Volume 30,Issue 10,2014 Table of Contents

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  • 1  Effects of Acrolein Oxidization on Muscle Structure and Myofibrillar Protein Structural Properties in Large Yellow Croaker (Pseudosciaena crocea)
    LI Xue-peng WANG Qi ZHOU Kai QU Hong-yan GAO Yan-lei ZHANG Xiao-lin LIU Yu LI Jian-rong
    2014, 30(10):1-7.
    [Abstract](1844) [HTML](0) [PDF 726.69 K](808)
    Abstract:
    In order to investigate the effects of small molecular aldehydes (among secondary lipid oxidation products) on the muscle structure and structural properties of myofibrillar proteins in large yellow croaker (Pseudosciaena crocea), the fish muscle was treated with different concentrations (0~10 mmol/L) of acrolein in an ex vivo oxidation experiment. The results showed that treatment with acrolein could lead to increased gaps between myofibers in large yellow croaker. Muscle fiber fracture and fragmentation occurred when the acrolein concentration reached 10 mmol/L, and the water-holding capacity of the fish muscle decreased when the acrolein concentration was greater than 0.1 mmol/L. The carbonyl content, bityrosine content, and surface hydrophobicity of the myofibrillar proteins increased significantly with an increase in the acrolein concentration above 0.1 mmol/L, whereas the contents of total sulfhydryl groups decreased significantly. Active sulfhydryl groups were sensitive to acrolein, and their contents decreased by 40.8% compared with the control at an acrolein concentration of 0.01 mmol/L. The SDS-PAGE results showed that acrolein oxidation could cause conjunction of some protein subunits, which formed aggregates in the area above 200 ku. In addition, the oxidation caused damage of the gel properties of the myofibrillar proteins, including decreases in the gel strength, water-holding capacity, and gel whiteness. All these results indicate that acrolein can damage the muscle structure of large yellow croaker and cause oxidation of the myofibrillar protein, thus damaging the structure and functional properties of the protein.
    2  PCR-DGGE Analysis of the Microbial Diversity in Naturally Fermented Suan-cai from Northeast China
    WU Ri-na YU Mei-ling MENG Ling-shuai XU Xin YUE Xi-qingi WU Jun-ru
    2014, 30(10):8-12.
    [Abstract](1291) [HTML](0) [PDF 693.85 K](1139)
    Abstract:
    In order to reveal the microbial diversity and predominant microflora in traditional naturally fermented suan-cai from Northeast China, kinetic changes in microbial communities during the fermentation of suan-cai were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results indicated that the naturally fermented suan-cai contained many types of bacteria, but relatively few fungi. The most active bacterium was Leuconostoc sp., observed in the early stage of the fermentation process, followed by the fermenting and acid-producing bacteria L. acidophilus, L. fermentum, and L. plantarum, before the fermentation was completed by L. plantarum. Leuconostoc sp. was the predominant microorganism in the early fermentation stages, whereas L. plantarum was predominant in the middle and later stages. Debaryomyces hansenii, Candida tropicalis, and Penicillium expansum were the dominant fungi during the fermentation process. The number of fungi decreased with increasing fermentation time, and the types of fungi also varied with the different stages of fermentation.
    3  Effects of 7S and 11S Soy Protein on the Qualities of Dough and Chinese Steamed Bread
    GAO Xue-li CHEN Fu-sheng ZHANG Li-fen BU Guan-hao FAN Ming-tao
    2014, 30(10):13-18.
    [Abstract](1440) [HTML](0) [PDF 537.25 K](843)
    Abstract:
    This study was devised to evaluate the effect of the soy protein, 7S and 11S soy protein on farinograph of wheat dough, pasting, the distribution and migration of the water behaviour and texture quality attributes of Chinese steamed bread (CSB). The results showed that flour mixtures with CSP was able to increase the soy/wheat dough stability (S) and decrease the degree of softening (DS), while with 7S or 11S separately was able to decrease the soy/wheat dough stability (S) and increase the degree of softening (DS); The anti-aging degree and water holding capacity of mix flour dough decreased in the order of 11S>7S>CSP. The hardness, chewiness,and cohesiveness of CSB decreased in the order of CSP>7S>11S soy protein. Therefore, The CSB made of adding 3%11S soy protein wheat flour have the highest sensory score (90 point). These results provide theoretical basis for the application of soy protein, 7S, and 11S in the CSB.
    4  Histological Characteristics of Grass Carp Muscle during Cold Storage
    WANG Jian-hui JIN Na LIU Dong-min LIU Yong-le CHEN Qi WANG Fa-xiang LI Xiang-hong YU Jian
    2014, 30(10):19-23.
    [Abstract](1417) [HTML](0) [PDF 655.33 K](724)
    Abstract:
    The histological features and changes in lipid and protein characteristics of grass carp muscle during cold storage at 2 ℃~4 ℃ were investigated using transmission electron microscopy, gas chromatography-mass spectrophotometry, and sodium dodecyl sulfate- polyacrylamide gel electrophoresis. The results showed that there was a large number of lipid droplets accumulated below the sarcolemma of fresh grass carp muscle and most of these droplets showed signs of discharging. Additionally, there were numerouslipid droplets with diameter of 0.25~0.5 μm around the mitochondria, observed between myofibrils in the abdominal muscle of the fish. However, no lipid droplets were found between the myofibrils in the muscle of the back region. During cold storage at 2 ℃~4 ℃, varying degrees of rupture were observed in the myofilaments of grass carp muscle, and the cell structure gradually disintegrated. In severe cases, autolysis or watery transformation appeared in a large area of myofibrils; vacuole-like cells and degenerated cell debris were noted; severe edema accumulated in sarcoplasmic reticulum and mitochondrias; intracellular lipid droplets gradually migrated toward the sarcolemma, where they slowly degraded. Meanwhile, with increasing cold storage time, monounsaturated fatty acids, polyunsaturated fatty acids, and their main corresponding fatty acids degraded gradually, while saturated fatty acids and their main corresponding fatty acids increased. Furthermore, myofibrillar content and sarcoplasmic proteins gradually degraded. The significant degradation of myosin heavy chains and actin led to a gradual rupture of myofilament in the muscle and visual blurring of cell structures, which eventually led to deterioration of fish meat quality.
    5  Influence of Glycation on Biological Activity and Functional Properties of Egg White Protein-maltooligosaccharide Conjugation
    WANG Jun WANG Zhong-he SONG Feng-yan YU Shu-juan LI Gui-li GU Xiao-hong
    2014, 30(10):24-29.
    [Abstract](1067) [HTML](0) [PDF 577.07 K](723)
    Abstract:
    In this study, egg-white protein and maltooligosaccharides were used for non-enzymatic glycation. The extent of glycation was evaluated in terms of degree of browning and grafting. The results showed that the glycation products obtained after heating for 2 h by moist-heat method showed the highest grafting degree and the lowest browning degree. Reaction products were generated mainly at the end of the initial or intermediate stages. The non-enzymatic glycation reaction not only improved the metal reducing power and DPPH-scavenging capacity of egg-white protein but also enhanced its Fe2+-chelating ability. The analysis of functional characteristics indicated that non-enzymatic glycation enhanced the solubility and thermostability of egg white protein, but did not affect its emulsifying activity and emulsion stability. Meanwhile, in vitro digestion experiments showed that non-enzymatic glycation reduced the digestibility of egg-white protein, which might be due to degradation by intestinal microorganisms in the large intestine. The above results indicate that non-enzymatic glycation reaction provides an effective approach to significantly enhance functional and bioactive properties of proteins.
    6  Moisture Sorption Characteristics and Mathematical Models of Rapeseed (Brassica napus)
    YANG Ling CHEN Jian XU Wu-ming YANG Ming-jin LIU Bin NIU Po LAN Yu-bin
    2014, 30(10):30-35.
    [Abstract](1112) [HTML](0) [PDF 464.37 K](720)
    Abstract:
    The moisture sorption characteristics of rapeseed (Brassica napus) affect the storage quality of the crop and the techniques used in harvesting and storage. To provide a technical basis for the harvesting, storage, and management of rapeseed, this paper experimentally studied the moisture sorption characteristics of rapeseed at 0~30 ℃ and relative humidity of 32%~38%, and compared the applicability of seven mathematical models in the moisture sorption process of rapeseeds. The results showed that temperature and relative humidity were the main factors affecting the moisture sorption of rapeseed. With increasing temperature, the time needed for sorption equilibrium decreased, and with increasing relative humidity the equilibrium moisture content and time needed for sorption equilibrium increased. The net isosteric heat of rapeseed sorption exponentially decreased with increasing equilibrium moisture content. The Peleg model was considered to be the best mathematical model in describing the moisture sorption characteristics of rapeseed, with a correlation coefficient of 0.999, Chi-square value of 0.154, and root mean square error of 0.160. With increasing temperature, the critical relative humidity of rapeseed increased, and it is therefore considered that the critical relative humidity could be effectively decreased by decreasing the storage temperature. With the increase of equilibrium moisture content, the net isosteric heat of sorption of rapeseed exponentially decreased.
    7  Synthesis of Dihydromyricetin-theanine Complex and Its Antioxidant Activity
    CAO Min-hui JIANG Qing ZHENG Xi-zhou PENG Wen NI De-jiang
    2014, 30(10):36-41.
    [Abstract](1946) [HTML](0) [PDF 599.30 K](872)
    Abstract:
    Dihydromyricetin is currently attracting extensive scientific attention because of its various physiological functions. Although the content of dihydromyricetin in Ampelopsis grossedentata is up to 25.6%, its poor water solubility at room temperature and low bioavailability limit the scope of its application. In order to improve the water solubility of dihydromyricetin, its structure was modified and a dihydromyricetin-theanine complex was prepared. The structure was characterized by UV, IR, MS, and 1HNMR spectra, its physical and chemical properties were measured, and the antioxidant activity of the complex was investigated. Based on structural analysis, the complex was found to be formed via hydrogen bonding interactions between C3-OH, C5-OH, C7-OH, C3'-OH, and C5'-OH in dihydromyricetin and active hydrogens in theanine. The scavenging capacity of the complex against hydroxyl free radicals was stronger than that of dihydromyricetin and Vc, and was equivalent to that of dihydromyricetin against superoxide and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, but was better than that of Vc. It is therefore considered that the complexation of dihydromyricetin with theanine not only improved the water solubility of dihydromyricetin but also enhanced its antioxidant activity.
    8  Effect of 1-Methylcyclopropene Treatment on Peach Softening and α-L-Arabinofuranosidase Activity and Gene Expression
    KAN Juan LIU Jun JIN Chang-hai
    2014, 30(10):42-46.
    [Abstract](1183) [HTML](0) [PDF 736.28 K](785)
    Abstract:
    In this study, ‘Yuhuasanhao’ (melting-flesh) and ‘Jianayan’ (non-melting-flesh) peach cultivars were used to study the effect of 1-methylcyclopropene (1-MCP) treatment on the basic physiological changes and activity of α-L-arabinofuranosidase (an important enzyme related to the degradation of cell wall polysaccharides) during the softening of the peach fruit. This study could provide a theoretical basis for further study of the ripening mechanism of drupe fruits. The main results were as follows: 1-MCP effectively delayed the decline of peach firmness and inhibited ethylene release during the first eight days of storage for ‘Yuhuasanhao’ and after four days of storage for ‘Jianayan’ cultivars. 1-MCP treatment showed a certain inhibitory effect on the respiration rate of different flesh types of peaches, which were observed during the first ten days of storage for ‘Yuhuasanhao’ variety, but after six days of storage for ‘Jianayan’ variety. 1-MCP treatment led to inhibition of α-L-arabinofuranosidase translation and enzyme activity, and the inhibition rate after six days of storage for ‘Yuhuasanhao’ and 12 days of storage for ‘Jianayan’ was 50%. Peach fruit softening was delayed, further demonstrating that the role of α- L-arabinofuranosidase on cell wall degradation was regulated by ethylene.
    9  Synthesis and Antimicrobial Activity of Fumaric Acid Amino Acid Ester Derivatives
    NING Zheng-xiang SU Lan LIAO Wen-zhen YUAN Er-dong WEI Qing-yi
    2014, 30(10):47-51.
    [Abstract](1436) [HTML](0) [PDF 565.29 K](784)
    Abstract:
    In this study, eight kinds of fumaric acid amino acid ester derivatives were synthesized through amidation and isomerization, by using maleic anhydride and amino acid ester as raw materials and anhydrous aluminium chloride as an isomerization catalyst. Using a ratio of maleic anhydride to amino-acid ester to anhydrous aluminum chloride as 0.2 mol:0.2 mol:1.0 g, the yield of these products was more than 75%. The molecular structure of the compounds was determined by melting point determination and 1H nuclear magnetic resonance imaging. Antimicrobial activity of these compounds against Escherichia coli, Staphylococcus aureus, Salmonella sp., Bacillus subtilis, Lactobacillus sp., bacteria causing milk spoilage, as well as skin smear tests were conducted. The results showed that the minimum inhibitory concentration of fumaric acid amino acid ester derivatives were comparable to that of dimethyl fulminate. Moreover, fumaric acid amino acid ester derivatives did not cause skin allergy, while dimethyl fumarate caused strong skin allergic reactions (red rash). Cell viability of normal liver cells (L02) and hepatoma cells (HepG2) exposed to fumaric acid amino acid ester derivatives was also evaluated, which showed no toxic effect on either cell type.
    10  Purification, Identification and Evaluation of the Stability of Angiotensin I-converting Enzyme Inhibitory Peptides Derived from By-products of Casein Phosphopeptides
    ZHAO Li-chao NING De-shan LONG Zi-qi LIU Fei CHEN Fei-long CAO Yong
    2014, 30(10):52-57.
    [Abstract](1396) [HTML](0) [PDF 624.63 K](681)
    Abstract:
    By-products of casein phosphopeptide contain abundant functional peptides, from which angiotensin I-converting enzyme (ACE-I) inhibitory peptides with antihypertensive activity can be recycled. This is of significance for utilizing waste and protecting the environment. Based on previous research on technology that accumulates bioactive peptides, the peptide monomers with antihypertensive activity were isolated and purified from crude-enriched products, and the molecular weights of peptide monomers, their primary sequences, and stabilities were studied. The results showed that, using the crude products as raw materials, ACE-I inhibitory peptide monomers with high activity, P16 and P18, could be obtained in just two steps, including anion-exchange chromatography and HPLC. The molecular weight of P16 was 742.6 and its primary sequence was GPFPIIV, which was discovered for the first time. The molecular weight of P18 was 1385.8 and its primary sequence was FFVAPFPEVFGK. Both P16 and P18 possessed high acid-base resistance and thermal stability. Various degrees of decomposition occurred in both peptides in the in vitro gastrointestinal digestion test. Nevertheless, the activity of P16 increased by 12.8%, while that of P18 decreased by 37.5%. Thus, the rise and decline were related to the exposure or destruction of the active centers.
    11  Antimicrobial Activity of Pickled and Dried Mustard Extracts and their Application in Pork Preservation
    HUANG Shi-rong LI Hao-jie DAI Jie-hui WANG Chao TANG Yu-fang
    2014, 30(10):58-62.
    [Abstract](1498) [HTML](0) [PDF 540.93 K](763)
    Abstract:
    Anti-microbial activity of ethanolic crude extract and three kinds of solvent sub-fractions (petroleum ether fraction [PEF], ethyl acetate fraction [EAF], and the residual fraction [RF]) from pickled and dried mustard extract against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Aspergillus niger were investigated. The effect of EAF on pork preservation was also studied. The inhibition-zone diameter and minimum inhibition concentration (MIC) of various samples against all tested strains were determined using agar disk diffusion method and broth dilution method, respectively. The effect of EAF on pork preservation was evaluated by total plate counts, pH, total volatile basic nitrogen (TVB-N) content, and thiobarbituric acid-reactive substance (TBARS) content. The results showed that all samples had no obvious antimicrobial activity against Aspergillus niger, but they exhibited strong antibacterial activities against the other three bacteria tested. Among all fractions, EAF showed the strongest antibacterial activity, and its MIC against Bacillus subtilis, Staphylococcus aureus, and Bacillus coli was 0.1, 0.1, and 3 mg/mL, respectively. EAFs at concentrations of 3 and 5 mg/mL could effectively reduce the total plate counts, TVB-N, pH, and TBARS values of pork stored at 4 ℃. Compared with the control group, treatment of pork samples with EAF could extend its shelf life by 3~6 days.
    12  Effects of Hydrocolloids on the Quality of Wheat-corn Mixed Flour and Steamed Bun
    LI Wen-zhao SHI Zong-yi DU Yi-deng SHI Ying-zhou GAO Rui-fei RUAN Mei-juan
    2014, 30(10):63-67.
    [Abstract](1422) [HTML](0) [PDF 607.96 K](775)
    Abstract:
    Using corn and wheat flour as raw materials, the effects of four hydrocolloids (xanthan gum, guar gum, carboxymethyl cellulose sodium, and konjac gum) at different dosages (0.5 %, 1%, 1.5%, and 2%) on the farinograph properties of mixed flour (water absorption, dough formation time, stabilization time, and degree of softening) and the qualities of wheat-corn mixed-flour steamed bun (specific volume, hardness, springiness, and sensory evaluation) were investigated. The farinograph properties were analyzed by a farinograph. The specific volume of wheat-corn mixed-flour steamed bun was measured by a volume meter. The hardness and springiness were measured by a texture analyzer. The results showed that all four hydrocolloids increased the water absorption, dough formation time, and stabilization time of the mixed flour while reducing the degree of softening, albeit some differences were observed. Although the effect of xanthan gum on the farinograph properties was the most remarkable, its effect on wheat-corn mixed-flour steamed bun was out of expectation. The qualities of wheat-corn mixed-flour steamed bun were improved by adding appropriate amounts of guar gum, sodium carboxymethyl cellulose, and konjac glucomannan. Specifically, the specific volume of the mixed steamed bun was the maximum with adding 2% konjac glucomannan, the hardness was the minimum with adding 0.5 % konjac glucomannan, and the springiness and sensory quality scores were the highest with adding 2% sodium carboxymethyl cellulose.
    13  Relationship between Color index a* Values and Other Quality Indicators of Litchi Pericarp during Storage
    GUO Jia-ming LV En-Li LU Hua-zhong LI Ya-hui ZENG Zhi-xiong
    2014, 30(10):68-73.
    [Abstract](1445) [HTML](0) [PDF 615.23 K](647)
    Abstract:
    Browning is one of the main factors affecting sales of litchi fruit. In order to understand the relationship between color change and other quality indicators of litchi fruit, ‘Guiwei’ litchi fruit was chosen for this study. The fruit was packaged in PE packaging bags with holes and stored under cold storage and controlled atmosphere storage conditions, for 30 days. The change of color index a* values of litchi pericarp and other quality indicators were studied, and the data were fitted to a linear relationship. The results showed that controlled atmosphere storage was advantageous in suppressing the change of color index a* value of litchi pericarp, which decreased from 35.0 to 28.97 under controlled atmosphere conditions, whereas it decreased to 20.96 under cold storage conditions. In addition, a* value of litchi pericarp showed a linear relationship with the rate of pericarp moisture loss, browning index, anthocyanin content, weight loss rate, and sensory evaluation score, with an average correlation coefficient of 0.8609. However, a* value of litchi pericarp did not show a significant linear relationship with conductivity and pH value, while the average correlation coefficients were 0.5392 and 0.4977, respectively. Under cold storage conditions, expect for sensory evaluation value, a* value of litchi pericarp showed better linear correlations with other quality indicators when compared to those under controlled atmosphere conditions, where the average correlation coefficient was 0.7752 under controlled atmosphere conditions, but was 0.9465 under cold storage conditions. The results of this study provide a reference for predicting litchi shelf life by color index of the pericarp.
    14  Effect of Chlorogenic Acid on Formation of 5-Hydroxymethylfurfural in Fructose-acid Reaction Systems
    WU Tai-gang HUANG Cai-huan BAI Wei-bin QIU Rui-xia LIU Liu ZHANG Zhen-hua OU Shi-yi
    2014, 30(10):74-79.
    [Abstract](1413) [HTML](0) [PDF 532.39 K](777)
    Abstract:
    In this study, a reaction system consisting of fructose, citric acid, and sodium citrate buffer solution was developed to investigate the effect of chlorogenic acid on the formation of 5-hydroxymethylfurfural (HMF) and the intermediate product 3-deoxyglucosulose (3-DG) under different pH environments, to mimic drying of plum fruit under high temperature conditions. The results showed that chlorogenic acid could influence the formation of HMF and 3-DG, which was also affected by pH conditions. At pH values of 2.80 and 3.70, the addition of chlorogenic acid inhibited the formation of HMF and 3-DG; the lower the pH value, the higher the inhibition rate. At pH values of 4.70 and 5.70, the addition of chlorogenic acid significantly promoted the formation of HMF; with increasing pH, an increased production of HMF as well as 3-DG was observed. However, at the same pH, chlorogenic acid did not have a significant promoting effect on the formation of 3-DG. At pH 6.0, a high dose (42 mmol/mL) of chlorogenic acid could significantly increase the rate of HMF formation. When the reaction was carried out at 90 ℃ for 48 h, HMF yield was increased by 1.14-fold. Thus, at lower pH, fructose tended to form HMF via the fructofuranosyl cation pathway and chlorogenic acid could inhibit the formation of 3-DG to decrease the HMF content. At higher pH, fructose was more likely to form HMF via the 3-DG pathway and chlorogenic acid could increase the HMF content by promoting the conversion of 3-DG to HMF.
    15  The Effects of Immersion Chilling and Freezing on Prepared Grass Carp (Ctenopharyngodon idellus) Fillet Quality during the Freezing Process
    LIN Wan-ling YANG Xian-qing SONG Ying HU Xiao LI Lai-hao WEI Ya YANG Shao-ling HAO Shu-xian WU Yan-yan HUANG Hui
    2014, 30(10):80-87.
    [Abstract](1170) [HTML](0) [PDF 646.18 K](798)
    Abstract:
    In this study, the effects of immersion chilling and freezing (ICF) and static air freezing (SAF) on the quality of prepared grass carp fillets (PGCFs) were examined using texture, pH, lipid oxidation, protein content, water content, total volatile basic nitrogen (TVB-N), color, and sensory evaluation as indices, combined with an examination of the freezing curve. The results indicated that maximum ice crystal formation in PGCFs frozen by ICF and SAF required 3.0 min and 19.5 min, respectively. The hardness, springiness, chewiness, protein content, and water content of PGCFs frozen by both techniques showed significant decreases; however, these variables showed higher values for PGCFs frozen by ICF than for those frozen by SAF. In contrast, pH, lipid oxidation, TVB-N content, and color were lower for PGCFs frozen by ICF than by SAF. These results showed that PGCF proteins denatured and their quality gradually decreased during frozen storage. The results of a sensory evaluation further indicated that the structure, flavor, appearance, and taste of PGCFs frozen by ICF and SAF declined by various degrees. The sensory evaluation scores of PGCFs frozen by ICF were higher than those of PGCFs frozen by SAF. In summary, the quality of PGCFs was better maintained using ICF than SAF during frozen storage.
    16  Effect of N-acylhomoserine Lactones on Biogenic Amine Production from Bacteria and Analysis of Biofilm Formation Characteristics
    LU Jing LU Shi-ling LIU Yu-han JIANG Cai-hong WANG Shao-mei
    2014, 30(10):88-95.
    [Abstract](1221) [HTML](0) [PDF 872.74 K](705)
    Abstract:
    In this study, Klebsiella spp., Enterobacter cloacae, and Pantoea agglomerans, which are dominant biogenic amine-producing bacteria in smoked and fermented horsemeat sausages, were used as test strains; quorum-sensing compounds were detected by a parallel line assay of Agrobacterium tumefaciens A136, and experimental evidence showed that quorum sensing was observed in all three of the dominant strains. N-acylhomoserine lactone (AHL) activity assay, detection, and quantification of biogenic amines, as well as correlation analysis between β-galactosidase activity and biogenic amines were conducted. The results indicated that both Klebsiella spp. and the β-galactosidase activity in P. agglomerans showed a significant positive correlation (RPearson > 0.817, P < 0.01) with putrescine, cadaverine, histamine, and tyramine. The β-galactosidase activity in E. cloacae was significantly correlated with cadaverine (RPearson is 0.923, P = 0.00 < 0.01). In addition, the secretion of AHLs affected the accumulation of biogenic amines, showing a synergistic effect. Meanwhile, biofilm formation and cell hydrophobicity experiments were carried out at 28 ℃ and 37 ℃, respectively. The results indicated that the absorption capacities of xylene, chloroform, and ethyl acetate, as well as cell hydrophobicity values were different for the three dominant strains. Furthermore, the ability of Klebsiella spp. to form biofilms did not show significant difference (P = 0.095 > 0.05), while significant differences (P = 0.0315 < 0.05, P = 0.047 < 0.05) were observed for E. cloacae and P. agglomerans. Therefore, cell hydrophobicity, incubation time, and temperature affected the ability of the dominant bacteria to form biofilms.
    17  Effects of NCgl1221 Knockout and pyc Overexpression on Glutamine Fermentation
    JIANG Yan-zhe ZHANG Cheng-lin WANG Zhi-gang XIE Xi-xian XU Qing-yang CHEN Ning
    2014, 30(10):96-101.
    [Abstract](1460) [HTML](0) [PDF 799.02 K](848)
    Abstract:
    Glutamine has important effects in biological systems and has been widely used in many areas, including in the food and medicine industries. Glutamic acid is the precursor for glutamine biosynthesis, and is the most common by-product in glutamine fermentation. Previous studies have shown that the protein encoded by NCgl1221 is an important glutamic acid exporter and that pyruvate carboxylase is a key enzyme in the feedback pathway of Corynebacterium glutamicum. In order to reduce glutamic acid accumulation during glutamine fermentation and to improve the yield of glutamine, in this study, NCgl1221 of the glutamine-producing strain GM34 was knocked out using homologous recombination technology, resulting in the construction of the mutant strain GM34ΔNCgl1221. Pyc encoding pyruvate carboxylase was also overexpressed in the constructed strain GM34-pXMJ19pyc. Fermentation carried out in 5-L bottles showed that NCgl1221 knockout reduced glutamic acid accumulation by 19.05%. Overexpression of pyc resulted in a promotion of glutamine production and conversion rate by 5.54% and 2.37%, respectively. Taken together, these results demonstrate that NCgl1221 knockout and pyc overexpression can effectively reduce glutamic acid accumulation and improve glutamine production.
    18  Effects of Three Sugar Alcohols on the Gelatinization Characteristics and Gel Structure of Sorghum Starch
    YU Jing XIONG Liu SUN Qing-jie HAN Zhong-jie
    2014, 30(10):102-107.
    [Abstract](1028) [HTML](0) [PDF 629.14 K](686)
    Abstract:
    In this study, the effects of sugar alcohols (erythritol, xylitol, maltitol) at different concentrations (sorghum starch/sugar alcohol ratios of 1:1, 1:2, 1:5, m/m, respectively) on the characteristics and gel structure of sorghum starch were studied using rapid visco Analyzer (RVA), texture profile analyzer (TPA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). As compared to the original sorghum starch, with increasing sugar alcohol (erythrose, xylitol, maltitol) content, the degree of sorghum starch swelling decreased, especially at 75 ℃, 85 ℃, and 95 ℃. RVA measurements revealed that peak viscosity and breakdown values of sorghum starch decreased with increasing sugar alcohol contents, while the gelatinization temperature of sorghum starch increased. The hardness of sorghum starch gel increased with increasing the addition amount of sugar alcohol. DSC measurements showed that the gelatinization onset temperature, peak gelatinization temperature, gelatinization termination temperature, and enthalpy change of sorghum starch increased with increasing sugar alcohol contents. The SEM photographs indicated that the microstructure of sorghum starch with sugar alcohol was more compact.
    19  Isolation and Identification of Dibutyl Phthalate-degrading Strain and Its Degradation Characteristics
    LI Jian-long SHAO Xiang-li LIU Shu-liang YAO Kai ZHAO Qin HU Xin-jie DENG Wei-qin
    2014, 30(10):108-114.
    [Abstract](1518) [HTML](0) [PDF 630.58 K](812)
    Abstract:
    In this study, a high-efficiency degrading strain, JF, that utilized dibutyl phthalate (DBP) as the sole source of carbon and energy for growth was isolated from vegetable field soil in Ya’ an, Si Chuan province, where mulch film was used. The strain was identified as Bacillus subtilis based on morphology, physiological and biochemical features, and 16S rDNA sequence analysis. Study on growth dynamics of strain JF in LB medium showed that degradation of dibutyl phthalate conformed to a first-order kinetics equation model. Based on substrate concentration, temperature, and pH, the half-life of DBP was estimated to be between 3.11 and 6.98 h. Additionally, the reaction rate was greatly influenced by substrate concentration and temperature but was not largely affected by pH. The strain was able to degrade DBP as well as its intermediate product phthalic acid. Degradation rate of 200 μg/mL di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DOP), and butyl benzyl phthalate (BBP) in 72 h was 90.10%, 79.10% and 76.30%, respectively. This study could provide theoretical basis for the removal of pollutant phthalic acid ester from both, the environment and agricultural products.
    20  Effect of Inclusion of 4-Hydroxychalcone in Hydroxypropyl-β-Cyclodextrin
    CHEN Chun-gang YUAN Chao LI Jia-qi MO Hai-zhen MA Han-jun LIU Ben-guo
    2014, 30(10):115-119.
    [Abstract](1483) [HTML](0) [PDF 728.31 K](689)
    Abstract:
    In order to study the inclusion mechanism of the complex of hydroxypropyl-β-cyclodextrin (HP-β-CD) and chalcone, the thermodynamic parameters of the inclusion process of β-CD, HP-β-CD and 4-hydroxychalcone were measured by phase solubility study. And the physicochemical properties of the complex were investigated by infrared spectrometry (IR), X-ray diffractometry (XRD) and thermogravimetric/differential scanning calorimetry (TG/DSC). It was found the inclusion effect of HP-β-CD on 4-hydroxychalcone was higher than that of β-CD. And the Gibbs energy values were negative for the formation of the complex of HP-β-CD and 4-hydroxychalcone. And the inclusion was a spontaneous process, which was driven by hydrophobic force. IR and XRD analysis showed that the physical phase of 4-hydroxylchalcone had been changed, which were completely dispersed in HP-β-CD. TG/DSC analysis found the heat stability of 4-hydroxychalcone had been significantly enhanced by complexing with HP-β-CD.
    21  Separation, Identification, and Characterization of Food Spoilage Bacteria in Soy Sauce
    LI Na FENG Feng LI Pan LUO Li-xin
    2014, 30(10):120-125.
    [Abstract](1215) [HTML](0) [PDF 765.56 K](844)
    Abstract:
    Lactic acid bacteria (LAB) and Enterobacter species commonly cause spoilage in traditional fermented foods. In this study, three bacterial strains suspected to cause food spoilage were isolated from traditional Chinese grain soy sauce and swollen canned soy sauce. The morphological and physiochemical characteristics and 16S rRNA sequences of the strains were studied. Using PCR-restriction fragment length polymorphism (PCR-RFLP), enterobacterial intergenic consensus–PCR (ERIC-PCR), and species-specific PCR, these strains were identified as Enterobacter aerogenes, Enterococcus faecium (isolated from grain soy sauce), and Lactobacillus acidipiscis (isolated from swollen canned soy sauce). The results showed that E. aerogenes possessed very strong gas-producing abilities, and L. acidipiscis was also a weak gas-producer. When the three bacterial strains were inoculated into soy sauce products, slight changes in the pH values of products were observed. In addition, all of the isolates were temperature-, pH-, and salinity tolerant. Both E. aerogenes and E. faecium are opportunistic pathogens and are potentially harmful to consumers. Furthermore, the presence of L acidipiscis in soy sauce could cause gas production and a reduction in pH, thus resulting in spoilage. The separation and identification of three bacterial strains were important to ensure adequate quality and food safety of soy sauce.
    22  Effect of Glucose Oxidase on Moisture Status and Protein Structure of Dough
    LIU Yan-qi LI Meng-qin ZHOU Yu-jin LI Chao-ran
    2014, 30(10):126-133.
    [Abstract](1554) [HTML](0) [PDF 827.14 K](1212)
    Abstract:
    Nuclear Magnetic Resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) were used to study the effect of glucose oxidase (GOD) (0~0.5%) on moisture distribution and parameter changes of protein structures in dough. A correlation analysis of each experimental indicator was conducted based on the thermodynamic properties of dough and the changes in disulfide bond content. The results showed that the addition of GOD could reduce the relaxation times (T2) for water in dough. In the range of 0~0.5%, the T21 and T22 values decreased first and then increased, whereas when the dose was 0.4%, the measured T21 and T22 values were the lowest; thus, GOD concentration had a significant negative correlation (p < 0.05) with T21 and T22. The amount of β-pleated sheet, β-sheet, α-helix, unordered structure, and β-turn increased first and then decreased, and a significant positive correlation (p < 0.01) was found between GOD concentration and r values. GOD could increase the gelatinization temperature and thermal stability of the dough, promote sulfhydryl groups (-SH) to be converted to disulfide groups (S-S), and significantly affect changes in disulfide groups (S-S). The moisture migration in dough showed significant correlation (p < 0.05) with the gelatinization temperature of dough, disulfide (S-S) content, α-helix, β-turn, and unordered structure. The gelatinization peak temperature (Tp) had significant positive correlation with disulfide groups (S-S), α-helix, and β-turn (p < 0.05).
    23  Effect of Slurry Ice Treatment on the Quality of Fresh Litopenaeus vannamei
    WANG Qiang ZHANG Bin MA Lu-kai WANG Bin
    2014, 30(10):134-140.
    [Abstract](1704) [HTML](0) [PDF 744.63 K](939)
    Abstract:
    The aim of this study was to evaluate the effect of slurry ice on the preservation of fresh aquatic products. We used fresh Litopenaeus vannamei as the study organism,, flake ice and cold storage (blank) as controls to study the effect of slurry ice treatment on the sensory quality, physicochemical properties, and texture properties of the shrimp samples. The results indicated that, after 12 days of storage at -4 ℃, the sensory quality of the blank- and flake ice-treated samples were severely degraded, while the slurry ice-treated samples were slightly browned, the muscle was still resilient and elastic, and the shrimp had clear shells, tentacles, and fantails. Compared with the results of elasticity and chewiness of the blank-treated (0.53 mm and 6.01 mJ) and flake ice-treated shrimp samples (0.66 mm and 7.46 mJ, respectively), the corresponding values for slurry-ice treated shrimp samples were 0.73 mm and 8.53 mJ, respectively, indicating that slurry ice treatment effectively maintained the texture properties (p < 0.05). During the entire storage period, the values of pH, total volatile basic nitrogen (TVBN), and thiobarbituic acid (TBA) were increased in all three groups, while the slurry ice treatment was best at preserving freshness. The ice particles of the slurry ice filled in gaps in the shrimp’s body, which effectively blocked the contact between the shrimp and outside oxygen. At the same time, the rapid cooling effect of slurry ice treatment suppressed or inhibited the activity of polyphenol oxidase in the shrimp, leading to decreased melanosis (p < 0.05). The slurry ice treatment is suitable for ocean and long-distance transporting ice-chilled shrimp, as well as for storing fresh shrimp in markets.
    24  Comparative Evaluation of Functional Components and Antioxidant Activity between Green and Black Tea Extracts
    CHEN Ting-qiang LIU Shu-min HUANG Hui-hua
    2014, 30(10):141-146.
    [Abstract](1417) [HTML](0) [PDF 577.78 K](849)
    Abstract:
    As one of the globally recognized nonalcoholic beverages, tea and their products have high nutritional values and unique health benefits. In this study, the antioxidant activities of two types of tea, homemade green and black teas, were measured and compared using the 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH), oxygen radical absorbance capacity (ORAC), and cellular antioxidant activity (CAA) methods. The difference between the contents of the functional components of green and black tea extracts was also measured. The results showed that both the homemade tea extracts had high antioxidant activity; however, their antioxidant activity decreased with increasing fermentation time. IC50 of DPPH ingreen tea (14.58 μg DM/mL) was lower that in black tea (24.14 μg DM/mL); while ORAC and CAA values of green tea (5313.92 ± 318.75 μmol TE/g DM and 26.23 ± 0.43 μmol QE/100 mg DM, respectively) were higher than those of black tea (3684.14 ± 233.59 μmol TE/g DM and 16.41 ± 0.17 μmol QE/100 mg DM, respectively). The results indicated that with increasing fermentation time, the total dry matter of tea extracts decreased; in particular, the amount of tea polyphenols (TP) showed the highest decrease among the functional components. Thus, tea polyphenols are the major functional components that affect the antioxidant activity of tea extracts.
    25  Effects of Different Strain Combinations on the Quality of Fermented Cantonese Sausages
    HUANG Jin-zhi YANG Rong-ling TANG Dao-bang QU Zhi LIU Xue-ming
    2014, 30(10):147-153.
    [Abstract](1078) [HTML](0) [PDF 592.04 K](769)
    Abstract:
    Cantonese sausages are popular with consumers as a Chinese traditional specialty meat product. Studies on Cantonese sausages are on the rise as more attention is paid to the quality, safety, and use of modern production technology for traditional meat products in China. However, there are relatively fewer studies on the application of fermentation agents in Cantonese sausages. In this study, the effects of different combinations of fermentation agents on the physicochemical characteristics of fermented Cantonese sausages were studied using Lactobacillus plantarum, Pediococcus pentosaceus and Debaryomyces hansenii as fermentation agents. The results indicated that fermentation agents with different combination ratios had a different impact on the quality of fermented Cantonese sausages. The best quality of fermented sausages was obtained using the combination of L. plantarum and P. pentosaceus (2:1, V/V) with inoculum size of 106 cfu/g meat, and the results showed the following properties: moisture content, 19.93%; pH, 5.95; total acid content, 35.60 g/kg; acid value, 3.38 mg/g; peroxide value, 0.059 g/100 g; nitrite residue content, 4.46 mg/kg; flexibility, 0.93; hardness, 9498.86 N; cohesiveness, 0.79; chewiness, 6917.93 N; L * value, 50.86; a * value, 6.66; and b* value, 3.87. Meat products prepared using microbial combinations during processing showed better physicochemical properties than those fermented naturally.
    26  Kinetics of Cadmium, Lead and Aluminum Bioaccumulation by Enteromorpha prolifera
    LIU Zhi-yu WU Jin-na LI Lin YANG Miao-feng HE Chuang-bo ZHENG Sheng-hua CHEN Shao-jun
    2014, 30(10):154-158.
    [Abstract](1506) [HTML](0) [PDF 505.14 K](648)
    Abstract:
    In this study, we investigated the accumulation of cadmium (Cd), lead (Pb), and aluminum (Al) by the alga Enteromorpha prolifera. The metal ions, Cd2+ (5, 20, 80 μg/L), Pb2+ (5, 20, 80 μg/L), and Al3+ (5, 20, 80 μg/L), were added to different culture ponds. Inductively coupled plasma mass spectrometry was used to determine the content of Cd, Pb, and Al in Enteromorpha prolifera. The changes in mineral content were fitted nonlinearly and their kinetic parameters were obtained. The results showed that the accumulation of Cd, Pb, and Al in Enteromorpha prolifera positively correlated with exposure concentration. Accumulation of Cd and Pb satisfied the two-compartment kinetic model, while Al fitted the logistic kinetic model. The two-compartment regression accumulation rate constants (Ka) for Cd were 418.68, 234.30, and 105.57, while the bioaccumulation factors (BCFs) were 1785.12, 1429.67, and 625.69. For Pb, Ka values were 1257.30, 768.81, and 863.83, while the BCFs were 11028.95, 50249.08, and 9119.79. Logistic model regression accumulation rate constants for Al were 0.39, 0.42, and 0.46. Enteromorpha prolifera had relatively strong accumulation effect to Cd, Pb, and Al, which can be significantly predicted for Cd and Pb by the two-compartment model and for Al, by the logistic model.
    27  Removal of Fluoride from Groundwater Using New Biochar Adsorbents
    ZHANG Rui-ling LI De-sheng QIN Song-yan WANG Liang ZHOU Ya-nan WEN Hua HE An
    2014, 30(10):159-164.
    [Abstract](1380) [HTML](0) [PDF 597.67 K](836)
    Abstract:
    In this study, new biochar adsorbents were first prepared from the peanut shell, chestnut shell, walnut shell, and orange peel under different pyrolysis temperatures, and then the fluoride removal effects of these new biochar adsorbents were compared. The results showed that the biochar derived from the peanut shell with pyrolysis at 650 ℃ provided the best defluoridation effect. The surface structure of the peanut shell-derived biochar was then characterized and the effects of factors such as the adsorption equilibrium time, dosage of biochar, pH value, and initial concentration of fluoride ions on the defluoridation of the peanut shell-derived biochar were investigated. The results indicated that the optimum dosage of the biochar was 1 g/100 mL, the optimum pH was approximately 5.5~6, the adsorption equilibrium was attained after approximately 60 min when the removal rate was 82.25%, and that the adsorption capacity was 0.82 mg/g. With an increasing initial concentration of fluoride, the fluoride removal rate showed a declining trend. However, the adsorption capacity showed an increasing trend with increasing fluoride concentration. The simulated results of the adsorption isotherm of fluoride on the peanut shell-derived biochar indicated that the experimental data fitted well with both the Langmuir and Freundlich models. The maximum absorption capacity of this peanut shell-derived biochar on fluoride in groundwater was 1.11 mg/g. This study therefore provides new prospects in the recycling use of waste agricultural biomass and defluoridation of groundwater.
    28  Preparation of Antioxidant Peptides from Pacific Saury and Characterization of Their Antioxidant Activities
    ZHAO Qiang-zhong LIU Dan
    2014, 30(10):165-171.
    [Abstract](1437) [HTML](0) [PDF 763.34 K](782)
    Abstract:
    In this study, trypsin was used for the enzymatic hydrolysis of proteins from Pacific saury. Based on the protein utilization ratio and oxidative free radical absorbance capacity (ORAC), the enzymatic hydrolysis technology was optimized for the preparation of antioxidant peptides from Pacific saury proteins by using a resonance surface analysis. The characteristics of the enzymatic hydrolysates were also examined. The optimal enzymatic hydrolysis conditions were as follows: enzyme dosage, 1,085 U/g; liquid-to-solid ratio, 3:1; and hydrolysis duration, 8 h. Under these conditions, the protein utilization ratio was 76.86%, and ORAC value was 883.40 μmol Trolox equivalent/g. The total amino acid content was 4,576.69 mg/100 mL in the enzymatic hydrolysates from Pacific saury, of which 34.28% were free amino acids and 65.31% were peptides. Among the total amino acids, essential amino acids accounted for 34.76% and antioxidant amino acids and branched-chain amino acids accounted for 26.25%. These results indicated that Pacific saury has high nutritional value. Hydrolysates with molecular weights of 1000~3000 Da were the most abundant and accounted for 44.18% of the enzymatic hydrolysates of Pacific saury. Moreover, the enzymatic hydrolysates showed DPPH radical scavenging activity (IC50 value, 3.32 mg/mL), O2- radical scavenging activity (IC50 value, 5.08 mg/mL), and light absorption power (0.67 at 10.0 mg/mL). Thus, enzymatic hydrolysates of Pacific saury have relatively high antioxidant activities.
    29  High Static Pressure and Enzymatic Hydrolysis-assisted Preparation of Super-fine Bone Powder
    ZHANG Yin WANG Xin-hui WANG Wei ZHANG Jia-ming
    2014, 30(10):172-175.
    [Abstract](1148) [HTML](0) [PDF 487.04 K](712)
    Abstract:
    To optimize the milling ratio, promote recycling and utilization efficiency of livestock and poultry bones, the effect of high static pressure treatment and enzymatic hydrolysis on milling ratio of porcine bones was evaluated in this study. The process of enzymatic hydrolysis was optimized using response surface technology. The calcium and phosphorus content of milled bone powder was measured. The results showed that the milling ratio was higher when the bones were enzymatically hydrolyzed after high static pressure treatment than prior to treatment. Optimization of the enzymatic hydrolysis process using response surface technology showed that the milling ratio reached a maximum of 82.0% with enzymatic hydrolysis at 55 ℃ for 2.01 h, at pH 7.0 and with enzyme addition of 10,363 U/g. The corresponding milling ratio increased by 9.45% as compared with the non-optimized treatment. Analysis of calcium and phosphorus content in raw bones and milled bone powder indicated that the content of calcium and phosphorus was reduced to a lesser extent by high static pressure and enzymatic hydrolysis-assisted milling. These results suggested that the milling ratio of porcine bone was effectively increased by high static pressure and enzymatic hydrolysis-assisted milling, where the calcium and phosphorus content of milled bone powder were similar to that in raw bone.
    30  Quantitative Structure-activity Relationship Model of Anti-rheumatoid Immune-active Peptides Based on Partial Least Square Method
    CHENG Yuan CAO Hui XU Fei YU Jin-song YUAN Min LV Cui-cui
    2014, 30(10):176-181.
    [Abstract](1278) [HTML](0) [PDF 646.20 K](745)
    Abstract:
    In this study, partial least squares (PLS) method was used to build a quantitative structure-activity relationship (QSAR) model for anti-rheumatoid immune activity of peptides. First, based on the bioactivity-related non-bonding effects (such as electrostatic, steric, and hydrophobic interactions) of each atom, the amino acids descriptor best suited for QSAR model of immune activity of peptides was selected to construct a QSAR model for a 47-peptide data set. The results showed that Z-scales amino descriptor achieved multiple-position and multivariate quantitative structure description for amino acid residues and was the most suitable for describing physicochemical properties of anti-rheumatoid immune-active peptides. Using the Z-scales descriptor, the model built on principle component analysis and PLS showed good reliability and predictive ability, with multiple correlation coefficient of 0.986, root mean square error (RMSE) of 0.253, leave-one-out cross-validation correlation coefficient of 0.893, and external validation coefficient of 0.971. Based on the structure-activity relationship of immune-active peptides, this study provides new opportunities for screening and design of new tolerogens for rheumatoid arthritis, thus providing a new approach for the development innovative functional food products.
    31  Preparation and Identification of Artificial Antigen of Furazolidone Metabolite
    LI Jing-yu HE Xiao-wei LI Min LIU Xiao-yun LI Wen-mei
    2014, 30(10):182-186.
    [Abstract](1277) [HTML](0) [PDF 611.75 K](822)
    Abstract:
    The furazolidone metabolite 3-amino-2-oxazolidinone (AOZ) was synthesized at a high yield from the raw materials dimethyl carbonate and ethanol hydrazine hydrate using a catalyst and tetrahydrofuran as a solvent. The results showed that the optimum reaction conditions for maximum AOZ yield (82.7%) were as follows: catalyst dosage, 12%; reaction temperature, 75 ℃; and reaction time, 3 h. Subsequently, a hapten derivative was obtained from the structural transformation of AOZ. Then, immunogens and coating antigens were successfully prepared using a method involving glutaraldehyde to conjugate AOZ and its hapten derivative with activated ovalbumin (cOVA) and bovine serum albumin (cBSA). The hapten and immunogen were identified by gas chromatography-mass spectrometry (GC-MS), elemental analysis, and UV spectrophotometry. The GC-MS data demonstrated the successful preparation of AOZ. The elemental analysis indicated successful formation of the hapten. UV spectrophotometry results showed that conjugation of the hapten with cOVA and cBSA was successful, and the conjugation ratios of immunogen I and immunogen II were 16.74 and 24.05, respectively.
    32  Preparation and Application of a Special Oil for Quick-frozen Foods Based on Enzymatic Interesterification
    CUI Xiu-xiu WANG Yan ZHAO Ya-li ZONG Min-hua LI Bing WU Hong
    2014, 30(10):187-193.
    [Abstract](1156) [HTML](0) [PDF 639.21 K](956)
    Abstract:
    Interesterification of palm stearin and soybean oil with a mass ratio of 7:3 was catalyzed using immobilized lipase Lipozyme TLIM. After interesterification, the content of glycerol tripalmitate (PPP), which has a high melting point in the mixed oil, decreased from 27.61% to 9.50%. In this study, five types of base oils with different plastic ranges and solid fat contents were designed using the interesterified oil as the major component, and five kinds of special oil for quick-frozen foods were then prepared using these five base oils as the raw materials. The resulting special oil was applied to prepare quick-frozen glue puddings. The results showed that the special oil with the best freeze resistance performance was composed of interesterified oil, soybean oil, and palm stearin at a ratio of 84:13:3 (wt%). In addition, with this special oil, the freeze cracking rate in quick-frozen glue puddings was only 5%, which was much lower compared to that in such puddings made with commercial special oil (30%), special oil with non-interesterified oil as the base oil (20%), and those made without any special oil (50%). Additionally, glue puddings made with the above-mentioned special oil had a fine, smooth, elastic surface. Furthermore, they tasted good and delivered the highest sensory evaluation score, indicating that this high-quality special oil prepared by enzymatic interesterification is useful in the production of quick-frozen foods.
    33  Correlation of PEG/(NH4)2SO4 Aqueous Two-phase Equilibrium Data and Modeling of Partition of Papain
    DONG An-hua PENG Jian XU Ying-hao WANG Wei-tao JIANG Xin-xin ZHANG Hai-de
    2014, 30(10):194-199.
    [Abstract](1507) [HTML](0) [PDF 742.51 K](827)
    Abstract:
    In order to investigate the partition of papain in aqueous two-phase systems, the liquid-liquid phase equilibrium data of the aqueous two-phase systems containing poly(ethylene glycol) (2000, 4000, 6000) /ammonium sulfate was measured by cloud point measurements at T=298.15 K. The experimental binodal data and liquid-liquid phase equilibrium data were correlated using the Merchuk, Othmer-Tobisa, and Bancroft equations. A model was established to describe the partition of papain in the PEG/(NH4)2SO4 aqueous two-phase system. The degree of correlation between the component concentrations and partition coefficients in different groups of the aqueous two-phase system was examined using relevant coefficients. The logarithm of the partition coefficient and the concentration difference between the two-phase components had a relatively high correlation; meanwhile, an empirical equation describing the papain partition coefficient and concentration difference between the aqueous two-phase components was developed. The mean relative deviation between the experimental and calculated papain partition coefficients was less than 10%, and was also less than the values from similar models. This confirmed that the established model revealed a good correlation between papain in PEG/(NH4)2SO4aqueous two-phase system and could be used for calculation of papain partition coefficients. The result provided references for engineering calculations of papain partition coefficients in aqueous two-phase systems and design of aqueous two-phase extraction processes.
    34  Synthesis and Characterization of Trimethylsilyl Starch Ether
    LIU Xiu-guo SONG Xian-liang HU Feng LIAO Yong-xin FENG Yi-zhu ZHAO Yan-qiong
    2014, 30(10):200-204.
    [Abstract](1033) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Silicon-based starch is a new type of starch derivative, with important applications in construction, textile, and paper industries. Trimethylsilyl starch ether (TMSS) was synthesized from cornstarch by gelatinization and acid hydrolysis, followed by etherification with trimethylchlorosilane (TMSCl) and pyridine (catalyst). The effect of the amount of TMSCl on the physicochemical properties of the product was evaluated, and the microstructure of the product was characterized. The results indicated that after gelatinization and etherification, the starch granule structure was modified, and its polarization disappeared. With the increase in the amount of TMSCl, the apparent viscosity and freeze–thaw stability of TMSS gradually decreased, while the solubility increased significantly compared to the original starch. The light transmittance rate of TMSS first decreased and then increased with the increase in TMSCl; however, the transparency of TMSS was higher than the original starch. This study provides a better understanding of the basic properties of silicon-based starch derivatives and an experimental basis for further research and applications.
    35  Influence of Different Tumbling Methods on Meat Quality and Protein Structure of Goose Muscle during Postmortem Aging
    XIE Mei CAO Jin-xuan PAN Dao-dong HUANG Hong-bing SHEN Jian-liang
    2014, 30(10):205-211.
    [Abstract](1130) [HTML](0) [PDF 607.76 K](888)
    Abstract:
    In the present study, the protein structure and quality of goose meat treated by two different tumbling methods were investigated during postmortem aging, with the aim of improving the meat quality. Meat samples from 100-day-old geese were randomly divided into three groups, namely a control and two treatment groups: one exposed to tumbling for 30 min (vigorous tumbling) and the other for 10 min (mild tumbling). Meat samples of each group were placed at 4 ℃for postmortem aging, and the shear force value and cooking loss rate were measured at 12, 36, 72, and 120 h, while the protein structures were determined by Raman spectroscopy. The results indicated that goose muscle exposed to vigorous tumbling had the lowest cooking loss rate, followed by the mild tumbling group, while the control group showed the highest cooking loss rate, and the highest value was observed at 36 h in all groups. From 12 to 120 h, the control group showed significantly higher shear force value than those observed in the mild tumbling group (P < 0.05) and vigorous tumbling group (P < 0.01). The lowest shear force value was observed in the vigorous tumbling group, with the samples exhibiting the best meat tenderness. At 12 h, the α-helix content in goose muscle from control group samples reached as high as 80.04%, which was significantly higher than the values found in the other two groups. The effect of tumbling on the microenvironment is mainly achieved via hydrophobic interactions among the aliphatic amino acids, which were found to be significantly increased by vigorous tumbling.
    36  Heat Pump Drying Characteristics and Mathematical Modeling of Chinese Yam
    LI Li SUN Jian SHENG Jin-feng LI Jie-ming LI Chang- bao ZHENG Feng-jin FENG Dao-ning YOU Xiang-rong
    2014, 30(10):212-217.
    [Abstract](1437) [HTML](0) [PDF 538.09 K](809)
    Abstract:
    The heat pump drying characteristics and mathematical modeling of fresh Chinese yam were studied. The effects of different factors such as the temperature and thickness of yam on heat pump drying characteristics were investigated. Moreover, the obtained experimental data were processed using the SAS 8.0 software for mathematical modeling, and a heat pump drying curve and a drying rate curve were obtained. When the temperature was higher and the slice thickness was smaller, the drying speed was faster, and the drying time of Chinese yam was shorter. The drying rate was significantly affected by the temperature, but less affected by the slice thickness. The heat pump drying model for Chinese yam was in good agreement with the Page model. There was a good agreement between the predicted and experimental values, indicating that this model can describe and predict the moisture dynamics of Chinese yam during heat pump drying process. The quality of heat pump drying products was compared with that of hot air drying products. Chinese yam dried by the heat pump showed good rehydration behavior, with a milky white color and a good sensory quality.
    37  Optimization of Production Conditions and Separation Methods for Plantaricin
    JIANG Li-ming LUO Yi-yong WANG Liang-cai LI Xiao-ran LIU Chen-jian
    2014, 30(10):218-225.
    [Abstract](1274) [HTML](0) [PDF 763.03 K](753)
    Abstract:
    At present, the yield of plantaricin produced by Lactobacillus plantarum through conventional fermentation is relatively low. Therefore, optimization of plantaricin production conditions and methods of isolation and purification is an effective approach to improve its yield. In this study, three strains of L. plantarum were chosen as fermentation agents and the effects of fermentation time, temperature, initial pH of the culture, and medium composition on the production of plantaricin were investigated. Based on the results of such optimization techniques, five different methods for separation and purification of plantaricin were explored and the best combination was identified as follows: fermentation time of 28~35 h; temperature at 30 ℃~37 ℃; initial pH of the culture medium at 6.5~7.0; 10 g/L glucose and 10 g/L sucrose as carbon sources; 10 g/L peptone, 5 g/L beef cream, and 5 g/L yeast powder as nitrogen sources; 2 g/L potassium hydrogen phosphate, 0.2 g/L magnesium sulfate, 0.05 g/L manganese sulfate, 2 g/L ammonium citrate, and 5 g/L sodium acetate as inorganic salts; and 1 ml/L tween-80 as emulsifier. Under these optimized culture conditions plantaricin yield increased by at least 1.5 times. The optimal separation method identified as ultrafiltration, where the recovery rate reached 71% after fermentation broth was extracted by ultrafiltration. Results from this study thus provide theoretical and technical evidence for increasing plantaricin yield which will be useful for industrial applications.
    38  Shelf-life Prediction of Scallop Skirt Sausages
    WANG Hui-qing LIU Hong-ying WANG Jie
    2014, 30(10):226-230.
    [Abstract](1345) [HTML](0) [PDF 558.45 K](731)
    Abstract:
    In this study, the shelf-life of scallop skirt sausages stored at different temperatures was studied, and changes in the pH, sensory scores, total volatile basic nitrogen (TVB-N), and total bacterial count during storage were determined. The results showed that the pH values and sensory scores declined with storage time-the higher the storage temperature, the greater the rate of change. TVB-N values increased with storage time; therefore, with an increase in the storage temperature, the change was more prominent. The total bacterial count increased with storage time-the higher the storage temperature, the higher the rate of change. This conformed to the first-order kinetics model. The dynamic model of the total bacterial count was established. All correlation coefficients of the Arrhenius equation and the first-order (chemical reaction) kinetic equation were greater than 0.9, showing a high goodness of fit. It was verified that the relative error of the expected shelf-life and the actual shelf-life was within 5%. Therefore, the shelf-life of scallop skirt sausages was predictable as per the total bacterial count. In this study, the shelf-life of scallop skirt sausages was predicted in a short time with the help of accelerated shelf-life testing.
    39  A Comparison of Fermentation Methods to Produce 100% Barley Beer
    ZHU Ming-guang CUI Yun-qian ZHU Wei-yue WANG Min
    2014, 30(10):231-236.
    [Abstract](1346) [HTML](0) [PDF 704.95 K](769)
    Abstract:
    In this study, Novozymes Ondea Pro? enzyme was used to produce 100% barley beer. Samples of beer produced using top fermentation and bottom fermentation techniques were assessed. The sugar spectrum composition, amino acid content, Lundin fraction value, α-amino nitrogen content in the wort, and flavor substances in 100% barley beer samples were examined. In particular, the characteristic flavor substance 4VG in beer produced using the top fermentation technique was examined, and members of the National Alcohol Tasting Committee were invited to conduct sensory evaluations. The wort brewed by Ondea Pro? provided sufficient nutrients for yeast and resulted in high-quality, 100% barley beer. The flavor substance contents of the 100% barley beer beverage brewed using the top fermentation technique were much higher than those of the bottom fermentation product, and the taste was also much better owing to the special top-fermenting yeast strain and the relatively high fermentation temperature. Thus, the 100% barley beer produced using the top fermentation technique has considerable market potential and promotional value.
    40  Composition Analysis and Nutritional Evaluation of Zizyphus jujuba Mill. cv. Xiaokou
    WANG Yong-gang MA Yan-lin LIU Xiao-feng WANG Xiao-li WANG Yu-li REN Hai-wei LENG Fei-fan
    2014, 30(10):237-244.
    [Abstract](1429) [HTML](0) [PDF 727.11 K](778)
    Abstract:
    In this study, the main composition, including the active and aroma-contributing components of Zizyphus jujuba Mill. cv. Xiaokou, a product of the National Geographical Logo brand, was evaluated. The results showed that the total sugar content was 64.69%; the potassium content (13170 mg/kg) was the highest among all mineral elements. In addition, the jujube is a rich source of active components, including various vitamins and flavonoids, among which the concentrations of water-soluble flavonoids, alcohol-soluble flavonoids, cyclic adenosine monophosphate (cAMP), and total triterpenes were 8.1, 452.8, 13.88, and 425 mg/100g, respectively. The composition of total amino acids (TAA) was 4.95%, and the ratio of essential amino acids (EAA)/TAA and EAA/nonessential amino acids (NEAA) was 33.89% and 51.28%, respectively. All EAAs were found in a balanced proportion, and the first limiting amino acid was lysine. Additionally, 22 aroma-contributing compounds were identified, including three alcohols, two aldehydes, two ketones, eight acids, and seven esters. Compared with You jujube, Mu jujube, and Tuan jujube, Zizyphus jujube Mill. cv. Xiaokou contained ethyl butyrate, methyl decanoate, and ethyl caproate at concentrations of 0.86%, 1.04%, and 0.46%, respectively. The results indicate that Zizyphus jujube Mill. cv. Xiaokou has high nutritional value.
    41  Antibiotic Resistance of Lactic acid bacteria in Yogurt from Guangzhou
    SHI Lei LI Yan-li LIANG Nuan-yi DONG Chun-yang MENG He-cheng YAN He
    2014, 30(10):245-250.
    [Abstract](1491) [HTML](0) [PDF 515.83 K](841)
    Abstract:
    The aim of this study was to evaluate the antibiotic sensitivity of Lactic acid bacteria isolated from commercially available yogurt in Guangzhou. The bacteria isolated from 31 commercially available yogurt samples (used before expiry date) were identified by physiological and biochemical reactions and 16s rDNA sequence analysis. The sensitivity of these strains to 18 different antibiotics was determined using Kirby-Bauer method. The minimum inhibitory concentration (MIC) of the drug-resistant strains in this study was determined by the Epsilometer test (E-test). In all, 48 isolates were identified, including 25 Streptococcus thermophilus strains, 20 Lactobacillus bulgaricus strains, and 3 Lactobacillus paracasei strains. All strains were found to be susceptible to ceftazidime, cefotaxime, and erythromycin; resistant to kanamycin and streptomycin; and showed different degrees of resistance to ciprofloxacin, gentamicin, and vancomycin. Moreover, multi-drug resistance (resistance to ≥3 antibiotics) was detected in 79.2% of isolates. The E-test results showed that MIC for all vancomycin-resistant strains was greater than 1024 μg/mL, except that for Lactobacillus bulgaricus MR10 (256 μg/mL). Strains from different yogurt samples showed resistance to different drugs, and multi-drug resistance was observed in lactic acid bacteria. Therefore, continuous monitoring of antibiotic resistance and safety evaluation of lactic acid bacteria is recommended.
    42  Development of a Test Kit for β-lactam Antibiotic Residues in Milk
    LIU Dong-mei GUO Jun LIANG Jie-ying WU Hui YU Yi-gang LI Xiao-feng TANG Yu-qian
    2014, 30(10):251-256.
    [Abstract](1171) [HTML](0) [PDF 772.19 K](905)
    Abstract:
    We used β-lactam antibiotic residues in milk as the target to develop a rapid detection kit. Based on sensitivity of Bacillus stearothermophilus 10208 to acid and β-lactam antibiotics, growth conditions were optimized and a test kit that could show a color reaction within 2.5 h was developed. The results of the single-factor experiment showed that when the inoculum was 5%, initial growth pH was 8.0, culture temperature was 55 ℃, and the quantity of peptone was 0.50%, the logarithm values of growth for the bacterium were 2.9, 7.5, 7.3, and 5.8, respectively. The results of an orthogonal test showed that when a nutrient broth containing 0.50% peptone was added and the mixture was inoculated with 5% seed broth and incubated for 24 h at 65 ℃, the logarithm value of growth for the bacterium was 7.6. This optimized test kit could be used to detect residual β-lactam antibiotics in milk within 2.5 h. The parameters were as follows: reaction volume, 0.5 mL; agar, 1.5%; bromocresol purple, 0.01 g/L; total BS 10208 cell number, 1.30 × 108 cfu, and optimum reaction temperature, 65 ℃. The detection limit on penicillin sodium was 2~4 ?g/L. The test kit could also detect residual tetracyclines, sulfonamides, macrolides, aminoglycosides, and other antibiotics in milk.
    43  Double-antibody Sandwich ELISA for the Quantitative Detection of Cry1Ac Protein in Transgenic Plants
    LV Xue-fei ZHOU Xiao-ping MAN Yan ZHANG Jing-hua WANG Peng-ju LIU Yang
    2014, 30(10):257-262.
    [Abstract](1194) [HTML](0) [PDF 530.24 K](846)
    Abstract:
    In this study, CrylAc protein, encoded by insect-resistance gene CrylAc, was selected as the target antigen and its monoclonal antibody and horseradish peroxidase labeled anti-monoclonal antibody were prepared. Using optimized antibody purification techniques, the purified antibody was obtained and double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for detection of CrylAc protein in corn. CrylAc monoclonal antibody was used as the coating antibody and horseradish peroxidase-labeled CrylAb monoclonal antibody was used as the detection antibody. The results showed that the newly developed ELISA had good stability and the coefficient of variation was within 3%. In the concentration range of 10~200 ng/mL, the linear regression equation was y = 0.0114x + 0.0768 (R2 = 0.9989), while the detection limit of the assay was 9.49 ng/mL. The recoveries of Cry1Ac in corn extract ranged from 102.5% to 103%. The established sandwich ELISA provides an effective method for the quantitative detection of Cry1Ac protein in corn and is therefore a promising detection method for the inspection and quarantine of transgenic products and may have high application value in entry-exit inspection and quarantine.
    44  Study on Brand Discrimination of Fish Oil Based on Multiple Spectroscopy Techniques
    ZHANG Yu TAN Li-hong CAO Fang HE Yong
    2014, 30(10):263-267.
    [Abstract](1325) [HTML](0) [PDF 482.13 K](721)
    Abstract:
    In this paper, multiple spectroscopy techniques were used to distinguish different brands of fish oil in a rapid and non-invasive manner. Spectral characteristics of seven brands of fish oil, collected by visible spectroscopy, short wave near infrared spectroscopy (SNIR), long-wave near infrared spectroscopy (LNIR), mid-infrared spectroscopy (MIR), and nuclear magnetic resonance (NMR) spectroscopy, were set as inputs in partial least squares discrimination analysis (PLS-DA) and a least-squares support vector machine (LS-SVM) to establish the discrimination models. The discrimination results of the PLS-DA and LS-SVM models were subsequently compared. The results showed that LNIR achieved the highest discriminant accuracy, and the accuracies of modeling set and prediction set were up to 100%. The LS-SVM model using MIR and NMR spectroscopy also yielded a discriminant accuracy of 100%. On the other hand, the discriminant accuracies of those based on visible spectroscopy and SNIR were poor. In addition, LS-SVM was more suitable than PLS-DA to build identification models for fish oil brands using spectroscopic data. The results indicated that LNIR spectroscopy technique could effectively distinguished fish oil brands, providing the technical support and theoretical basis for developing portable instruments for the analysis of fish oil quality in the future.
    45  Label-free Electrochemical Immunosensor for Sensitive Detection of Pesticide Residue in Vegetables
    HAN En ZHOU Li-na YAN Jing-kun CAI Jian-rong TIAN Qing-rong ZENG Ni
    2014, 30(10):268-273.
    [Abstract](1270) [HTML](0) [PDF 650.19 K](759)
    Abstract:
    This study describes the application of a label-free electrochemical immunosensor that was designed for highly sensitive detection of pesticide residue using a layer-by-layer self-assembly technique. This electrochemical immunosensor was first constructed by placing self-assembling gold nanoparticles on the sodium alginate functionalized glassy carbon electrode (GCE) using in situ electrodeposition. Subsequently, further in situ assembly of the pesticide antibody was conducted by utilizing the strong adsorption between the gold nanoparticles and protein molecules in order to successfully construct the label-free electrochemical immunosensor. In the experiment, carbofuran was used as the pesticide model. An immune complex was produced by the specific immune reaction between carbofuran and the antibody on the self-assembled GCE. This immune complex clearly blocked the electron transfer of electrochemical probes on the electrode surface and resulted in a significant reduction of current signal of the immunosensor. Rapid and highly sensitive detection of pesticide carbofuran was achieved, as inferred based on the relationship between the changes of current signal and the pesticide concentration. Under optimal conditions, the linear detection range of this electrochemical immunosensor to carbofuran was from 1 to 105 μg/L, with a low detection limit of 1 μg/L. Furthermore, the immunosensor could be employed for the detection of carbofuran pesticide residue in various vegetable samples with high sensitivity.
    46  Sensory Characteristics and Volatile Components of Three Pummelo (Citrus maxima) Essential Oils
    HONG Peng CHEN Feng YANG Yuan-fan CHEN Yan-hong CAI Hui-nong NI Hui
    2014, 30(10):274-281.
    [Abstract](1654) [HTML](0) [PDF 626.31 K](994)
    Abstract:
    To investigate the quality of essential oils (EOs) of the major pummelo (Citrus maxima) fruits in China, the sensory characteristics and volatile components of the essential oils (EOs) of Guan Xi, Sha Tian, and Liang Ping pummelos were analyzed by sensory evaluation and gas chromatography-mass spectrometry (GC-MS). The results of the sensory evaluation showed that the three EOs had similar aroma. Guan Xi pummelo EO had a strong floral scent, while the aroma of Sha Tian pummelo EO was similar to mint. Liang Ping pummelo EO had a relatively strong citrus and sweet scent. The GC-MS results showed that although the three types of EOs contain the same major volatile constituents, e.g., d-limonene (476, 150-741, and 595 μg/mL) and β-myrcene (13, 859-207, and 255 μg/mL), Guan Xi pummelo EO had higher concentrations of β-ocimene, linalool, and some aldehydes. The odor activity values (OAVs) showed that Guan Xi pummelo EO (5,015,965) had a much higher OAV than Sha Tian (1,307,088) and Liang Ping (1,159,532) pummelo EOs. Furthermore, the strong floral scent of Guan Xi pummelo EO mainly originated from β-myrcene (2,093,489) and linalool (387,578). The results indicated that although the three pummelo EOs had similar aroma and volatile components, their qualities differed to a certain extent. These results provide a theoretical basis for further comprehensive development and utilization of pummelo EOs in China.
    47  A Review of the Chemical Composition and Biological Activities of the Edible and Medicinal Plant Chrysanthemum coronarium L.
    WAN Chun-peng LIU Qiong ZHANG Xin-long FAN Shu-ying
    2014, 30(10):282-288.
    [Abstract](1502) [HTML](0) [PDF 660.39 K](978)
    Abstract:
    Chrysanthemum coronarium L., genus Chrysanthemum, family Compositae, is an edible and medicinal plant. Many recent academic reports have described the separation and identification of its chemical components and biological activities. Chemical component analyses have revealed that the plant mainly contains flavonoids, phenolic acids, sesquiterpene lactones, monoterpenes, diterpene, glycosyl diglycerides, alkaloids, phytosterols, heterocyclic compounds, polyacetylenes, and volatile oils. Active components such as flavonoids and polyphenols are the main chemical components of C. coronarium L., and are widely found in Compositae family. C. coronarium L. shows various biological activities, including the elimination of phlegm; plant allelopathy; and nematicidal, anti-tumor, antioxidant, free-radical scavenging, insect anti-feedant, hepatic protection, and antimicrobial activities. Flavonoids and phenolic acids show plant allelopathy and antioxidant activities; polyacetylenes and volatile oils show insect anti-feedant and anti-microbial activities; and terpenes, especially sesquiterpene lactone, exhibit anti-tumor and anti-microbial activities.

    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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