Volume 31,Issue 6,2015 Table of Contents

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  • 1  Participation of Nrf2-ARE Signaling in Curcumin Inhibition of Amyloid-β-induced Cellular Oxidative Stress and Cell Apoptosis
    HUANG Han-chang LU Shu-yan CHANG Ping ZHENG Bo-wen ZHANG Lian JIANG Zhao-feng
    2015, 31(6):1-5. DOI: 10.13982/j.mfst.1673-9078.2015.6.001
    [Abstract](1128) [HTML](0) [PDF 823.81 K](1437)
    Abstract:
    This study investigated the protective effects of curcumin on cellular oxidative damage and cell apoptosis induced by amyloid-β (Aβ) in human neuroblastoma SH-SY5Y cells and discussed the role of the Nrf2-antioxidant response element (ARE) pathway in this protective effect. Cells were treated with 10 μM Aβ1-40 at 37 ℃ for 24 h with or without curcumin pre-treatment. The changes in morphology were observed under the microscope, and the MTT colorimetric assay was used to assess cell viability. Lactate dehydrogenase (LDH) in the culture medium was determined to evaluate cell membrane damage. The relative levels of H2O2 in the culture medium and intracellular reactive oxygen species (ROS) were assessed. In addition, the protein expressions of Nrf2 and HO-1 were detected by western blot analysis. Compared with the vehicle-only control group, cell bodies in the Aβ-damaged group became rounded, with fewer and shorter protuberances. Cell viability decreased, and the level of released LDH increased, while the oxidative stress level was significantly elevated. Compared with the Aβ-damaged group, curcumin treatment promoted cell growth and the protuberances became longer; cell viability increased while released LDH decreased, and the level of oxidative stress also decreased significantly. Notably, curcumin promoted Nrf2 expression and attenuated Aβ-induced up-regulation of phosphorylated Nrf2 at Ser-40 as well as HO-1 expression. Curcumin attenuated cellular oxidative damage and cell apoptosis induced by Aβ, which might be linked to the regulation of the Nrf2-ARE pathway by curcumin.
    2  The Effect of Mulberry Polyphenol Extract and Mulberry Wine Polyphenol Extract on Proliferation and Differentiation of BAT-cMyc Cells
    YOU Yi-lin SHENG Qi-ming ZHANG Qian-wen HUANG Wei-dong ZHAN Ji-cheng
    2015, 31(6):6-12. DOI: 10.13982/j.mfst.1673-9078.2015.6.002
    [Abstract](1036) [HTML](0) [PDF 793.76 K](1168)
    Abstract:
    The effects of mulberry polyphenol extract (MPE) and mulberry wine polyphenol extract (MWPE) on the proliferation and differentiation of brown adipose tissue (BAT)-cMyc cells were investigated in this study. After treatment of BAT-cMyc cells with different concentrations of MPE and MWPE for 48 hours, the cells were collected, the growth inhibition effect of MPE and MWPE on BAT-cMyc cells was determined by MTT assay, and the IC50 values were calculated. The relative expressions of genes associated with cell proliferation, such as Ki67 and proliferating cell nuclear antigen (PCNA), were detected by real-time polymerase chain reaction (PCR). BAT-cMyc cells were then treated with MPE and MWPE until the sixth day of differentiation. Cells were collected and the efficiency of adipocyte differentiation was measured by Oil Red O staining and real-time PCR. The results showed that the IC50 value of BAT-cMyc cells was 186.37 μg/mL for MPE and 158.78 μg /mL for MWPE. Furthermore, growth of BAT-cMyc cells was inhibited in a dose-dependent manner. MPE and MWPE had no effect on BAT-cMyc cell proliferation, but could significantly increase the efficiency of the differentiation of BAT-cMyc cells into adipocytes and upregulate the expression levels of brown adipocyte differentiation-related genes, such as AP2 and C/EBPδ, during brown adipogenesis.
    3  Effects of Lotus Seedpod Procyanidins on Extremely Low-frequency Electromagnetic Field-induced Reproductive Injury in Male Mice
    ZHANG Hai-hui FAN Rong CHENG Yan-xiang HE Yuan-qing DUAN Yu-qing
    2015, 31(6):13-17. DOI: 10.13982/j.mfst.1673-9078.2015.6.003
    [Abstract](984) [HTML](0) [PDF 756.85 K](1098)
    Abstract:
    The protective effects of lotus seedpod procyanidins (LSPCs) on injury to the reproductive system in male mice, induced by extremely low-frequency electromagnetic fields (ELF-EMF). A total of 50 male, ICR mice were randomly divided into five groups: control group, ELF-EMF group, and ELF-EMF+30, 60, and 90 mg/kg LSPC groups. LSPC was administered intragastrically to the mice daily for 75 consecutive days. ELF-EMF exposure was initiated 15 days after LSPC administration began and continued for 60 days. After ELF-EMF exposure, the mice were sacrificed, and their epididymis and testes were obtained to determine the weight. Parameters such as testicle to body weight ratio, sperm motility, and malformation rates, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content were measured as well as testicular pathological changes were noted. Administration of LSPCs (especially 60 and 90 mg/kg) for 75 days effectively alleviated testicular morphological damage, significantly improved testicle to body weight ratio, sperm motility, SOD activity in the testes, reduced sperm malformation rate, and testicle MDA content. The results suggest that treatment with LSPCs could significantly alleviate reproductive injury induced by ELF-EMF in male mice.
    4  Effect of Different Calcium Supplements on in vitro Acid Consumption and Gastric Acid Secretion in Rats
    YANG Ji-guo ZHANG Song YAN Xiao CHEN Shao-jie
    2015, 31(6):18-22. DOI: 10.13982/j.mfst.1673-9078.2015.6.004
    [Abstract](1184) [HTML](0) [PDF 610.97 K](1425)
    Abstract:
    Four calcium supplements including calcium citrate malate (CCM), calcium carbonate, yak bone meal, and calcium L-aspartate were administered to rats to compare their effect on gastric secretion as well as gastric acid consumption capacity in rats. The objective of this study was to identify appropriate calcium supplements for human consumption. Using a simulated gastric environment in vitro, the quantity of gastric acid consumed to quench the calcium ions released by the calcium supplements in artificial gastric juice was measured. The effects of calcium supplements on quantity, pH, and secretion of gastric juice were established using the pylorus-ligation rat model. The results showed that the hydrogen ion content increased significantly (p < 0.01) in artificial gastric juice after dissolving CCM, while it decreased significantly (p < 0.05) when the other three calcium supplements were dissolved. In vivo tests in rats showed that, as compared to the control group, the volume, acidity, and secretion of gastric acid decreased significantly (p < 0.01) in the CCM and bone meal groups, increased significantly in the calcium L-aspartate group, and did not show significant difference (p > 0.05) in the calcium carbonate group.
    5  Effect of Buckwheat on Lipid Metabolism in High-fat Diet-fed Rats
    WANG Dan GE Hong-juan ZHANG Xiao ZHANG Lan SONG Chun-mei
    2015, 31(6):23-28. DOI: 10.13982/j.mfst.1673-9078.2015.6.005
    [Abstract](1120) [HTML](0) [PDF 653.50 K](1021)
    Abstract:
    The aim of this study was to elucidate the effect of buckwheat (BW) on lipid metabolism in high-fat diet-fed rats. Fifty male rats were randomly divided into the following groups: control diet, high-fat diet (HFD), low-dose BW (1 g/kg?d), medium dose BW (5 g/kg?d), and high dose BW (10 g/kg?d). The rats were fed once a day for 30 days. Blood samples were subsequently collected from the posterior abdominal aorta, and the liver, in addition, perirenal fat, and epididymal fat were collected. The levels of total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C) in the serum and liver were measured, and pathological sections of the liver tissues were observed. The results showed that compared to the HFD group, the weight and food intake of all the BW groups were significantly lower, the weights and indexes of the liver and fat tissues were also significantly reduced, the concentration of TC, TG, and LDL-C in the serum and liver were decreased, and the concentration of HDL-C was increased. Meanwhile, the liver structure observed under the light microscope showed that hepatic steatosis in all BW groups was alleviated, with the most significant effect observed in the high-dose BW group. These results demonstrate that a BW intervention on a HFD can have a hypolipidemic effect, improve liver lipid metabolism, protect the liver, and reduce the incidence of related diseases.
    6  Research on Prokaryotic Expression of Vibrio parahaemolyticus vanM Gene and N- acyl-homoserine Lactone Identification
    WU Kui WU Qing-ping ZHANG Ju-mei XU Xiao-ke
    2015, 31(6):29-35. DOI: 10.13982/j.mfst.1673-9078.2015.6.006
    [Abstract](1166) [HTML](0) [PDF 814.57 K](1501)
    Abstract:
    The vanM sequence was amplified for V. parahaemolyticus ATCC33847 genome and inserted into pMD19-T vector for clone sequencing and sequence alignment. The correct vanM fragment was double-digested by NdeI and EcoRI and ligated into the pET22b vector for gene expression. IPTG was used to induce vanM prokaryotic expression. An acyl-HSL bio-reporter strain KYC55 was used to detect the acyl-HSL activities of ATCC33847 and Escherichia coli carrying the vanM gene. HPLC-MS assay was performed to identify vanM-associated acyl-HSL molecules in extracts from ATCC33847 and Escherichia coli. The ATCC33847 vanM sequence was aligned with that of V. anguillarum vanM, with the similarity of 57%. The expression vector pET22b-vanM was constructed and induced to produce the highest level of VanM protein by induction with 0.6mmol/L IPTG in BL21(DE3). ATCC33847 and BL21(DE3) containing pET22b-vanM presented an acyl-HSL activity, which was detected by KYC55. HPLC-MS results indicated that both 3-Hydroxybutanoyl-HSL (3-OH-C4-HSL) and 3-Hydroxydecanoyl-HSL (3-OH-C10-HSL) were detected in extracts from ATCC33847 and BL21(DE3)(pET22b-vanM). In this study, the prokaryotic expression of V. parahaemolyticus vanM confirmed that V. parahaemolyticus vanM was responsible for the synthesis of V. parahaemolyticus quorum sensing signals, 3-OH-C4-HSL and 3-OH-C10-HSL.
    7  Interaction of Gossypol and Its Oxide with Bovine Serum Albumin
    CHAI Xiu-hang BI Yan-lan PENG Dan WANG Ya
    2015, 31(6):36-43. DOI: 10.13982/j.mfst.1673-9078.2015.6.007
    [Abstract](1005) [HTML](0) [PDF 1.20 M](1241)
    Abstract:
    The interaction of gossypol and its oxide with bovine serum albumin (BSA) was investigated by fluorescence spectroscopy and ultraviolet-visible spectroscopy (UV-vis). The experimental results indicated that the quenching mechanism of BSA by gossypol and its oxide was a combined dynamic and static quenching, with a blue-shift of the emission maximum of BSA. The calculation of various binding parameters showed that the binding constants for gossypol-BSA and gossypol oxide-BSA were in the order of 105, indicating a strong interaction between gossypol/gossypol oxide and BSA. There was one binding site involved in the interaction between gossypol/gossypol oxide and BSA. The negative value of ΔH, positive value of ΔS, and negative value of ΔG indicated that hydrophobic and hydrogen-bonding interactions played major roles in the binding of gossypol or its oxide with BSA. Based on Forster-type nonradiative energy transfer, the binding distances (r) between the donor (BSA) and acceptor (gossypol or its oxide) were 2.94 nm and 3.12 nm, respectively, and they could interact with BSA by energy transfer. The UV-vis absorption spectra, synchronous fluorescence spectra, and three-dimensional fluorescence spectra showed that the binding of gossypol/gossypol oxide to BSA induced conformational changes in BSA.
    8  Effects of Meat Protein Environments on Niche-specific Genetic Expression of Lactobacillus sakei
    XU Hui-qing GAO Lu TIAN Ying JIANG Yun-sheng PENG Jin CHEN Yu
    2015, 31(6):44-49. DOI: 10.13982/j.mfst.1673-9078.2015.6.008
    [Abstract](950) [HTML](0) [PDF 939.73 K](1115)
    Abstract:
    Lactobacillus sakei is a ubiquitous heterofermentative lactic acid bacterium that is frequently used as a meat industrial starter culture. To investigate its adaptations to a meat protein environment, quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze the niche-specific genetic expression of L. sakei strain La22 when cultured in myofibrillar and sarcoplasmic protein-supplemented chemically defined media (CDM). The results showed that pH decreased with time, and that the pH value in CDM containing myofibrillar proteins was higher than that in CDM with sarcoplasmic proteins. Genetic expressions of arcA, arcB, arcC, and arcT in CDM containing myofibrillar proteins and arcR in CDM containing sarcoplasmic proteins were significantly higher compared to the control. The remaining arc operon genes were also upregulated in both culture media, but the increases were not significant. Stress response genes lsa00513, usp4, and usp2 in CDM containing myofibrillar proteins were significantly upregulated, and six genes encoding ABC transporter were significantly upregulated in both protein media. The results suggested that L. sakei had adapted to a meat protein environment by energy conversion and modulation of genetic expression.
    9  Effect of Tea Polyphenols on Grass Carp Rheological Characteristics
    LIU Ze-yu LIU Yan LUO Can ZHU Qi
    2015, 31(6):50-58. DOI: 10.13982/j.mfst.1673-9078.2015.6.009
    [Abstract](853) [HTML](0) [PDF 1.24 M](1270)
    Abstract:
    Fresh grass carp meat was treated with different concentrations of tea polyphenols (TP) and stored at 4°C. Spectrophotometry, texture analysis, rheometry, and scanning electron microscopy (SEM) was used in order to investigate changes in quality parameters such as emulsification, gelation, rheology, and ultra-microstructure during storage. The results indicated that adding more than 0.03% TP delayed the deterioration of emulsification properties and improves emulsion stability of grass carp fish protein. Adding more than 0.05% TP increases the gel strength of minced fish, lowers the storage modulus and loss modulus of fish products, eliminates free radicals produced by lipid oxidation, and delays the degradation rate of fish proteins. Within the experimental range, higher concentrations of TP resulted in greater protection of the rheological properties of fish protein, but without a dose-effect relationship. There were no significant differences between 0.05% and 0.07% TP groups. Therefore, taking into account the production cost, addition of 0.05% TP is recommended during cold storage of grass carp to preserve the quality.
    10  Correlation between Mechanical Properties of Three Freshwater Fish Skin Collagen Films and the Primary Structure of the α1Chain in Collagen
    TANG Lan-lan CHEN Shu-lin HAO Geng-xin SU Wen-jin WENG Wu-yin
    2015, 31(6):59-66. DOI: 10.13982/j.mfst.1673-9078.2015.6.010
    [Abstract](937) [HTML](0) [PDF 1004.21 K](1298)
    Abstract:
    The study aimed to investigate the correlation between mechanical properties of three freshwater fish skin collagen films and the primary structure of the collagen α1 chain (COL1A1). The results showed that the tensile strength of tilapia skin collagen films reached up to 51.24 MPa, which was higher than those of the silver carp and grass carp skin films. Moreover, the color values of tilapia skin collagen films were closer to those of a white standard plate. Significant differences were observed in the ratios of positive to negative peak (RPN) calculated from the circular dichroism (CD) spectra of the three types of fish collagen solutions, while similar RPN values were observed in the resulting collagen films. Furthermore, the silver carp COL1A1 gene sequence was cloned using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The 4923-bp full-length cDNA of silver carp COL1A1 (GenBank No. KJ848743) was obtained, which encoded 1448 amino acids. The constructed phylogenetic tree showed that the COL1A1 sequences of silver carp and grass carp clustered together, but were distant from that of tilapia. The analysis of the primary structure of COL1A1 indicated that there were more proline residues in the C-peptide and G-X-Y sequences of the triple-helical domain of tilapia COL1A1; therefore, strong collagen films could be formed using tilapia skins.
    11  Effect of Selenoarginine on the Quality of Selenium-enriched Pleurotus ostreatus Fruiting Body
    ZHU Chuan-wang LIU An-jun ZHENG Jie TENG An-guo ZHU Hong LIU Chen LI Su
    2015, 31(6):67-72. DOI: 10.13982/j.mfst.1673-9078.2015.6.011
    [Abstract](845) [HTML](0) [PDF 788.45 K](1070)
    Abstract:
    Selenoarginine was added to the cultivation material to produce selenium-enriched Pleurotus ostreatus and the effects on the quality of its fruiting body were investigated, in terms of selenium-accumulation ability, glutathione peroxidase (GSH-PX) activity, volatile compound content, protein content, and protein distribution. The results showed that selenium concentration in the fruiting bodies had a significantly positive correlation (R=0.9967) with that in the cultivation material. Within the same cultivation material, selenium concentration in the cap was higher than that in the fruiting body. A larger amount of selenium was accumulated in proteins than in the polysaccharides. However, there were no significant changes in protein content and glutathione peroxidase activity. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that selenium-enriched Pleurotus ostreatus had a simple composition of volatile compounds, with a relatively high alcohol content, than that of the non-enriched Pleurotus ostreatus. However, the relative content of 1-octen-3-ol in selenium-enriched Pleurotus ostreatus was higher than that of the non-enriched Pleurotus ostreatus. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated that selenium did not change the distribution of proteins in the fruiting bodies of Pleurotus ostreatus.
    12  Inhibitory Effects of Citral and Octanal Mixture on Penicillium digitatum
    TAO Neng-guo DUAN Xiao-fang FAN Feng HUANG Shi-rong
    2015, 31(6):73-77. DOI: 10.13982/j.mfst.1673-9078.2015.6.012
    [Abstract](931) [HTML](0) [PDF 589.36 K](1050)
    Abstract:
    The effects of citral, octanal, and citral/octanal mixture (4:1, V/V) on the mycelial growth of Penicillium digitatum were investigated by using the agar dilution method. In addition, preliminary investigation was performed on the corresponding inhibitory mechanism of citral/octanal mixture against P. digitatum. Results showed that the citral/octanal mixture significantly inhibited mycelial growth of P. digitatum, with a minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of 2.50 μL/mL for both. In contrast, the MIC and MFC of citral were 2.50 and 5.00 μL/mL, respectively, and those of octanal were 0.63 and 2.50 μL/mL, respectively. Scanning electron microscopy (SEM) showed that citral/octanal mixture treatment resulted in severe collapse and multiple folds on the hypha surface, causing irregular distortions in the structure and destroying cell integrity. Moreover, extracellular pH, extracellular conductivity, and absorbance at 260 nm significantly increased after treatment with citral/octanal (4:1, V/V). These results indicated that the citral/octanal mixture could destroy cellular integrity and increase the cell membrane permeability of P. digitatum, thereby causing leakage of cellular components, leading to the death of P. digitatum.
    13  Identification of Prodigiosin-producing Serratia marcescens HFUT1301 Strain Isolated from Mandarin Fish Intestine
    ZHANG Dan-feng YANG Pei-zhou JIANG Shao-tong
    2015, 31(6):78-83. DOI: 10.13982/j.mfst.1673-9078.2015.6.013
    [Abstract](960) [HTML](0) [PDF 826.05 K](1358)
    Abstract:
    Prodigiosin, a pigment with anti-cancer effects, is produced by Serratia marcescens. A strain producing a red pigment was screened from the intestinal canal of mandarin fish and identified on the basis of colony morphology, physiological and biochemical characteristics, and 16S rDNA analysis. The structural characteristics of the red pigment was determined using ultraviolet-visible (UV-Vis) spectrophotometry, liquid chromatography-mass spectrometry (LC-MS), and Fourier transform infrared spectroscopy (FT-IR). The results showed that it appeared round colonies on basic medium, the diameter was within 1 to 3mm, the middle of the colony was red and opaque with a slight bulge in the center, and with smooth edges, while 16S rDNA fragment (1445 bp in size) showed 99% similarity with S. marcescens. This isolated strain was designated as S. marcescens HFUT1301. The purity of the red pigment exceeded 95% after ultrasound-assisted ethanol extraction and silica gel column chromatography. In pH 3- and pH 10-methanol solutions, there were significant absorption peaks at 535 and 470 nm, respectively. LC-MS showed that the main ion peaks were 323.5486 and 324.8468. The main absorption wavenumbers for FT-IR were 3396, 2923, 2851, 1710, 1465, and 1164 cm-1. Red pigment production reached 3.22 g/L in the fermentation medium. Based on previously reported structural characteristic of prodigiosin, the red pigment produced from S. marcescens HFUT1301 was speculated to be prodigiosin.
    14  Functional Properties of Starch from Nine Mung Bean Cultivars
    ZHANG Ling-wen JI Hong-fang BAI Shi-shi YANG Ming-duo MA Han-jun JIANG Ping
    2015, 31(6):84-90. DOI: 10.13982/j.mfst.1673-9078.2015.6.014
    [Abstract](1213) [HTML](0) [PDF 658.11 K](1250)
    Abstract:
    The chemical composition, pasting properties, solubility, swelling power, and freeze-thaw stability of starch from nine mung bean cultivars was investigated. Correlation between amylose content and functional properties was also analyzed. The results showed that the amylose content of samples tested were different among cultivars, which ranged from 33.10% to 44.08%. The pasting properties of starch from different mung bean cultivars varied significantly; the peak viscosity of starch from Weilv No.4 and Zhonglv No. 1 was significantly higher than that of the other cultivars (p < 0.05), the breakdown of Anlv No. 8 was the lowest (p < 0.05), and the retrogradation of Maolvdou and Anlv No.092 were significantly lower. The solubility and swelling power of starches increased with an increase in temperature. The syneresis of starch gel was significantly higher after one freeze-thaw cycle and increased with additional cycles. Correlation analysis indicated that amylose content positively correlated with final viscosity and retrogradation (r=0.674 and r=0.725, respectively; p < 0.05), and significantly negatively correlated with swelling power (r = -0.805, p < 0.01).
    15  Correlation of Fruit Texture Development and Softening with Cell Wall Degradation and Related Gene Expression in Gala Apples
    QI Xiu-dong WEI jian-mei ZHAO Ling-li
    2015, 31(6):91-96. DOI: 10.13982/j.mfst.1673-9078.2015.6.015
    [Abstract](1137) [HTML](0) [PDF 906.72 K](1233)
    Abstract:
    Changes in cell wall composition, enzyme activity, and gene expression during development and softening of Gala apples was investigated to identify correlations. The results indicated that the content and composition of cell wall material (CWM) showed a dynamic trend during development. Covalent soluble pectin (CSP) showed the highest content among the three pectins assessed and cellulose content was always significantly higher than that of hemicellulose. Firmness correlated significantly with CSP and hemicellulose content. Additionally, changes were noted in the activity and gene expression of cell wall enzymes during this stage, showing that cell wall degradation was involved in the physiological process of fruit development. After harvest, CSP content decreased rapidly with softening, water soluble pectin (WSP) content began to increase, while cellulose and hemicellulose contents decreased, all of which, correlated significantly with firmness loss. Among the cell wall enzymes, β-galactosidase (β-Gal) activity and MdGal gene expression increased most rapidly, followed by that of α-Arabinofuranosidase (α-Af) and PG polygalacturonase (PG), while pectin methylesterase (PME) activity and MdPME increased at a later stage. Moreover, correlation with firmness and cell wall components was stronger for β-Gal and α-Af than that for PG and PME. PG activity correlated strongly with CSP and hemicellulose content, while PME activity showed the least correlation with changes in cell wall components. This indicated that cell wall metabolism had a close relationship with texture softening of ‘Gala’ apple, and both, β-Gal and α-Af may play relatively more important roles in fruit softening.
    16  Inhibitory Effect of Lemon Essential Oil on Mushroom Tyrosinase Activity in vitro
    HU Jun-jiao LI Xiang LIU Xiao-hui ZHANG Wan-ping
    2015, 31(6):97-105. DOI: 10.13982/j.mfst.1673-9078.2015.6.016
    [Abstract](1384) [HTML](0) [PDF 932.30 K](1117)
    Abstract:
    The mechanism of tyrosinase inhibition by lemon essential oil and its six individual components was studied in terms of tyrosinase activity, radical-scavenging activity, and copper-chelating capability. The results indicated that lemon essential oil and some of its volatile components exhibited good inhibitory effect on tyrosinase activity through non-active-site-inhibition mechanisms such as steric effect and oxygen radical-scavenging activity. Among the components of lemon essential oil, inhibitory rate on tyrosinase activity exerted by citral (2.16% m/m) and beta-pinene (14.30% m/m) was 76.64% and 61.82%, respectively, while that of d-limonene (61.41% m/m) was only 33.25%. Additionally, inhibition exerted by the mixture of all six volatile components was higher than that of lemon essential oil due to a synergistic effect and the inhibitory effect was higher with increasing concentration. Moreover, the inhibitor concentration causing 50% loss of activity (IC50 value) was 620 ± 15.72 μg/mL. The Lineweaver-Burk plot showed that inhibitory activity of lemon essential oil (Km = 0.30 ± 0.003 mM) was noncompetitive. The 1,6-bis(diphenylphosphino) hexane (DPPH) assay showed that lemon essential oil and citral had relatively strong radical-scavenging activity, with IC50 values of 123.65 ± 20.20 and 176.54 ± 23.20 mg/mL, respectively. Copper chelating demonstrated that the six components did not bind to the active sites of tyrosinase while exhibiting good inhibitory effect. These results indicate that lemon essential oil is a natural material with potential biological function that can be applied to food and cosmetic industries.
    17  Physicochemical Properties of a Potato Starch-Derived Oligosaccharide
    HAO Li-min LU Ji-ke FAN Ming LI Zhao-feng CUI Yan ZHANG Li-ming GU Zheng-biao ZHANG You-song
    2015, 31(6):106-110. DOI: 10.13982/j.mfst.1673-9078.2015.6.017
    [Abstract](1024) [HTML](0) [PDF 725.78 K](1167)
    Abstract:
    Scanning electron microscopy (SEM), gel filtration chromatography (GFC), infrared spectroscopy (IR), and differential scanning calorimetry (DCS) were used to characterize the properties of Jxsac 4, a novel oligosaccharide derived from potato starch, including its physicochemical properties, particle morphology, molecular weight distribution, pasting properties, thermal properties, and in vitro digestion-resistance capacity, for use in sports drinks. The results showed that Jxsac 4 was a highly hydrolyzed starch product with an average molecular weight of 786 D. In Jxsac 4, the water content was 6.70%, there was a certain amount of ash (0.84%), while protein and fat contents were relative low (less than 0.10%), amylose content was very low (0.11%), the blue value was zero, and reducing sugar content was 29.05 g/100 g. The solubility of Jxsac 4 was 97.00%, and it was soluble in cold water. Light transmittance and sedimentation volume of this sugar were 97.00% and 4 mL/100 mL, respectively, demonstrating that Jxsac 4 was highly hydrophilic. The FT-IR spectrum of Jxsac 4 showed the characteristic absorption peak for the functional groups derived from starch. The oligosaccharide had a high rapidly digestible starch content (94.02%), while the slowly digestible starch content was 5.80%. Jxsac 4 is a potential ingredient of sports drinks that can provide stepwise energy supply.
    18  Analysis of the Interactions between Tannic Acid and Sodium Caseinate
    LI Yan GONG Shi-lei GAO Huan-yuan CAO Qing JIN Li-e
    2015, 31(6):111-115. DOI: 10.13982/j.mfst.1673-9078.2015.6.018
    [Abstract](1319) [HTML](0) [PDF 919.95 K](1469)
    Abstract:
    The digestion and absorption of protein by the human body can be affected by a solidified material formed through the interaction between tannic acid (TA) and sodium caseinate (SC) in food. In order to clarify this interaction, the effects of TA on SC were investigated by thermogravimetry/differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FT-IR), and fluorescence spectrophotometry. The results showed that TA has an important effect on the structure of SC. FT-IR demonstrated that the secondary structure of SC was modified in the presence of TA. The contents of β-sheets and β-turns decreased, while those of α-helices and random coil structures increased. Fluorescence spectra also confirmed that there was static quenching of SC fluorescence. The double logarithmic regression curve plotted using the fluorescence intensity rate of change and the TA concentration was used to obtain the binding constant and the number of binding sites, which were 1.30×103 L/mol and 1.20, respectively. TG-DTA showed that the temperatures of glass transition and thermal denaturation of TA-SC increased by 20 ℃ and 86 ℃, respectively. Analysis of the experimental results showed that the presence of TA enhanced the force between SC molecular chains, which impeded the movement of the chains and formed a larger three-dimensional network structure, thereby increasing stability.
    19  Correlation between Pattern of Nitrogen Transformation and Process Control during Fermentation of Rice Dreg Protein for Sauce Production
    LIN Can YUAN Jiang-lan DENG Chong KANG Xu XU Ning
    2015, 31(6):116-121. DOI: 10.13982/j.mfst.1673-9078.2015.6.019
    [Abstract](945) [HTML](0) [PDF 932.23 K](1130)
    Abstract:
    Rice dreg protein (RDP) was used as the main material for fermentation to produce sauce, and the correlation between the process control and nitrogen transformation pattern during the fermentation was investigated. The fermentation temperature, salt concentration, amount of added brine, and other control conditions were optimized via dynamic monitoring of the changing patterns of total nitrogen content, amino nitrogen content, soluble protein, and total nitrogen conversion rate in RDP sauce during a 30-d fermentation. The amino nitrogen and total nitrogen contents of RDP sauce and soy sauce obtained under the same conditions were compared, and the antioxidant activity of RDP sauce was evaluated preliminarily. The results showed that the conversion of nitrogen in RDP sauce peaked on the second day of fermentation at 50 ℃; fermentation at 35 ℃ required a longer duration, favored the conversion of nitrogen, and yielded a high-quality product. Moromi with a salt concentration of 11% was conducive to conversion of nitrogen. When the amount of brine was 2.2, 2.5, and 2.8 times as much as the koji weight, no significant effects on the total nitrogen and amino nitrogen contents were observed, while a higher amount of brine promoted the degradation of RDP protein and increased the total nitrogen conversion rate in RDP sauce. Based on this comprehensive analysis, the optimized processing conditions were as follows: the amount of added brine was 2.8 times the koji weight; the fermentation temperature was below 35 ℃; and the salt concentration of the moromi was 11%. Under these conditions, an RDP sauce with a total nitrogen conversion rate of over 70% was obtained. The amino nitrogen and total nitrogen contents of RDP sauce were significantly higher than those of soy sauce, and RDP sauce possessed significant antioxidant activity.
    20  Effects of Biogenic Amine Oxidase Producing Strains During the Maturation of Smoked Horsemeat Sausages
    ZHANG Hui-chao LU Shi-ling MA Yu-xia LI Xiang-peng JIANG Cai-hong WANG Shao-mei
    2015, 31(6):122-128. DOI: 10.13982/j.mfst.1673-9078.2015.6.020
    [Abstract](900) [HTML](0) [PDF 995.92 K](1193)
    Abstract:
    Six bacterial strains (namely Lactobacillus rhamnosus, Bacillus subtilis, Staphylococcus saprophyticus, Staphylococcus xylosus, Pediococcus pentosaceus, and Lactobacillus plantarum) producing biogenic amine oxidase, screened from Xinjiang smoked horsemeat sausage, were added to smoked horsemeat sausages. The dynamic changes in bacterial colonies were determined by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The variation in the content of biogenic amines (trypmine, putrescine, phenylethylamine, histamine, tyramine, cadaverine, spermine, and spermidine) was determined by HPLC. The content of biogenic amines was reduced by the starter cultures during sausage maturation. Inhibitory effects of Staphylococcus saprophyticus were most significant on trypmine, while those of Staphylococcus saprophyticus, Staphylococcus xylosus, Lactobacillus rhamnosus, Staphylococcus saprophyticus, and Bacillus subtilis were most prominent on phenylethylamine, cadaverine, putrescine, histamine, and tyramine, respectively. The rates of reduction were 45.49%, 57.54%, 40.75%, 51.03%, 49.28%, and 64.33%, respectively. These results provide a good theoretical basis for controlling the safety of fermented meat.
    21  Effect of Protein and Lipid Content on Yuba Film-formation
    ZANG Xi-xi WU Jing PAN Si-yi XU Xiao-yun
    2015, 31(6):129-135. DOI: 10.13982/j.mfst.1673-9078.2015.6.021
    [Abstract](1267) [HTML](0) [PDF 786.04 K](1427)
    Abstract:
    Yuba is one of the oldest traditional soybean products in China. The effects of protein and lipid content, denaturation and composition of protein on the film-forming process of yuba was studied in order to boost yuba production yield, improve its mechanical properties, and increase its nutritional content. A simulated soymilk system was employed with soybean protein extracts and soybean oil as raw materials. The results showed that the improvement of soybean lipid content could accelerate the film-forming rate, increase elasticity, and enrich the protein and lipid content of yuba. However, the addition of excess lipids had a negative impact on the variables mentioned above. The addition of protein increased the film-forming rate, hardness, and protein content of yuba, while the lipid content first increased and then decreased. High levels of denatured protein increased the film-forming rate, and improved the mechanical properties and nutritional value of yuba. Although different protein compositions had minimal effect on the film-forming rate, changing the 11S/7S ratio had a direct impact on the mechanical properties of yuba; specifically, a higher 11S/7S ratio led to better mechanical properties.
    22  Preparation and Characterization of Nano-sized Emulsions Produced from Acid-soluble Soy Protein and Polysaccharide Complexes
    QI Jun-ru WENG Jing-yi KANG Yan-hui FENG Ji-lu LIU Qian-ru LIU Li-sen LIAO Jin-song
    2015, 31(6):136-141. DOI: 10.13982/j.mfst.1673-9078.2015.6.022
    [Abstract](1336) [HTML](0) [PDF 844.92 K](1299)
    Abstract:
    Due to its superior stability during storage, against aggregation and creaming, nano-sized emulsion is an effective method to improve the bioavailability and solubility of fat-soluble substances. The preparation process of nano-sized emulsion produced from acid-soluble soy protein (ASSP) and soluble soy polysaccharide (SSP) complex were investigated, the effect of changes in pH, oil content, pressure, ASSP to SSP ratio, and temperature on the formation and stability of the resulting emulsions were also analyzed. The results showed that a stable emulsion (i.e. having a mean droplet size of 269.33 ± 2.26 nm) was obtained with 400 bar pressure, pH between 3.0 and 4.0, ASSP to SSP ratio of 1:4, and 5% to 20% oil content; the average droplet size of the resulting emulsion did not change significantly (p > 0.05) after 60 days. In addition, pH values, high pressure, and heat treatment had a significant effect on the emulsion stability (p < 0.05); emulsion prepared from ASSP and SSP complex can be used in acidic medium, high temperature, and high salt concentration in the food industry. Furthermore, the morphology of the emulsion produced from ASSP and SSP complex was also studied through the addition of pectinase. As the complex was well fixed on the surface of the emulsion droplets, the emulsions exhibited excellent long-term stability and dispersion property.
    23  Changes in Mussel Quality during Heat-pump Drying
    LV Fei SHEN Jun-liang DING Yu-ting
    2015, 31(6):142-149. DOI: 10.13982/j.mfst.1673-9078.2015.6.023
    [Abstract](876) [HTML](0) [PDF 1.07 M](1300)
    Abstract:
    Quality parameters including protein denaturation, lipid oxidation as well as changes in flavor and color were monitored during heat-pump drying of mussels. The results showed that protein denaturation of mussel meat occurred mainly at drying temperatures between 55 ℃ and 60 ℃, while contraction of protein fibers and formation of hydrogen bonds increased tissue elasticity and hardness. Electron microscopy showed that the gap between muscle fibers decreased and degree of protein aggregation increased, while the texture test confirmed an increase in chewiness. Lipid oxidation, measured in terms of thiobarbituric acid-reactive substances (TBARS) content, increased at the beginning of the drying period and subsequently decreased. The flavor compounds varied in accordance with the changes in protein and lipid, thus generating the unique flavor of mussel meat. There was an increase in the level of free glutamic acid and aspartic acid, which produced a fresh flavor, and that of free glycine and alanine, which produced a sweet flavor, thereby causing the dried products to taste fresh. Gas chromatography-mass spectrometry (GC-MS) results showed that there were interconversions between aldehydes and hydrocarbons during the drying period. Changes in volatile odor compounds eliminated the fishy smell and produced a unique aroma in dried mussel meat. The color of dried mussels was a dark brown. Thus, heat pump drying technology can be used to yield high-quality dried mussel products in terms of color, fragrance, and flavor.
    24  Cloning, Expression, and Purification of the Nitrite Reductase Gene from Lactobacillus plantarum DMDL 9010
    WANG Pan FEI Yong-tao LIU Dong-mei HUANG Juan WU Hui YU Yi-gang TANG Yu-qian XIAO Xing-long
    2015, 31(6):150-155. DOI: 10.13982/j.mfst.1673-9078.2015.6.024
    [Abstract](1486) [HTML](0) [PDF 692.74 K](1184)
    Abstract:
    The nitrate reductase gene (nir), encoding the nitrite reductase enzyme (NiR) in Lactobacillus plantarum DMDL 9010, was cloned, and the expressed product was purified. The nir fragment was amplified by polymerase chain reaction (PCR) using L. plantarum DMDL 9010 DNA as template. Sequencing studies revealed that the nir fragment was 1638 bp in size. The gene was cloned into plasmid pET-32a(+) and was transferred into competent Escherichia coli DH5α cells in order to construct the pET-32a(+)-nir-DH5α recombinant plasmid. pET-32a(+)-nir was transferred into the expression strain E. coli BL21 to construct the denitrification recombinant bacterium, pET-32a(+)-nir-BL21. The recombinant bacterium was induced by 1 mmol/L IPTG to produce NiR protein when the induction temperature was maintained at 30 ℃ for 4 h, and more than 90% of NaNO2 (50 ?g/ml) was degraded. High-purity NiR was obtained by His-Tag nickel affinity chromatography (Ni Sepharose 6 Fast Flow), and the molecular weight of NiR, as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), was approximately 60 kDa. In summary, nir from L. plantarum DMDL 9010 was successfully cloned, and the recombinant bacterium pET-32a (+)-nir-BL21 effectively degraded nitrite. High-purity NiR can be obtained by affinity chromatography.
    25  Thermal Sterilization of Listeria Monocytogenes and Kinetics of Quality Changes in Cold Smoked Salmon
    SHI Ya-ge LIU La-pin YUE Tian-li TANG Ju-ming WANG Shao-jin
    2015, 31(6):156-163. DOI: 10.13982/j.mfst.1673-9078.2015.6.025
    [Abstract](1066) [HTML](0) [PDF 1.07 M](1309)
    Abstract:
    In order to provide a theoretical foundation for the thermal sterilization of cold smoked salmon, the influence of heat treatments on the inactivation of Listeria monocytogenes and the changes in the quality of cold smoked salmon were investigated. A sample of cold smoked salmon inoculated with a strain of L. monocytogenes (ATCC19113) was sealed in a capillary tube, and subjected to heat treatment at 58 ℃, 60 ℃, 62 ℃, 64 ℃, and 66 ℃ for 18 min, 8.8 min, 4 min, 2 min, and 1 min, respectively. The changes in viable bacterial cell count at the different temperatures was monitored. Small samples (D 30 mm × H 6 mm) were sealed in an aluminium heating unit (D 35 mm × H 6 mm) and heated in a water bath at 50 ℃, 57 ℃, 64 ℃, and 70 ℃ for 120 min, 90 min, 60 min, and 40 min, respectively. The corresponding changes in quality were studied. The results showed that the inactivation curve exhibited a logarithmic linear relationship (R2 ≥ 0.94). The quality indexes of cold smoked salmon, including cooking loss, the a* value, b* value, and the shear force followed first-order reaction kinetics, while the L* value followed zero-order reaction kinetics. As the a* value of cold smoked salmon was closely linked to thermal inactivation of L. monocytogenes, the overlapping region between thermal-death-time curves of L. monocytogenes (ATCC19113) and the a* quality deterioration curve was the operational range to carry out the combination of temperature and heat treatment time, which could meet the requirements for sterilization without deteriorating quality of cold smoked salmon.
    26  Influence of High Pressure Processing on the Reversibility of LDPE and PA6 Food Packaging Materials
    WANG Shu-juan CHENG Xin TANG Ya-li
    2015, 31(6):164-171. DOI: 10.13982/j.mfst.1673-9078.2015.6.026
    [Abstract](997) [HTML](0) [PDF 1.10 M](1325)
    Abstract:
    This study investigated the tensile strength, heat-sealing properties, thermal properties, barrier properties, and reversibility of LDPE and PA6 films under different conditions of high-pressure processing (HPP) compared to control samples processed at atmospheric pressure. The results showed that the effects of pressure, dwell time, and storage time on the heat-sealing properties of LDPE and PA6 materials were not significant, but the tensile strength of LDPE and PA6 samples increased significantly as the pressure increased; When the pressure was lower than 300 MPa, the water vapor transmission rate (WVTR) of LDPE increased gradually, while the WVTR gradually decreased when the pressure was higher than 300 MPa. For PA6 samples, when the pressure was higher than 100 MPa, the WVTR decreased from 10.13 g/(m2?day) (0.1 MPa/10 min) to 6.79 g/(m2?day) (200 MPa/10 min), but the reduction was not significant with increasing pressure. The melting enthalpy of LDPE and PA6 samples increased under HPP treatment, which was recovered after storage for 24 h. Compared with 0.1 MPa, the permeation of p-cymene through LDPE and PA6 films was reduced by about 50% and 58%, respectively, under different HPP treatments, but returned to levels observed at atmospheric pressure almost immediately when the pressure was released. The results show that the properties of LDPE and PA6 films are reversible under HPP treatment, hence both are suitable for HPP.
    27  Properties of Isolated, Thermally Induced Soy Protein Fibrillar Aggregates
    CHEN Zhen-dong CHEN Jia-qi WANG Jin-mei YANG Xiao-quan
    2015, 31(6):172-177. DOI: 10.13982/j.mfst.1673-9078.2015.6.027
    [Abstract](1160) [HTML](0) [PDF 831.96 K](1260)
    Abstract:
    Soy protein isolate (SPI) spontaneously forms fibrillar aggregates under acidic heat treatment; however, certain peptides still do not self-assemble into aggregates and the ratio between fibrillar aggregates and peptides has a great impact on functional properties of the protein. Fibrillar aggregates and peptides were separated in bulk by ultrafiltration, in order to study their physicochemical properties. The results showed that 100 ku ultrafiltration membrane can produce a good separation effect after two separation cycles. After heat treatment, SPI solubility at the isoelectric point increased, but that at neutral pH decreased. Additionally, protein hydrolysis caused the absolute value of the surface potential to increase. Amino acid composition and surface potential of fibrillar aggregates were similar to those of heated SPI, but its solubility at isoelectric point and neutral pH decreased significantly. Peptides contained fewer hydrophobic amino acids and more negatively charged amino acids; solubility at pH 2.0 to 9.0 was relatively higher, while the electric charge and electrostatic repulsive force were lower at acidic pH, leading to the amorphous formation of aggregates. Thus, high charge at neutral pH results in weakened interactions among peptides and the dissociation of amorphous aggregates.
    28  Electrophoretic Separation of Proteins and Peptides in Bone Extract and Bone Extract Hydrolysates
    ZHANG Yin WANG Xin-hui WANG Wei LU Xiao-fang HU Jian-yu
    2015, 31(6):178-182. DOI: 10.13982/j.mfst.1673-9078.2015.6.028
    [Abstract](914) [HTML](0) [PDF 723.50 K](1102)
    Abstract:
    Bone extract (BE) and BE hydrolysate proteins and peptides were isolated and purified, and the differences in BE protein, bone protein, and muscle protein were compared. Bone protein and muscle protein were used as the controls, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to separate BE protein and BE hydrolyzed peptides. The effect of different running gel concentrations (5%, 7.5%, 10%, 15%) on the separation of BE protein, bone protein, and muscle protein was investigated. The results showed that bone protein and muscle protein were separated successfully, while BE protein was not separated by SDS-PAGE. In contrast, BE hydrolysate peptides were separated by N-Tris-(hydroxymethyl)-methylglycine gel electrophoresis. Analysis of the relationship between the electrophoresis migration ratio of BP and the running gel concentrations for SDS-PAGE revealed an extremely significant (R2≥0.996, p<0.01) correlation between the migration ratio and the running gel concentration. Combining this correlation with the correlation equation of the molecular weight of the proteins and the migration ratio allows us to choose the running gel concentration according to the molecular weight of a protein, or in turn to calculate the molecular weight of a protein based on its migration ratio.
    29  Effect of Immersion Chilling and Freezing on Muscle Structure of Litopenaeus vannamei during Frozen Storage
    LIN Wan-ling YANG Xian-qing WANG Jin-xu WEI Ya HAO Shu-xian WU Yan-yan LI Lai-hao HOU Cai-ling
    2015, 31(6):183-189. DOI: 10.13982/j.mfst.1673-9078.2015.6.029
    [Abstract](1257) [HTML](0) [PDF 1.27 M](1075)
    Abstract:
    Changes in fiber profile, intercellular gaps, myofilament, sarcomere, and intermyofibrillar space during frozen storage of shrimp, Litopenaeus vannamei was investigated to determine the effects of immersion chilling and freezing (ICF) as well as refrigerator freezing (RF) on shrimp musculature. The results indicated that muscle fiber of ICF shrimp was tighter and the intercellular ice crystals were smaller and well-distributed, whereas that of RF shrimp was loose, and the intercellular ice crystals were larger and wider. The myofibril diameter of ICF shrimp were shorter than that of RF shrimp. As the storage period increased, the ice crystals in the ICF shrimp grew larger, while cell nuclei gradually decreased. After storing for 90 d, cell nuclei could not be found in tissue slices of RF shrimp, myofilament had largely disappeared, the thick and thin filaments were blurred, the length of the sarcomere was severely shortened, and sarcomere structures had disappeared. Moreover, the complete structure of mitochondria in the tissue of RF shrimp could hardly be found. However, the myofilament structures, and the thick and thin filaments still existed in ICF shrimp. The degree of shortening in myofilament lengths was smaller than that in RF shrimp, while some mitochondrial structures remained intact in the tissues of ICF shrimp. In summary, ICF appeared to be more beneficial to maintain the quality of shrimp during frozen storage.
    30  Influence of Moisture Content on the Physicochemical Properties of Mechanically Activated Rice Starch
    ZHANG Zheng-mao ZHAO Si-ming XIONG Shan-bai
    2015, 31(6):190-197. DOI: 10.13982/j.mfst.1673-9078.2015.6.030
    [Abstract](908) [HTML](0) [PDF 1.17 M](1168)
    Abstract:
    In order to obtain a suitable moisture content of starch for mechanical activation and to improve the mechanical activation effect for reducing the duration of mechanical activation, the influence of the moisture content on the physicochemical properties of mechanically activated rice starch isolated from three rice cultivars was investigated. The results indicated that when the duration of mechanical activation was prolonged, the gelatinization degree, cold-water solubility, transparency, and reducing power of rice starch increased, while the blue value (BV) decreased. Indica rice starch was easily decomposed by mechanical force when the moisture content was 6.02%, while the moisture content of Japonica rice starch and glutinous rice starch was about 8.50%. In terms of the gelatinization degree and cold-water solubility, Indica rice starch reached the maximum value at a moisture content of 6.02%, while Japonica rice starch and glutinous rice starch reached the maximum at about 8.50%. For transparency, all three rice starches reached the maximum value at a moisture content of about 8.50%. Regarding the reducing power and the BV, Indica rice starch exhibited the most rapid change at a moisture content of 3.50%, while that of Japonica rice starch and glutinous rice starch was determined at about 6.00%. It was concluded that the moisture content had some influence on the mechanical activation of rice starch, and moisture contents of 6.00%~8.50% were determined as the optimum for mechanical activation.
    31  Preparation and Evaluation of Solidifying Yoghurt Supplemented with Hemp Seed Oil
    WEI Yue-yuan LI Li
    2015, 31(6):198-204. DOI: 10.13982/j.mfst.1673-9078.2015.6.031
    [Abstract](1134) [HTML](0) [PDF 1.06 M](1605)
    Abstract:
    Solidifying yogurt was supplemented with hemp seed oil to improve flavor of the resultant yogurt; homogenous mixture was obtained using microfluidization. Subsequently, the rheological properties, microstructure, volatile flavor components, and sensory evaluation of the yogurt prepared from skim milk powder and microfluidized hemp seed oil (HMY) were compared to control samples (skim milk yogurt [SMY] and whole milk yogurt [WMY]). Using 3.0% hemp seed oil in yogurt, the water holding capacity, rheological properties, and microstructure of the yogurt was similar to those of WMY. However, the characteristic, volatile flavor components and sensory evaluation results were significantly different: the content of 3-hydroxy-2-butanone and 2,3-diacetyl in 3.0% hemp seed oil yogurt was significantly lower than those in WMY, whereas caryophyllene, D-limonene, and β-myrene were detected in 3.0% hemp seed oil yogurt. With 1.5% hemp seed oil in yogurt, the titratable acidity was 97oT, water-holding capacity (WHC) was 85%, yield stress (τ0) was 15 Pa, and apparent viscosity (η50) was 0.54 Pa?s; while it showed no significant difference (p < 0.05) with regard to overall acceptability, compared with WMY. It was concluded that addition of 1.5% hemp seed oil possessed high overall acceptability and shows good potential for commercial application.
    32  Enhancement of β-1,3-glucanase Production in Salt-tolerant Zygosaccharomyces rouxii by Exponential Fed-batch
    XIE Ting LIU Fei LI Min WANG Zhi CHEN Xiong LI Xin ZENG Yu-lei QIN Wan-fang
    2015, 31(6):205-210. DOI: 10.13982/j.mfst.1673-9078.2015.6.032
    [Abstract](1108) [HTML](0) [PDF 984.05 K](1207)
    Abstract:
    High salt-tolerant Zygosaccharomyces rouxii A (tolerant of 24% NaCl) was used to produce ?-1,3-Glucanase in 10 L fermenter. Glucose (YEPD) is the optimum carbon source for yeast growth and enzyme production. Fermentation efficiency with YEPD batch culture is significantly higher than that with glycerol (YEPG) and ethanol (YEPE), respectively. Meanwhile, batch culture efficiency with acetate as carbon source was poor. The growth efficiency (biomass), the largest ?-1,3-Glucanase and enzyme productivity with YEPD batch cultivation was increased by 1.89% and 29.88%, 114% and 19.65%, 188% and 33% than that with YEPG and YEPE batch culture, respectively. Compared with the YEPD batch cultivation, exponential fed-batch with YEPF medium from 15 to 23 h, the time of maximum biomass was shorten by 12 h and the maximum biomass was increased by 19.29%. Moreover, ?-1,3-glucanase was nearly logarithmically synthesized to the largest enzyme activity (44.99 U/mL), the time of synthesis was shortened by 6 h and enzyme productivity was up to 2.14 U/(mL?h) that was increased by 76.86%. Exponential fed-batch model for effective enhancement of biomass and β-1,3-glucanase production by Z. Rouxii A was confirmed by the results above, which laid the foundations for the effective production of high salt-tolerant Z. Rouxii A, ?-1,3-glucanase products and the application of them in highly active fermentative function food industry.
    33  Study on the Effect of Organic Calcium Spray on the Preservation of Blueberry Fruit during the Growth Period
    WANG Rui HU Xu-lin XIE Guo-fang JI Ning MA Li-zhi LIU Zhi-gang CEN Shun-you LIU Xiao-yan
    2015, 31(6):211-218. DOI: 10.13982/j.mfst.1673-9078.2015.6.033
    [Abstract](1091) [HTML](0) [PDF 1.21 M](1250)
    Abstract:
    Organic calcium spray was applied to blueberry fruits of two cultivars, ‘Gardenblue’ and ‘Powderblue’, during the growth period to improve the preservation effect. The results showed that the calcium content of blueberry fruits was effectively increased with the organic calcium spray. The increases through the growth period in respiratory rate, ethylene production rate, malondialdehyde content, and soluble pectin content in the blueberry fruits of two cultivars were inhibited, while the activities of polyphenoloxidase (PPO), peroxidase (POD), and polygalacturonase (PG) were decreased. As a result, fruit senescence was delayed, and the rates of rotting and soft fruit were decreased. Compared with the controls, the rates of rotting and soft fruit of ‘Powderblue’ after treatment with the organic calcium spray were decreased by 7.41% and 5.62%, respectively, and those of ‘Gardenblue’ after treatment with organic calcium spray were decreased by 11.62% and 9.57%, respectively. With regard to fruit quality, the changes in the soluble solid content, total acids, soluble pectin content, total phenols, anthocyanin content, and weight loss rate of the treated fruits were inhibited to varying degrees. Apart from this, the peel color and flavor index of the fruits treated with organic calcium spray were also effectively maintained. In summary, application of the organic calcium spray during the growth period can improve the preservation of blueberry fruits of the two cultivars ‘Gardenblue’ and ‘Powderblue’.
    34  Investigation on the Antioxidant Activity of Silver Carp Peptide Maillard Reaction Products Isolated by Ultrafiltration
    LIU Min MENG Yan-li DONG Shi-yuan ZENG Ming-yong
    2015, 31(6):219-223. DOI: 10.13982/j.mfst.1673-9078.2015.6.034
    [Abstract](937) [HTML](0) [PDF 767.46 K](1329)
    Abstract:
    Maillard reaction products (MRPs) from silver carp peptide were isolated using a 5-kDa and 1-kDa ultrafiltration system, which was followed by solvent fractionation in order to investigate the antioxidant activity and chemical properties of different fractions. Measurements of the free-radical scavenging activity, metal ion chelating activity, and total antioxidant capacity of different fractions showed that high molecular weight (HMW) compounds displayed higher antioxidant activity than that of low molecular weight (LMW) compounds in the water-soluble fraction. In contrast, the antioxidant activity of HMW compounds was lower than that of LMW compounds in the alcohol-soluble fraction. The DPPH radical scavenging activity, metal ion chelating activity, and ferric reducing/antioxidant power (FRAP) of the water-soluble fraction F-3 (> 5 kDa) in silver carp peptide MRPs were the highest. The browning intensities of F-3 and F-2 (1~5 kDa) were the strongest and the fluorescence intensity of F-3 was the highest. Fourier transform infrared spectroscopy (FT-IR) showed that MRPs had a strong absorption peak at 860.66 cm-1, while F-2 and F-3 had sharp absorption peaks at 860.01 cm-1 and 948.61 cm-1, respectively, indicating that the reducing sugar may be linked to the peptide skeleton, which thus, leads to structural changes. Therefore, the water-soluble substances from MRPs play a major antioxidant role, and the colored water-soluble products with relatively HMW show strong antioxidant activity.
    35  Effect of Infrared Drying Temperature on the Drying Characteristics and Quality of Jujube with Ultrasonic Pre-treatment
    CHEN Wen-min PENG Xing-xing SUN Tian-kui DONG Fang-hui XU Huai-de
    2015, 31(6):224-229. DOI: 10.13982/j.mfst.1673-9078.2015.6.035
    [Abstract](829) [HTML](0) [PDF 1003.95 K](1161)
    Abstract:
    In order to improve the quality of dried jujube and reduce the drying time, medium-short wave infrared radiations at different temperatures (50, 55, and 60 ℃) were utilized to dry jujubes with and without ultrasonic treatment. Compared with the traditional multi-stage air-drying, the effects of different drying methods on the drying characteristics and the quality of jujube were analyzed. The results showed that compared with the traditional multi-stage air-drying, the drying time and energy consumption for drying the jujube with no ultrasonic treatment but by medium-short wave infrared radiation were reduced to 6.67~13 h and 7.05~13.05 kW?h, respectively, while the jujube subjected to ultrasonic treatment were reduced by 9~13.67 h and 9.67~14.93 kW?h, respectively. With increasing medium-short wave infrared drying temperature, the drying rate increased and energy consumption decreased. During the medium-short wave infrared drying process, both the internal and external temperatures of jujube quickly reached the setted temperature, and the surface temperature was higher than the internal temperature. Moisture from the skin easily vaporized, the degree of browning was low, and small amounts of nutrients were lost. Seven kinds of drying methods were comprehensively evaluated. Compare to all the drying methods, when the jujube was dried by medium-short wave infrared radiation at 50 ℃, the drying energy consumption was low, the sugar acid ratio was the highest, the contents of total vitamin C, total flavonoids, total phenols were relatively high, and chewiness, color, and appearance quality were the best, while the degree of browning was the lowest. Therefore, these conditions were identified as a good method for drying jujube.
    36  Improving Pesticide Inhibition of Chicken Liver Esterase via Enzyme Purification
    YU Xiao-hang ZHU Nian-xin XU Fei CAO Hui YU Jin-song YUAN Min
    2015, 31(6):230-235. DOI: 10.13982/j.mfst.1673-9078.2015.6.036
    [Abstract](921) [HTML](0) [PDF 798.10 K](1120)
    Abstract:
    Chicken liver esterase was purified using three different methods: including fractional ammonium sulfate precipitation, fractional ammonium sulfate precipitation + dialysis, and fractional ammonium sulfate precipitation + exclusion chromatography. Four types of organophosphate with different structures and carbamate pesticides were used to detect the effects of these purification methods on the sensitivity of purified chicken liver esterase to pesticide inhibition. The results showed that the sensitivity of the esterase to pesticide increased significantly after purification. Compared with crude esterase, pesticide inhibition rates of purified esterase increased by 6.49%~11.30% with fractional ammonium sulfate precipitation, 14.30%~26.26% with fractional ammonium precipitation + dialysis, and 10.95%~39.87% with fractional ammonium precipitation + exclusion chromatography. The recovery rates of sensitive esterase were 86.07%~89.96%, 66.60%~73.57%, and 33.01%~41.62%, respectively. Due to the low recovery of sensitive esterase obtained by fractional ammonium sulfate precipitation + exclusion chromatography, fractional ammonium sulfate precipitation + dialysis is preferable for the large-scale preparation of enzymes. In addition, the esterase sensitive to the four different types of pesticides was always in the same fraction, regardless of the purification method. Thus, the sensitive esterase might be one or several kinds of esterases with similar solubility and molecular weight.
    37  Changes in Bacterial Flora and Predominant Spoilage Bacteria in Squid during Low Temperature Storage
    SHEN Ping LI Xue-ying YANG Xian-shi CHI Hai HUANG Hong-liang
    2015, 31(6):236-242. DOI: 10.13982/j.mfst.1673-9078.2015.6.037
    [Abstract](1161) [HTML](0) [PDF 751.20 K](1368)
    Abstract:
    Bacterial flora in squid stored at 0, 5, 10, and 15 ℃ were analyzed qualitatively and quantitatively. The results showed that the bacterial flora of squid was complex on initial storage, with 91.48% gram-negative bacteria and 4.26% gram-positive bacteria. The predominant bacterial flora was composed of Aeromonas spp. (27.66%), Chryseomonas luteola (23.40%), and Pseudomonas spp. (17.02%). In addition, a certain proportion of Acinetobacter lwoffii and Pantoea agglomerans was also detected. During aerobic storage at 0, 5, 10, and 15 ℃, the bacterial flora gradually became more uniform and a trend of increasing Pseudomonas spp. was apparent. The high quality lives (HQL) of the squid samples were 360, 239, 96, and 47 h, respectively, while the shelf lives (SL) were 525, 286, 147, and 86 h, respectively. In addition, at the end of HQL at 0, 5, 10, and 15 ℃, total volatile base nitrogen (TVBN) was 17.15 ± 0.29 mg/100 g, and total viable count (TVC) was 5.89 ± 0.40 LgCFU/g. The percentages of Pseudomonas spp. were 84.09%, 72.09%, 65.52%, and 76.36%, respectively, with an average percentage of 75.92%. At the end of SL at 0, 5, 10, and 15 ℃, TVBN was 30.05 ± 0.92 mg/100 g and TVC was 8.33 ± 0.30 LgCFU/g. The percentages of Pseudomonas spp. were 93.24%, 90.53%, 88.57%, and 81.95%, respectively, and the average percentage was 87.63%. Therefore, Pseudomonas spp. was the predominant spoilage bacteria of squid stored between 0 and 15 ℃.
    38  Effect of Preservation by Impregnation under Vacuum Pre-cooling Conditions on the Quality of Fresh-cut Lotus Root
    LIAO Cai-hu SHAN Bin ZHONG Rui-min ZHU Jian-hua ZHAI Hai-min
    2015, 31(6):243-248. DOI: 10.13982/j.mfst.1673-9078.2015.6.038
    [Abstract](4068) [HTML](0) [PDF 1.13 M](1193)
    Abstract:
    Different technologies, including cold storage room pre-cooling, vacuum pre-cooling, and vacuum pre-cooling coupled with constant pressure treatment (when the final temperature was reached, the vacuum pump and valve were closed for 0, 2, 4, and 6 min, respectively), were utilized to pre-cool (final pre-cooling temperature: 5 ℃) fresh-cut lotus root that was impregnated in the compound fresh-keeping solution for 12 min. After pre-cooling, all samples were packaged in a modified atmosphere and stored in the cold storage room (5 ± 2 ℃). The effects of different pre-cooling methods on the quality of fresh-cut lotus root were evaluated by measuring the physiochemical and biochemical indexes during the storage. The experimental results showed that the cooling rate of vacuum pre-cooling was almost ten times that of cold room pre-cooling. In the cooling process when a constant pressure was maintained for a long duration, a significant trend towards increased water loss was observed (P < 0.05), while no significant difference was observed in the overall appearance (P > 0.05). The physicochemical and biochemical indexes obtained for the fresh-cut lotus root that was vacuum pre-cooled to 5 ℃ followed by maintenance at constant pressure for 2, 4, and 6 min were similar to that of the fresh lotus roots than that of the control group. In particular, vacuum pre-cooling coupled with constant pressure treatment not only reduced the maximum peak value of polyphenol oxidase (PPO) activity, but also prolonged the time to reach such a peak value. The best preservation effect was achieved when the sample was vacuum pre-cooled to 5 ℃ and constant pressure was maintained for 4 min.
    39  Soy Isoflavone Transformation during Grey Sufu Fermentation
    MA Yan-li XIA Ya-nan WANG Jie LIU Ya-qiong SUN Jian-feng MU Jian-lou
    2015, 31(6):249-253. DOI: 10.13982/j.mfst.1673-9078.2015.6.039
    [Abstract](1355) [HTML](0) [PDF 721.53 K](1307)
    Abstract:
    Soy isoflavone composition and content were compared between grey, red, white, and low-salt sufu (or fermented tofu). Changes in soy isoflavone content during the fermentation of grey sufu were also investigated. The results showed that soy isoflavone glucosides were almost completely converted to aglycones in all four types of sufu. Isoflavone content in grey sufu was significantly lower than that in the other types of sufu, in addition to being only 33.01% of the content in red sufu. Additionally, daidzein and genistein content was significantly higher than that of glycitein in all four types of sufu. Monitoring soy isoflavone conversion in grey sufu during the fermentation process showed that glucosides were the main forms of soy isoflavone in pizi, among which, genistein content was higher than daidzein and glycitin content. Soy isoflavone glucosides were converted to soybean isoflavone aglycone during the pre-fermentation process. There was a slight decrease in soy isoflavone glucoside content during the salting process. The total amount of soybean isoflavone aglycone decreased significantly at 30 d post-fermentation. Among soybean isoflavone aglycones, daidzein might be partially converted to equol, which resulted in the lower content of soy isoflavones in grey sufu than in other types of sufu. It remains to be seen if the transformed substance was equivalent in the four types of sufu.
    40  Isolation and Identification of Ethanol-utilizing Strains and Application in Low-alcohol Cider
    SONG Jing-jing YUAN Ya-hong LIU Bin WANG Hu-xuan CEN Tao
    2015, 31(6):254-258. DOI: 10.13982/j.mfst.1673-9078.2015.6.040
    [Abstract](992) [HTML](0) [PDF 766.44 K](1277)
    Abstract:
    The popularity of low-alcohol ciders has risen owing to increasing health awareness. Here, yeast strains were repeatedly isolated and screened using culture media with yeast extract peptone dextrose (YPD) and ethanol as the sole carbon source, which resulted in the isolation of three ethanol-utilizing strains, SJ01, SJ02, and SJ03. The ethanol tolerance and ethanol-utilizing curve of the three strains were measured. In addition, the colony and cell morphology was observed, and the phylogenetic tree based on 26S rDNA sequence analysis was constructed to determine the genetic location of the isolates. The results showed that after incubation in media containing ethanol as the sole carbon source for 20 days, the ethanol utilization rates of SJ01, SJ02, and SJ03 were 39.9%, 35.7%, and 31.8%, respectively, while ethanol tolerance was 10%, 8%, and 9%, respectively. SJ01 and SJ02 were identified as Pichia kudriavzevii and SJ03 as Candida ethanolica. Finally, based on the growth characteristics of the strains with ethanol as sole carbon source, SJ01 and SJ03 were selected for the brewing of low-alcohol apple cider. The alcohol contents of apple cider were reduced by 17.5% and 27.8%, respectively, and the quality of the ciders was improved.
    41  Effect of Ultra-high Pressure on the Physicochemical Properties of Tilapia Actomyosin
    GUO Bao-yan LIANG Yan ZHOU Ai-mei XIAO Su-yao LIU Xin CAO Yong
    2015, 31(6):259-263. DOI: 10.13982/j.mfst.1673-9078.2015.6.041
    [Abstract](912) [HTML](0) [PDF 709.33 K](1137)
    Abstract:
    Changes in the physicochemical properties of tilapia actomyosin under ultra-high pressure (100, 300, and 500 MPa for 15, 30, and 45 min) were investigated. The results revealed that an increasing pressure and a longer holding time could reduce the solubility of tilapia actomyosin, and the lowest solubility (89.17%) was observed with 500 MPa treatment for 45 min, indicating that ultra-high pressure could promote protein accumulation and denaturation. The Ca2+-ATPase activity of tilapia actomyosin was lost under ultra-high pressure, suggesting the degeneration of myosin. As the pressure and holding time increased, the surface hydrophobicity of actomyosin also increased, and the highest hydrophobicity was achieved with 300 MPa treatment for 45 min, indicating that ultra-high pressure allowed more hydrophobic groups to be exposed. The total sulfhydryl content of actomyosin was reduced with increasing pressure, and the lowest value was reached with the 500 MPa treatment for 30 min; the disulfide bond content increased, and the highest level was achieved with the 300 MPa treatment for 45 min, indicating that the sulfhydryl group of actomyosin underwent oxidation to form disulfide bonds. These changes in the physicochemical properties demonstrate that the conformation of tilapia actomyosin changes after ultra-high pressure processing.
    42  Influence of Flour Maturation Time on the Quality of Steamed Bread
    XU Tian-yun LIU Chong ZHENG Xue-ling BIAN Ke
    2015, 31(6):264-271. DOI: 10.13982/j.mfst.1673-9078.2015.6.042
    [Abstract](1113) [HTML](0) [PDF 584.69 K](1170)
    Abstract:
    The effect of flour maturation time on the quality of Chinese steamed bread was studied, steamed bread was prepared from different flour types and systems in order to optimize the process. Correlation analysis showed that sensory evaluation, L value (lightness) and hardness were positively correlated, while chromaticity and a* value (redness) were negatively correlated with the maturation time. On the other hand, b* value (yellowness), springiness, cohesiveness, and resilience were significantly negatively correlated with the maturation time. As for the effects of different types of flour and systems used, steamed bread made from wheat flour with medium hardness was of superior quality as compared to that from durum wheat flour in terms of sensory quality and color, but inferior in terms of textural properties. The quality of tail flour was poor due to high bran content, while that of head flour was better in terms of color, springiness, and resilience, due to low bran content. Analysis of variance (ANOVA) showed that the influence of maturation time on steamed bread quality was significant, with significant differences among the various indices with time. In conclusion, quality of steamed bread prepared from flour stored for 40 to 50 days was found to be of the highest quality.
    43  Nutritional Contents and Flavor Substances in Fruit Bodies and Leftovers of Pleurotus eryngii
    LI Xiao-bei YANG Yan ZHOU Feng CHEN Wan-chao LIU Yan-fang FENG Tao
    2015, 31(6):272-278. DOI: 10.13982/j.mfst.1673-9078.2015.6.043
    [Abstract](1056) [HTML](0) [PDF 846.08 K](1144)
    Abstract:
    The fruit bodies and leftovers (mushroom buds and slices) of Pleurotus eryngii were analyzed and the nutritional components, including crude protein, crude fiber, carbohydrates, etc., and flavor substances such as soluble sugars, organic acids, free amino acids, and 5′-nucleotides were measured. In addition, the changes in the nutritional components and flavor substances before and after growth of the fruit bodies of Pleurotus eryngii were compared. The results showed that after the fruit bodies of Pleurotus eryngii were harvested, the contents of crude fibre and protein (7% and 13% respectively) as well as total carbohydrates in the substrates decreased to some extent. In addition, with the exception of the mannitol content, which was significantly increased, the content of each flavor substance in the substrate declined. The crude protein content in the mushroom buds, fruit bodies, and mushroom slices of Pleurotus eryngii followed the order: mushroom buds > fruit bodies > mushroom slices, ranging from 108.68 to 230.12 mg/g; the opposite order was identified for the carbohydrate content, which ranged from 565.53 to 366.61 mg/g. Except for trehalose, fructose, acetic acid, and glutamic acid, the content of each flavor substance was higher in the mushroom buds than in the fruit bodies, while the contents of flavor substances in mushroom slices were lower than or close to those of the fruit bodies. The equivalent umami concentrations in the mushroom buds, fruit bodies, and mushroom slices of Pleurotus eryngii were present in the order as mushroom slices > mushroom buds > fruit bodies, and were in the range of 19.05~24.10 g MSG/100 g. These results indicate that the leftovers of Pleurotus eryngii still exhibit high application values.
    44  Determination of Procyanidins in Extracts of Chinese Hawthorn Fruits by Quantitative 1H-NMR
    CUI Tong CHEN Jian-qiao WANG Xiao-ke WANG Rong-fang LI Xi-yue AN Xiao-nan CUI Can GAO Zhe
    2015, 31(6):279-283. DOI: 10.13982/j.mfst.1673-9078.2015.6.044
    [Abstract](1130) [HTML](0) [PDF 667.35 K](1419)
    Abstract:
    An analytical method to determine the content and the mean degree of polymerization (mDP) of the procyanidins in Chinese hawthorn extract was developed using quantitative nuclear magnetic resonance spectrometry (qNMR). 1H-NMR spectra were recorded using DMSO-d6 (dimethyl sulfoxide-d6) as the solvent and potassium biphthalate as the internal standard. According to the weight of the internal standard WR, the weight of sample WD, the absorption peak area AR(δ 7.529)of H-4 and H-5 from the internal standard, the absorption peak area A6,8(δ 5.787,5.702)of H-6 and H-8 from procyanidins, and the peak area Ae(δ 2.362)of H-4e at the end of the epicatechin unit, the mDP and content of the procyanidins in hawthorn extracts prepared from different batches were calculated based on the equations N = A6,8/Ae - 1 and C = (144 N + 1) A6,8 WR/51 (N + 1) ARWD ×100%, respectively. The results showed that there was a good linearity (r = 0.9996) within the range of 0.4~24 mg/mL and the average recovery was 104.6%. This method was applied to determine the content and mDP of procyanidins in hawthorn extract samples from two batches. The contents were 42.1% and 44.2% respectively; and the mDP values were 3.0 and 3.4, respectively.
    45  Immunodetection and Molecular Recognition Mechanism of Antibodies against Enrofloxacin
    ZHANG Xiu-yuan HE Kuo HUANG Zhi-hong CHEN Yi WANG Li-xia ZHAO Rui-ping
    2015, 31(6):284-289. DOI: 10.13982/j.mfst.1673-9078.2015.6.045
    [Abstract](813) [HTML](0) [PDF 953.21 K](1034)
    Abstract:
    Enrofloxacin (ENR) is a veterinary drug with strongly toxic side effects in humans. Therefore, the detection of ENR in food has important implications for food safety. Anti-ENR monoclonal antibody (mAB) was prepared by immunizing BALB/c mice with conjugates of ENR and bovine serum albumin (BSA). The resulting monoclonal antibody was used to establish a direct competitive enzyme-linked immunoabsorbent assay (ELISA) to detect ENR in goat milk samples. The limit of the detection (IC15) was 0.04 ± 0.02 ng/mL and half inhibition rate (IC50) was 0.71 ± 0.05 ng/mL. The recovery rates were 96.56% to 105.10% when ENR concentrations were between 10 and 200 ng/mL in goat milk. ELISA and high-pressure liquid chromatography (HPLC) showed a good linear correlation (R2=0.9998). Finally, the 3-dimentional (3D) structure of the ENR antibody variable region was modelled and docked using computer bioinformatics. The results showed that Arg98, Asp99, Gly101, Thr50, Ser51, Ala82, and Tyr85 performed key functions during antibody-antigen recognition. The results of this study provide theoretical guidance for future antibody structure modifications.
    46  Quality Changes during Tomato Shelf-life Based on Texture Profile Analysis and Visible/Near-infrared Spectroscopy
    WU Gui-fang JIANG Wei WANG Chun-guang LI Lin WANG Hong-bo
    2015, 31(6):290-294. DOI: 10.13982/j.mfst.1673-9078.2015.6.046
    [Abstract](892) [HTML](0) [PDF 725.49 K](1110)
    Abstract:
    Texture profile analysis (TPA) was applied to study the quality changes, i.e., changes of tomato texture parameters, during tomato shelf-life. Typical textural property curves were obtained by TPA, and textural parameters such as hardness, adhesiveness, cohesiveness, springiness, gumminess, and chewiness were calculated by analyzing the textural property curves. A correlation matrix was constructed by correlation analysis between the textural parameters. The results show that tomato textural parameters decreased to different extents with increasing storage time. Tomato hardness and cohesiveness showed a significant correlation (P<0.01). Tomato chewiness was correlated to other textural properties (P<0.05). Tomato shelf-life was divided into three periods: earlier stage (1~3 days), middle stage (4~6 days), and later stage (7~9 days) according to the variation patterns of textural parameters. Visible/near infrared spectroscopy combined with principal component analysis (PCA) was used to identify tomatoes in different stages of shelf-life, and the recognition rate was 97.2% based on PC1 and PC2. This method has laid the theoretical foundation for the further construction of a quality prediction model during fruit and vegetable shelf life.
    47  Aroma analysis of Chicken Flavorings with Different Degrees of Hydrolysis
    TIAN Huai-xiang LI Feng-hua QIN Lan YU Hai-yan MA Xia
    2015, 31(6):295-302. DOI: 10.13982/j.mfst.1673-9078.2015.6.047
    [Abstract](954) [HTML](0) [PDF 991.33 K](1472)
    Abstract:
    Chicken flavorings were prepared by the Maillard reaction using chicken skeleton hydrolysates that were hydrolyzed to different degrees as raw materials. The chicken flavorings with different degree of hydrolysis were used to investigate the aroma attributes using sensory evaluation and an electronic nose. The volatile compounds were identified by gas chromatography-mass spectrometry (GC-MS). Principal component analysis (PCA) was used to differentiate the chicken flavorings. The correlation between the sensory attributes and the volatile compounds was analyzed using partial least square regression (PLSR). The sensory evaluation indicated significant differences between the different chicken flavorings in the aroma properties of chicken, fat, spicy, garlic, onion, soy sauce, harmony, and overall flavor. The results of the electronic nose in combination with PCA explained 99 % of the variance, which showed that the electronic nose had the ability to differentiate chicken flavorings with different degrees of hydrolysis. A total of 82 volatile compounds including aldehydes (17), ketones (7), nitrogen- and sulfur-containing compounds (12), alkenes (15), alcohols (19), esters (2), and acids (10) were identified using GC-MS. Thirty-six volatile compounds showed good correlation with six sensory attributes according to the PLSR models. The results demonstrate that the electronic nose and GC-MS combined with multivariate statistical analysis were effective identification tools for the discrimination of chicken flavorings with different degrees of hydrolysis.
    48  Simultaneously Detecting Chlorophenols and Isothiazolinones in Food Contact Paper Packaging Materials using Ultrahigh-performance Liquid Chromatography Tandem Mass Spectrometry
    ZHANG Cong HUANG Jin-feng CAI Wei-hong LI Xiu-ying GUO Xin-dong HE Min-heng FENG Xiang
    2015, 31(6):303-308. DOI: 10.13982/j.mfst.1673-9078.2015.6.048
    [Abstract](1391) [HTML](0) [PDF 754.79 K](1455)
    Abstract:
    A comprehensive analytical method was developed to simultaneously detect chlorophenols and isothiazolinones (MI, CMI, BIT, 2,4-DCP, 2,4,6-TCP, 2,3,4,6-TCP, PCP, and OPP) in food contact paper packaging materials using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and solid phase extraction (SPE). The paper samples were subjected to ultrasonic methanol extraction, concentrated, and purified with an Oasis HLB SPE cartridge. The extract was separated in a Phenomenex Kinetex C18 column (100 mm × 3.0 mm, 2.6 μm) using gradient elution with a methanol-water mobile phase. The MS/MS analysis was performed in electrospray ionization mode with multiple reaction monitoring (MRM) and separated into two segments of positive and negative ionization modes. Eight compounds were identified by retention time and the ratio of characteristic ions, and these were quantified using the external standard methods. Under optimal conditions, the calibration curves for the eight analytes were linear within the range of 2.0 to 400 μg/L, with correlation coefficients more than 0.997. The quantitation limits of the method (S/N=10) for the eight compounds were 10 to 30 μg/kg. The mean recoveries for paper samples at spiked concentration levels of 10 to 300 μg/kg were between 80.3% and 107%, while the relative standard deviations (RSDs, n = 6) ranged from 3.5% to 9.3%.
    49  Qualitative Investigation of Sunflower Oil Peroxide Value Based on LF-NMR and Discriminant Analysis
    XIA Yi-miao WANG Xin LU Hai-yan LIU Bao-lin
    2015, 31(6):309-314. DOI: 10.13982/j.mfst.1673-9078.2015.6.049
    [Abstract](868) [HTML](0) [PDF 832.67 K](1180)
    Abstract:
    A rapid, qualitative method was developed to determine whether the peroxide value of sunflower oil exceeded the limit using low-field nuclear magnetic resonance (LF-NMR). One hundred and sixty-two samples oxidized to different degrees, including 74 oil samples exceeding the limit, were collected from 8 brands (LH, JLY, FLM, RQ, HS, KW, DL, and RS) and were studied. A direct discrimination method was used to determine the peroxide values using LF-NMR relaxation characteristics (T21, S21, T22, S22, T23, S23, and T2W) as independent variables. The results indicated that consistency could be found between the relaxation characteristics and oxidation time. The overall accuracy of the discrimination model was 85.8%, among which those of RQ and RS sunflower oil were above 90%, while the rest were above 80%, except for that of HS (77.27%)。These results indicate that there was a good discriminatory effect. Therefore, it is feasible to rapidly assess peroxide values using LF-NMR relaxation characteristics of sunflower oil, which is a time and energy-saving method and has important practical implications.
    50  Determining the Geographic Origin of Cooked Chicken Based on Near-infrared Spectroscopy
    SUN Xiao SHI Yan
    2015, 31(6):315-321. DOI: 10.13982/j.mfst.1673-9078.2015.6.050
    [Abstract](1075) [HTML](0) [PDF 943.88 K](1228)
    Abstract:
    One hundred and eighty chicken samples of the same age obtained from different factories within four production areas in Shandong were processed by three cooking methods (steaming, boiling, and cooking in a microwave), pretreated, crushed, and sieved. The samples were then scanned with a safe and rapid near-infrared (NIR) spectroscopic technique, followed by cluster analysis (CA) and principal component analysis (PCA) of the spectroscopic data, in order to establish a qualitative discrimination model for the traceability of cooked chicken. There were significant differences among the three cooking methods within the wavenumber range of 4000~7000 cm-1 after second derivative (13 point smoothing) and standard normal variable (SNV) pretreatment. The discrimination accuracy of CA was greater than 90%, while the principal components for the chicken samples were distributed in different geographical locations. The discrimination model, calibrated by using known samples, was used to predict unknown chicken samples, which attained a discrimination accuracy of 90%–95%. These results show that applying NIR spectroscopy to trace the geographical origins of cooked chicken is feasible.
    51  Variations in Fatty Acid Composition of Camellia Oleifera Abel. Seeds during Development
    LIU Xing-xing XIAO Ping LUO Huo-ling HUANG Xue-yong FU Yu-xin LUO Li-ping
    2015, 31(6):322-328. DOI: 10.13982/j.mfst.1673-9078.2015.6.051
    [Abstract](961) [HTML](0) [PDF 1023.94 K](1125)
    Abstract:
    To rapidly determine the variations in fatty acid composition during the development of Camellia oleifera Abel. seeds, the seeds of C. oleifera, peanuts (Arachis hypogaea), and sesame (Sesamum indicum) were pre-treated with shaking + methyl esterification and soxhlet extraction + methyl esterification. The fatty acid compositions of the seeds were analyzed by gas chromatography-mass spectrometry (GC-MS). The morphology of C. oleifera seed oil body in the cotyledon was observed by laser scanning confocal microscopy (LSCM). The results showed that the method of shaking + methyl esterification was more suitable for the rapid detection of fatty acids in large numbers of samples due to its convenience, precision, and speed. The oil content peaked at 47~54 weeks after flowering (WAF), which was between September and the picking season. Oleic acid was the main type of fatty acid throughout the development of C. oleifera seeds, and it increased gradually during growth and its content in mature seeds was above 78%. However, palmitic acid, stearic acid, and linoleic acid showed clear decreasing trends during the same period. Cytological observations also indicated that the peak period for oil conversion in this Camellia strain was between 45 to 48 WAF.
    52  Determination of Trehalose in Saccharide Mixtures Based on Trehalase-catalyzed Hydrolysis
    WANG Qing-yun WANG Yue LIN Qin-lu
    2015, 31(6):329-333. DOI: 10.13982/j.mfst.1673-9078.2015.6.052
    [Abstract](897) [HTML](0) [PDF 550.16 K](1225)
    Abstract:
    Based on the specificity of trehalase in hydrolyzing trehalose to glucose, a simple and rapid method for the determination of trehalose in saccharide mixtures was established. Excess trehalase ensured that trehalose would be hydrolyzed completely into glucose in a short time period, and then, the dinnitrosalicylic acid (DNS) method was used to determine the reducing sugar content in both samples before and after hydrolysis. The trehalose content could be calculated using the difference in reducing sugar content. The data of trehalose content in mixed solutions containing a trehalose standard, maltose, fructose, glucose, and sucrose were analyzed, and the results showed that the recovery rates of trehalose were in the range of 91.12%~105.92% and relative standard deviation was 2.22%~3.43%. Other saccharides in the mixture did not interfere with the content data with a detection limit of 70 μg/mL. The trehalose content in the intermediate product of fermentation was determined via the trehalase hydrolysis method and high performance liquid chromatography (HPLC). A t test showed that there was no difference between the two groups. The trehalase hydrolysis method was rapid, accurate, and sensitive. It can be used for samples with complex sugar compositions, and has a wide range of applications.

    Editor in chief:李琳

    Inauguration:现代食品科技

    International standard number:ISSN 1673-9078

    Unified domestic issue:CN 44-1620/TS

    Domestic postal code:46-349

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