Volume 31,Issue 10,2015 Table of Contents

1 Effect of Wheat Arabinoxylan on the Immunological Activity and Intestinal Metabolites of S180 Tumor-bearing Mice

ZHAO Meng-li , WANG Li-li , LIU Li-ya , ZHONG Kui , TONG Li-tao , LIU Xing-xun , ZHOU Xian-rong , ZHOU Su-mei

2015, 31(10):1-6. DOI: 10.13982/j.mfst.1673-9078.2015.10.001

[Abstract](1201) [HTML](0) [PDF 635.96 K](1099)

Abstract:
Acid-hydrolyzed arabinoxylans extracted with alkali (AX1) and water (AX2) were prepared to study their effects on the immune activity and intestinal metabolites in S180 tumor-bearing mice. Chemical analysis showed that both the protein content (1.50%) and ferulic acid content (7.6 μg/g) of AX1 were lower than those of AX2 (protein, 7.97%; ferulic acid, 366.3 μg/g). The weight-average molecular weights (Mw) of AX1 and AX2 were similar and were about 3 × 104 u. Compared with the negative control group, AX samples could inhibit the tumor growth in the mice, especially AX2, whose anti-tumor capability was comparable with that of ganoderma lucidum polysaccharides (GLP). Both AX1 and AX2 could significantly increase NK cell activity in mice; AX2 had a stronger effect than AX1. Besides, AX1 and AX2 could increase the phagocytosis of intraperitoneal macrophage following intragastric administration and AX2 showed a comparable effect with that of GLP. In addition, GLP, AX1, and AX2 had significant effects on the delayed type hypersensitivity (DTH) reaction (P < 0.05) compared with the negative control group. Short-chain fatty acids (SCFA) in colon contents of mice were also detected by gas chromatography and the results showed that SCFA of the AX1 and the AX2 groups were significantly higher than those of the negative control group and the GLP group (P < 0.05).

2 Comparative Study on the Effects of Lactoferricins from Different Sources on Proliferation and Cytokine Secretion of Spleen Lymphocytes in Mice

ZHAO Ning , XU Xiao-xi , ZHANG Yan-jie , ZHANG Shu-yi

2015, 31(10):7-12. DOI: 10.13982/j.mfst.1673-9078.2015.10.002

[Abstract](779) [HTML](0) [PDF 935.34 K](981)

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The effects of human lactoferricin (LfcinH) and bovine lactoferricin (LfcinB) on the proliferation and cytokine secretion of spleen lymphocytes in mice were studied, and the differences and correlation between LfcinH and LfcinB were compared and analyzed, respectively. The cell counting kit-8 (CCK-8) assay was used to measure the effects of different concentrations of LfcinH or LfcinB alone on the proliferation of mouse spleen lymphocytes and of different concentrations of LfcinH or LfcinB combined with a mitogen on the proliferation of mouse T and B lymphocytes. The IL-2, IL-4, TNF-α content was determined by enzyme-linked immunosorbent assay (ELISA). The results showed that LfcinH and LfcinB could significantly promote the proliferation of spleen lymphocytes and enhance the T lymphocyte proliferation induced by concanavalin A (ConA) and B lymphocyte proliferation induced by lipopolysaccharide (LPS). Moreover, Lfcin could significantly increase the secretions of IL-2, IL-4, TNF-α in spleen lymphocytes. The results also showed that Lfcin has a synergistic effect on the proliferation of T and B spleen lymphocytes with Con A or LPS; the mechanism may be related to the immune enhancement achieved by promoting cytokine secretion.

3 Effects of the S-layer Protein of Lactobacillus acidophilus on Intestinal Mucosal Immune Function in Mice Infected with Escherichia coli

ZHANG Dan , ZHANG Dan-dan , ZHANG Jin-ye , GUO Yu-xing , PAN Dao-dong

2015, 31(10):13-17. DOI: 10.13982/j.mfst.1673-9078.2015.10.003

[Abstract](1111) [HTML](0) [PDF 846.42 K](1075)

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The influence of the S-layer protein of Lactobacillus acidophilus on the intestinal mucosal immune function in BALB/c mice infected with pathogenic Escherichia coli was investigated. Lactobacillus acidophilus cells without the S-layer protein was obtained using lithium chloride solution (5 M) to extract the S-layer protein from Lactobacillus acidophilus. The SPF grade BALB/c mice were randomly divided into six groups: control group, pathogenic Escherichia coli-infected group, Lactobacillus acidophilus prevention group, Lactobacillus acidophilus treatment group, Lactobacillus acidophilus without S-layer protein prevention group and Lactobacillus acidophilus without S-layer protein treatment group; the experiment was conducted for 14 days. After the mice were sacrificed, the eye blood, intestine, and intestinal mucosa of the mice were collected to examine the changes in morphology of the intestinal mucosa and the differences in the expression of functional factors in it. Compared with control group, the intestinal mucosal morphology changed significantly in pathogenic Escherichia coli-infected group. After the Escherichia coli-infected mice were administered Lactobacillus acidophilus by gavage, the SIgA and IL-8 contents in each mucosa were significantly increased, and the serum contents of TNF-α and IL-1β were significantly reduced compared with the infected group. The result indicated that Lactobacillus acidophilus can reduce the incidence of inflammation and has a better protective effect on the intestinal mucosal immune function than Lactobacillus acidophilus without the S-layer protein. The S-layer protein in Lactobacillus acidophilus plays an important role in its colonization in the intestinal mucosa and the formation of a biological barrier to protect the intestinal mucosal immune function.

4 Stability and Structural Properties of Food Lipid Nanoparticles Modified by Trehalose

WEN Zhen , LIN Jing , ZHENG Zong-kun , LI Shi-ting , SU Jun-qing , MI Hong-wei

2015, 31(10):18-23. DOI: 10.13982/j.mfst.1673-9078.2015.10.004

[Abstract](1041) [HTML](0) [PDF 628.60 K](1182)

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Trehalose is used to modify lipid-based carriers, i.e., food lipid nanoparticles (FLNs), to increase their stability. Resveratrol, a model functional food factor, was loaded in trehalose-modified food lipid nanoparticles (TMFLPs) to yield functional food colloid particles. The modification conditions of trehalose are discussed. The micromorphology, particle size distribution, phase characteristics, and crystalline features of resveratrol-loaded TMFLPs were characterized. In addition, the stabilities of resveratrol in the TMFLPs and the TMFLPs themselves were investigated. The relationship between the stability and the microstructure of the TMFLPs was studied. The entrapment efficiency, loading capacity, and average size of the resveratrol-loaded TMFLPs were 81.37±1.50%, 8.71±0.13%, and 157.48±1.86 nm, respectively. The size was normally distributed. The TMFLPshad higher loading capacity and long-term stability than that of FNPss. Trehalose was dispersed in the lipid carriers in an amorphous form and it formed a trehalose/lipid eutectic mixture carrier with crystal lattice disfigurement, leading to lower X-ray diffraction intensity. The results confirm that the modification on food lipid nanoparticles (FLNs) via trehalose resulted in a matrix skeletal structure with lipid crystallographic defects, which play an important role in maintaining high loading capability and stability.

5 Corbiculidae-derived Polysaccharide Structure and Protection against Carbon Tetrachloride-induced Liver Damage in Mice

JIANG Chang-xing , LI Song-lin , XIONG Qing-ping , NIE Ling-hong , CHEN Xiao-ming

2015, 31(10):24-28. DOI: 10.13982/j.mfst.1673-9078.2015.10.005

[Abstract](927) [HTML](0) [PDF 641.11 K](1086)

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The structure of purified components (f2 and f3) of Corbiculidae polysaccharide (CPS) was studied using periodate oxidation, Smith degradation, gas chromatography (GC), methylation, and GC-mass spectrometry (MS) techniques. The results showed that f2 and f3 had different sugar chain structures. The main chain of f2 was composed of a α-D-(1→3) linked glucose (Glc) and α-D-(1→4) linked Glc, with the branch being composed of α-D-(1→2) linked Glc and α-D-(1→6) linked Glc. The main chain of f3 contained α-D-(1→3) linked Glc and α-D-(1→3) linked galactose, while the branch contained α-D-(1→6) linked Glc. The hepatoprotective activity of CPS was evaluated using a mouse model of carbon tetrachloride (CCl4)-induced liver injury. The results showed that oral administration of CPS significantly reduced the elevated serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and liver malondialdehyde (MDA) level (P < 0.05) and significantly increased the activities of liver superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) (P < 0.05). This suggests that CPS exhibits potent hepatoprotective effects on CCl4-induced liver damage in mice, which may be related to the enhancement of antioxidant capacity and inhibition of lipid peroxidation in mice.

6 Effect of Simulated Intestinal Fluid on Immunogenicity of Pen a1 and Its Epitopes

ZHAO Xin , GAO Mei-xu , WANG Zhi-dong , ZHI Yu-xiang , MOU Hui , SHEN Yue

2015, 31(10):29-34. DOI: 10.13982/j.mfst.1673-9078.2015.10.006

[Abstract](903) [HTML](0) [PDF 734.26 K](1095)

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Simulated intestinal fluid (SIF) was used to digest Pen a1, and changes in the immunogenicity of Pen a1 after digestion were analyzed. After digestion of shrimp antigen Pen a1 and the epitope peptides of Pen a1, a Pen al antibody and epitope-specific antibody were used to measure changes in the immunogenicities of Pen a1 and its epitopes, and the digestive stabilities of the epitope peptides of Pen a1 were determined. The results showed that the immunogenicity of Pen a1 decreased significantly within 60 min of digestion and continued to decrease slowly after 90 min. The generated protein fragments remained immunogenic, but were gradually degraded until they could no longer be detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Similar changes were observed for the immunogenicities of five epitopes of Pen a1. Western blot results indicated that the binding degrees of the five epitope antibodies with the proteolytic fragments of Pen a1 after the SIF digestion were different. The numbers of 20~30 ku fragments bound to antibody No. 3, 4, and 5 were greater than those bound to antibody No. 1 and 2. Enzyme-linked immunosorbent assay results indicated that after 4-h digestion, the immunogenicity had only decreased by 80%. The digestive stabilities of the five epitopes of Pen a1 were as follows: No. 2 > No. 1 > No. 3 > No. 4 > No. 5. In contrast, the digestive stabilities of the five epitope peptides of Pen a1 were in the following order: No. 3 > No. 1 > No. 4 > No. 2 > No. 5, which was negatively correlated with the number of cleavage sites on the epitope peptide. In conclusion, epitope No. 2 showed the highest digestive stability, while epitope No. 5 showed the lowest digestive stability.

7 Effects of Selenic Acid Cartilage Polysaccharide on Mitochondrial Membrane Potential and Cell Apoptosis of K562 Cells

ZHU Hong , LIU An-jun , ZHENG Guo-qiang , ZHU Chuan-wang , LIU Hao-yu , SUO Jia-li , XU Xiao-ming

2015, 31(10):35-39. DOI: DOI: 10.13982/j.mfst.1673-9078.2015.10.007

[Abstract](1567) [HTML](0) [PDF 705.46 K](1113)

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The effect of selenic acid cartilage polysaccharide (CA-Se) on the mitochondrial membrane potential of K562 human chronic myeloid leukemia cells and on the induction of apoptosis of K562 cells were studied. The inhibitory effect of CA-Se on the proliferation of K562 cells was studied using the MTT (3,-(4,5-dimethylthiazol-2-y))-2,5-diphenyl tetrazolium bromide) colorimetric assay, while the changes in the morphological characteristics after Hoechst 33342/PI staining were observed under a microscope. The changes in the mitochondrial membrane potential (ΔΨm) after rhodamine-123 staining were assessed by flow cytometry (FCM), and the protein and gene expressions of caspase-9 were analyzed by immunofluorescence and real-time polymerase chain reaction (RT-PCR), respectively. The results showed that the proliferation of K562 cells was significantly inhibited by CA-Se in a dose- and time-dependent manner. After CA-Se treatment, the morphological characteristics of cells were dramatically changed, and a reduction in cell volume, irregularities in cell membranes, and chromatin condensation were observed. The ΔΨm values reduced after CA-Se treatment from 96.10% (the control) to 78.07% (CA-Se treatment). The protein and gene expressions of caspase-9 both increased significantly. All the results indicated that CA-Se can induce apoptosis of K562 cells by reducing the ΔΨm, upregulating the expression of the caspase-9 (initiator caspase) gene, and activating caspase-9 protein.

8 Protective Effect of Chinese Jujube Vinegar on Alcohol-induced Liver Damage in Mice

XIANG Jin-le , LI Chen-lu , GUO Shuai , LIANG Hua , LUO Lei

2015, 31(10):40-44. DOI: 10.13982/j.mfst.1673-9078.2015.10.008

[Abstract](865) [HTML](0) [PDF 648.22 K](1230)

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A mouse model of alcoholic liver injury was established by administering alcohol (50%, V/V, 10 mL/kg) to the mice for 42 days, and the protective effect of Chinese jujube vinegar on alcoholic liver injury in mice was studied. The results showed that different doses of Chinese jujube vinegar significantly reduced the activities of aspartate aminotransferase (AST) and alanine transaminase (ALT), concentrations of triglycerides (TG) and total cholesterol (TC) in the serum and lipid peroxidation (LPO) level in the liver of chronic alcohol-intoxicated mice, and the live tissue enlargement was significantly improved. Meanwhile, different doses of Chinese jujube vinegar significantly increased the glutathione (GSH) content and the activities of total superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) and protected the antioxidant system in the liver system of chronically alcohol-intoxicated mice. The results of liver histopathological examination showed that Chinese jujube vinegar may significantly alleviate chronically alcohol-induced liver injury, and the underlying mechanism is related to its inhibitory effect on LPO as well as the enhancement of liver antioxidant enzyme activities and the non-enzymatic antioxidant capacity.

9 Low-field Nuclear Magnetic Resonance Relaxation Properties and Principal Component Analysis of Gelatin-Sucrose/Sodium Chloride

HUANG Yuan-fen , WANG Xin , LIU Bao-lin

2015, 31(10):45-52. DOI: 10.13982/j.mfst.1673-9078.2015.10.009

[Abstract](1401) [HTML](0) [PDF 1.17 M](1574)

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The effects of sucrose and sodium chloride (NaCl) solutions at different concentrations on the low-field nuclear magnetic resonance (LF-NMR) relaxation properties of gelatin gel system were studied. Principal component analysis (PCA) was used to analyze the correlation of relaxation properties of gelatin gel system with gel strength. The results for the gelatin-sucrose gel system indicate that the relaxation time of bound water (T21) was prolonged, while that of free water (T22) was reduced, with increasing concentration of sucrose. Additionally, mono-component relaxation time (T2w) was shortened, while proportions of bound water (S21%) and free water (S22%) were increased and reduced, respectively. The results for gelatin-NaCl gel system show that with increase in NaCl concentration, the T21, T22, and T2w were relatively prolonged, while S21% and S22% were similarly increased and reduced, respectively. The two gel systems and their corresponding solvents could be distinctly distinguished from each other on the principal component (PC) score plot, and the gel strength of gelatin-sucrose/NaCl gel systems showed good correlation with the LF-NMR-PCA comprehensive score. The results of this study indicate that LF-NMR technique effectively reflects changes in the state of water and its corresponding proportion in gelatin-sucrose/NaCl gel systems, while also reflecting changes in gel strength. This may have applications in gelatin-based food production and processing. Key words: gelatin; low-field nuclear magnetic resonance; principal component analysis; sucrose; sodium chloride

10 Comparison of Physicochemical and Immunomodulatory Properties of Polysaccharides from Fresh and Dried Longan Pulp Products

YI Yang , SUN Jie , WANG Li-mei , ZHANG Ming-wei

2015, 31(10):53-62. DOI: 10.13982/j.mfst.1673-9078.2015.10.010

[Abstract](1021) [HTML](0) [PDF 869.84 K](1100)

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Longan is a popular fruit and is widely distributed throughout the subtropical area. The dried pulp of longan has been used in traditional Chinese medicine and is made up of polysaccharides as one of the main bioactive ingredients. The nutritional difference between fresh and dried longan pulp products was investigated using analytical methods and the physicochemical properties and immunomodulatory activity of polysaccharides were evaluated. Gas chromatography-mass spectrometry (GC-MS), ion exchange chromatography, gel filtration chromatography, viscometry, ultraviolet (UV) spectroscopy, and infrared (IR) spectroscopy were performed. The results showed that the longan polysaccharides from fresh and dried fruits (i.e., LPF and LPD, respectively) were polysaccharide-protein complexes, but significant differences were found in their binding protein contents, neutral/acid polysaccharide ratios, monosaccharide compositions, molecular weight distributions, and intrinsic viscosities. Cellular in vitro tests confirmed LPD strongly stimulated lymphocyte proliferation and macrophage phagocytosis compared to LPF in the dose range of 50~400 μg/mL. Both polysaccharides significantly stimulated ConA-induced lymphocyte proliferation and nitric oxide production from macrophages (P < 0.05), but had a weak effect on lipopolysaccharide (LPS)-induced lymphocyte proliferation. The drying process of longan pulp may enhance the in vitro immunomodulatory activity of water-soluble polysaccharides by changing their physicochemical characteristics.

11 Structure and Antioxidant Activity of HAP-I in Russula vinosa

HE Ting , YAN Sheng-fan , CHEN Jian

2015, 31(10):63-68. DOI: 10.13982/j.mfst.1673-9078.2015.10.011

[Abstract](829) [HTML](0) [PDF 1.05 M](1091)

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A purified single polysaccharide (HAP-I) that was isolated from the fruit bodies of Russula vinosa was used as the study object, and its molecular weight distribution and purity were determined based on the separation results from gel permeation chromatography (GPC) with dextran-based Sephadex G-100. The chemical structure of the HAP-I molecule was studied by Fourier transform infrared spectroscopy (FT-IR), gas chromatography (GC), periodate oxidation, Smith degradation, and nuclear magnetic resonance (NMR). The antioxidant activity of HAP-I was evaluated by measuring its reducing power and in vitro scavenging activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion (O2-), and hydroxyl (OH) free radicals. The results revealed that the weight-average relative molecular mass (MW) of HAP-I was 16,861; FT-IR spectra indicated the presence of characteristic absorption peaks of polysaccharides and an amino-group-containing β-D-glucose ring structure in HAP-I. GC results showed that HAP-I contained four monosaccharides, rhamnose (Rha), mannose (Man), glucose (Glu), and galactose (Gal), with a molar ratio of 1:8.29:7.45:18.13. The results from periodate oxidation and Smith degradation revealed that HAP-I had a D-glucopyranose ring containing mannosidase, including α- and β-configurations; the branches of HAP-I were composed of 66.7% (1→3) glycosidic linkages, 22.24% (1→6) and (1→) sugar residues, and 11.06% (1→2) sugar residues (without (1→4) glycosidic linkage). NMR results showed that HAP-I contained galactosyl pyranose with both α- and β-configurations. The in vitro antioxidant activity test suggested that HAP-I had strong scavenging activities on DPPH, O2-, and OH radicals, as well as strong reducing power.

12 Patterns of Protein Degradation and Peptide Formation during Sourdough Fermentation

WANG Jin-shui , YANG Sen , JIA Feng , ZHOU Xiao-pei , FENG Jing-li

2015, 31(10):69-73. DOI: 10.13982/j.mfst.1673-9078.2015.10.012

[Abstract](940) [HTML](0) [PDF 602.70 K](1223)

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Sourdough, yeast-fermented dough, and Lactobacillus-fermented dough were prepared with wheat flour, yeast, and Lactobacillus plantarum M616 and the protein degradation and the peptide formation patterns were studied via by SDS-PAGE, the changes in protein content were analyzed by Bradford method, and the formed peptide content was measured using HPLC. The results showed that yeast had almost no effect on the degradation of proteins in the dough. Lactobacillus plantarum M616 played a relatively important role in protein degraded during fermentation, demonstrated by the gradual decrease in the content of proteins during fermentation, which was the most obvious at 4~10 h. Additionally, the degradation of soluble proteins and of those with medium molecular weight was the most obvious. The content of gliadins increased first and then decreased at 0-10 h. The analysis of the content of peptides before and after fermentation indicted that L. plantarum M616 could promote the formation and accumulation of peptides in the dough.

13 Aerobic Plate Count and Bacterial Diversity on the Surface of Eggshells

CHEN Li-li , YANG Yi-lei , QING Wen-zhe , LIU Yan , LOU Ai-hua

2015, 31(10):74-79. DOI: 10.13982/j.mfst.1673-9078.2015.10.013

[Abstract](1032) [HTML](0) [PDF 737.03 K](1445)

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The aerobic plate count (APC) and the bacterial population structure and diversity on the eggshell surface were studied on the basis of GB 4789.2-2010 and 16SrDNA sequence analysis using the Illumina Miseq Platform. The results showed that the APC values of eight samples ranged from 3.79 ± 0.67 to 5.06 ± 0.75 log CFU/eggshell ± SD. The 163214 sequences of the eight samples belonged to Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, Fusobacteria and Cyanobacteria, among which Enterococcus, Bacillus, Escherichia-Shigella, Pantoea, and Pseudomonas were dominant in eight samples. In each sample, Pseudomonas, Escherichia-Shigella, Acinetobacter, Bacillus, Stenotrophomonas, and Enterococcus showed the highest relative abundance, which were 67.89%, 36.15%, 68.08%, 40.12%, 21.59%, and 26.98%, respectively. The experimental results demonstrated that there were several bacteria and large bacterial populations present on the eggshell surface, and there were abundance differences for the given bacteria among different egg samples. Egg spoilage may be related to the presence of these bacteria on the eggshell surface and this aspect needs to be studied further.

14 Effect of the Aggregation State of Wheat Gluten on the Degree of Deamidation as a Function of Concentration

LIAO Lan , HAN Xue-yue , LI Zhang-fa , ZHAO Mou-ming

2015, 31(10):80-85. DOI: 10.13982/j.mfst.1673-9078.2015.10.014

[Abstract](1141) [HTML](0) [PDF 884.14 K](1129)

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Abstract A series of diluted and concentrated wheat gluten solutions were used in this experiment to carry out deamidation under moist heat. During the moist-heat-induced denaturation, the effect of molecular structure and aggregation state of wheat gluten on the degree of deamidation was analyzed. The results showed that the degree of deamidation, degree of hydrolysis, and zeta potential significantly decreased with increasing aggregation of native wheat gluten. Additionally, both degree of deamidation and hydrolysis had a good linear relationship with the changes in the aggregation state of wheat gluten. The intermolecular force of wheat gluten significantly increased with increasing aggregation of native wheat gluten, and the red shift became smaller. The intermolecular noncovalent bonds, including hydrogen bonding and hydrophobic interaction, were the main molecular forces for the aggregated wheat gluten; disulfide bonds had a minimal effect. These results demonstrated that the aggregation state of native wheat gluten is closely related to the rate of wheat gluten deamidation via moist heat treatment using food-grade organic acid. The aggregation state of native wheat gluten is the most important factor for the unfolding degree of protein molecules and aggregation trends of wheat gluten.

15 Study of the Separation, Purification, and Anti-tumor Activities of Peptides Prepared from Enzymolyzed Cuora trifasciata Meat

HE Sheng-jie , MAO Xin-Liang , ZHANG Xue-wu

2015, 31(10):86-90. DOI: 10.13982/j.mfst.1673-9078.2015.10.015

[Abstract](990) [HTML](0) [PDF 778.01 K](1287)

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Here, minced Cuora trifasciata meat was used as a raw material from which peptides with anti-tumor activities were prepared by controlled enzymolysis. Alcalase, papain, trypsin, and protamex were used to carry out the hydrolysis of minced Cuora trifasciata meat, and 12 different molecular weight hydrolyzates were obtained after ultrafiltration. A 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay showed that hydrolyzate E, produced from tryptic digestion with a molecular weight of <3000 u, exhibited the best anti-tumor effect. When the concentration was 1 mg/mL, the anti-proliferation rates of hydrolyzate E against human liver cancer cells (HepG-2) and human breast cancer cells (MCF-7) were 92.95% and 67.08%, rpesectively. Hydrolyzate E was further purified by Sephadex G-15 gel filtration, and two polypeptide fractions (E1 and E2) with strong activity were selected based on an MTT assay. E1 had a stronger anti-proliferative effect on HepG-2 cells (IC50 = 77.29 μg/mL) than the positive control 5-fluorouracil (IC50 = 136.27 μg/mL), while E2 had a stronger anti-proliferative effect on MCF-7 cells (IC50 = 214.17 μg/mL) than the positive control 5-fluorouracil (IC50 = 245.82 μg/mL). In this study, peptides with anti-tumor activity were isolated from Cuora trifasciata for the first time, which will have important implications in the development of anti-tumor drugs and health products using Cuora trifasciata as the raw material.

16 Removal Effect of Cadmium from Mussel (Mytilus edulis) Using a Protein Hydrolyate-Fe2+ Complex

ZHANG Bin , WANG Xiao-ling , SHI Zhou-rong , DENG Shang-gui , DING Qiu-ying

2015, 31(10):91-96. DOI: 10.13982/j.mfst.1673-9078.2015.10.016

[Abstract](1425) [HTML](0) [PDF 587.23 K](1245)

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In order to determine an efficient method for the removal of residual cadmium (Cd) from mussel (Mytilus edulis) tissues, mussels were temporarily raised in seawater containing Trichiurus haumela protein hydrolysate-Fe2+ complex (TPH-Fe2+), and the changes in the Cd content of different tissues and organs were measured. The results indicated that the amounts of accumulated Cd in different mussel organs were in the following order: visceral mass > gill > posterior adductor muscle > mantle > anterior adductor muscle; no obvious change of the Cd content in mussel (Mytilus edulis) tissues was observed (P > 0.05) during the 10-day natural depuration period. After the ten-day treatment with 10 mg/L of TPH-Fe2+, there were no significant changes in the Cd concentrations in the visceral mass and gill of mussel. After a four-day treatment with 15~25 mg/L of TPH-Fe2+, the Cd content in the visceral mass, gill, posterior adductor muscle, mantle, and anterior adductor muscle decreased to various degrees (P < 0.05). After a ten-day treatment with 20 mg/L of TPH-Fe2+, The highest removal rates were 41.00%, 37.43%, 29.81%, and 29.01% for gill, visceral mass, mantle, posterior/anterior adductor muscle, respectively. Similar results were observed after a ten-day treatment with 25 mg/L of TPH-Fe2+ (P > 0.05). The results indicated that TPH-Fe2+ can effectively remove residual Cd in mussels and can be used as an aquaculture feed additive for bivalve mollusks.

17 Effects of Peanut Protein Concentrate on Heat-induced Gel Properties of Chicken Breast Muscle Salt-soluble Proteins

FENG Ting , SUN Jing-xin , WU Zhen , XU Xing-lian , WANG Shu-ling , LI Peng , XIA Meng

2015, 31(10):97-102. DOI: 10.13982/j.mfst.1673-9078.2015.10.017

[Abstract](913) [HTML](0) [PDF 998.67 K](1053)

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The effects of alcohol-leached peanut protein concentrate on heat-induced gel properties of chicken breast muscle salt-soluble proteins were examined. With the addition of alcohol-leached peanut protein concentrate, the texture properties, dynamic rheological properties, and thermal properties of the heat-induced gel of chicken breast muscle salt-soluble proteins were determined, and its microstructure was observed by scanning electron microscopy (SEM). The results showed that after adding alcohol-leached peanut protein concentrate, the heat-induced gel properties of chicken breast muscle salt-soluble proteins were improved. When the amount of alcohol-leached peanut protein concentrate was 2.5%, the maximum gel hardness and strength were reached, and they were 52.5 g and 93.02 g × cm, respectively. The storage modulus G’ was increased significantly (P < 0.05), and loss tangent value (tanδ) was decreased significantly (P < 0.05). Transition temperatures (Tmax) and enthalpy of denaturation (ΔH) of heat-induced gel were increased significantly (P < 0.05). With the addition of 3.5% alcohol-leached peanut protein concentrate, three transition temperatures (Tmax1, Tmax2, and Tmax3) and ΔH of heat-induced gel were maximally increased, and the maximum values were 54.02 ℃, 65.02 ℃, 76.52 ℃, and 0.694 J/g, respectively. Three-dimensional network microstructure of heat-induced gel with the addition of alcohol-leached peanut protein concentrate was even more compact and orderly, and the crosslinking degree between proteins became higher. Therefore, alcohol-leached peanut protein concentrate can effectively improve hardness, strength, elasticity, thermal stability, microstructure and other heat-induced gel properties of chicken breast muscle salt-soluble proteins.

18 Changes of ATP-Related Compounds Contents and Its Degradation Pathways in Shrimps during Chilled Storage

QIU Wei-qiang , XIE Jing , CHEN Shun-sheng , QU Ying-hong , SONG Xue , WANG Dan-ni

2015, 31(10):103-108. DOI: 10.13982/j.mfst.1673-9078.2015.10.018

[Abstract](1058) [HTML](0) [PDF 856.83 K](1360)

Abstract:
The changes of ATP-related compounds and ATP degradation pathways in Penaeus monodon and Macrobrachuim rosenbergii meat were studied during chilled storage at (4±1) ℃. Hyperchloric acid was used to precipitate proteins, 9 ATP related compounds were analysed by high performance liquid chromatography (HPLC). Results showed that all 9 ATP related compounds were completely separated within 25 minutes. Good linearity was observed in the concentration ranging from 1~250 μg/mL. Limit of detection was between 0.02~0.10 μg/mL and spike recoveries were between 72.5%~110%. This method is reliable and accurate for the analysis of ATP-related compounds in shrimp meat samples. ATP and ADP content decreased dramatically on day 1 during chilled storage. AMP, IMP and HxR all increased first then decreased latter. Hx、AdR、Xt increased linearly during storage time, Ad was not detected. The total content of 9 ATP-related compounds in the two shrimps didn’t change. The degradation pathways of ATP in the two shrimps during chilled storage were proposed as ATP→ADP→AMP→IMP→HxR→Hx→Xt (major, more than 99%) and ATP→ADP→AMP→AdR→HxR→Hx→Xt (minor, less than1%). IMP and AMP were predominantly accumulated in P. monodon, while IMP was predominantly accumulated in M. rosenbergii.

19 L-苏氨酸是人类必需氨基酸，在医药、食品、饲料领域有广泛的应用。在L-苏氨酸发酵生产过程中,乙醛酸循环起到部分回补途径的功能。本实验利用Red重组技术，以L-苏氨酸生产菌Escherichia coli THRD 为出发菌株，构建了iclR基因缺失菌株THRD ΔiclR以及不同强度启动子替换aceBAK启动子的菌株THRD P1和THRD P2。通过实时荧光定量PCR检测表明，苹果酸合酶基因（aceB）的表达量分别是原菌的1.89倍、2.11倍以及2.96倍。摇瓶发酵结果显示，THRD ΔiclR的L-苏氨酸产量及糖酸转化率分别为42.60±1.23 g/L和32.77 g/g，较原菌THRD（35.32±1.07 g/L和27.17 g/g）分别提高20.61%和20.70%。THRD P1 L-苏氨酸产量及糖酸转化率分别为36.50±1.42 g/L和28.08 g/g，较原菌THRD（35.32±1.07 g/L和27.17 g/g）分别提高3.34%和3.39%。而THRD P2 8 h后菌体生长停滞，L-苏氨酸产量及糖酸转化率分别为8.31±1.31 g/L和20.78 g/g，较原菌THRD（35.32±1.07 g/L和27.17 g/g）分别降低了76.47%和23.52%。综上所述，适当增强乙醛酸循环有利于L-苏氨酸的积累，而过强的乙醛酸循环影响菌体的正常代谢。

ZHOU Qian , ZHENG Hui-ming , LIU Hui , XIE Xi-xian , XU Qing-yang , ZHANG Cheng-lin , CHEN Ning

2015, 31(10):109-114. DOI: 10.13982/j.mfst.1673-9078.2015.10.019

[Abstract](1197) [HTML](0) [PDF 683.16 K](1278)

Abstract:
L-threonine, an essential amino acid, is widely used in the agricultural, pharmaceutical, and cosmetic industries. In the L-threonine fermentation process, the glyoxylate cycle functions as part of the feedback pathway. In this work, Escherichia coli THRD that can produce L-threonine were used as original strains. Red reconstruction technology was used to construct a strain lacking iclR (Escherichia coli THRD ΔiclR) and THRD P1 and THRD P2, in which aceBAK promoter in E. coli THRD was replaced by promoters of various strength.. Fluorescent quantitative real-time PCR analysis showed that the expression of the aceB gene in the different strains was upregulated by 1.89-, 2.11-, and 2.96-fold, respectively, compared with the original strain. The results from fermentation in shaken flasks showed that the L-threonine and sugar-acid conversion rate of E. coli THRD ΔiclR were 42.60±1.23 g/L and 32.77 g/g, respectively, which were 20.61% and 20.7% higher than those of the control strain THRD (35.32±1.07 g/L and 27.17 g/g). The L-threonine and sugar-acid conversion rate of E. coli THRD P1 were 36.50±1.42 g/L and 28.08 g/g, which increased by 3.34% and 3.39% from those obtained from the control strain, respectively. However, E. coli THRD P2 stopped growing after 8 h and resulted in L-threonine production of 8.31±1.31 g/L and a sugar-acid conversion rate of 20.78 g/, which were 76.47% and 23.52%, respectively, lower than those of the control strain THRD. In conclusion, moderate enhancement of the glyoxylate cycle benefited L-threonine accumulation, while excessive enhancement of glyoxylate cycle had a negative effect on the normal cell metabolism.

20 Isolation and Characteristics of Histamine-producing Bacteria from Pickled Wax Gourd in East Zhejiang

XU Sai-nan , WU Zu-fang , ZHANG Xin , WENG Pei-fang

2015, 31(10):115-121. DOI: 10.13982/j.mfst.1673-9078.2015.10.020

[Abstract](1013) [HTML](0) [PDF 841.82 K](1081)

Abstract:
Selective culture and high-performance liquid chromatography (HPLC) screening were performed to study histamine production by bacteria in the traditional fermentation system of pickled wax gourd from Eastern Zhejiang. Histamine-producing strains were identified by 16S ribosomal DNA (rDNA), and histamine production capacity of each strain was determined. Additionally, the effects of temperature, pH, and salinity on bacterial growth and histamine production were investigated. The results showed that all five strains obtained from the early- and mid-fermentation stages belonged to two species, designated as M1 and M3, from the genus Enterobacter and showed close genetic relationships with E. aerogenes and E. xiangfangensis, respectively. The optimum growth temperature and pH for the two strains were 30 ℃and 7, respectively. The growth of the strains was stable at salinity below 5%. In the histamine fermentation medium, pH 4 was found to be optimum for histamine production by both strains. In the temperature range (20 ℃~35 ℃) suitable for bacterial growth, the optimum temperature for histamine production was 35 ℃. The yield of histamine decreased with increasing salinity. Under optimal conditions, values for maximum bacterial growth shown by M1 and M3 were 11.65 and 14.30 log CFU/mL, while values for maximum histamine production were 35.66 and 39.54 mg/L, respectively. Thus, these results provide a reference for processing and quality control of pickled wax gourd from Eastern Zhejiang.

21 Antioxidant Activity of Whole Wheat Flour during in Vitro Simulated Digestion

WANG Hui-Qing , LIU Dong , SUN Hai-yan , MING Jian

2015, 31(10):122-128. DOI: 10.13982/j.mfst.1673-9078.2015.10.021

[Abstract](789) [HTML](0) [PDF 1.15 M](1045)

Abstract:
The polyphenol and flavonoid content as well as antioxidant activity were determined during in vitro simulated digestion of three wheat varieties (AK58, xinong979, yangmai16). The results showed that enzymes had a significant effect on the release of polyphenols during the simulated digestion. The maximum release amount was 3.04~3.14 times that of 0~h stomach digestion, while the maximum release of intestinal digestion was 5.24~5.94 times that of 0~h stomach digestion and 1.77~1.94 times 0~h intestinal digestion. Stomach acid and enzymes had significant effects on the release of flavonoids. The maximum release during stomach digestion was 1.72~1.94 times of 0 h stomach digestion, while the maximum release during intestinal digestion was 2.34~3.14 times of 0 h stomach digestion and 1.57~1.71 times of 0 h intestinal digestion. The oxygen radical absorbance capacity (ORAC) of the wheat flour significantly increased during the digestion. The strongest ORAC during stomach digestion was 2.14~3.92 times that of 0 h stomach digestion, while that of intestinal digestion was 7.19~10.18 times that of 0 h stomach digestion and was 2.72~3.24 times that of 0 h intestinal digestion. In addition, there was a significant positive correlation between the antioxidant activity and the release of polyphenols (rs=0.90-0.99，p<0.01).

22 Structure and Thermal Properties of Glutelin from Euryale ferox Seeds

LI Wei , MAO Jian , QI Bin

2015, 31(10):129-133. DOI: 10.13982/j.mfst.1673-9078.2015.10.022

[Abstract](963) [HTML](0) [PDF 632.29 K](1120)

Abstract:
The Osborne procedure was used to extract glutelin from Euryale ferox, and the subunit molecular weight, thermal properties, and secondary structures of glutelin were preliminarily studied using reducing and non-reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FT-IR), respectively. The results showed that E. ferox glutelin mainly contained six subunits, and most of the high-molecular-weight polypeptide chains were connected through intermolecular or intramolecular disulfide bonds. The highest denaturation enthalpy(ΔH) and temperature (Td) of E. ferox glutelin were observed at the isoelectric pH (pH 5.0), while the lowest ΔH and Td were observed at an alkaline pH (pH 9.0). The progressive increase in the Td of E. ferox glutelin and no pronounced changes in the ΔH were observed with increasing salt concentrations, suggesting salt-induced formation of of a conformation with higher thermal stability for E. ferox glutelin. FTIR analysis indicated that the main structure of E. ferox glutelin was ordered, and the proportion of β-sheet (31.16%) was the highest in the secondary structures. The present results indicate that E. ferox glutelin has numerous disulfide bonds, good thermal stability, and a stable structure. These results provide a theoretical basis for future studies of the functional characteristics and application of E. ferox glutelin.

23 Effect of Red Rice Polyphenol on in Vitro Carbohydrate Digestion and Adsorption

HU Bai , ZHANG Yu , ZHANG Hui , WANG Li , QIAN Hai-feng , QI Xi-guang

2015, 31(10):134-139. DOI: 10.13982/j.mfst.1673-9078.2015.10.023

[Abstract](912) [HTML](0) [PDF 842.48 K](1089)

Abstract:
The extraction of polyphenols from red rice bran was investigated and the purification conditions of red rice polyphenols were established by selecting macroporous resin and eluent concentration. Additionally, the major components of red rice polyphenols were identified, and the effect of red rice polyphenol on the related digestive enzyme activities and glucose adsorption during in vitro small intestinal digestionas well as adsorption of carbohydrate was evaluated. The results showed that the adsorption and desorption rates of red rice polyphenol were relatively high when using macroporous resin HPD400A, and the desorption rate of red rice polyphenol could reach 0.97 with ethanol at a concentration of 70%. The main contents of red rice polyphenol are proanthocyanidins. Red rice polyphenol could inhibit the activities of α-amylases, α-glucosidase, maltase, and sucrase, with 50% inhibitory concentration (IC50) values of 3.61 μg/mL, 2.81 mg/mL, 5.48 mg/mL, and 6.55 mg/mL, respectively. Furthermore, the higher the concentration of red rice polyphenols was, the stronger the inhibitory effect became. Additionally, red rice polyphenols could inhibit in vitro intestinal glucose uptake; the higher the concentration of red rice polyphenols was, the stronger the inhibitory effect became. At the concentration of 2.01 mg/mL, the inhibition rate of red rice polyphenols against glucose uptake was 72.32%.

24 In Vitro Antioxidative and Anti-aging Effects of Agrocybe aegerita Polysaccharide Yogurt

LI Guang-fu , CHEN Wei , FAN Lu-ping , QI Hui-ying , LI Guang-fu , CHEN Wei , FAN Lu-ping , QI Hui-ying , LI Guang-fu , CHEN Wei , FAN Lu-ping , QI Hui-ying , LI Guang-fu , CHEN Wei , FAN Lu-ping , QI Hui-ying

2015, 31(10):140-145. DOI: 10.13982/j.mfst.1673-9078.2015.10.024

[Abstract](1045) [HTML](0) [PDF 672.44 K](1282)

Abstract:
The in vitro antioxidant activities and anti-aging effects of probiotic yogurt incorporated with Agrocybe aegerita polysaccharides in D-galactose-induced aging mouse model were determined to provide a basis for the anti-aging mechanism of A. aegerita polysaccharide yogurt. The results showed that the A. aegerita polysaccharide yogurt could effectively remove hydroxyl free radicals, 1,1 -Diphenyl- 2-picrylhydrazyl radical 2,2- Diphenyl -1- (2,4,6-trinitrophenyl) hydrazyl (DPPH) and 2,2′- azino-bis (3- ethylbenzo- thiazoline-6 -sulfonic acid diammonium salt (ABTS) free radicals, and their scavenging capabilities were positively correlated with the amount of added polysaccharides within a certain concentration range. A. aegerita polysaccharide probiotic yogurt also significantly increased the activities of SOD, CAT, and GSH-PX and reduced MDA content in the aging mouse model in different tissues and serum (P < 0.05), and the high-dose group (1200 mg/kg/d) had the strongest effect. Compared with the aging model group and the yogurt group, the SOD activity of high dose group in the serum, liver, and brain tissues increased by 55.87%, 79.09%, and 58.08%, and 27.48%, 15.52%, and 22.36%, respectively. The serum and liver GSH-PX activity increased by 60.86% and 41.37%, and 21.07% and 21.63%, respectively. The MDA content in the serum, liver, and brain tissues decreased by 78.75%, 65.48%, and 44.93%, and 65.48%, 46.23% and 31.77%, respectively. The CAT activity in the brain and the liver increased by 76.51% and 57.21%, and 50.15% and 33.66%, respectively. Conclusion: A. aegerita polysaccharide yogurt possesses the synergistic in vitro antioxidative capacity via scavenging free radicals and anti-aging function in mice consuming A. aegerita polysaccharides and probiotic yogurt.

25 Screening of Protease Production in Non-Saccharomyces Yeasts and Study of Its Enzymology Characteristics

XU Ya-nan , SHI Xue-wei , TONG Jun-mao , TAN Si-wei , AN Yang-yang , XIAO-jing

2015, 31(10):146-150. DOI: 10.13982/j.mfst.1673-9078.2015.10.025

[Abstract](914) [HTML](0) [PDF 624.98 K](1222)

Abstract:
Non-Saccharomyces dominated in the early stages of fermentation on the natural fermentation process. Proteins are present in varying quantities in the grape and, along with polysaccharides, are responsible for increasing must and wine turbidity. Although these proteins can be eliminated with bentonite, this nonspecific process also leads to loss of aromas and compounds that influence flavor. Protease treatment, on the other hand, specifically hydrolyzes proteins and improves the clarity and stability of the wine. The smaller, more soluble peptides and amino acids generated by this enzymatic hydrolysis are also nitrogen-containing compounds. The aim of the present work was to determine the ability of non-Saccharomyces from Cabernet Sauvignonn variety to produce proteases. A strain with good capacity of producing proteases was isolated from must. After ultraviolet-microwave compound mutation, the enzyme activity increased 1.47 times. It was identified by morphology and ITS sequence analysis. The strain was indentified as Hanseniaspora uvarum and named H.uvarum XYN162. Thereafter, the proteases produced went through enzymatic evaluation, the results showed that the optimum pH was 8.0 and the proteases activity remained more than 90% in pH 7.0-8.0; the optimum temperature was 37 ℃ and stable at 35 ℃ by the analysis of thermal stability. Moreover, metal ions has a great influence on the activity, the proteases can be activated by Fe2+ and Ca2+ and inhibited by Mg2+ and Cu2+. These results showed the strain with the potential of producing proteases possesses tremendous development value.

26 Synergistic Effect of Konjac Oligosaccharides/Isomalto-oligosaccharide Complex on the Growth of Lactobacillus acidophilus

WANG Ling , TAN Sha-sha , SONG Rong , LI Bin

2015, 31(10):151-155. DOI: 10.13982/j.mfst.1673-9078.2015.10.026

[Abstract](828) [HTML](0) [PDF 697.39 K](1085)

Abstract:
Konjac oligosaccharides (KOS), a new food raw material, can promote probiotics proliferation, but its commercial application is restricted by its high cost. The present study aimed to prepare a complex of KOS and low-cost isomalto-oligosaccharide (IMO) to examine the synergistic effect of the complex on the growth of Lactobacillus acidophilus. Different concentrations and molecular weights of KOS and IMO as well as different ratios of KOS/IMO complexes were used as carbon sources to conduct the in vitro culture experiments of L. acidophilus. The effect on the L. acidophilus proliferation was evaluated by measuring the optical density (OD) value, the total number of colonies, and pH value. The results showed that the proliferative effect of low-molecular-weight KOS was better than those of medium- and high-molecular-weight KOS, and the optimum amounts of KOS and IMO addition were 2%. Compared with the addition of single oligosaccharides, addition of the KOS/IMO complex at a ratio of 1:1 enhanced the proliferation of L. acidophilus and reduced the acidity of the fermentation broth. Therefore, the KOS/IMO complex can effectively reduce the production cost, enhance the proliferation of L. acidophilus, and is more suitable for food production.

27 16S Ribosomal DNA-based Analysis of Bacteria in Shrimp Sauce: Effect of Fermentation Temperature on Protease System and Product Quality

HU Xiao-xi , DUAN Shan , WANG Xiang-jun , LIAO Guang-qiang , WU Yong-he , KUANG Hao-bin , YANG Liu

2015, 31(10):156-162. DOI: 10.13982/j.mfst.1673-9078.2015.10.027

[Abstract](1096) [HTML](0) [PDF 929.62 K](1351)

Abstract:
Changes in the bacterial flora and the protease system in shrimp sauce at different fermentation temperatures were analyzed using 16S ribosomal DNA (rDNA) high-throughput sequencing and zymography methods, respectively. The role of bacteria in the fermentation of shrimp sauce was examined by measuring various quality indicators. The results showed that the bacteria count were significantly higher than that of fungi, indicating the important contribution of bacteria to the fermentation of shrimp sauce. The bacterial flora in shrimp sauce was very complex and showed significant differences at different temperatures. The bacterial flora and protease system underwent dynamic changes during fermentation. At 25 ℃ and 35 ℃, fewer proteases were deactivated and a large number of flavor-forming bacteria were detected, including Tetragenococcus and Virgibacillus. However, at 45 ℃, severe protease inactivation was observed and the detected bacteria were not related to flavor formation. Additionally, sensory evaluation showed the lowest values in these groups. Therefore, 45 ℃ is not a suitable temperature for the fermentation of shrimp sauce. The contents of amino nitrogen, saltless soluble solids, and total volatile base nitrogen (TVN-N) and trimethylamine (TMA) reached the maximum values after 30 days of fermentation, and then generally remained constant. However, there were significant changes in the bacterial flora; one novel protease was detected, and the flavor of shrimp sauce continued to improve.

28 Synthesis and Structural Characterization of Rhodinol-β-D-glucosidically bound Flavor Precursors linkage

LEI Sheng , YANG Xi-hong , XIE Wan-cui , ZHANG Ling , CHENG Dong-wei , LIU Xiao-min , ZHANG Tian-dong , GAO Qian

2015, 31(10):163-167. DOI: 10.13982/j.mfst.1673-9078.2015.10.028

[Abstract](926) [HTML](0) [PDF 858.18 K](1269)

Abstract:
To determine a method for improving the aroma quality and strengthening the undertone, and to explore the possibility of using glycosidic flavor precursors as raw materials in thermo-flavoring, a natural identical flavor precursor in monoterpenol glycosidically bound form was synthesized and the corresponding properties were studied. For stereoselective synthesis, rhodinol with typical pure-sweet and floral notes was chosen as the main raw material to carry out the glycosylation reaction with tetra-O-acetate-α-D-glucopyranosyl bromide. Rhodinol-β-D-glucoside pentaacetate was obtained by using the modified Koenigs-Knorr reaction, and the deacetylation reaction in alkaline conditions was conducted to yield a flavor precursor with a rhodinol-β-D-glucosidic linkage. The target product was obtained after the crude products were separated and purified by preparative liquid chromatography, and its natural identical structure was confirmed by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H-NMR), and liquid chromatography–mass spectrometry (LC-MS). Finally, the content was determined to be 99.46% by reverse phase high performance liquid chromatography (RP-HPLC). The results provide important data for the stereoselective synthesis of flavor precursors with a monoterpenol-β -D-glucopyranosidic linkage as well as a method to prepare flavoring raw materials for the study of properties of glycosidic flavor precursors and their application in high-temperature-resistant foods.

29 Factors Affecting Horizontal Deflection Angle during Automatic Orientation of Blunt and Tapered Ends of Ovoid Objects

JIANG Song , YAO Jun , XU Bin , CHEN Shu-lai

2015, 31(10):168-173. DOI: 10.13982/j.mfst.1673-9078.2015.10.029

[Abstract](1021) [HTML](0) [PDF 749.70 K](1289)

Abstract:
In order to explore the main factors affecting the horizontal deflection angle of axial movement of an ovoid object, the effects of basic characteristics and device operating parameters on the horizontal deflection angle of ovoid objects (aluminum ovoid object, plastic ovoid object, chicken egg, and duck egg) were studied. The results showed that when the center distance of conveyor rollers was fixed, the horizontal deflection angle of four ovoid objects had a positive linear correlation with the diameter of conveyor rollers and the coefficient of determination was above 0.950. When the spacing of conveyor rollers was fixed, the horizontal deflection angle of four ovoid objects had a negative linear correlation with the diameter of conveyor rollers and the determination coefficient was above 0.900. The horizontal deflection angle of four ovoid objects had a negative linear correlation with the spacing of convey rollers, and the determination coefficient was above 0.900. The linear speed of conveyor roller rotation had no significant effect on the horizontal deflection angle of ovoid objects. The value of J/L had a negative linear correlation with the horizontal deflection angle of ovoid objects and the determination coefficient was 0.985. The obliquity of ovoid objects had a negative linear correlation with the horizontal deflection angle and the determination coefficient was above 0.850. The optimal operating parameters obtained from the test were as follows: the diameter of conveyor rollers: Φ40 mm; the spacing of conveyor rollers: 15-25 mm; the linear speed of the conveyor roller rotation: 50~70 mm/s.

30 Enzymatic Characteristics and Thermal Inactivation Kinetics of Lipoxygenase from Fresh Jujube

LI Jun-lan , ZHENG Xiu-fang , CHENG Ming , JIAO Yang , FENG Jiu-hai , LI Cai-xia , QI Fu-jian

2015, 31(10):174-181. DOI: 10.13982/j.mfst.1673-9078.2015.10.030

[Abstract](799) [HTML](0) [PDF 892.42 K](1439)

Abstract:
Using linoleic acid as a substrate, the enzymatic characteristics and thermal inactivation kinetics of lipoxygenase (LOX) from fresh jujube were studied by ultraviolet (UV) spectrophotometry. The effects of temperature, pH, metal ions, and complexing agents on LOX activity were investigated, and the kinetic parameters for the LOX enzymatic reaction and thermal inactivation were determined. The results showed that the maximum absorption wavelength of fresh jujube LOX was 265 nm, while the optimum temperature and pH were 40 ℃ and pH 7.0, respectively. LOX activity was relatively stable at pH 5.0~6.0. Kinetics of the enzymatic reaction followed the Michaelis-Menten equation for single-substrate enzyme-catalyzed reaction, and the values of Km and Vmax were 0.14 mmol/L and 0.26 U/min, respectively. Fresh jujube LOX showed good affinity to the substrate linoleic acid. In addition, the thermal inactivation of LOX could be described by a first-order kinetic model, and activation energy (Ea) was 105.20 KJ/mol. The enzyme activity was enhanced by 2 mmol/L Cu2+ and 10 mmol/L Cu2+, Mn2+, and Ca2+, but was inhibited by 2 mmol/L Mg2+, Zn2+, and Mn2+, as well as 10 mmol/L Mg2+ complexing agents (P < 0.05). The results provide useful reference data for the control of LOX activity during processing and storage of fresh jujube.

31 Effect of Different Packaging Methods on Microbial Growth and Physicochemical Properties of Pre-processed Roast Pork at IceTemperature Storage

REN Jing , CHENG Long , HAN Qi , ZHANG Huan , KONG Bao-hua

2015, 31(10):182-189. DOI: 10.13982/j.mfst.1673-9078.2015.10.031

[Abstract](863) [HTML](0) [PDF 1.00 M](966)

Abstract:
The purpose of this study was to determine the influence of different packaging methods on the microbial growth and physicochemical properties of uncooked, pre-processed roast pork ice-temperature storage (at -1 ℃). The results showed that the total bacterial count of tray-packed samples after 28-d storage at -1 ℃ (7.53 lg cfu/g) was significantly higher than that of vacuum-packaged samples (5.54 lg cfu/g) (P < 0.05). The dominant spoilage bacteria of the tray-packed samples were Pseudomonas and Brochothrix thermosphacta; the dominant spoilage bacteria of the vacuum-packaged samples were B. thermosphacta, Lactobacillus, and Pseudomonas. After 28 days of storage, for tray-packed samples, the a* value, pH value, thiobarbituric acid reactive substances (TBARS) value, and total volatile base nitrogen (TVB-N) value were 9.88, 6.37, 3.02 mg/kg, and 56.6 mg/100 g, respectively, and the sensory quality was unacceptable; for vacuum-packaged samples, the a* value, pH value, TBARS value, and TVB-N value were 10.87, 6.13, 1.62 mg/kg, and 43.9 mg/100 g, respectively, and sensory quality remained acceptable. The results of sodium dodecyl sulfate-polyacrylamide-gel electrophoresis (SDS-PAGE) showed that the intensity of all protein bands of vacuum-packaged samples were stronger than that of tray-packed samples and were still thick and clear by the end of storage period. The study showed that ice temperature storage coupled with vacuum packaging can effectively extend the shelf life of raw, pre-processed roast pork.

32 Effects of Phosphorylation and Calcium Cross-linking on the Gel Properties of Sea Cucumber Collagen Aggregates

PENG Zhe , HOU Hu , FENG Yan-lin , CAI Shi-xian , HUANG meng , ZHANG Zhao-hui , XUE Chang-hu , ZHAO Xue , LI Ba-fang

2015, 31(10):190-195. DOI: 10.13982/j.mfst.1673-9078.2015.10.032

[Abstract](872) [HTML](0) [PDF 619.78 K](951)

Abstract:
Phosphorylation and calcium cross-linking are important factors affecting the gel properties of sea cucumber collagen aggregates. A texture profile analysis (TPA), a stress relaxation experiment, low field nuclear magnetic resonance (LF-NMR), and Van Gieson staining were performed to investigate the textural characteristics, moisture migration, and changes in chemical bonds as well as in the characteristics of collagen fibers of phosphorylated and calcium cross-linked collagen gels. The results showed that phosphorylation with 2% sodium tripolyphosphate adversely affected the gelling properties of sea cucumber collagen aggregates. Compared with the control group, the phosphorylated collagen aggregates had lower viscosity, chewiness, η1, E1, and bound water content, and higher free water content and water activity (Aw). Calcium crosslinking (with 1% calcium chloride) after phosphorylation had a significant impact on the gelling properties of sea cucumber collagen aggregates, resulting in greater hardness, higher viscosity, and lower Aw. The degree of binding between collagen aggregates and water increased and the gelling properties were enhanced, thus leading to a more stable structure of collagen fibers. Compared with the high pressure and high temperature treatment, the combination of calcium crosslinking and phosphorylation can improve the gelling properties of sea cucumber collagen fibers, and provide a new route for the processing and performances of sea cucumbers.

33 Establishment of a Rapid Method for Differentiating Fresh and Thawed Meat Based on β-hydroxyacyl-CoA-dehydrogenase Activity

SUN Hao , NI Hui , CHEN Feng , ZHANG Su-fang , CAI Hui-nong

2015, 31(10):196-202. DOI: 10.13982/j.mfst.1673-9078.2015.10.033

[Abstract](1083) [HTML](0) [PDF 901.98 K](1083)

Abstract:
In order to differentiate fresh and thawed pork rapidly, fresh pork (fresh chilled pork and freshly slaughtered pork) and thawed pork were used as research objects, and a method based on the β-hydroxyacyl-CoA-dehydrogenase (HADH) activity value for the rapid differentiation of fresh pork and thawed pork was established and optimized. The results showed that the optimum conditions were as follows: the optimum time for analyzing HADH activity, 150 s; the optimum amount of added acetoacetyl-CoA, 10 μL; the optimum reaction volume of extracts, 22.5 μL; and the optimum reaction time of extracts, 15 min. No significant differences were found on HADH activity value between fresh chilled pork belly, rib, tenderloin, and foreleg and their corresponding freshly slaughtered pork counterparts. Significant differences were found in HADH activity value between different cuts of fresh pork (fresh chilled pork and freshly slaughtered pork) and the corresponding thawed pork counterparts. The combination of discriminant analysis and significance analysis showed that the unknown sample was fresh pork if the HADH value was lower than 186; it was thawed pork if the HADH value was higher than 250; and the sample should be re-analyzed if the value was between 186 and 250. The accuracy of test samples using this threshold was 100%. This research provides a reference for rapidly distinguishing fresh pork from thawed pork, and builds a theoretical foundation for the in-depth study of the identification of thawed pork.

34 Study on the Desalination and Ultrafiltration Treatment of Angiotensin Converting Enzyme (ACE) Inhibitory Peptides Derived from Ovalbumin and Their Physicochemical Properties

CHENG Yuan , ZHAO Ying , CHI Yu-jie , SUN Bo , WANG Jun-tong

2015, 31(10):203-209. DOI: 10.13982/j.mfst.1673-9078.2015.10.034

[Abstract](1007) [HTML](0) [PDF 814.77 K](1096)

Abstract:
The preparation of angiotensin converting enzyme (ACE) inhibitory peptides from ovalbumin, the main protein in egg whites, can provide a reference for their value-added application. The desalination of crude enzymatic hydrolysates from ovalbumin in this paper was performed by ion exchange chromatography, using the following desalting conditions: room temperature (25 ℃), sample load of 20 mL, and flow rate of 8 BV/h. Under these conditions, the desalination rate of hydrolysates, nitrogen recovery rate, and ACE inhibition rate were 83.6%, 87.71%, and 80.31%, respectively. Two ultrafiltration membranes with molecular weight cut-offs of 10 ku and 3 ku were employed to separate the desalinated hydrolysates into three fractions: >10 ku, 3~10 ku, and <3 ku. The optimal operating conditions were as follows: ultrafiltration time of 40 min, operating pressure of 1.5 bar, and temperature of 35 ℃ for 10 ku or 30 ℃ for 3 ku. All three fractions showed ACE inhibitory activity, and the highest activity was found in the <3 ku fraction. Compared to crude hydrolysates, the total and surface hydrosulfuryl contents of the <3 ku fraction were significantly decreased (p < 0.05), the surface hydrophobicity was increased (p < 0.05), and thermal stability was improved. Therefore, desalination and ultrafiltration treatments can effectively reduce the salt content of crude enzymatic hydrolysates of ovalbumin and produce a fraction with high ACE inhibitory activity.

35 Preparation, Characterization, and Application of Cross-linked Enzyme Aggregates of β-glycosidases from Bovine Liver

QIN Ye-zhi , YE Min , LI Ning , ZONG Min-hua

2015, 31(10):210-214. DOI: DOI: 10.13982/j.mfst.1673-9078.2015.10.035

[Abstract](987) [HTML](0) [PDF 856.86 K](1123)

Abstract:
β-glycosidase from bovine liver is a biocatalyst that can catalyze the synthesis of disaccharide nucleosides via regioselective glycosylation of nucleosides. In previous reports, the used biocatalysts were free enzymes, which limit the large-scale applications. As novel carrier-free immobilized enzymes, cross-linked enzyme aggregates (CLEAs) have many advantages, such as easy preparation, low cost, and high enzyme volumetric activities. CLEAs of β-glycosidase from bovine liver were prepared, their enzymatic properties and structures were studied, and their application for the synthesis of disaccharide nucleoside was explored. The optimal precipitant, cross-linking agent and cross-linking time were 70% saturated ammonium sulfate, 50% (V/V) dextran polyaldehyde, and 8 h, respectively. Under optimal conditions, the activity recovery of CLEAs reached 58%. The optimal pH, temperature, Vmax and Km of the CLEAs were 8.5, 60 ℃, 0.13 μmol/(min?mg), and 1.43 mM, respectively. Additionally, the CLEAs showed good operational stability. After they were reused for six batches, the relative yield in the CLEA-catalyzed synthesis of 5′-O-β-glucosyl-2′-deoxyuridine had decreased only by 20%. The CLEAs had an amorphous structure.

36 Effects of Light Stress on Astaxanthin Accumulation and Antioxidant Activities in Haematococcus pluvialis

JIANG Hong-xia , LEI Meng-yun , LIN Xiong-ping , KONG Xiang-hui

2015, 31(10):215-221. DOI: 10.13982/j.mfst.1673-9078.2015.10.036

[Abstract](871) [HTML](0) [PDF 914.04 K](1086)

Abstract:
The effects of light stress with different light intensities (120~270 μmol/m2?s) and photoperiods (light/dark: 0/24-24/0 h) on the astaxanthin accumulation, superoxide dismutase (SOD) and catalase (CAT) activities, total antioxidant capacity (T-AOC), and superoxide anion free radical (O2-?) scavenging ability of Haematococcus pluvialis were examined. The results showed that at green, brown, and red cell stages, a higher light intensity led to higher astaxanthin content and greater T-AOC and O2-? scavenging ability. The activities of the antioxidant enzymes (SOD and CAT) increased at the green cell stage and decreased at the red cell stage, with increasing light intensity. The highest astaxanthin content and greatest T-AOC and O2-? scavenging ability were obtained at the red cell stage, whereas the highest antioxidant enzyme activities were obtained at the brown cell stage. when H. pluvialis grew for ten days under different photoperiods and a light intensity of 270 μmol/m2?s, the astaxanthin content and T-AOC and O2-? scavenging ability increased with the extensions of the daily illumination period, whereas the activities of the antioxidant enzymes decreased after the initial increase. In summary, H. pluvialis showed the highest astaxanthin content and antioxidant capacity after continuous illumination at a light intensity of 270 μmol/m2?s for ten days. This finding provides a new reference for the production and application of astaxanthin as a natural antioxidant food additive.

37 Elimination of Mycotoxins in Semi-dried Fish Products with Electrolyzed Water Treatment

SUN Wen-shuo , JIN Meng-tong , WU Ai-bo , PAN Ying-jie , ZHAO Yong

2015, 31(10):222-226. DOI: 10.13982/j.mfst.1673-9078.2015.10.037

[Abstract](826) [HTML](0) [PDF 580.16 K](1115)

Abstract:
The effects of electrolyzed water on the elimination of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2) and ochratoxin A (OTA) standard solutions (50 μg/L) were explored in the present study. Acidic electrolyzed water solutions (AcEW-1, AcEW-2 and AcEW-3) and alkaline electrolyzed water solutions (AlEW-1, AlEW-2 and AlEW-3) were prepared via the electrolysis of sodium chloride solutions at concentrations of 1.5, 2.0, and 2.5 g/L, respectively, and their abilities to eliminate five mycotoxins from artificially contaminated semi-dried fish products (2 ± 0.5 g, 40 μg/kg) were compared. Additionally, this ability was also compared among AcEW-3, AlEW-3, and de-ionized water(DW). The results showed that alkaline electrolyzed water could effectively eliminate five mycotoxin standards with elimination rates of more than 90%. The elimination effect of AcEW-3 on the five mycotoxins was better than that of AcEW-1 and AcEW-2. There were no significant differences in the elimination effects of AlEW-1, AlEW-2, and AlEW-3 on the five mycotoxins (p > 0.05). The elimination effects of AcEW-3 and AlEW-3 on aflatoxin were significantly higher than that of DW (p < 0.05), but no significant differences were found (p > 0.05) between AcEW-3 and AlEW-3. The elimination effect of AlEW-3 on OTA was significantly higher than that of AcEW-3 and DW (p < 0.05). Therefore, alkaline electrolyzed water can be used to soak semi-dried fish products to remove the residual salts, eliminate potential mycotoxins, and reduce the occurrence of food safety issues caused by mycotoxins.

38 Effects of Defatting Coupled with Deproteinization on the Physiochemical Properties of A- and B-type Wheat Starch

WU Gui-ling , LI Wen-hao , GUO Hong-mei , GAO Jin-mei , HUANG Qian , ZHANG Guo-quan

2015, 31(10):227-233. DOI: 10.13982/j.mfst.1673-9078.2015.10.038

[Abstract](1114) [HTML](0) [PDF 1.07 M](1217)

Abstract:
Using the Yumai 49-198 variety, wheat starch was prepared by the dough-washing method, and A- and B-type wheat starches were separated by sedimentation. Subsequently, A- and B-type starch were defatted and deproteinized. The effect of lipids and particle-bound proteins on physiochemical and structural properties of A- and B-type wheat starch were studied in terms of changes in starch composition, particle structure, solubility, swelling power, pasting properties, and thermal properties before and after treatment. The results indicated that compared with untreated wheat starches, the particles of defatted and deproteinized wheat starches were smoother and had more uniform dispersion. The position and shape of birefringence were not significantly changed, but the clarity was markedly higher. The solubility and swelling degree was dramatically increased with increasing temperature. The onset temperature, peak temperature, final temperature, transparency, peak viscosity, breakdown value, and setback value were also significantly increased. However, the freeze-thaw stability and peak-time value were markedly decreased, and no significant changes were observed in gelatinization enthalpy. These results may have theoretical reference for industrial use of A- and B-type wheat starches.

39 Establishment of a Model to Predict the Shelf Life of Restructured Shrimp

CHEN Jian-lin , ZHANG Xue-jiao , WANG Xiang-hong , WANG Jie , ZHANG Ya-zhuo , SANG Ya-xin

2015, 31(10):234-240. DOI: 10.13982/j.mfst.1673-9078.2015.10.039

[Abstract](850) [HTML](0) [PDF 1013.64 K](1223)

Abstract:
The technology of processing by-products of aquatic products in China is currently lagging behind. To tackle this, we used by-products produced in the processing of Fenneropenaeus chinensis, chopped shrimp, as raw material, to produce restructured shrimp meat by using additives such as glutamine transaminase (TG) and non-meat proteins. Based on the analysis of its quality during storage (physical and chemical indexes and sensory index), we determined the key factor of the quality changes of the restructured shrimp: volatile base nitrogen (TVB-N). We further used the Arrhenius equation between TVB-N change rate constant and the storage temperature, and first-order dynamic equation between storage time and TVB-N content to establish a prediction model for the shelf life of restructured shrimp meat. The results showed that the higher the storage temperature, the faster the decrease in the quality of the recombinant shrimp and the shorter the shelf life, and the relative error was within 10% between the predicted value and the actual value of shelf life. The model can be used to predict the changes in the quality during storage and the shelf life of the restructured shrimp. This study provided a theoretical basis for the comprehensive utilization of chopped shrimp and the development and production of new prawn meat products.

40 Properties and Aggregation Characteristics of Rice Residue Proteins Obtained by Different Extraction Methods

CHEN Jia-yi , ZHONG Jun-zhen , LIU Cheng-mei

2015, 31(10):241-246. DOI: 10.13982/j.mfst.1673-9078.2015.10.040

[Abstract](792) [HTML](0) [PDF 782.95 K](1038)

Abstract:
Rice residue proteins were obtained by either alkaline extraction-acid precipitation process (alkali-extraction) or dilute alkali degreasing (purification), and the functional properties (solubility and emulsifying properties) of the resulting two types of proteins were studied. The results showed that between pH 2.0 and 11.0, the solubility and emulsifying properties showed an upward trend after an initial decline, where the alkaline-extracted protein exhibited superior solubility and emulsifying properties compared to the purified protein. To further investigate differences in their functional properties, changes in the aggregation state of the two proteins were studied by measuring surface hydrophobicity, particle size distribution, molecular weight, and surface morphology. The alkaline-extracted sample showed higher surface hydrophobicity and smaller particle size. Scanning electron microscopy showed that the surface of alkaline-extracted protein was rough with packed particles and that of purified protein was relatively smooth with cross-linked particles. The results indicated that the proteins extracted by the above two extraction methods formed different aggregation states. Compared with the purified protein, alkaline-extracted protein showed smaller aggregated particles and exposed more hydrophobic groups, thus exhibiting higher surface hydrophobicity. Therefore, the alkaline-extracted protein exhibited better solubility and emulsifying properties.

41 Effects of Different Cooking Methods on Lipid Oxidation and Volatile Compounds in Rabbit Chops

CHEN Jia-qi , ZHANG Hou-cheng , LI Miao-miao , XU Da-lun , WANG Jin-feng , ZHANG Jin-jie

2015, 31(10):247-256. DOI: 10.13982/j.mfst.1673-9078.2015.10.041

[Abstract](983) [HTML](0) [PDF 916.53 K](1176)

Abstract:
Rabbit chops were treated by four different cooking methods: shallow-frying, deep-frying, microwaving, and roasting. The lipid oxidation and volatile compound profiles of the cooked chops were compared. The lipid oxidation caused by cooking of rabbit chops was the most significant after microwaving and roasting (P < 0.05), as measured by thiobarbituric acid reactive substance assay (TBARS) to quantify malondialdehyde (MDA). The TBARS values were 1.31 mg MDA/kg sample and 1.23 mg MDA/kg sample, respectively. A total of 56 volatile compounds were detected in the cooked rabbit chops. The amounts of the volatile compounds varied in rabbit chops cooked by different methods. The roasted rabbit chops had the highest total volatile compound content. The dominant volatile compounds in fresh rabbit chops were esters, while the main volatile compound in cooked rabbit chops was aldehyde. The percentages of aldehydes in all volatile compounds after shallow-frying, deep-frying, microwaving, and roasting were 54.31%, 53.21%, 59.99% and 65.19%, respectively. The lipid oxidation index, thiobarbituric acid reactive substance value, and the total ester content showed a negative correlation, while the contents of total aldehydes, total furans, and total volatile compounds showed positive correlation. The correlation coefficient with aldehyde was 0.793. These results indicate that the lipid oxidation products were the main contents of volatile compounds in cooked rabbit chops.

42 Effect of Fermentation with Lactic Acid Bacteria on the Physicochemical Properties of Litchi Pomace

GONG Xiao-jie , YU Yuan-shan , XU Yu-juan , WU Ji-jun , XIAO Geng-sheng , ZOU Bo

2015, 31(10):257-262. DOI: 10.13982/j.mfst.1673-9078.2015.10.042

[Abstract](946) [HTML](0) [PDF 699.99 K](1118)

Abstract:
Changes in the quality parameters, including the sugar consumption, organic acid content, protein type, total phenolic content, and color, of the litchi pomace during fermentation with Lactobacillus casei were investigated, and the fermentation conditions were optimized. Additionally, under optimal fermentation conditions, fermentation characteristics and the quality of the litchi pomace following fermentation were evaluated using five other lactic acid bacteria and compared with those observed with Lactobacillus casei. Results showed that the litchi pomace was abundant in proteins and phenolics. Following the addition of sodium hydroxide (NaOH) and 3 g/L calcium carbonate to adjust the pH to 6.0 and kill bacteria, respectively, the litchi pomace was suitable for the growth of lactic acid bacteria. The viable count of six strains of lactic acid bacteria in the litchi pomace reached more than 8.0 lg CFU/mL after 24 h of fermentation at 30 ℃. During fermentation, no significant changes (P > 0.05) in color and protein type were observed, and the pH of the litchi pomace decreased rapidly along with the consumption of sugar and the production of lactic acid. After fermentation, significant differences (P < 0.05) in the glucose and fructose content, pH, total phenolic content, antioxidant activity, and other quality indicators were observed among the litchi pomaces fermented with different types of lactic acid bacteria.

43 Effects of Six Mold Strains on The Physicochemical Properties of Functional Vitamin Drinks

XU Hong , LIU Xiao-bo , GUO Wei-peng , WU Xiu-hua , LIU Ting-ting , MO Shu-ping

2015, 31(10):263-268. DOI: 10.13982/j.mfst.1673-9078.2015.10.043

[Abstract](773) [HTML](0) [PDF 779.42 K](1039)

Abstract:
Recently, since the consumption level continuously increases, functional vitamin drinks become increasingly popular as new, healthy, and safe beverages. However, due to the restrained preservative use and limitations of the sterilization process in production, these drinks are vulnerable to microbial contamination, especially from mold. To understand the common contaminating bacteria in vitamin drinks, a sample of the typical functional vitamin beverage A with market complaints was collected in this study, and six common mold strains were isolated and identified as Paecilomyces, Neosartorya hiratsukae, Penicillium, Byssochlamys nivea, Penicillium aculeatum, and Aspergillus fischerianus. In order to further investigate the hazards of six mold strains on beverage A, all strains were inoculated into beverage A, respectively, a long-term incubation was carried out at 28 ℃ for 28 days, and the main physicochemical factors of beverage A were determined regularly. These six mold strains showed significant impact on the vitamin B3 content in beverage A and could deplete this vitamin within a short period of time (14 days). Moreover, the fastest vitamin B3 depletion rate was found in the case of Penicillium, which had no effects on the pH, brix value, total acidity, and content of vitamin C and vitamin B6 in beverage A.

44 Patterns in the Formation of Biogenic Amines in Chinese Rice Wine during Primary Fermentation Process

ZHANG Wu-ji , XIA Xiao-le , ZHANG Bing , XIA Mei-fang , YANG Hai-lin , WANG Wu

2015, 31(10):269-274. DOI: 10.13982/j.mfst.1673-9078.2015.10.044

[Abstract](906) [HTML](0) [PDF 893.35 K](1169)

Abstract:
The patterns f biogenic amine formation during primary fermentation of Chinese rice wine and the factors influencing these formation patterns were analyzed. Reversed-phase high-performance liquid chromatography (RP-HPLC) was used for quantitative determination of biogenic amines. This method was accurate and reliable, showing symmetrical peak shapes, good resolution, and a rapid analysis time. The effects of dominant microbes, amino acids, acidity of fermented mash, sugar content, alcohol content, and pH value on the formation of biogenic amines were analyzed. The results showed that the degree of influence of the primary fermentation process on the formation of biogenic amine was 77.67%, with the highest increase in biogenic amine level (7.63 mg/L) occurring during the first harrowing period. The total content of biogenic amines was positively correlated with the number of lactic acid bacteria in brewing microorganisms, and the highest growth rate of lactic acid bacteria (7.13 × 106 CFU/(mL?h)) was found during the nest period. Moreover, the total content of biogenic amines was also positively correlated with the acidity of fermented mash, alcohol content, pH value, and precursor amino acids, but negatively correlated with thesugar content during primary fermentation. The pattern in biogenic amine formation during primary fermentation was analyzed in this study. These results can be used to develop a safer and more reasonable process for lowering the content of biogenic amines in Chinese rice wine.

45 Volatile Components and in Vitro Digestibility of Silkworm Pupae Protein

MEI Xin , CAI Sha , WU Hui , FAN Jin , SHI Jian-bin , GUAN Jian , CHEN Xue-ling , HE Jian-jun

2015, 31(10):275-281. DOI: 10.13982/j.mfst.1673-9078.2015.10.045

[Abstract](823) [HTML](0) [PDF 803.14 K](1211)

Abstract:
Silkworm pupae proteins were obtained by alkali extraction and acid precipitation procedure. Subsequently, the obtained protein dispersions were either oven-dried or freeze-dried to yield protein powders, and the volatile components of them were compared by gas chromatography–mass spectrometry (GC-MS). Additionally, effects of heat-treatmetent temperatures and/or durations as well as processing conditions on in vitro digestibility of silkworm pupae proteins were studied as well. The results showed that 26 and 35 volatile compounds were identified from oven-dried and freeze-dried silkworm pupae proteins, respectively. The main volatile compounds in silkworm pupae proteins were identified as aldehydes, while the foul smell was caused by low concentrations of alcohols and sulfides and in part by aldehydes. Heat treatment significantly improved the in vitro digestibility of silkworm pupae protein (p < 0.05), in the following order: irradiation (10 kGy) > boiling (100°C, 1 h) > microwave (700 w, 3 min) > boiling (100 ℃, 20 min) > dry heat (130 ℃, 1 h) > untreated. After heating for 60 min, trypsin inhibitor activity of silkworm pupae proteins was 14.52%, and the trypsin inhibition rate was decreased to 38.37%.

46 Comparison of HPLC-FLD with GC-MS in Estimation of Benzo[a]pyrene in Sesame Oil

CHENG Wei-wei , WANG Xue-de , LIU Bing-ge , LIU Guo-qin

2015, 31(10):282-286. DOI: 10.13982/j.mfst.1673-9078.2015.10.046

[Abstract](1968) [HTML](0) [PDF 576.18 K](1363)

Abstract:
The high-performance liquid chromatography-fluorescence detector (HPLC-FLD) method was optimized to determine benzo[a]pyrene (BaP) in sesame oil, and its applicability was compared with that of gas chromatography-mass spectrometry (GC-MS) with regard to methodology. Based on the Chinese standard method, GB/T 22509-2008, liquid–liquid extraction and neutral alumina column purification were used for pretreatment. Compared with GB/T 22509-2008, gradient elution was used in the HPLC-FLD method. Chromatographic conditions for GC-MS were as follows: column, HP-5MS capillary column (30 m × 0.25 mm × 0.25 μm); temperature program, gradient; injection port and transfer line temperature, 280 ℃; injection mode, pulsed splitless mode; carrier gas ?ow rate, 1.2 mL/min. The MS conditions were as follows: ionization mode, electron ionization (EI); temperature of ionization source, 230°C; quadrupole temperature, 150 ℃; with single ion monitoring (SIM) mode for quantitative analysis. The linear equations, limits of detection (LODs), recovery rates, and corresponding relative standard deviation(RSDs) for HPLC-FLD and GC-MS methods were Y = 817883X + 39074 (R2 = 0.9999) and Y = 1771.9X - 636.6 (R2 = 0.9997), 0.037 and 0.062 μg/kg, 82.40%~96.21% and 76.21%~94.19%, and 3.72%~6.64% and 5.18%~7.84%, respectively. For the same sesame oil sample, the BaP content determined by HPLC-FLD was higher than that determined by GB/T 22509-2008 and was significantly higher than that determined by GC-MS (P < 0.05). The results showed that both methods met the requirements for determination of BaP content in edible oils and fats. The HPLC-FLD method was better compared with GB/T 22509-2008 and its accuracy was greater than that of GC-MS.

47 Establishment of Methods for Rapid Identification of Natural and Artificial Shark Fins

LIN Wan-ling , YANG Shao-ling , YANG Xian-qing , LI Lai-hao , WU Yan-yan , HAO Shu-xian , HU Xiao , HUANG Hui , WEI Ya

2015, 31(10):287-294. DOI: 10.13982/j.mfst.1673-9078.2015.10.047

[Abstract](910) [HTML](0) [PDF 714.82 K](1209)

Abstract:
In order to improve the accuracy, operability, and rapidity of the identification of natural and artificial shark fins, a facile method based on responses to repeated heat and cold treatments and/or tissue structure was establised in this work.. The results of the repeated heat and cold treatments showed that the natural shark fins had obvious characteristics of repeated heat-contraction and cold-expansion, and the optimum conditions were two cycles of 5-min heat and 30-min cold treatments. To further validate the feasibility of these conditions, the data of repeated heat and cold treatments on different parts of the shark fins and different types of natural shark fins were statistically analyzed. Results showed that the data had good precision, small error, good accuracy, and followed a normal distribution, and that the mean values were representative. Additionally, the artificial shark fins had different characteristics, repeated heat-expansion and cold-contraction. The tissue morphology results showed that the natural shark fin needle was in the shape of an irregular concentric ring, and that the annular arrangements were relatively homogeneous, a unique characteristic of annual ring formation in fish. However, the artificial shark fins did not have this characteristic. Therefore, the difference of microstructure between the natural shark fins and the artificial shark fins was obvious. In general, the heat-contraction and cold-expansion method and tissue morphology analysis are rapid, easy, and accurate methods to distinguish between natural and the artificial shark fins.

48 Determination of Total Folate Content and Polyglutamate Folate Distribution in Winged Beans Using UPLC-MS/MS

DAI Jin-feng , XU Ming-fang , DUAN Han-ying , QIU Rui-xia , WANG Chao

2015, 31(10):295-300. DOI: 10.13982/j.mfst.1673-9078.2015.10.048

[Abstract](976) [HTML](0) [PDF 844.29 K](1292)

Abstract:
An ultra-high performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS) method was established to determine the total folate content and polyglutamate folate distribution in winged beans. Coarsely chopped winged beans were boiled to inactivate endogenous polyglutamate hydrolase and degrade folate-binding proteins so that the bound folate was converted to free form. After filtration, the extracted folate in various forms was converted to 5-methyl tetrahydrofolate polyglutamyl (5MTHFGlun), salt was removed using a C18 SPE cartridge, and UPLC was performed to separate the different forms of 5MTHFGlun. The content of 5MTHFGlun in different forms were determined using positive electrospray ionization (ESI+) under multiple reaction monitoring (MRM) mode. Quantitative analysis was conducted using PteGlu(1–6) as the internal standard and 5MTHFGlu(1–6) as external standards. The method showed high sensitivity, with a limit of detection of 40~1133 fmol and a limit of quantification of 120~3400 fmol. The precision of determination ranged from 0.5% to 6.8% and the average recovery was 43%. The results showed that the predominant form of polyglutamate folate in winged bean was pentaglutamyl folate (65%), followed by 5MTHF, accounting for 29.6%; other forms accounted for only 5.6%. The total folate content in fresh winged beans was 1.1 μmol/100 g, which was significantly higher than that in spinach and broccoli. This method is fast, sensitive, and accurate, and is suitable for determining total folate and polyglutamyl folate distribution in different vegetables.

49 Simultaneous Determination of Six Aflatoxins in Food by Immunoaffinity Purification-high Performance Liquid Chromatography Combined with a Large Volume Flow Cell

XU Yan-qun , LUO Zi-sheng , XU Ting-qiao , WEI Yun-xiao , LI Gang

2015, 31(10):301-306. DOI: 10.13982/j.mfst.1673-9078.2015.10.049

[Abstract](1245) [HTML](0) [PDF 655.06 K](1136)

Abstract:
A method without derivative based on immunoaffinity purification and fluorimetric detection combined with large volume flow cell was developed for simultaneous determination of six kinds of aflatoxins in food. The samples were ultrasonic-extracted with acetonitrile-aqueous solution (84:16, V/V), cleaned up by immunoaffinity column, and then were separated by XBridgeTM C18 column (150 mm×4.6 mm, 5μm). The analytes were detected by large volume flow cell fluorescence detection in a mobile phase of acetonitrile-aqueous solution (84:16, V/V) without derivatization. External standard method was used for quantitative. All analytes were successfully separated within 6 min, and one sample determination from pretreatment to result analysis was finished within 50 min. The detection limit (LOD, S/N=3) of aflatoxin B1, B2, G1, G2, M1, M2 respectively were 0.05 μg/kg, 0.02 μg/kg, 0.05 μg/kg, 0.02 μg/kg, 0.04 μg/kg, 0.03 μg/kg, meeting the national limits of aflatoxins in food. The correlation coefficient of six kinds of aflatoxins, r2, were more than 0.999, and the spiked recoveries were in the ranges of 77.6%~90.5%, and relative standard deviation (RSD, n=3) were 2.42%~6.08%. The method was simple, effective and sensitive, detecting the aflatoxins without derivatization and suitable for the simultaneous determination of six kinds of aflatoxins in food.

50 Establishment of a Polymerase Chain Reaction Denaturing Gradient Gel Electrophoresis (PCR-DGGE) Method to Analyze Bacteria from Xiaoqu of Soybean-flavor Liquor

JIANG Wen-yu , XU Xue-feng , YANG You-hui

2015, 31(10):307-312. DOI: 10.13982/j.mfst.1673-9078.2015.10.050

[Abstract](871) [HTML](0) [PDF 798.14 K](1095)

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The bacterial populations in Xiaoqu of soybean-flavor liquor were used as the study object in this paper, and the technical parameters related to DNA extraction, polymerase chain reaction (PCR) amplification, denaturing gradient gel electrophoresis (DGGE) time, and staining protoco for PCR-DGGE analysis were compared and optimized. The results revealed that among four DNA extraction methods (kit, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and SDS-CTAB), the SDS-CTAB method produced the highest DNA yield with a low protein content and good integrity. Despite the slightly complicated steps, SDS-CTAB was better than other methods. After optimization was achieved using the uniform design method, the optimal PCR conditions were as follows: annealing temperature of 50℃, primer concentration of 0.4 μmol/L, and 2.5 μL (34 ng) of template DNA. Under these optimal conditions, the clearest bands were obtained, the yield of products was the highest, and the DNA bands in the corresponding DGGE analysis exhibited the best diversity and abundance. The performance of DGGE with different run times was compared using time-travel experiments, and the results showed that when the electrophoresis was conducted for nine hours using a denaturing gradient concentration range of 30%~60% at 85 V and a temperature of 60 ℃, the DNA bands on the DGGE gel were sufficiently separated with an appropriate distribution. Additionally, it was found that silver staining was better than Goldview staining. In summary, a PCR-DGGE method to analyze the microorganisms in Xiaoqu of soybean-flavor liquor was preliminarily established.

51 Determination of Shelf Quality after Storage of Muscat Grape by Electronic Nose Combined with GS-MS

CHEN Chen , LU Xiao-xiang , ZHANG Peng , CHEN Shao-hui , LI Jiang-kuo

2015, 31(10):313-320. DOI: 10.13982/j.mfst.1673-9078.2015.10.051

[Abstract](1192) [HTML](0) [PDF 912.55 K](1187)

Abstract:
Changes in the volatile substances of Muscat grape after storage were detected using electronic nose and headspace solid phase micro-extraction/gas chromatography mass spectrometry (HS-SPME/GC–MS), and the shelf quality of grapes was evaluated to identify aroma components. After storage at 0 ℃ for 20 days, the grapes were stored on shelves at temperatures of 18~20 ℃, and 8~10 ℃, which simulated room temperature and supermarket grape sale conditions, respectively. Physicochemical, sensory, and nutritional indices within five-day shelf life were measured using the electronic nose and GC-MS. The electronic nose detection results showed that principal component analysis and linear discriminant analysis methods could effectively distinguish between samples with different shelf times. The results of GC-MS analysis with the peak area normalization method showed that the content and composition of volatile substances in Muscat grape changed during the shelf life. For the main characteristic aroma components, the content of (E)-2-hexenal, geraniol, citronellol, and nerol decreased; the contents of ethanol, hexanol, and acetic acid increased; and the total peak area decreased. The pattern of the changes was generally consistent with the results of physicochemical indices and electronic nose analysis. Therefore, electronic nose combined with GC-MS is feasible for determining the aroma quality of Muscat grape during its shelf life.

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Volume 31,Issue 10,2015 Table of Contents