Volume 30,Issue 7,2014 Table of Contents

1 In vivo Antitumor Activity of the Active Protein Components from Agrocybe aegerita on Tumor-bearing Mouse Model

LIANG Yi , GUO Lian-xian , SUN Hui

2014, 30(7):1-5.

[Abstract](1660) [HTML](0) [PDF 504.79 K](612)

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The regulation effect of active antitumor protein components Yt from macrofungi Agrocybe aegerita on immune system were investigated in this research. The antitumor activity, the antibody titer, and the immune memory effect were detected on H22-bearing mouse model treated by intratumoral injection of Yt (5 mg/kg). The alteration expression of serum cytokines IL-2 and TNF-α was also measured by ELISA. The results showed that Yt significantly inhibited the tumor growth. The treatment of Yt, the protein component Yp, and the low weight molecules component Ys did not induce the production of high titer antibody and result in toxicity. Yt induced the long-term memory effect to protect the animals from the tumor cell challenge, up-regulated the expression of serum IL-2 (84.6±37.6 pg/mL, p<0.05), and did not significantly change the expression of TNF-α. All these data indicated that Yt could active the immune system, and thus can be potentially used as the immune adjuvant of tumor vaccine.

2 Influence of the Low-molecule-weight Polysaccharides of Agaricus blazei Murrill on Proliferation and Invasion in Gastric Cancer BGC823 Cells

CHEN Qiong-xia , LIANG Biao , LI Yue , PENG Yong-sheng , KONG Fan-qi , LIU Li-jiang , HU Xiao-bo

2014, 30(7):6-9.

[Abstract](1323) [HTML](0) [PDF 548.21 K](624)

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The effect of polysaccharides with low molecule weight from Agaricus blazei Murrill (LABP) on proliferation and invasion in gastric cancer cell line BGC823 was observed by WST-1 and Transwell assay, and the expression changes of some related molecules in proteinic level were determined by Western blot, to explore the mechanism of LABP affected on BGC823 cells. Compared with the control group, LABP group cells were significantly declined (P<0.05) in a dose-dependent manner. BGC823 cell inhibition rates by LABP were 33.4% and 69.8%, respectively on LABP concentration of 1 × 10-4g/mL. The cells permeated the membrane of LABP groups were obviously less and the protein expression of Caspase 3 of LABP group was dramatic increased (P<0.05). The expression of MMP 9 was dramatic down-regulated (P<0.05), while E-cadherion had no significant difference (P>0.05). Thus, low-molecule polysaccharide of Agaricus blazei Murrill (LABP) had a dramatic inhibiting effect on growth and invasion in gastric cancer BGC823 cells. LABP inhibited the gastric cancer BGC823 cells growth, possibly by up-regulating the protein expression of Caspase 3 and down-regulating MMP 9.

3 Inhibitory Activities of Phenols from Toona sinensis Leaves on Key Enzyme Linked to Type 2 Diabetes in vitro

FU Xiong , ZHANG Wei , ZHU Si-ming , LI Chao , YOU Li-jun , ZHAO Zhen-gang , LIU Rui-hai

2014, 30(7):10-15.

[Abstract](1578) [HTML](0) [PDF 582.55 K](762)

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To clarify the postprandial glucose suppression effects of phenols from Toona sinensis leaves, its inhibitory effects against key enzymes (porcine pancreatic α-amylase, rat intestinal sucrase and maltase) linked to type 2 diabetes were investigated. Results showed that the crude extract of Toona sinensis leaves had significant enzyme inhibitory activities. Its IC50 values for the three key enzyme activities were 0.45, 1.29, and 1.41 mg/mL, respectively. The 70% ethanol sub-fraction of the ethyl acetate fraction was mainly responsible for enzymes inhibitory activities, which showed the strongest enzyme inhibitory activities with IC50 values of 0.091, 0.97, and 1.00 mg/mL, respectively, on porcine pancreatic α-amylase, rat intestinal sucrase and maltase. PGG (1, 2, 3, 4, 6-penta-O-galloyl-β-D-glucopyranose) and EG (ethyl gallate) isolated from 70% ethanol sub-fraction were identified as the active monomer compounds. PGG exhibited significant enzyme inhibitory activity against α-amylase with IC50 value of 0.069 mg/mL. The EG had inhibitory effects on sucrase and maltase to some extent. Its IC50 value for sucrase and maltase were 0.82 and 0.81 mg/mL, respectively. This study revealed that Toona sinensis leaves may be helpful to develop drug and functional foods for diabetes and related symptoms.

4 Effect of n-3/n-6 Polyunsaturated Fatty Acid on the Proliferation and Differentiation of 3T3-L1 Preadipocytes

CHEN Rong , GUO Li-xia , YIN Zhong-yi , LIU Bai-hua , ZHENG Xu-xu

2014, 30(7):16-22.

[Abstract](1356) [HTML](0) [PDF 686.25 K](525)

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The effects of alpha-linolenic acid (ALA) and linoleic acid (LA) on the proliferation and differentiation of 3T3-L1 preadipocytes were investigated by MTS assay, cell morphology analysis and spectrometric method of induction differentiation combined with oil red O staining. MTS results showed that ALA and LA significantly inhibited proliferation of 3T3-L1 preadipocytes in a dose- and time-dependent manner within a certain concentration range, and ALA inhibited proliferation more strongly than LA. Cell morphology analysis showed that ALA and LA were cytotoxic to 3T3-L1 preadipocytes because of high concentration of the fatty acids. The inverted electron microscope observing and oil red staining and detection results showed that ALA, LA and ALA/LA mixed fatty acid (1:1, n/n) significantly inhibited differentiation of 3T3-L1 preadipocytes in a dose-dependent manner in the range of 12.5~200 μmol/L, and ALA inhibited differentiation more efficiently than LA, and the ALA/LA mixed fatty acid (1:1, n/n) showed the strongest inhibition effect on differentiation at the same concentration above 100 μmol/L. When the concentration was 200 μmol/L, the ALA/LA mixed fatty acid (1:1, n/n) showed slightly lower inhibition effect on the differentiation of 3T3-L1 preadipocytes than the ALA/LA mixed fatty acid (1:2, n/n) and the ALA/LA mixed fatty acid (1:4, n/n).

5 Protective Effects of Chlorogenic Acid on Lipopolysaccharide-induced Chronic Liver Injury in Rats

YANG Yu-hui , ZHOU Yan , RUAN Zheng , MI Shu-mei , ZHOU Li-li , WEN Yan-mei , LI Xiao-lan , JIANG Min , YIN Yu-long

2014, 30(7):23-26.

[Abstract](1164) [HTML](0) [PDF 498.55 K](634)

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Rats were randomly divided into the model group and chlorogenic aid (CGA)-supplemented group, and at the 28th day the rats were sacrificed. The growth performance, liver weight and liver index of each rat were analyzed. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) and the contents of total bilirubin (TBIL) and total protein (TP) in serum were assayed. Hepatic pathological changes were observed by H&E staining method. The activities of superoxide dismutase (SOD) and the malondialdehyde (MDA) content in liver were determined. Compared with the model group, the finish body weight, average daily gain and food efficiency ratio (FER), liver weight and liver?index in CGA-supplemented group were significantly decreased (P<0.05). The activities of ALT, AST, ALP and the level of TBIL in serum declined significantly (P<0.05 or P<0.01), and the declining rates were 12%, 13%, 17% and 50%, respectively. TP content in serum and SOD activity in liver were significantly increased (P<0.01 or P<0.05), and the increasing rate was 17% and 23%, respectively. MDA content in liver declined significantly (P<0.05), and the declining rate was 33%. H&E staining indicated that the hepatic pathological injury in CGA-supplemented group was attenuated. Therefore, CGA has a protective effect on chronic liver injury induced by lipopolysaccharide.

6 Differentiation of Food-borne Fatty Acid Biomarkers in Hybrid Abalone Haliotis discus hannai and Haliotis discus discus

GE Chang-zi , WANG Hai-qing , MAO Yu-ze , HUANG Yao , SUI Hai-dong

2014, 30(7):27-30.

[Abstract](1391) [HTML](0) [PDF 557.02 K](678)

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To determine suitable tissue in hybrid abalone used for long-term food sources, distribution characteristics of food-borne fatty acid biomarkers in digestive gland, muscle and visceral mass of bottom-sowed hybrid abalone were investigated, which were useful to differentiate long-term food sources of hybrid abalone. There were no significant differences in diatom fatty acid biomarkers (∑C16/∑C18 and C20:5n-3) and heterotrophic bacteria fatty acid biomarkers (C18:1n-7/C18:1n-9) among visceral mass, digestive gland and muscle of hybrid abalone with similar body size. The Chlorophyta fatty acid biomarkers (C18:2n-6+C18:3n-3) in digestive gland was higher than that in muscle (p＜5 %), while Phaeophyta fatty acid biomarker (C20:4n-6) had the opposite result to Chlorophyta. Fatty acid compositions in visceral mass were affected by the development of gonad; fatty acid content in muscle was low. Total fatty acid content in digestive gland was the highest, and the fatty acid composition varied with the seasonal differentiation of food sources. From points of factors influencing composition of fatty acids and measurement sensitivity, it was better to determine digestive gland as long-term food sources of abalone by fatty acid biomarkers analysis.

7 Biocatalytic Asymmetric Reduction of Ethyl Acetoacetate with Immobilized Acetobacter sp. CCTCC M209061 Cells in a Micro-water-containing Organic Solvent

XU Yu , WANG Xiao-ting , LOU Wen-yong , ZONG Min-hua

2014, 30(7):31-37.

[Abstract](1181) [HTML](0) [PDF 800.38 K](594)

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In present study, the highly anti-Prelog stereoselective reduction of ethyl acetoacetate (EAA) to (R)-ethyl-3-hydroxybutyrate (EHB) with immobilized Acetobacter sp. CCTCC M209061 cells was successfully conducted in a micro-water-containing organic solvent. Use of organic solvent-containing system as the reaction medium, in place of aqueous monophasic system, could not only effectively eliminate the inhibition of the substrate and product, but also improve the concentration of the substrate and the product yield of the tested organic solvents, n-hexane was selected as the most suitable organic phase for the reaction, due to its good ability to dissolve the substrate and biocompatibility with Acetobacter sp. CCTCC M209061 cells. Therefore, the bioreduction reaction with n-hexane became faster and the achieved product yield was relatively higher. Isopropanol was found to be the best co-substrate for the bioreduction and its optimal concentration was 60 mmol/L. For the bioreduction of EAA with immobilized Acetobacter sp. CCTCC M209061 cells, the optimum percentage of n-hexane, reaction temperature, substrate concentration were 100.00% (containing around 0.01 wt% water), 35 ℃, 40 mmol/L, respectively. Under the optimized reaction conditions, the obtained initial reaction rate, yield and product e.e. was 0.72 μmol/min, 85.24% and 99.00% above, which was better than the results observed with aqueous monophasic system as the reaction medium.

8 Effects of Salinity on Proteases Composition, Bacterial Population and Quality of Shrimp Sauce During Fermentation

DUAN Shan , HU Xiao-xi , LIAO Guang-qiang , WU Yong-he , KUANG Hao-bin , YANG Liu , LI Ting , ZHOU Xing-zhi

2014, 30(7):38-43.

[Abstract](1408) [HTML](0) [PDF 581.45 K](681)

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Shrimp processing wastes (heads, shells and tails) were fermented at differet salinity (16%, 20% and 24% ) to make shrimp sauce. The changes of protease composition, bacterial population and quality during fermentation were investigated. The results showed that the spoilage of shrimp sauce was effectively inhibited by using 20% or higher salinity. The protease composition and bacterial population varied during fermentation. The activities of most endogenous proteases gradually decreased. Meanwhile, some new microbial proteases appeared and showed relatively high activity. In the initial phase of fermentation, the non-halotolerant bacterial were dominant, while in the later phase the halotolerant bacteria increased. Thus, the bacteria played a significant role in fermentation. High salinity significantly inhibited the growth of bacteria and suppressed the production of the related putrefactive substance, such as total volatile basic nitrogen (TVB-N) and trimethylamine (TMA). It also decreased the protease activity and reduced the production of amino acid nitrogen (AAN). The shrimp sauce fermented at 24% salinity has a balanced ratio in terms of amino acids and flavor, and hence tastes better.

9 Isolation and Identification of a γ-PGA Producing Strain and its Product Properties

ZHANG Wen , LIU Li-ge , ZHANG Yan , QI Xiang-jun

2014, 30(7):44-50.

[Abstract](1184) [HTML](0) [PDF 738.13 K](588)

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A γ-polyglutamicacid (γ-PGA) producing strain (JPND618) was isolated using streaked plate method. The strain was identified through strain morphological, physiological-biochemical characteristics and sequence contrastive analysis of 16S rRNA. The fermenting product was identified, and its water absorption property, scale property, flocculation property and biodegradable property were studied. The results showed that, the physiological-biochemical characteristics of strain JPND618 were similar to bacillus genus, and the homelogy of 16S rDNA sequence with Bacillus amyloliquefaciens NBRC 15535 reached 98%, thus strain JPND618 was identified as Bacillus amyloliquefaciens. The yield of γ-PGA was 4.86 g/L. γ-PGA showed much better water absorption and biodegradable property than Polyacrylamide (PAM), and similar water-retaining property with PAM. The anti scale rates towards CaSO4, CaCO3 reached more than 70%, and flocculation towards Gaolin suspension was good. γ-PGA produced by strain JPND618 was proved as a kind of environmental friendly biological materials with high performance, which has a better application prospect. This study supplies a new strain for producing γ-PGA.

10 Effect of Luteolin on Activity and Conformation of Tyrosinase

LIU Hua , LI Shi-xiang , ZHONG Ye-jun , WU Dan

2014, 30(7):51-55.

[Abstract](1421) [HTML](0) [PDF 622.50 K](650)

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The effects of luteolin on inhibitory action, inhibitory type and inhibitory kinetics of tyrosinase were investigated using the method of enzyme inhibition kinetics in 37 ℃, pH 6.8 sodium phosphate buffer (100 mmol/L) system, the changes of surface hydrophobicity and secondary structure of tyrosinase were also probed. The results showed that luteolin was a reversible and noncompetitive inhibitor (the half inhibition concentration (IC50) and inhibition constant (Ki) were obtained to be 55.35 μg/mL and 63.57 μg/mL, respectively). The time-courses analysis of inactivation kinetics indicated that luteolin interacted with tyrosinase quickly and inhibited the acticity of enzyme rapidly. Fluorescence spectrum analysis showed that luteolin significantly increased the surface hydrophobicity of tyrosinase. Circular dichroism spectra analysis showed the binding of luteolin to tyrosinase induced the unfolding of conformation and the gradual increase of α-helix content of tyrosinase (from 31.3% to 41.6%). The results of spectra analysis indicated that the binding of luteolin to tyrosinase altered the conformation of tyrosinase which was not conducive to the formation of active center, thereby reducing the activity of tyrosinase.

11 Inhibition Effect of Quercetin on Aflatoxin B1 Production

WANG Miao-yan , ZHANG Hao , YANG Jie , HU Liang-bin , MO Hai-zhen

2014, 30(7):56-62.

[Abstract](1459) [HTML](0) [PDF 564.28 K](779)

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Many polyphenol monomers could inhibit aflatoxin B1 production and Quercetin had higher inhibitory activity than other catechin polyphenols.To explore the inhibition effect of quercetin on aflatoxin B1 production, the antioxidant system of Aspergillus flavus was monitored and the toxin genes express after quercetin treatment were analyzed. The results showed that quercetin treatment decreased the ROS and MDA concentration, confirming that this treatment could alleviate the oxidative stress of Aspergillus flavus. RT-PCR result showed that quercetin was able to activate the transcription factor Yap1 in antioxidant system to increase antioxidant enzyme activity, such as POD, COT and SOD activity. This induction may be a key factor for quercetin inhibition on AFB1. Quercetin downregulated the expression of AflRand AflS And AflS could regulate toxin production by combining AflR expression gene, which is possibly the key mechanism of the inhibition effect of quercetin on AFB1. This was also associated with activation of antioxidant systems in easing the fungi oxidative stress in vivo. In the case of AflR downward, the toxin gene expression was inhibited. Hence, quercetin can be employed as an efficient aflatoxin synthesis inhibitor with great application potential.

12 The Antimicrobial Resistance and Resistant Genes in Bacteria from Bulk Cooked Meats in Guangzhou

JIANG Xiao-bing , YU Tao , MENG He-cheng , MA Jian-min , SHI Lei

2014, 30(7):63-68.

[Abstract](1353) [HTML](0) [PDF 520.00 K](577)

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The aerobic bacteria were isolated from cooked meats in Guangzhou, identified by 16S rDNA amplification and biochemical identification, and the antimicrobial resistance to tetracycline and trimethoprim/sulfamethoxazole and the prevalence of corresponding resistant genes were investigated in this study. Of the 169 isolates collected from 40 samples, Enterobacter, Pseudomons and Citrobacter were found more frequently in these cooked meats. Fifty-five (32.54%) of all isolates were resistance to tetracycline and 40 (23.67%) of them were resistance to trimethoprim/sulfamethoxazole. Among seven tetracycline resistance genes in this study, tetM (14.20%) was found in the highest frequency, followed by tetA (10.06%), tetS (5.92%)and tetB (2.96%), while sulI (10.65%) was observed in the highest frequency in trimethoprim/sulfamethoxazole resistance genes. Multiple antimicrobial resistance genes were detected in 19 of 169 (11.24%) isolates. The prevalence of resistance genes in isolates from cooked meats indicates that these bacteria might act as a reservoir of antimicrobial resistance genes and play a role in the dissemination of resistance along the food chain.

13 Relationship between Development of Porcine PSE Characteristics and Initial Postmortem Temperature

ZHU Xue-shen , LU Ya-yu , HUANG Xue-fang

2014, 30(7):69-73.

[Abstract](1096) [HTML](0) [PDF 486.84 K](632)

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Pork longissimus muscle were taken at 20 min postmortem, kept at 0, 20 and 40 ℃ until 2 h postmortem and then stored at 4 ℃, respectively. 20 min, 1 h, 2 h and 24 h postmortem pork samples were selected and rapidly frozen in liquid nitrogen, and stored at -40 ℃ before analyzed. During incubation, rapid increase of R value, accumulation of lactic acid and decrease of pH value were found in the high temperature group (40 ℃).These data indicated that glycolysis could be activated much more in the high temperature group (40 ℃). When analyzing the extracted proteins with SDS-PAGE, it revealed that both 100 ku and 35 ku polypeptides from sarcoplasmas faction was associated with the myofibrillar fraction. Moreover, the 40 ℃ group had higher L * values and cooking loss compared with the other two groups. These result indicated that high initial postmortem temperature could resulted in pale and exudative characteristics in pork, partly because the glycolysis was activated at high temperature.

14 Metabolic Flux Analysis and Key Enzymes Activities Determination for the Production of Poly Malic Acid using Aureobasidium pullulans

QIAO Chang-sheng , ZHENG Zhi-da , MENG Di , SONG Yu-min , GE Li-feng

2014, 30(7):74-80.

[Abstract](1374) [HTML](0) [PDF 692.75 K](666)

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In this paper, metabolic flux and enzyme activity analysis for wild type Aureobasidium pullulans TKPM00006 and its mutant strain CGMCC3337 was conducted in 5 L bioreactor in the same conditions. The mechanism of biosynthesis of PMLA using Aureobasidium pullulans was investigated. The results showed that the biomasses in the two strains during the fermentation process were almost the same, but the accumulated yield was 20.54 g/L and 30.2 g/L, respectively. Through the metabolic flux analysis and key enzyme activity determination, it was found that pyruvate carboxylation pathway and glyoxylate pathway were the main pathways in PMLA synthesis, while TCA pathway was weak in the two strains at the post fermentation. This was confirmed by adding metabolic inhibitors and intermediate metabolites into medium. Enzyme activity analysis also confirmed that pyruvate carboxylation pathway was strengthened in the high yield strain whose PMLA synthesis ability stronger than the wild strain. The carbon flux distribution on pyruvate node could be manipulated by genetic manipulation and fermentation control. The enhanced flux in pyruvate carboxylation pathway decreased other pathways flux, thereby reducing the byproduct generation and improving PMLA yield.

15 Comparison of Coriolopsis gallica and High Laccases Production Mutant

HAN Zhen-ya , XU Xiao-li , ZHANG Ai-ping , XIE Jun

2014, 30(7):81-86.

[Abstract](1102) [HTML](0) [PDF 687.81 K](654)

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Laccase is a kind of polyphenol oxidase, and it has important application values in food, energy, environment industries and other fields. A mutant strain from wild Coriolopsis gallica was selected, and its morphological characteristics were very different from the wild strain. The production of laccase by the mutant was up to 303 U/mL, which was three times higher than that by the wild strain. In this article, the physiological and biochemical differences between the wild and mutant, and their genetic differences with RAPD were compared and analyzed. Twenty stable specific bands were amplified with 140 random primers, and three of them were recovered and cloned. Then comparison analysis of their sequencing results with BLASTX, NCBI database showed that the 809 bp band from primer S381 was corresponding to a hypothetical protein of Trametes versicolor. The 654 bp band from primer S225 was corresponding to 30 S ribosomal protein S4 of Oribacterium sp, and the 1027 bp band from primer S193 was corresponding to glycoside hydrolase of Dichomitus squalens. This test would provide a theoretical basis for investigating molecular mechanism of the mutant yielding high laccase, and building high yield laccase engineering stain by directed mutation.

16 Effect of Dextran Conjugation on the Conformational and Functional Properties of Arachin

LIU Yan , ZHAO Guan-li , ZHAO Mou-ming , SU Xin-guo

2014, 30(7):87-91.

[Abstract](1134) [HTML](0) [PDF 502.67 K](737)

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Arachin can react with dextran to form conjugation products with high molecular weight. It was found that the acid subunits of arachin were easier to glycosylate with dextran than basic subunits. The heat-pretreatment of arachin could not increase the speed of Maillard reaction with dextran. Proteins in mixtures/conjugates might have a more compacted tertiary conformation than that in arachin, which might limit the extent of glycosylation. The conjugation with dextran could improve the solubility and emulsifying properties of arachin, while it was hard to improve the functional properties of arachin when pretreated by heat. Non-heat pretreatment arachin conjugated with polysaccharide had high solubility and emulsifying activity, and they could reach the highest values of 95% and 149 m2/g after dry heat of 14 days.

17 Isolation, Identification and Salt-tolerance Analysis of Aroma-producing Yeasts from the Chinese Traditional Shrimp Paste

LIAN Xin , YANG Xi-hong , XIE Wan-cui , YANG Ya-dong , WU Shuai , JI Hong-wu , LIU Shu-cheng , MAO Wei-jie

2014, 30(7):92-97.

[Abstract](1409) [HTML](0) [PDF 570.99 K](641)

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Because of the distinct flavor and rich nutrition, shrimp paste was generally consumed as a traditional Chinese aquatic seasoning. But its difficult in industrialization development was hampered because of long production cycle, high salinity, technology instability and insecurity. In order to obtain the aroma producing yeasts for shrimp paste fermentation and improve the fragrance of the shrimp paste for meeting industrialization requirement of traditional food, an aroma producing yeast was isolated from traditional Chinese shrimp paste with the method of dilution plating on the medium of potato dextrose agar (PDA) and aroma sensory analysis. The morphological identification, physiological and biochemical identification, ITS rDNA analysis and phylogenetic tree were used to identify species in this paper. By Sequence alignment from database of NCBI showed that it belonged to Pichia gilliermondii. The salt-tolerance analysis indicated that the strain could survive in 10% NaCl solution. The results showed that the aroma producing ability and salt tolerance of strain were good, and the salt-tolerance of strain could be domesticated for low-salt shrimp paste fermentation as one of shrimp paste composite starter cultures. The aroma producing yeast isolated from the traditional shrimp paste can improve the aroma and quality of fermented shrimp paste.

18 Functional Properties of Soy Protein Enriched with Soybean Isoflavones

YANG Juan , WANG Cheng-gen , PENG Jie , YANG Xiao-quan

2014, 30(7):98-102.

[Abstract](1253) [HTML](0) [PDF 550.82 K](534)

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Soy protein enriched with isoflavones was prepared under different heating conditions and its functional characteristics were studied. The insolubility of isoflavones in protein was greatly changed. Soy protein enriched with natural soybean isoflavones (SPIG) and aglycone isoflavones (SPIA) prepared under pH 6.4 and pH 7.0 were selected. Compared with soybean protein isolate (SPI), the foaming abilities of the heated SPI (HSPI), SPIG and SPIA were enhanced after isoflavone was added. When the pH value was 7.0, the foaming ability of SPIG was 165.77 ± 2.90 %, which was stronger than that of the other proteins enriched with isoflavones. However, water holding ability of the soybean proteins decreased after adding isoflavone, and SPIA 6.4 demonstrated the lowest water holding ability. Then, SPI, the mix of soy protein and natural soybean isoflavones and aglycone isoflavones (MixG and MixA), SPIG and SPIA were respectively adopted to make emulsion. The d43 of fresh emulsion was determined; the average droplet size of SPI was 1.35 ± 0.12 μm, while the average droplet size of MixG and MixA was 25.41 ± 1.32 and 24.57 ± 1.73 μm, respectively. After heating, the average droplet size of SPIG and SPIA increased to 38.99 ± 0.89 μm and 34.50 ± 0.48 μm, respectively. The emulsion stability coefficients of SPIG and SPIA under centrifugal condition were relatively low, but the emulsion had better plasticity than the emulsion of SPI. The conclusion derived?from confocal laser scanning photomicrographs (CLSM) was corresponded with d43.

19 Effect of Sodium Alginate on the Physicochemical Properties of Corn Starches with Different Amylose Contents

ZHAO Yang , XU Peng-cong , CHEN Hai-hua , WANG Yu-sheng

2014, 30(7):103-109.

[Abstract](1453) [HTML](0) [PDF 592.94 K](724)

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The effect of sodium alginate on the properties of corn starches with different amylose contents was studied by rapid viscosity analyzer, differential scanning calorimeter, dynamic rheometer and texture analyzer. The results showed that properties of high amylose corn starch, common corn starch and waxy corn starch were significantly influenced by sodium alginate and amylose content. With addition of sodium alginate, it was more difficult for corn starches to be pasted, meanwhile, onset temperature, peak temperature, endpoint temperature and enthalpy value were improved. Viscosity of corn starch pastes was increased, in terms of higher peak viscosity, final viscosity, apparent viscosity and loss modulus. Thermal stability and anti-retrogradation capacity of high amylose corn starch was enhanced with adding sodium alginate, while breakdown value and retrogradation rate of high amylose corn starch decreased. Gelling capacity of high amylose corn starch was reduced by adding sodium alginate, with higher tanδ and lower gel hardness.

20 Effect of Protein Oxidation on Functional Properties of Whey Protein Isolates

TIAN Tong-tong , GONG Zi-lu , ZHU Xin-rong , ZOU Sheng-dong , ZHANG Jian

2014, 30(7):110-116.

[Abstract](1170) [HTML](0) [PDF 619.43 K](681)

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The objective of this study was to explore the effect of protein oxidation on the functional and rheological properties of whey protein isolate (WPI). There were two different oxidation systems containing H2O2 (1 mmoL/L~20 mmoL/L) and FeCl3 (0.1 mmoL/L~2 mmoL/L) in this experiment. WPI was treated by the oxidation systems for 1 h, 3 h and 5 h respectively. The result revealed that the emulsifying activity of WPI decreased over 50% under the condition of 20 mmoL/L H2O2 for 5h. The gel hardness decreased 94.5% owing to 1mmoL/L FeCl3 for 3 h. Additionally, results also showed that the elasticity of WPI was decreased from 0.976 to 0.713 and 0.721 respectively by 20 mmoL/L H2O2 for 5 h and 1 mmoL/L FeCl3 for 3 h treatment. In addition, 20 mmoL/L H2O2 led to the decrease of elastic modulus value of WPI decreased from 8154 Pa to 5399 Pa and decrease of the complex modulus value from 10890 Pa to 6653 Pa. When 1 mmoL/L FeCl3 was used, the elastic modulus value declined from 8154 Pa to 4935 Pa and the complex modulus value was reduced from 10890 Pa to 6049 Pa. The spatial structure of proteins severely affected at the long time oxidizing conditions of high concentration. Therefore the functional properties and the gel texture of WPI were damaged significantly. Thus, protein oxidation should be avoided as much as possible in actual production for maintaining the nature characteristics of WPI, thereby preventing nutrient losses and promoting application value .

21 The Quality Change of Peach Juice during Storage

BI Jin-feng , RUAN Wei-hong , LIU Xuan , LU Yong , MIAO Peng-fei , JIAO Yi

2014, 30(7):117-123.

[Abstract](1263) [HTML](0) [PDF 605.10 K](1259)

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To study the effect of storage conditions on the quality changes of peach juice pretreated by sterilization, the experiments were carried out at three storage temperatures of 4, 25 and 37 ℃. The changes of physical and chemical indicators, nutrients and aroma components during storage were tested and analyzed. The result showed that browning degree index was increased by 0.14, 0.33 and 0.56 at the three different temperatures, respectively. The total sugar contents of the three samples were decreased by 49.06%, 53.59% and 57.19%, respectively. The vitamin C contents were 46.27%, 43.05% and 51.06%, and the protein contents were 31.82%, 57.14% and 64.00% respectively. There was no significant change in the total acid contents before and after storage, while the effect of storage time and temperature on the browning degree, pH, total sugar, Vitamin C, protein, total phenol and pectin content were highly remarkable (p < 0.01). Thirty-five aroma compositions were identified in the peach juice. The fresh juice had good aroma, and the characterized flavor undecan-4-olideand 5-decanolide reached 1.25% and 4.45%. After 40 days storage, the amount of identified aroma components declined to 79.90%, 60.14% and 54.59% of the total mass fraction at 4, 25 and 37 ℃, respectively. Therefore, low temperature storage could keep the quality of peach juice.

22 Analysis and Evaluation of Muscle Quality in Different Edible Parts of Farmed Crocodylus siamensis

XIAO Kun , WANG Xi-chang , LI Meng-fan

2014, 30(7):124-130.

[Abstract](1272) [HTML](0) [PDF 577.35 K](603)

Abstract:
Nutritional quality, eating quality and technological quality of different edible parts of farmed Crocodylus siamensiswere evaluated to provide theoretical directions for its further comprehensive utilization and sustainable development of aquaculture industry. The results showed that the protein content in tail (20.25%) was higher than that of leg (18.70%) and torso (18.36%), but the total amino acid (TAA) in tail (70.47%) was lower than that of leg (72.17%) and torso (72.58%). The fat content in tail (0.98%) was higher than in leg (0.70%) but lower than in torso (1.12%). The unsaturated fatty acid (UFA) ratio in tail (68.22%) was significantly higher than that of body (66.66%) and leg (64.91%). Total proportions of EPA and DHA were richer in leg muscle than that of tail and body. Farmed Crocodylus siamensis muscle, especially in leg, was rich in Ca, Zn, Fe elements. According to the detection of several indicators, WHC, cooking loss, pH, hydroxyproline content and myofibril fragmentation index (MFI), the muscle quality was evaluated. It was found that the tenderness of white tail muscle was the best, followed by red leg muscle; and torso muscle had the poorest tanderness. Texture profile analysis showed that hardness, adhesiveness, chewiness and resilience presented a rule as leg muscle > tail muscle > body muscle. These results indicated that farmed Crocodylus siamensis muscle had high nutritional, edible value and development prospect.

23 Effect of Defatted Soybean Flour Pretreatment on Structure of Soybean β-conglycinin

WU Wei , CAI Yong-jian , LIN Qin-lu , DENG Ke-quan , HUA Yu-fei

2014, 30(7):131-135.

[Abstract](1204) [HTML](0) [PDF 711.40 K](598)

Abstract:
Fresh defatted soybean flour, dry heating of defatted soybean flour, and solvent extraction of defatted soybean flour were used as materials to prepare soybean β-conglycinin. Protein carbonyl, free sulphydryl, and total disulphide/sulphydryl content of β-conglycinin which prepared by fresh defatted soybean flour were 2.93 nmol/mg, 1.39 nmol/mg, and 11.87 nmol/mg, respectively; while those by dry heating of defatted soybean flour and solvent extraction of defatted soybean flour were separately 5.24 nmol/mg, 0.41 nmol/mg, 5.42 nmol/mg and 1.85 nmol/mg, 1.93 nmol/mg, 15.64 nmol/mg. The results indicated that dry heating of defatted soybean flour increased oxidation extent of soybean β-conglycinin, while solvent extraction of defatted soybean flour reduced oxidation extent of soybean β-conglycinin. As oxidation extent of soybean β-conglycinin prepared by three kinds of defatted soybean flour increased, the contents of α-helix and β-sheet, surface hydrophobicity, and intrinsic fluorescence intensity of soybean β-conglycinin decreased, and blue shift of the maximum emission wavelength were increased, accompanied by formation of protein aggregates, which indicated that protein oxidation resulted in aggregation of soybean β-conglycinin.

24 Effect of Steam Explosion Treatment on Starch Molecular Structure of Indica Rice Starch

LI Guang-lei , ZHANG Guo-cong , LIU Ben-guo , LI Fei , MA Han-jun , SUN Jun-liang

2014, 30(7):136-141.

[Abstract](1107) [HTML](0) [PDF 566.68 K](677)

Abstract:
The influences of steam exploded pressure, retained time, and sample moisture content on starch molecular structure of indica rice starch treated with steam explosion were analyzed by gel chromatography (GPC), ultraviolet–visible spectroscopy (UV), and Fourier transform infrared spectroscopy (FT-IR). The results showed that, with the increase of steam exploded pressure, retained time, and sample moisture content, molecular weight of indica rice starch were decreased, and the proportion of starch short chain pieces was increased. In addition, the intermediate absorption peak gradually disappeared, and the degree of polymerization of indica rice starch chains was decreased. The maximum absorption wavelength of UV spectrum showed a blue shift. As the intensity of steam explosion treatment increased, the intensity of aldehyde group absorption peak at 1650 cm-1 in the infrared absorption spectrogram increased, and starch infrared crystallization index (ICI) increased. Steam explosion technology effectively degraded the polymerization degree of indica rice starch chains and increased the crystallinity starch granule .

25 Development of a Molecular Predictive Model of Vibrio Parahaemolyticus in Ready-to-eat Shrimps by Real-time PCR

SUN Wen-shuo , JIN Meng-tong , WANG Jing-jing , ZHANG Zhao-huan , SUN Xiao-hong , PAN Ying-jie , ZHAO Yong

2014, 30(7):142-148.

[Abstract](1315) [HTML](0) [PDF 779.75 K](668)

Abstract:
A molecular predictive model of Vibrio parahaemolyticus on ready-to-eat shrimps was developed and four Vibrio parahaemolyticus strains in ready-to-eat shrimps at 4~30 ℃ were quantitated by Real-time PCR method. Gompertz model was selected as the primary model, which was fitted to achieve maximum growth rate (MGR) for Vibrio parahaemolyticus on ready-to-eat shrimps at 10~30 ℃. The MGR was then used to establish secondary molecular models as linear model, square root model and Ratkowsky model, and these models were validated subsequently. Weibull model, Log-linear model, and Logistic model were applied to predict inactive curves of V. parahaemolyticus at 4 ℃ and 7 ℃, respectively. Results showed that the V. parahaemolyticus growth data could be well fitted by Gompertz model (R2 > 0.96). The R2 values of linear model, square root model and Ratkowsky model were all above 0.94, and the Af and Bf values were within the acceptable limit, indicating that the relationship between the growth rates of V. parahaemolyticus and storage temperatures could be well described by the models, especially the Linear model. However, Real-time PCR method could not be used to develop the inactive model of V. parahaemolyticus at 4 ℃ and 7 ℃. Accuracy molecular predictive models developed by real-time PCR method can aid to establish models of certain pathogens more accurately in the presence of other bacteria.

26 Enzymatic Kinetics of Small Peptides Prepared from Rice Proteins with Alcalase

LV Le , LIU Dong , WAN Hong-xia , LI Yan , ZHOU Li-zhen , CHEN Yuan , SUN Hai-yan , YANG Hai-yan , YU Yi-gang

2014, 30(7):149-153.

[Abstract](2600) [HTML](0) [PDF 699.54 K](691)

Abstract:
Enzymatic conditions for preparing small peptides from rice proteins with alcalase 2.4L were optimized by single factor experiment and the enzymatic kinetics was established. The optimal enzymatic conditions were as follows: temperature 55 ℃ pH 8.5, enzyme-substrate ratio 0.096 AU/g (substrate). Product inhibition was observed during the enzymatic hydrolysis process, but no substrate inhibition was observed within tested substrate concentration (<90 g/kg). The enzymatic kinetic parameters were: k2 = 0.28 mmol/(AU·min), Km = 5.76 (g·min)/mmol, and Vmax = 0.67 mmol/(kg·min). The kinetic enzymatic equation was: 1/V0 = 56.29/[S0][E0] + 1/0.28[E0]. After enzymolysis for three hours under the optimal enzymatic condition, the degree of hydrolysis (DH) reached 16% and the hydrolysates content with molecular weight between 264~584 u reached 94%. The molecular weight distribution of hydrolysates was barely changed after 3 h enzymolysis.

27 Effects of Compound Biological Preservative Combined with Modified Atmosphere Packaging on Fresh-keeping of Argopectens irradias in Cold Storage

QI Feng-sheng , LIU Hong-ying , WANG Jie

2014, 30(7):154-159.

[Abstract](1134) [HTML](0) [PDF 574.68 K](637)

Abstract:
This article attempts to evaluate the fresh-keeping effects on Argopectens irradias, which was treated with compound preservative combined with modified atmosphere packaging (MAP), and the changes of total bacteria count (TBC), physicochemical and sensory indexes during freezing (0±1)℃ were measured. Results showed that total volatile base nitrogen (TVB-N), TBC, sensory evaluation, pH and Ca2+-ATPase activity were related to the processing period (p<0.05).The shelf-life of Argopectens irradias by air package was 4 d, while in biological fresh-keeping agents was 9 d. The combined preservative combined with modified atmosphere packaging remarkably extended its shelf period, and explored good fresh-keeping and antibacterial effects. High CO2 MAP had better antimicrobial effect, but drip loss became more serious with increasing CO2 concentration. After ten days of fresh-keeping with biological fresh-keeping agents combined with air-conditioned packing with 80% CO2 and 20% N2, total bacteria of Argopectens irradias turned out 5.20 lg(cfu/g) with TVB-N of 0.12 mg/g, and the activity of Ca2+-ATPase was 0.0310 μmol Pi/(mg·h). Thus, the combination of compound preservative and modified atmosphere packaging could effectively extend the shelf-life of Argopectens irradias during refrigerated storage．

28 Fermentation of Fruit Vinegar from Hovenia acerba

XIANG Jin-le , DU Lin , LI Xin , ZHU Wen-xue , LI Zhi-xi

2014, 30(7):160-164.

[Abstract](1288) [HTML](0) [PDF 544.52 K](661)

Abstract:
Hovenia acerba is a nutritional food material for fermentation due to its high sugar content. Fruit vinegar was produced from the peduncles by pulping with water, alcoholic fermentation and acetic fermentation. The applicable “two-step” fermentation method and technological parameters were investigated. Skin-on fermentation was carried out in the alcoholic fermentation stage with technological parameters as addition of water to 1.5 times, inoculation with 0.1% Angel fruit wine yeast , fermentation at 16 ℃ for 80 h. The alcohol concentration of wine reached 8.13% (m/V). Semicontinuous submerged fermentation was conducted in the acetic fermentation stage with a 5 L laboratory-scale fermenter for fruit vinegar production. The technological parameters of the acetic fermentation were as follows: inoculum size of acetic acid bacteria 10%, and fermentation temperature 34 ℃. It took 72 h to finish the first cycle of acetification with the titratable acidity of 5.42% (m/V), and 30 h to finish the second cycle. The optimized processing method and technological parameters could be applied directly in the industrialized production of Hovenia acerba vinegar.

29 Effects of Stunning Method and Carcass Orbit Time on Stress and the Meat Quality of Pigs

WU Xiao-wei , ZHANG Chun-hui , LI Xia , JING Xiao-liang , TANG Chun-hong , WANG Chun-qing

2014, 30(7):165-170.

[Abstract](1074) [HTML](0) [PDF 555.07 K](587)

Abstract:
Influences of electrical stunning, CO2 stunning and different durations in orbit (32, 38 and 44 min) on blood stress indicators, pre-cooling loss and pork quality of Dudachang crossbred pig were studied in the paper. The results showed that lactic acid content, cortisol content, creatine kinase content and lactate dehydrogenase content in CO2 stunning pig blood were lowered significantly by 85.50 mg/dL, 161.62 ng/mL, 2828.36 U/L and 192.71 U/L (p＜0.05), respectively, compared with that by electrical stunning. The bone breakage rate was lowered by 2.82%. Body chamber temperature (after being sprayed) and pre-cooling loss were reduced by 1.72 ℃ and 0.28 %, respectively when duration in orbit was prolonged from 32 min to 44 min under CO2 stunning condition, and the pre-cooling losses reached the minimum level (0.89%). In addition, the redness value a* was the maximum (7.55), with higher tenderness, while drip loss (3.22%), cooking loss (29.90%), suspected incidence of PSE meat (19.13%) and the incidence of PSE meat (9.10%) were the lowest in all treatments, when CO2 stunning was adopted under the orbit duration process conditions for 44 min. Therefore, CO2 stunning with proper orbit duration prolongation in practical production could reduce stress reaction, lower pre-cooling loss and improve pork quality.

30 Effect of Freeze-thaw Cycles on Proteins and Muscle Quality of Dosidicus gigas

JIANG Qing-qing , LI Shan , LIU Wen-juan , LU Jun , CHEN Shi-guo , YE Xing-qian , HU Ya-qin

2014, 30(7):171-178.

[Abstract](1374) [HTML](0) [PDF 678.49 K](896)

Abstract:
Effects of different freeze-thaw cycles on proteins and muscle quality of Dosidicus gigas were studied to provide a theoretical basis for the preservation of aquatic products. Protein carbonyl content, total sulfhydryl content, surface hydrophobicity, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) pattern, turbidity, emulsifying activity index (EAI) and emulsifying stability index (ESI) of the treated samples were measured after 0, 1, 3 ,5 and 7 freeze-thaw cycles. And the thawing loss, cooking loss, color, tenderness, texture and thiobarbituric acid reactive substances (TBARS) of squid muscle were analyzed combined with organoleptic evaluation. With increasing the number of freeze-thaw cycles, protein carbonyl content and surface hydrophobicity increased but total sulfhydryl content of myofibrillar proteins exhibited the opposite trend. Aggregation of proteins was found during the process and EAI and ESI dropped markedly. Moreover, TBARS, thawing loss, cooking loss and b* significantly increased (p<0.05), while L*, a*, whiteness, tenderness, springiness and hardness decreased. Results from organoleptic evaluation were in consistence with the instrumental ones. In summary, repeated freeze-thaw cycles promotes oxidation of protein and lipid and has a detrimental effect on the qualities of squid muscle.

31 Purification, Identification and the Antioxidant Activity of Polysaccharides from Pyrus sinkiangensis

LIU Xiao-feng , LIU Lin , WANG Yong-gang , MA Yan-lin , ZHANG Wei-jie , ZHU Xin-qiang , WANG Chun-mei , WANG Xiao-li

2014, 30(7):179-186.

[Abstract](1378) [HTML](0) [PDF 657.19 K](688)

Abstract:
The polysaccharides of Piteguo (PTGP1) extracted by water-extraction and ethanol-precipitation methods were purified by Soxhlet extraction, Sevag method andDEAE-52 anion exchange column chromatography. The structure, composition and molecular weight of PTGP1 were analyzed by ultraviolet-visible spectra (UV-VIS), infrared spectrum (IR), scanning electron microscopy (SEM), gas chromatography tandem mass spectrometer (GC-MS) and high performance size exclusion chromatography multiangle laser light scattering (HPSEC-LLS). The in vitro antioxidant activities of PTGP1 were determined by the total reducing power, DPPH, superoxide radicals, hydroxyl radicals scavenging assays and the inhibition rate of malondialdehyde (MDA) in mice liver homogenate. Results showed that PTGP1 was a reducing sugar without starch and anthocyanins, whose surface was of holes fold fibrous structure. PTGP1was mainly consisted of rhamnose, arabinose, xylose, mannose, glucose and galactose, with the molar ratio of 3.06:2.32:1.56:4.87:3.28:2.18 in the form of pyranose containing α-glycosidic bond. HPSEC-LLS analysis showed that the PTGP1 was composed of three different polymers, whose average molecular weight was 5.81×105 Da and the main composition content was 76%. Oxidation test indicated that the total reduction ability of PTGP1 was 0.45 times compared with VC, the half inhibit concentration (IC50) of PTGP1 for scavenging hydroxyl free radicals, superoxide anion and DPPH free radicals were 1.24 mg/mL, 1.05 mg/mL and 2.13 mg/mL, respectively, which could effectively inhibit lipid peroxidation induced by hydroxyl free radicals, as well as the formation of MDA in mice liver homogenate.

32 Effect of Different Packaging on Quality of Tuna (Thunnus obesus)in Cold Chain Logistics

TANG Yuan-rui , XIE Jing , XU Hui-wen , CHEN Yu-zhou , ZHANG Ning

2014, 30(7):187-192.

[Abstract](1251) [HTML](0) [PDF 539.92 K](839)

Abstract:
The present study was undertaken to investigate the influences of air packaging, modified atmosphere packaging (MAP, 60%CO2+15%O2+25%N2) and vacuum packaging (VP) on the quality degradation of tuna (Thunnus obesus) in cold chain logistic process. Sensory evaluation, microbiological analysis, chemical and physical indices (a* value, pH, TBA, TVB-N and histamine) were assayed periodically in simulated situation of logistics. The result showed that both MAP and VP had dampening effects on quality degradation of tuna caused by the temperature variation in inadequate cold chain logistics. However, MAP was better for maintaining the flesh color, inhibit microbial growth and histamine generation. Total viable count and histamine of MAP tuna were 3.68 lg(CFU/g) and 8.86×10-2 mg/g, respectively. All indices did not exceed the safety levels of tuna sashimi. The results suggested that MAP could reduce the quality degradation rate of tuna in inadequate cold chain logistics effectively.

33 Isolation and Nutrient Composition of Protein Isolates from Penaeus monodon using Isoelectric Solubilization/Precipitation

HONG Wei , SUN Cheng-bo , ZHOU Chun-xia , HONG Peng-zhi , WANG Yun

2014, 30(7):193-196.

[Abstract](1065) [HTML](0) [PDF 724.22 K](663)

Abstract:
In this study, effect of pH conditions in the extraction process on protein yield, changes of nutritional components and nutritional value of protein isolates from whole and muscle of tiger shrimp (Penaeus Monodon) using isoelectric solubilization/precipitation (ISP) was investigated. Protein isolates were obtained from tiger shrimp at a ratio of 1:9 with cold distilled water, dissolved at pH 2.0, 3.0 and pH 11.0, 12.0, subsequently precipitated at pH 5.5. Protein yields from whole and muscle of tiger shrimp were 75.67%~82.72% and 68.33%~80.5%, respectively. The highest protein extraction was observed at pH 2.0 and 12.0. Crude protein content in protein isolates extracted from both materials was more than 71% (dry weight), and the acidic treatments yielded significantly (p<0.05) higher contents of crude protein and ash in the recovered proteins than the basic treatments. The protein isolates from both pH treatments had increased contents of essential, semi essential and total amino acids as well as flavor amino acids but lowered content of shrimp-flavor amino acids than those of the starting materials. And their essential amino acids content met the FAO/WHO/UNU requirements. Both basic and acidic treatments gave rise to the removal of Cu, Mg, K, Zn and Mn, and the basic treatments yielded protein with significantly (p<0.05) higher amount of minerals than the acidic treatments. Therefore, protein isolates prepared from whole and muscle of tiger shrimp via ISP were high in protein yield and nutritional?value and may be used for the development of human food and animal feeds.

34 Effects of Milk (Milk Active Peptide) and Processing Technology on Quality of Bread

LI Zhi-cheng , LIU Sha , ZHENG Xiao-ying , FU Mang-juan , WANG Rui , HAO Jie

2014, 30(7):197-204.

[Abstract](1141) [HTML](0) [PDF 566.71 K](711)

Abstract:
In order to increase the consumption of dairy products, the influences of milk and active peptide from milk protein and processing technology on quality characteristics of bread were researched. The results showed that adding 6% (m/m) milk or 0.014% (m/m) active peptide from milk protein could increase the nutritional value, elasticity, specific volume and sensory quality of bread, and decrease the hardness of bread. The elasticity, hardness and specific volume of milk bread were 0.784, 901.46 g, and 6.3 mL/g, respectively, while those of the active peptide bread were 0.931, 1466.25 g, and 6.9 mL/g, respectively.The quality of bread was better than steamed bun and the formula for preparing bread can also be applied to steamed bun. The acrylamide content of bread was 92.6±8.4 μg/kg, which was significantly higher thanthat of steamed bun prepared by the combined steamed and roasted technologies (p<0.01). No acrylamide was detected in the steamed bun processed with the same formula. Therefore, the steamed bread is safer than bread in acrylamide content. It provides reference for customs to choose bread or steamed bun in both tasty and safety.

35 Effect of Sterilization Treatments on the Quality of Blueberry Juice

XIE Guo-fang , WANG Rui , ZHOU Xiao-li , MA Li-zhi

2014, 30(7):205-210.

[Abstract](1308) [HTML](0) [PDF 535.58 K](743)

Abstract:
Microorganisms, physical-chemical properties and sensory evaluation of blueberry juice by pasteurization, UHT and microwave treatment were investigated . Results indicated that the three treatments all met thecommercial sterilization requirements. The pH value, total soluble solid and total acid content of blueberry juice had no changes for the samples treated by the three methods. Pasteurization effectively maintained the suspension stability, color and anthocyanins content of blueberry juice. And the free radical scavenging ability against DPPH of the Pasteuring samples was lower than that of the microwave treatment, where the free radical scavenging ability against DPPH of microwave treatment was up to 88.24%. The sensory evaluation showed that the blueberry juice by microwave treatment was closest to the control sample than the other treatments, especially in color and aroma. Therefore, microwave treatment can effectively inactivate the microorganisms and keep the physical-chemical properties, sensory evaluation and antioxidant activity of blueberry juice.

36 Effects of Low-dose Irradiation and Vc Content on the Storge Quality of Refrigerated Chicken

LI Yang , WANG Chao , LIAO Li , WANG Lan , XIONG Guang-quan , CHENG Wei , LI Dong-sheng , QIAO Yu

2014, 30(7):211-217.

[Abstract](1255) [HTML](0) [PDF 557.49 K](657)

Abstract:
To extend the shelf life of refrigerated chicken, 60Co-γ irradiation and antioxidants were used and the effect of Vc on low-dose irradiation of chicken were investigated in this study. The best irradiated process was treating the chicken for 5 min by 0.4% Vc and vacuum packing under the 2 kGy irradiation dose and then storing them up for 28 d below 4 ℃.Total number of colonies, chrominance, shear force, TBA, TVB-N, pH were measured within 28 d storage. The results showed that the total number of colonies, TVB-N, tendness, pH of Vc-treated group had no obvious effects during the storage period. Chrominance of Vc-treated group was better than that of blank group, while TBA of Vc-treated group was less than that of blank group at 0 d, 14 d and 28 d, respectively. TBA of blank group at 0 d and that of Vc-treated group at 14 d had no significant differences (P>0.05), which showed that Vc-treated effectively inhibited the oxidation of irradiated chicken. Therefore, low-dose irradiation and antioxidants processing can inhibit microbial growth and fat oxidation in chicken, and lower the color variation, achieving good preservation effect.

37 Effects of Three Freezing Methods on the Quality Changes of Pseudosciaena crocea

LIAO Yuan-yuan , OU Chang-rong , TANG Hai-qing , CAO Jin-xuan , GAO Ya-wen , DU Jie-xiong

2014, 30(7):218-223.

[Abstract](1218) [HTML](0) [PDF 737.40 K](793)

Abstract:
Physicochemical study, texture analysis and low-field 1H NMR method were applied to analysis the changes of water holding capacity, texture property and water mobility of Pseudosciaena crocea frozen by different methods，including slow freezing (SF), quick freezing by immersing in ultra-low temperature ethanol (QF-UTE) and in liquid nitrogen (QF-LN). The results showed that the quick frozen samples revealed a relatively lower freezing loss and thawing loss, otherwise a relative higher juice loss and cooking loss, compared to the SF treated samples. Quick frozen samples also showed higher texture properties in hardness, adhesiveness, chewiness and resilience, while the adhesiveness, springiness and cohesiveness of SF samples were relatively closer to those of unfrozen fish. The transverse relaxation time of Low-field 1H NMR indicated that the mobility of bound water, extra-cellular water and free water in Pseudosciaena crocea increased after frozen by three methods , and the mobility increased in order of unfrozen sample, SF, QF-UTE and QF-LN. The content of bound water and extra-cellular water of the quick frozen samples were higher than that of SF treated samples, while free water content was lower than SF. Significant correlations were found between the NMR parameters and water holding capacity indices. The above results suggested that quick freezing caused greater changes in texture property and water holding capacity of fish flesh than SF, thus leading to higher juice loss and cooking loss after thawing, which was probably due to the cracking phenomena in the fish flesh during quick freezing.

38 Purification and Partial Characterization of Lectin from Broccolini

XU Ping-ping , ZHANG Xue-wu

2014, 30(7):224-229.

[Abstract](1160) [HTML](0) [PDF 528.96 K](619)

Abstract:
Broccolini lectin (BL) was extracted from Broccolini with normal saline, distilled water, Tris-HCl buffer and phosphate buffered saline (PBS), followed by ammonium sulphate precipitation, and finally purified by chromatography DEAE-52 and Sephadex G-75. Partial characterization of BL was also studied. The results showed that Tris-HCl buffer had the highest extraction rate of 3.57±0.02%. Molecular mass of BL was estimated as 27 ku by SDS-PAGE. The BL contained 7.60±0.03% sugar and its clotting activity was 28. The sugar inhibition test showed that its hemagglutinating activity of erythrocyte could be inhibited by D- mannose and arabinose. Moreover, the lectin remained stable at 20~90 ℃ and its optimum pH was 7~8. Its clotting activity was significantly decreased in strong acid?and?strong alkali environment. The lectin reaction was also influenced by divalent cations Ca2+, in which its hemagglutinating activity was increased.

39 Quality Characteristics of Black Garlic with Differet Processing Procedures

WANG Hai-su , WU Hao , YANG Shao-lan , ZHOU Yuan-ming , WANG Cheng-rong

2014, 30(7):230-236.

[Abstract](2000) [HTML](0) [PDF 722.80 K](688)

Abstract:
In this study, fresh garlic from Jinxiang was fermented to black garlic by -18 ℃ pretreatment combined with variable temperature fermentation for the first time. The total color difference, water content, texture, reducing sugar content, total phenol content, free amino acid content, volatile components and sensory indexes of black garlic were determined in order to compare the quality characteristics of lab-prepared fermented black garlic (FBG) and three kinds of commercial black garlic made by traditional processing. The results indicated that the fermentation period by the new processing method with frozen pretreatment decreased, which was shortened from 60~90 days to 15 days and FBG made by the new processing method was similar or better than the commercial black garlic by traditional processing in terms of sensory indexes, nutrition and functional components. The reducing sugar content, total phenol content, free amino acid content of FBG reached to (48.50±0.44)×10-2 g/g, 10.44 ± 0.53 mg/g, (54.90±0.61) ×10-2 mg/g, respectively, by the new method. At the same time, the contents of 17 kinds of amino acid and volatile components are equal or higher than those of the commercial black garlic. Therefore, the new processingtechnology for FBG shortened the fermentation period, and ensured the quality of black garlic products. These results provided references for black garlic processing industry in China.

40 Quality Evaluation of Dried Chinese Jujube based on Texture Profile Analysis

YAN Zhong-xin , LU Zhou-min

2014, 30(7):237-241.

[Abstract](1276) [HTML](0) [PDF 480.79 K](561)

Abstract:
In the present study, the quality of dried Chinese jujube was evaluated. Texture profile analysis (TPA) and chemical analysis were applied to evaluate texture parameters and TS-to-TA ratio of hot-air drying (at 50 ℃ for 27 h, 60 ℃ for 18 h and 70 ℃ for 12 h), natural drying (35 d) and sugar-preserved jujube, through correlation and cluster. These results demonstrated that texture parameters were significantly changed with drying. The hardness were significantly reduced and the adhesiveness were improved (P<0.05). Hot-air drying at 60 ℃(18 h) was better than those at 50 ℃(27 h), 70 ℃(12 h) and natural drying (35 d). The cluster analysis could be used to distinguish the texture quality of Chinese jujube with different drying conditions. It also provides a theoretical reference to distinguish the quality level of dried Chinese jujube.

41 Comparison of Methods for Rapid Determination of Total Lipid Content in Microalgae

WEI Dong , YUAN Xian-yuan , XIANG Wen-zhou

2014, 30(7):242-246.

[Abstract](1653) [HTML](0) [PDF 523.15 K](810)

Abstract:
The rapid, reliable and easy manipulated method for determination of total lipid content in microalgae is crucial important for screening oleaginous strains, evaluation of functional oil from microalgae and microalgal biological research. Using dry powder of three microalgae (Nannochloris sp., Chlorella vulgaris and Pavlova viridis) as feedstock, the difference of four methods (Bligh-Dyer, modified Bligh-Dyer, ASTM standard and direct saponification methods) was systematically compared in terms of determining total lipid content in microalgae. The fatty acid contents and compositions in crude extracts from different methods were further profiled by GC/MS with in suit transesterification method as control. The results showed that the modified Bligh-Dyer and ASTM standard methods had steady extraction outcomes with the highest fatty acid recoveries at 93.65% vs 93.74%, 85.02% vs 85.77%, and 88.62% vs 88.84% in three powders, respectively. Moreover, no significant difference (p>0.05) appeared in total lipid and fatty acid contents and compositions in extracts by the two methods. Obviously, the modified Bligh-Dyer method is a simple and preferred method with less amount demand of sample (0.25 g) and short time-consuming (1.0 h) for the rapid determination of total lipid content in microalgae, which is an alternative of ASTM standard method in laboratories.

42 Quantitative and Qualitative Analysis of Fish Freshness based on Electronic Tongue Technique

HAN Fang-kai , HUANG Xing-yi , MU Li-jun , GU Hai-yang

2014, 30(7):247-251.

[Abstract](1112) [HTML](0) [PDF 534.52 K](808)

Abstract:
In order to quantitatively and qualitatively evaluate the fish freshness , an electronic tongue was employed to detect the pomfret stored at 4 ℃ for different days. The total volatile basic nitrogen (TVB-N) and total viable count (TVC) of the fish samples were detected concurrently. K-nearest neighbor（KNN）model and back-propagation artificial neural network ( BP-ANN ) model were built to assess the freshness of the fish. Results showed that identification rate of training set and prediction set of KNN model were 99.11% and 98.21% respectively. While, the identification rate of training set and prediction set of BP-ANN model were 92.81% and 91.07% respectively. Support vector machine regression (SVR) model was established between the electronic tongue data and TVB-N as well as TVC for quantitative determination. The correlation coefficients between SVR predicted and measured TVB-N and TVC values were respectively 0.9727 and 0.9457, and root mean square error of prediction were 2.8×10-4 mg/g and 0.052 log(CFU/g), respectively. The overall results sufficiently demonstrate that the electronic tongue technique combined with appropriate pattern recognition method has a great potential to quantitative and qualitative evaluation of fish freshness rapidly.

43 Changes of Volatile Components in Abalone before and after Baking by SPME Coupled with GC-MS

ZHENG Rui-sheng , XU Ai-ping , REN Li-hua , WANG Ze-jin

2014, 30(7):252-257.

[Abstract](1036) [HTML](0) [PDF 546.57 K](577)

Abstract:
In order to reveal the origin of main characteristic flavor and promptly grasp the quality changes of different processing abalone, the changes of volatile components in abalone before and after processing were analyzed by the technology of solid phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The results showed that the volatile components of abalone changed obviously before and after processing. Thirty-nine kinds of volatile components in thawed abalone and 51 kinds in baked abalone were detected respectively, including ethanol, aldehydes, nitrogen and sulfur containing compounds, ketones, hydrocarbons, acids, esters, aromatic series, etc. Thawed abalone had clear and slightly fishy flavor. Ethanol and aldehydes were its main flavor substances, in which benzaldehyde (20.83%), 1-octen-3-ol (18.35%), oxime-methoxy-phenyl-(13.25%) were the most important characteristic flavor components. But the flavor in baked abalone changed dramatically. The inherent clear flavor in fresh abalone gradually disappeared and the barbecue flavor increased remarkably. And ethanol, nitrogen and sulfur containing compounds were its main volatiles sources, in which butanediol (42.64%) and methyl-pyrazine (12.41%) were the most important characteristic flavor components.

44 Determination of Casein Phosphopeptides in Calcium Tablets by High Performance Liquid Chromatography

ZHANG Shuai , LIU Fei , LUO Zhen , GUO Bin , PENG Wei , CAO Yong

2014, 30(7):258-262.

[Abstract](1251) [HTML](0) [PDF 527.08 K](733)

Abstract:
The contents of casein phosphopeptides (CPP) from five kinds of calcium tablet were determined by high performance liquid chromatography (HPLC) method. Mobile phase, detection wavelength, velocity and injection volume were the mixture of 1‰ TFA aqueous solution and 1‰ TFA acetonitrile solution, 215 nm, 1 mL/min, and 10 μL, respectively. The optimal condition of gradient elution was obtained by HPLC chromatogram analysis as organic phase of 5%~35% and elution for 45 min. Under the optimal conditions, CPP can be well seperated, and its recovery was between 96.75%~104.07%, which was close to the true value. This method was proved to be simple with high accuracy and sensitivity, and its detection limit was 6.81 μg/mL, which could be regarded as an excellent method to determine CPP in calcium tablets. In order to compare this HPLC method with the other methods, Barium-ethanol precipitation was used to determine the CPP contents in the same five calcium tables. Result showed that the recoveries of CPP in five samples were all more than 220%, which was inappropriate to determine the content of CPP in calcium tablets for the great deviation.

45 Development of an Enzyme-linked Aptamer-based Assay for the Detection of Tetracycline

ZHANG Xuan , LIU Xin-jia , LEI Hong-tao , LIU Ying-ju , WANG Hong , XU Zhen-lin , SUN Yuan-ming

2014, 30(7):263-267.

[Abstract](1638) [HTML](0) [PDF 526.98 K](690)

Abstract:
The Mannich method was employed to conjugate the tetracycline (TC) to horseradish peroxidase (HRP). The optimal coating concentration of streptavidin (SA) was 8 μg/mL and aptamer concentration was 20 nmol/L, which were determined by chequerboard titration. The optimized assay conditions were investigated by single-factor experiments. Coating buffer carbonate buffer (CB, 0.05 mol/L, pH 9.6), phosphatic buffer solution (PBS) plus 5 mmol/L MgCl2 and PBS were chosen as coating buffer assay buffer, and standard dilution buffer, respectively.was, The best dilution ratio of TC-HRP and incubation time of aptamer were 1/50 and 1 hour, respectively. An enzyme-linked aptamer assay (ELAA) method was thus established for the determination of TC. The half inhibition concentration (IC50) of the proposed method was 0.705 μg/mL, and the limit of detection (LOD) was 2.5 ng/mL. Compared with other structural analogues (eg. doxycycline, oxytetracycline and chlortetracycline) of TC, there were no conspicuous cross reactions except chlortetracycline (25.9%). This direct competitive ELAA method is specific and highly sensitive that could meet the requirements of quantitative analysis of TC, which is suitable for the rapid detection of TC in variable food samples.

46 Rapid Detection of Enterohemorrhagic Escherichia coli O157 by LAMP Real-time Turbidity Method

LI Bi-xia , YOU Shu-zhu , KUANG Xiao-shan , FENG Jia-wang , WANG Xiao-yu , TANG Shi-ming , CHENG Xiao-wei , XU Xi-lin

2014, 30(7):268-272.

[Abstract](1270) [HTML](0) [PDF 566.52 K](685)

Abstract:
Real-time monitoring of magnesium pyrophosphate produced from the loop-mediated isothermal amplification (LAMP) reaction was achieved by the turbidimeter. Four specific primers were designed according to the sequences of antigen gene rfbE of EHEC O157. Detection was completed at 63 ℃ on the real-time turbidimeter in 1 h. The specificity, sensitivity, stability of the method was evaluated. Results showed that after optimized, the lowest detection limit was 2.8×103 CFU/mL, and 100 times more sensitive than the PCR, and the minimal adding quantity of 2.8×100 CFU/25 g (or mL) could be detected. LAMP real-time turbidity method is rapid, sensitive, high specificity and easy to operate, which is a good pattern for fast screening of foodborne pathogens.

47 Physicochemical Properties of Different Dry Cured Duck and Differences of Volatile Compounds

QU Zhi , LIN Yao-sheng , TANG Dao-bang , LIU Xue-ming , TANG Qiu-shi

2014, 30(7):273-278.

[Abstract](1118) [HTML](0) [PDF 536.41 K](660)

Abstract:
In order to explore the quality of different regional dry cured duck, the physicochemical properties, microbial quantity, structural characteristics and flavor composition of three varieties of dry cured duck were compared. Hardness, elasticity, viscosity, cohesiveness and chewiness were analyzed for meat quality. Gas chromatography-mass spectrometry (GC-MS) was used to detect aroma components of samples. The results showed that physicochemical properties have difference in three samples, especially the moisture content, which was 34.30% in Sichuan dry cured duck, while 20~25% in Nanjing and Jiangxi dry cured duck. All of them had neutral range pH value and high salt content. Nanjing dry cured duck had the biggest hardness, the maximum elasticity was observed in Sichuan dry cured duck, and the best chewing was in Jiangxi dry cured duck. Sixty-three kinds of flavor components were identified. The main flavor compounds were alcohol, carboxylic acid, hydrocarbons, esters, ketones, aldehydes. Sichuan and Jiangxi dry cured duck had significant differences, especially the ketone compounds. The quality of different dry cured duck was different, especially in texture and flavor.

48 Identiﬁcation of Aroma-active Compounds in Watermelon Juice by AEDA and OAV Calculation

HE Cong-cong , SU Ke-ran , LIU Meng-ya , LIU Jian-bin , LIU Ye , SONG Huan-lu

2014, 30(7):279-285.

[Abstract](1479) [HTML](0) [PDF 708.78 K](767)

Abstract:
Solvent assisted flavor evaporation and gas chromatography?mass spectrometry?olfactometry (GC-O-MS) were used in this study to identify aromatic compounds in watermelon juice. Forty-nine volatiles were identi?ed, most of which were low molecular weight alcohols, aldehydes and sulfur-containing compounds. There was only one ester that detected in melon juice, considered as ethyl acetate with low concentration. Sulfur-containing compounds were identified for the first time as aroma compounds in watermelon. Eleven compounds, namely (Z)-3-Nonen-1-ol, (Z, Z)-3,6-nonadienal, (E,Z)-3,6-noandienol, (E)-2-nonenal, nonanal, 1-nonanol, 2-pentylfuran, hexanal, Octanal, (Z)-6-nonenal and (E)-2-octenal, were identi?ed as the potent odorants in watermelon juice by both odor active value(OAV) and aroma extract dilution analysis(AEDA). In addition, five odorants including (Z)-3-Nonen-1-ol, (Z, Z)-3, 6-nonadienal, (E, Z)-3, 6-noandienol, (Z)-6-nonenal, (Z)-2-nonenal were detected by all of the panelists and showed higher OAVs, indicating that AEDA and OAV resulted in relatively similar watermelon aroma patterns.

49 Analysis of Fruit Quality of Xinjiang Apricot and North China Apricot

ZHAO Cui , TIAN Ying-zi , YING Li , MA Qian-li , LUO Yu-nian , WANG Qing-qing

2014, 30(7):286-291.

[Abstract](1082) [HTML](0) [PDF 380.45 K](636)

Abstract:
In order to study the quality differences between Xinjiang apricot and North China apricot, ten different kinds of excellent apricot were selected from these two regions. Total soluble sugar, reducing sugar, total acid, vitamin C, single fruit weight, single kernel weight, single apricot-pit weight were determined. Other characters including diameter, length, flavor, color and luster were also determined to evaluate the Xinjiang apricot quality comprehensively. The results showed that, Xinjiang apricot had higher total soluble sugar content, reducing sugar content, sugar-acid ratio, kernel rate than north China apricot obviously. The average sugar-acid ratio of Xinjiang apricot was about 5.61 higher than that of north China one which made perfect flavor for Xinjiang apricot. It also had special color and luster which was more popular. In addition, proper water content made it taste very well. The average single fruit weight of north China apricot was heavier than that in Xinjiang one significantly as well as the edible rate. Slight changes was found in the total acid, vitamin C, kernel weight, apricot-pit weight of these apricots . There was no linear relationship between total sugar content and reducing sugar content among those apricots. Higher reducing sugar content was found in samples with higher total sugar content.

50 A Graphene/Ionic Liquid Modified Screen-printed Electrode for Detection of Rutin in Medicine

WANG Hui , LIU Gang , WANG Zhi-qiang , ZHANG Zhi-hao

2014, 30(7):292-297.

[Abstract](1672) [HTML](0) [PDF 705.43 K](608)

Abstract:
In this paper, a novel screen-sprinted electrode (GR-ILSPE) modified by n-octylpyridinum hexa?uorophosphate (OPFP) and graphene (GR) was fabricated and used for sensitive detection of rutin in medicine. The novel screen-sprinted electrode produced with low costs combined with good advantages of ionic conductivity, adhesiveness and electrochemical stability that existed at room temperature, and also with good performances of the large specific surface area, high electron transfer and catalytic ability of graphene that greatly enhanced the practical value and electrochemical properties. Different electrochemical methods such as cyclic vohammetry, impedance spectroscopy and differential pulse voltammetry were used to investigate the electrochemical behaviors of rutin on GR-ILSPE, and the electrochemical parameters were optimized. Under the optimal conditions, the oxidative peak current was linearly related to its concentration in the range from 5×10-8 to 5.5×10-6 mol/L with the detection limit estimated to 2.5×10-8 mol/L, and the linear regression equation was I (μA)= 1.01C(μmol/L) -0.024 (r=0.99). Finally, the developed electrode was successfully applied to detect the content of rutin in tablet, which displayed excellent selectivity and good stability.

51 Monitoring the Vinegar Aging based on Electronic Nose

QIAO Yan-xia , LI Zhi-xi , Niamat ULLAH , JIN Yu-hong , LI Rui

2014, 30(7):298-305.

[Abstract](1226) [HTML](0) [PDF 696.65 K](664)

Abstract:
Four kinds of vinegars were detected by PEN3 electronic nose. The volatile compositions emanating from the vinegars were collected by the systems, and their response values were obtained. Principal component analysis (PCA), linear discrimination analysis (LDA), fisher linear discrimination analysis (FDA) and multilayer perceptron neural network (MLPNN) were used to distinguish the vinegars from different aging time. The results showed that LDA was able to identify different aging time of vinegars and the contribution rate was above 90%. The identification of vinegars from different aging time by LDA was better than that by PCA. Moreover, LDA showed that the changes of vinegars volatile composition had an increasing tendency during the aging time, and had a great agreement with the total acid of the samples. FDA and MLPNN were also employed to predict the aging time of the samples, which indicated that the FDA prediction rates of Feng Xiang, Long Xian, Jin Tai, Wei Bin vinegar were 100%, 100%, 98% and 100% respectively, while the MLPN prediction rates of these samples were 100%, 100%, 96.92% and 100%, respectively. Therefore, the prediction rate monitored by electronic nose combined with FDA was better than that with MLPNN.

52 Research Progress of Heat and Mass Transfer and Optimization of Rapeseed Hot-air Drying

YANG Ling , YANG Ming-jin , GUO Meng-bao , LIU Bin , CHEN Jian

2014, 30(7):306-313.

[Abstract](1328) [HTML](0) [PDF 548.15 K](733)

Abstract:
Rape is grown for production of vegetable oil, protein, forage, nectar, and energy with high economic value and development potential. The process of drying and storage of rapeseed is a key link between rape planting and oil comprehensive process and utilization. Based on analysis of rapeseed drying characteristics and main drying technology, research progress of heat and mass transfer and optimization of rapeseed hot-air drying was summarized for providing basis for optimization of apparatus design, drying technique, parameter, and process control. Traditional drying theories and models are mostly based on Luikov Theory and Whitaker Theory, and made some simplification or modification. Since porous media was assumed as meanly distributed continuous material, the intrinsic relationship between the local and the whole porous media is hard to be revealed. Combining Fractal Theory and Pore Networks Model is an effective method for scale integration of porous media drying. Numerical researches on hot-air drying are made from macroscopic, multiscale and microscopic perspectives. By applying CFD technology, information of drying rate, energy consumption and moisture distribution can be effectively obtained, which can be employed to optimize the drying apparatus and control the drying process. Researches on rapeseed hot-air drying are mainly focused on drying characteristics, quality of the product and their measurement technology. The drying technique, drying parameters and drying process should be optimized in order to obtain good drying quality of the product.

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Volume 30,Issue 7,2014 Table of Contents