wen-hui , ZHOU Jin-yun , CAI Jing , ZHANG Jia-gan , FAN Ming , ZHANG Jun

2019, 35(10):164-173. DOI: 10.13982/j.mfst.1673-9078.2019.10.023

[Abstract](416) [HTML](217) [PDF 765.95 K](520)

Abstract:
The chemical oxygen demand (CODcr) and sugar content of 12 kinds of carbohydrates were measured by potassium dichromate method and phenol-sulfuric acid method. The change of sugar content and CODcr degradation efficiency of carbohydrates treated by low temperature plasma at different time were compared. Feasibility of treating fruit processing wastewater by body technology.The data show that the CODcr value of carbohydrates has a good linear relationship with their mass concentration and molar concentration. The relationship between the number of C, H, O atoms and CODcr is: 1 mmol (CH2O) CODcr value is 2.49±0.25 mg/L. The phenol sulfuric acid method was used to determine the sugar content. The sugar content and CODcr value of 12 kinds of sugar substances after different treatment time by ozone generator and low temperature plasma showed a downward trend. The CODcr value of the two treatments declined significantly in 10~40 minutes, and tended to be flat after 40 minutes. After 60 minutes of low temperature plasma treatment, CODcr value decreased to 42%~49% of the initial solution CODcr value, sugar content decreased to 44%~59% of the initial solution sugar content; after 60 minutes of ozone generator treatment, CODcr value decreased to 45%~53% of the initial solution CODcr value, sugar content decreased to 49%~65% of the initial solution sugar content. The results showed that the degradation effect of CODcr and the reduction of sugar content after low temperature plasma treatment were better than that of ozone generator, which indicated that low temperature plasma could degrade sugar substances in fruit processing wastewater and improve water quality.

24 A Thermal Synthesis of Yellow-green Carbon Dots as a Fluorescent Probe for the Study of the Pro-oxidation of Piceatannol

WU Ling , WEI Qing-yi , PU Hong-bin

2019, 35(10):174-181. DOI: 10.13982/j.mfst.1673-9078.2019.10.024

[Abstract](445) [HTML](222) [PDF 793.81 K](684)

Abstract:
In order to investigate the pro-oxidative activity of paclitaxel (Pic) in a cost-effective and time-saving manner, this study used o-phenylenediamine as the raw material for thermal synthesis of the yellow-green fluorescent carbon quantum dots (CDs). Then the CDs were characterized by UV-vis absorption spectrophotometry, fluorescence spectrophotometry, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR), with their stability at different temperatures, pHs, ionic strengths, and exposure time lengths also studied. Finally, the Cu2+-catalyzed quenching effect of Pic on CDs fluorescence and the dose-response relationship were investigated. The results revealed that the CDs in aqueous solution had the optimum emission wavelength of 570 nm and optimum excitation wavelength of 385 nm, with an average diameter of 7.4 nm and a surface rich in functional groups such as amide bonds. The CDs exhibited strong resistance to photobleaching, low sensitivity to temperature and ionic strength, and good luminescence in pH 5~10. In the presence of Cu2+ at 100 μmol/L, the degree of fluorescence quenching was linear with the concentration of piceatannol in the range of 1.5~12.5 μmol/L. When the concentration of piceatannol was higher than 12.5 μmol/L, the decrease in the system’s fluorescence approached a plateau while the pro-oxidative effect of Pic was no longer obvious. This study can provide a theoretical basis for the practical application of piceatannol as a functional food.

25 Electronic Tongue-based Study on the Effect of Clopidogrel Phenyl Urea (CPPU) on the Flavor Quality of Strawberry

GUO Lin-lin , LUO Jing , PANG Rong-li , WANG Rui-ping , QIAO Cheng-kui , LI Jun , PANG Tao , XIE Han-zhong

2019, 35(10):182-188. DOI: 10.13982/j.mfst.1673-9078.2019.10.025

[Abstract](477) [HTML](275) [PDF 417.18 K](570)

Abstract:
One week after the 'Sweet Charlie' strawberry trees produced flowers, they were sprayed with water or CPPU at either of the four concentrations (2.5, 5.0, 10, 20 mg/L). The contents of soluble solids, total acid, free amino acids, and tannins of the resultant strawberry fruits were measured. The taste indicators such as sourness, sweetness, bitterness, umaminess, saltiness, astringency, and aftertaste of bitterness and astringency were analyzed by the electronic tongue technique, to evaluate the effect of CPPU and its concentration on the flavor, nutritional quality and taste of strawberry, as well as the advantages of using electronic tongue to investigate the effect of CPPU on the taste of strawberries. The obtained results showed that the use of CPPU could increase the content of soluble solids, reduce the total acid content, increase the solid-to-acid ratio, and reduce the number of species and total amount of free amino acids in strawberry fruits. Low concentrations (2.5 or 5.0 mg/L) of CPPU could reduce the tannin content of strawberries, whilst high concentrations (10 or 20 mg/L) could increase significantly this content. The results of the electronic tongue analysis, the CPPU treatment at low concentrations could increase the sweetness and reduce sourness, with the corresponding reduction in the saltiness and umaminess along with their highly correlated bitterness (correlation coefficient: 0.99). There were positive correlations between the total amount of free amino acids and umaminess, the tannin content and astringency, the total acid content and sourness, the solid-to-acid ratio and sweetness. The CPPU treatments at low concentrations had a positive impact on the sweetness and sourness and associated flavor composition of strawberry. However, a CPPU treatment, regardless of its concentration, had a negative impact on salty and umami tastes and associated flavor composition.

26 Effect of Fermentation by Co-culture of Yeast and Lactic Acid Bacterium on the Quality of Lychee Juice

ZOU Ying , ZOU Bo , YU Yuan-shan , XU Yu-juan , WU Ji-jun , XIAO Geng-sheng , FU Man-qin

2019, 35(10):189-195. DOI: 10.13982/j.mfst.1673-9078.2019.10.026

[Abstract](636) [HTML](259) [PDF 488.05 K](678)

Abstract:
In this study, freshly squeezed lychee juice was used as the raw material for the fermentation by co-culture of Lactobacillus casei and three yeasts (BO213, D254, EC1118). The number of live lactic acid bacteria, pH, soluble solids content, sugar components, organic acids, DPPH free radical scavenging capacity, and sensory attributes during fermentation were analyzed. The results showed that the number of lactic acid bacteria in the lychee juice after fermentation was higher than 7 lg (cfu/mL), and all strains had certain probiotic functions. Thefermentation by co-culture of lactic acid bacteria and yeast could not only promote the growth of Lactobacillus casei, but also reduced the sugar content of the lychee juice with the alcohol content lower than 0.50% (which met the standard of non-alcoholic beverages). With the prolongation of fermentation time, the sugar content of each group decreased. After 24 hours of fermentation, the lactic acid content of juice fermented by Lactobacillus casei singly was significantly lower than that obtained via fermentation by different co-cultures. The lactic acid content decreased in this order: D254+Lactobacillus casei (6.62 g/L)>Ec1118+Lactobacillus casei (6.55 g/L)>BO213+Lactobacillus casei (2.35 g/L)>Lactobacillus casei (0.94 g/L). The in vitro antioxidant capacity (DPPH· scavenging ability) of the D254+Lactobacillus casei group and the Ec1118+Lactobacillus casei group after 24 h fermentation was superior to that of the Lactobacillus casei fermentation group. The fermented lychee juice had better flavor than unfermented juice, and the co-culture fermentation group was superior to the single-culture fermentation group, with the BO213+Lactobacillus casei group having the best flavor, followed by the Ec1118+Lactobacillus casei group. In summary, a fermented alcohol-free probiotic lychee beverage with good flavor and rich in nutrients could be obtained via fermentation by Ec1118+Lactobacillus casei.

27 Effects of Different Hydrolysis Methods on Antibacterial Activity and Tyrosinase Inhibition of Buckwheat Saponins

JI li-hong , XUE Jun , ZHAO Lei , DING Kui-ying , XU Fang-zhou , LI Yue , SHI Long-long , WANG Zhi-xin , XUE Peng

2019, 35(10):196-204. DOI: 10.13982/j.mfst.1673-9078.2019.10.027

[Abstract](497) [HTML](285) [PDF 547.97 K](599)

Abstract:
A large amount of saponins in quinoa bran was found to have biologically active. The activity of tyrosinase inhibition and bacteriostatic of less polar saponins in quinoa bran were investigated by different hydrolysis methods, such as biphasic acid hydrolysis method, direct acid hydrolysis and enzyme hydrolysis bran. Their active component was been speculated and conducted qualitatively and quantitatively. Bacteriostatic activity was determined by minimum bacteriostatic concentration (MIC), minimum bactericidal concentration (MBC) and paper disk method. The whitening effect of tyrosinase inhibition was evaluated. LC-MS/MS and HPLC were used to identify the active compounds qualitatively and quantitatively. The results showed that the compounds that hydrolyzed and converted by bipolar acid had the best activities with MIC of 0.60 mg/mL, MBC of 1.20 mg/mL for Staphylococcus aureus and Salmonella enteritidis, MIC of 0.30 mg/mL, MBC of 1.20 mg/mL for Staphylococcus epidermidis. It also had certain inhibitory effect on Pseudomonas aeruginosa. The inhibition rate of 0.5 mg/mL of the conversion compounds to tyrosinase reached 68.09%. According to LC-MS /MS and HPLC analysis, some saponins were hydrolyze after two-phase acid decomposition, resulting in the decrease of the polarity of the compounds. Extraction of saponins from quinoa bran by biphasic acid hydrolysis could improve the activity of compound and enhance the function of the inhibitory on bacteria and rosinase activity. The extraction rate was significantly higher than that of direct acid hydrolysis and single enzyme hydrolysis.

28 Effect of Different Processing Technics on the Antioxidant Properties and Aromatic Composition of Green Bean Powder

KANG Zhi-min , ZHANG Kang-yi , ZHU Xiao-peng , GAO Ling-ling , WEN Qing-yu , ZHANG Can

2019, 35(10):205-212. DOI: 10.13982/j.mfst.1673-9078.2019.10.028

[Abstract](437) [HTML](162) [PDF 530.51 K](598)

Abstract:
The effects of three processing technics (boiling, baking and freeze drying) on the basic components, antioxidant properties and aromatic composition of green bean powder were investigated. The results showed that the contents of starch, protein, flavonoids and polyphenols in flours pepared by different processing technologies were significantly different (p<0.05). The contents of total flavonoids and polyphenols in the green bean flour prepared by freeze drying were 0.40 g/g and 0.96 mg/g, respectively, and that in the green bean flour prepared by boiling method were 0.30 g/g and 0.71 mg/g, respectively. Compared to the baking technology, the free radical scavenging activity and reducing power of the flour prepared by boiling or freeze drying were found to be the highest. The antioxidant power of the powder obtained by baking green beans was the lowest. Analysis by solid-phase micro extraction (SPME) and gas chromatography-mass spectrometry (GC-MS) showed that a total of 17, 20, 41 and 21 volatile compounds were identified in fresh green beans, boiling, baking and freeze drying flours, respectively. Comprehensive analysis showed that the freeze driying and boiling green bean powder had higher antioxidant capacity. These above technologies could better preserve the nutritional value of green beans, and could better retain and increase the aroma of green beans. Due to a lot of energy consumption of freeze drying, boiling technology and then by hot air was selected.

29 One-Step Fabrication of Double Emulsions Stabilized by Soy Protein

XU Wen-liu , CHEN Zhen-dong , HOU Jun-jie , WANG Jin-mei

2019, 35(10):213-217. DOI: 10.13982/j.mfst.1673-9078.2019.10.029

[Abstract](462) [HTML](208) [PDF 556.66 K](758)

Abstract:
The present work found that at neutral pH, double emulsions could be simply fabricated with SPI preheated at acidic pH by one-step method. The effects of heating time on the solubility of SPI at pH 7.0 and the properties (e.g. cream rate, particle size) of double emulsions were further studied. The results showed that the acidic heating treatment decreased the solubility of SPI at pH 7.0 (native SPI, 78.60%; preheated SPI, 36.02%~53.39%), and the behavior was dependent on the heating time. This phenomenon may be related to the formation of insoluble protein fibrillar aggregates, which are mainly sustained by hydrogen bond and disulfide bond. The acidic heating treatment obviously improved the creaming stability of emulsions, and the longer heating time resulted in better effects (native SPI, 38.70%; SPI preheated with 2~6 h, 34.90%~36.50%; SPI preheated with 12~20 h, 17.50%~19.70%). However, the droplet size of emulsions became larger (native SPI, 24.63 μm; preheated SPI, 28.12~33.97 μm). In addition, an increase in the oil content also decreased the cream rate and droplet size. With the oil content increased from 20% to 60%, the cream rate decreased from 76.20% to 3.30%, and the droplet size decreased from 28.23 μm to 19.06 μm. The present work provides a new way to fabricate double emulsions with controllable properties.

30 Effect of Starch on the Quality of Fermented Soy Sauce

ZHOU Chao-hui , CHEN Zi-jie , LI Tie-qiao , GUAN Pei-jian , LU Li-ling

2019, 35(10):218-224. DOI: 10.13982/j.mfst.1673-9078.2019.10.030

[Abstract](416) [HTML](237) [PDF 421.17 K](519)

Abstract:
Under industrial production conditions, the sensory properties, physicochemical indicators, amino acid composition and volatile profiles of flour and wheat flour mixed fermented soy sauce (FWSS) and wheat flour fermented soy sauce (WSS) were compared in this work. The results showed that there was no significant difference in other physicochemical indicators except for total acid. Most of the amino acids of FWSS had higher contents than that of WSS, and glutamic acid content (FWSS of 21.11%, WSS of 20.35%) showed the most significant difference. The volatile compounds, such as 4-hydroxy-5-ethyl-2-methyl-3(2H) -furanone (HEMF, caramel) and 4-ethyl guaiacol (4-EG, smoky), showed a higher content in FWSS than that of WSS, which was consistent with the results of the sensory evaluation, i.e. FWSS released a stronger caramel and smoky smell. Therefore, 40% flour addition instead of wheat flour in soy sauce (FWSS) industrial fermentation could reduce the total acid content and improve the aromatic richness and tasty characteristics (total acid content of FWSS was 1.15 g/100 g, total acid content of WSS was 1.24 g/100 g). Results in this work coukd provide theoretical guidance for the improvement of flavor quality of high-salt liquid fermented soy sauce.

31 Preparation of Rice-milk Dual Protein Yogurt Based on Screening Two Lactobacillus Strains

WAN Hong-xia , SUN Hai-yan , LIU Dong

2019, 35(10):225-234. DOI: 10.13982/j.mfst.1673-9078.2019.10.031

[Abstract](427) [HTML](330) [PDF 611.86 K](578)

Abstract:
The fermentation medium and process conditions of rice-milk dual protein yogurt were optimized by using rice protein and whole milk powder as the main raw materials, self-screening bacterium (Lactobacillus farraginis and Lactococcus lactis subsp. Lactis) as fermentation strains. Sensory evaluation, fermentation acidity and viscosity were used as the evaluation standard. The results showed that the fermentation medium was that rice protein hydrolysate (7.5% degree of hydrolysis) was added below 40% (protein powder by more than 60%). The best fermentation conditions as follows: the breeding ratio of Lactobacillus farraginis and Lactococcus lactis subsp. Lactis of 2:1, the percentage of rice protein and milk protein of 30:70, the inoculation amount of 3%, and the culture temperature of 42 ℃. The best food additives were that the optimal adding amount of sucrose is 4%~6%, and the optimal adding combination of thickener is 0.15% pectin +0.60% gelatin or 0.40% gelatin +0.60% HPDSP. The stable curd, uniform color, delicate taste, and distinct rice flavorrice-milk dual protein yogurt could be obtained under the optimum medium, food additives and process conditions.

32 Effect of Roasting Degree on Volatile Aroma Components of Large-leaf Yellow Tea

GUO Xiang-yang , WAN Xiao-chun

2019, 35(10):235-245. DOI: 10.13982/j.mfst.1673-9078.2019.10.032

[Abstract](520) [HTML](221) [PDF 643.62 K](1014)

Abstract:
Large-leaf yellow tea (LYT) is famous for its crispy-rice-like odor, and “Lalaohuo” (roasted processing) is the key important processing to form the characteristic flavor. Using Gas Chromatography-Mass Spectrometry (GC-MS) technology to investigate the volatile compositions of Large-leaf yellow tea by means of steam distillation (SD), and the effect of roasting degree under small fire (120 ℃~130 ℃), medium fire (130 ℃~140 ℃) and old fire (145 ℃~155 ℃) on its volatile quality coupled with sensory evaluation was studied. The results revealed that heterocyclics, aromatics and esters compounds were the mail volatiles of LYT undergoing small fire, medium fire and old fire roasted processing, the former two owned less volatiles (had 84, 72 volatiles, respectively), and also had undesired odors that are (E)-4-hexen-1-ol and N-ethylbenzenamine, which are of grassy or burnt flavor; the latter one contained much more volatiles (104 volatile compounds were detected, and of which 99 volatiles were identified), especially for containing-nitrogen heterocyclics which are of roasted, caramel-like odor in tea. And also the sensory evaluation results matched well with the data of volatile compositions, the LYT undergoing old fire processing enriched in roasted and caramel-like odor, protruded the nutty flavor, and had the characteristic flavor of ‘Crispy-rice-like odor’ (had the highest evaluation score, 8.33). Old fire roasted processing can make an excellent volatile quality of LYT.

33 An Immunoassay Based on the Antibody Specific for Herbcide Metolachlor

XU Jing-jing , WANG Lan-teng , LAI Yu-jian , LI Xiang-mei , LEI Hong-tao , SHEN Xing

2019, 35(10):246-252. DOI: 10.13982/j.mfst.1673-9078.2019.10.033

[Abstract](434) [HTML](160) [PDF 555.29 K](753)

Abstract:
An antibody-based ic-ELISA was established to detect the pesticide residue of metolachlor in food and reduce its potential harm to human. Metolachlor hapten was synthesized from herbicide metolachlor and 3-mercaptopropionic acid, and identified by 1H-NMR and mass spectrometry. The artificial antigen of metolachlor was prepared by coupling the hapten with carrier protein using EDC method. Antibody against metolachlor was raised by rabbit. The optimal dilution times of antigen and antibody were determined by chessboard titration. The antibody dilution solution for ELISA reaction was PBS (1% PEG6000), and the drug dilution solution was PBS (10% methanol). On this basis, the established ic-ELISA calibration curve for metolachlor was conducted by antibody, which exhibited IC50 value of 14.64ng/mL, detection limit (LOD) of 0.8 ng/mL and linear detection range (IC20-IC80) of 1.51~141.92 ng/mL. The cross-reactivity with 14 structural analogues was less than 3%. The recoveries of spiked samples were in the range of 86.60%~102.16% with RSD ranging from 7.05%~13.30%. This antibody with high sensitivity and specificity can be used to detect metolachlor in the food or environment.

34 Study on Chemical Constituents of Ligustri Lucidi Fructus by UPLC-Q/TOF MS

XIAO Xue , XU Si-min , GAO Ying-min , LI Shan-shan , WU Chun-rong , YAN Shi-kai

2019, 35(10):253-260. DOI: 10.13982/j.mfst.1673-9078.2019.10.034

[Abstract](410) [HTML](251) [PDF 570.83 K](666)

Abstract:
Using a LC-TOF/MS method, the chemical constituents of Ligustri Lucidi fructus were analyzed, and the transformation rule of the different constituents in the processing of Ligustri Lucidi fructus with the salt was discussed. A Sharpsil-H C18 column (250 mm×4.6 mm, 5 μm) was used. The mobile phase was composed of acetonitrile and water with 0.1% formic acid in gradient mode. The flow rate was 1 mL/min, the column temperature was 25 ℃ and the injection volume was 5 μL. An AB Sciex Triple TOF 5600 and ESI ion source was used for mass spectra. The MS data were collected in both positive and negative modes. The result showed that a total of 19 compounds were identified in the kidney-shape Ligustri Lucidi fructus, a total of 21 compounds were identified in the kidney-shape Ligustri Lucidi fructus after processing, a total of 28 compounds were identified in the round Ligustri Lucidi fructus, a total of 24 compounds were identified in the round Ligustri Lucidi fructus after processing. Through UPLC-Q/TOF MS technology, the analytical method of high sensitivity, high degree of separation and quick analysis was established for the chemical composition analysis of the raw and salt products of Ligustri Lucidi fructus. It was also proved that the components in various shapes of Ligustri Lucidi fructus were different in the processing with the salt, which will lay the foundation for the follow-up quality control and pharmacological research.

35 Establishment of Real-time Fluorescence Loop-mediated Isothermal Assay for Detection of Classical Swine Fever Virus

GONG Han-yue , CAO Wei-wei , SHI Lei , CHEN Xun , SONG An-hua , YE Lei

2019, 35(10):261-267. DOI: 10.13982/j.mfst.1673-9078.2019.10.035

[Abstract](417) [HTML](207) [PDF 574.71 K](666)

Abstract:
In order to make early diagnosis and prompt prevention of swine fever, a real-time fluorescent loop-mediated isothermal amplification method for rapid detection of classical swine fever virus (CSFV) was established. Using Primer Explorer version 4 to design 4 sets of primers for the 5'UTR non-coding region of CSFV, the best primers were selected to establish a real-time fluorescent loop-mediated isothermal amplification assay for CSFV, and the specificity, sensitivity and applicability were verified. The results showed that the real-time fluorescent loop-mediated isothermal amplification method established in this experiment was consistent with the real-time fluorescent polymerase chain reaction detection method for 128 clinical samples and 22 artificial interference sample by hog cholera live vaccine. This method only has amplified reaction for classical swine fever virus and the minimum detectable concentration was 10 fg/μL. There were no amplified reactions for eight pathogens such as virulence, highly pathogenic highly pathogenic porcine reproductive and respiratory syndrome virus and porcine circovirus type 2. The real-time fluorescent loop-mediated isothermal amplification method established in this experiment has strong specificity, high sensitivity, good detection effect and simple operation, so is suitable for rapid detection of clinical samples of CSFV.

36 Design and Verification of Low-density Pest Monitoring System for Stored Grain Based on Image Processing

LUO Hui , MA Hai-le , WANG Yang , CAMEO TSUI , PAN Zhong-li , RAGAB GEBREIL

2019, 35(10):268-273. DOI: 10.13982/j.mfst.1673-9078.2019.10.036

[Abstract](339) [HTML](196) [PDF 573.48 K](699)

Abstract:
To solve the problems such as high cost of high-density pest control for stored grains and the lack of real-time and portable monitoring systems, web technology combined with self-designed grain pest traps was used to develop real-time monitoring system for low-density insect infection. The Raspberry Pi control trap collected images of insects and processed images to obtain the number of insects in each image. Then the data were transmitted to the cloud server. Users could obtain the history and real-time insect images and numbers through the web app. In the laboratory, the system was used to monitor the density of the red flour beetle in rice as 0.5, 1, 2, 3, 4 and 5 heads/kg. The sensitivity and feasibility of the system were evaluated based on the time required for capturing the first red flour beetle and the capture rate of the insects within 24 h, respectively, while the accuracy of the counting system was calculated based on the results obtained by direct manual counting as the reference. The results showed that the sensitivity of the system was high, with the capture rate higher than 61.98% under low-density pest conditions. The number of the insects captured by was the trap highly correlated with the total number of insects in grains. The counting accuracy of the system was 90%. Therefore, the system can be used for real-time monitoring of low-density pests during grain storage.

37 Determination of Hydrocortisone and Fludrocortisone Acetate in Infant Formulas Using QuEChERS-High Performance Liquid Chromatography-tandem Mass Spectrometry

YANG Ming , YI Jun , HU Xiao-jing , DONG Qiu-hua , XU Qing , LI Shou-dao , CHEN Dan , CHEN Ye-chao , LU Yue-peng , JIANG Xiao-ming , TU Feng-qin

2019, 35(10):274-278. DOI: 10.13982/j.mfst.1673-9078.2019.10.037

[Abstract](679) [HTML](189) [PDF 23.63 M](870)

Abstract:
An analytical method was developed for simultaneous determination of hydrocortisone and fludrocortisone acetate in infant formulas using QuEChERS sample preparation with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The samples were dispersed by water, extracted with acetonitrile, salted out with sodium chloride, and then the extract was cleaned up with primary secondary amine (PSA) and aluminum oxide (Al2O3-N). The target compounds were separated on a Waters XBridge C18 column, determined using electrospray ionization (ESI) source in positive mode with the multiple reaction monitoring (MRM) acquisition mode and quantified with the matrix-matched external standard method. Under the optimal conditions, the average recoveries for the two hormones at three spiked levels (1.25, 5.00, 12.50 μg/kg) were in the range of 80.6%~102.1% with the relative standard deviations of 1.64%~4.22%. The limits of detection (LODs) were 0.40 μg/kg, and the limits of quantification (LOQs) were 1.25 μg/kg. This method was applied to analyze 28 batches of infant formulas, and hydrocortisone was found in two of them. The method is simple, rapid, sensitive, and reproducible, and can be applied to the rapid determination of hydrocortisone and fludrocortisone acetate in infant formulas.

38 Analysis of Free and Bound Aroma Compounds of Three Fruits

HE Yin , ZHU Li-xia , ZHANG Jun

2019, 35(10):279-285. DOI: 10.13982/j.mfst.1673-9078.2019.10.038

[Abstract](595) [HTML](283) [PDF 32.14 M](988)

Abstract:
In this work, solid phase microextraction combined with gas chromatography-mass spectrometry (SPME-GC-MS) was used to determine the free and bound aroma compounds of strawberry, grape and apple in mature stage. The results showed that the free and bound aroma compounds of the three fruits were abundant. The 13 kinds of strawberry bound aroma substances and 9 kinds of free aroma compounds were detected. The 8 kinds of grape bound aroma compounds and 9 kinds of free aroma compounds were detected. and The 13 kinds of apple bond aroma compounds and 13 kinds of free aroma compounds were detected. According to principal component analysis, the main aroma compounds of strawberry were phenylethyl acetate, trans-methyl cinnamate and 1-pentanol. The main aroma compounds of grape were isoamyl acetate, 1-pentanol and 2-hexenal. The main aroma compounds of apple were mainly 1-hexanol, 2-methyl-1-butanol, phenylethyl acetate, 1-hexanal, ethyl butyrate, ethyl n-hexanoate, 2-methylbutyl Acid ester. The comparison and analysis of The free and bound aroma compounds of strawberry, grape and apple were compared and analyzed to obtain their main aroma compounds. These results could provide a basic reference for the study of its formation and the changes of environmental factors. It also provided a foundation for the later study of storage changes basis.

39 Study on the Detection Method of Fresh Level of Spanish Mackerel Based on Visual Image

HAN Xiu-zhi

2019, 35(10):286-291. DOI: 10.13982/j.mfst.1673-9078.2019.10.039

[Abstract](489) [HTML](198) [PDF 563.96 K](605)

Abstract:
Freshness of Spanish mackerel is an important factor to evaluate its quality. In order to improve the accuracy of Spanish mackerel freshness detection, a visual image-based method was established. The research object of this work is 30 Spanish mackerel purchased from a seafood market. Spanish mackerel visual images were selected by an acquisition system. The region filling algorithm and morphological opening operation were used to fill and remove the binary image of fish segmented by Otsu method. Noise, merge the uphill method and region growing method were used to segment fish eye region. The global dynamic threshold segmentation method was used to segment fish gill image. When extracting image features, the color features of fish body, fish eye and fish gill image were extracted by using the gray mean of R, G and I components of image, and the area of fish eye center area was extracted by using G component. The image features were input into Neuro Shell 2 neural network discriminant model to detect freshness of marine Spanish mackerel effectively. The average accuracy of Spanish mackerel fresh method detection was 98.28%. The highest accuracy of detection of freshness was obtained by using the fisheye center area + color grayscale average characteristics of Spanish mackerel. And detecting the accuracy in determination of the freshness of Spanish mackerel of different death time, was s 95%. Results showed that this detection of freshness of Spanish mackerel could provide a theoretical basis for seafood detection.

40 Self-assembly of Natural Saponins and Their Effects on the Functional Properties of Food Colloids

CHEN Xiao-wei , NING Xue-ying , MA Chuan-guo

2019, 35(10):292-302. DOI: 10.13982/j.mfst.1673-9078.2019.10.040

[Abstract](641) [HTML](387) [PDF 985.69 K](1172)

Abstract:
As a large class of glycosides, saponins are widely distributed in natural plant kingdom, has received extensive attention in recent years. In terms of molecular structure, natural saponins are composed of hydrophobic aglycone backbones of triterpenoids or steroidal glycosides (hydrophobic scaffolds) attached with hydrophilic sugar chains, resulting in a high surface activity. The structural diversity of natural saponins not only makes them possessing biological activity and unique physicochemical properties, but also promotes a wide range of applications in foods, cosmetics and other fields. Based on the recent research on the structural characteristics, self-assembly and interface properties of natural saponins, this study attempts to explore the effect of the structure on the assembly behavior at aqueous phase, and air-water interfaces, oil-water interfaces and solid-liquid interfaces, and on the functional characteristics of food colloids. Moreover, the self-assembly and interfacial structures may vary with the plant source and molecular structure: Saponins with a triterpenoid structure most likely form viscoelastic interfacial membranes, resulting in stable food colloids; while saponins with a steroid structure tend to possess special physiological activities. Among them, natural Quillaja saponins perform at their best. They have been proven capable of forming stable micelles, nanoemulsions, emulsion gels and foams for the delivery of bioactive substances, and gained approval for food applications in most ocountries such as China, the United States and the European Union.

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Volume 35,Issue 10,2019 Table of Contents