Volume 31,Issue 3,2015 Table of Contents

1 Effects of Total Saponins in Panax notoginseng Leaves on Behavior and Levels of cAMP, PKA, and BDNF in Rats Exposed to Chronic Unpredictable Mild Stress

ZHANG Hua-lin , ZHOU Zhong-liu , YANG Hong-yan , XIANG Hui

2015, 31(3):1-5. DOI: 10.13982/j.mfst.1673-9078.2015.3.001

[Abstract](1517) [HTML](0) [PDF 590.55 K](1152)

Abstract:
This study evaluated the antidepressant effects and corresponding mechanism of the total saponins in leaves of Panax notoginseng (TSLPN). A chronic unpredictable mild stress (CUMS) rat model of depression was established to evaluate the antidepressant effects of TSLPN and the effects of TSLPN on the levels of cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), brain-derived neurotrophic factor (BDNF) in the hippocampus of rats. Forty rats were randomly divided into five groups: control, CUMS, fluoxetine, medium dosage of TSLPN, and high dosage of TSLPN groups. After exposure to CUMS for four weeks, compared with the rats in control group, those in CUMS group showed decreases in three behavioral indices-body weight, sucrose preference, and locomotor activity by 8.56%, 22.48%, and 26.17%, respectively. Animals exhibited depression-like symptoms, such as loss in body weight, anhedonia, and decrease in locomotor activity, and the levels of cAMP, PKA, BDNF in the hippocampus also decreased by 53.60%, 53.60%, and 39.20%, respectively. After TSLPN treatment, compared with CUMS group, the above-mentioned three behavioral indices of the rats in high dosage TSLPN increased by 7.03%, 26.21%, and 26.21%, respectively; the levels of three biochemical indices–cAMP, PKA, and BDNF levels–also increased by 41.29%, 62.79%, and 49.05%, respectively. These results indicated that TSLPN could reverse the depression-like behaviors and regulate the levels of cAMP, PKA, and BDNF in the hippocampus. In conclusion, TSLPN was found to have excellent antidepressant effects, and its functioning mechanism was related to the regulation of cAMP, PKA, and BDNF levels in the hippocampus.

2 The Mechanism of Nereis Active Protease-induced Apoptosis in Lung Cancer SPC-A-1 Cells

ZHANG Guo-mei , YANG Zui-su , DING Guo-fang , HUANG Fang-fang , ZHAO Yu-qing

2015, 31(3):6-11. DOI: 10.13982/j.mfst.1673-9078.2015.3.002

[Abstract](1657) [HTML](0) [PDF 854.99 K](1276)

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This study aims to investigate the mechanism of Nereis active protease (NAP)-induced SPC-A-1 cell apoptosis. The effect of NAP on the activity of SPC-A-1 cells was examined by MTT assay. Typical morphologic changes were observed in the SPC-A-1 cells by inverted microscopy and AO/EB staining. The early-stage apoptotic rate and membrane potential were detected using flow cytometry, and the protein expressions of apoptosis-related genes were examined via western blotting. The results showed that NAP significantly inhibited the activity of SPC-A-1 cells in a time- and dose-dependent manner. The flow cytometry (FCM) studies revealed that the percentage of the early-stage apoptotic SPC-A-1 cells that were treated with increasing concentrations of NAP for 24 h increased from 13.50% to 22.98%, and the percentage of cells with decreased mitochondrial membrane potential increased from 12.59% to 25.28%. After treatment with 50 μg/mL NAP for 24 h, the Bcl-2/Bax expression ratio relative to the control group increased by a factor of 6.05. The expression levels of Cyt-C, Cleaved-caspase 9, Cleaved-caspase 3, and Cleaved-PARP relative to the control group significantly increased by a factor of 2.32, 3.07, 3.68, and 1.36, respectively. In conclusion, NAP inducing apoptosis of SPC-A-1 cells by decreasing the expression of the anti-apoptotic protein Bcl-2 and upregulating the expression of Bax, thereby inducing the decrease of mitochondrial membrane potential which then promoting the transfer of Cyt-C and activate the cascade of caspase family.

3 Effects of Patulin on the Proliferation and Apoptosis of Human Embryonic Kidney Cells

ZHANG Bai-gang , PENG Xiao-li , LI Guang-hui , XU Yun-feng , XIA Xiao-dong

2015, 31(3):12-17. DOI: 10.13982/j.mfst.1673-9078.2015.3.003

[Abstract](1058) [HTML](0) [PDF 1.06 M](1105)

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To study the mechanism of patulin on the proliferation and apoptosis of human embryonic kidney cells, HEK293 cells were cultured and treated with different concentrations of patulin in vitro. The effect of patulin on cell proliferation level was examined by LDH cytotoxicity assay. The morphological changes in patulin-treated HEK293 cells were observed using scanning electron microscopy and fluorescence microscopy. The cell apoptosis rate was detected by Annexin V-EGFP/PI double staining. The mitochondrial membrane potential was measured by a JC-1 probe. The expression levels of the mitochondrial related genes FIS1, ASL, SLC25A6, and COX17 were measured by real-time fluorescent quantitative PCR. The results showed that PAT inhibited the growth of HEK293 cells in a dose-dependent manner and resulted in apoptosis in HEK293 cells. Treatments with 2.5, 5, 7.5, 10, and 15 μM PAT for 8 h resulted in significant decreases in cell viability by 8.1%, 18.2%, 31.0%, 42.2%, and 63.1%, respectively. When treated with 5 μM patulin for 0, 3, 10, and 24 h, the cell survival rates were 94.2%, 78.1%, and 47.4%, respectively. After treatment with 5 and 10 μM PAT for 8 h, the number of apoptotic cells increased in a dose-dependent manner by 16.4% and 20.1%. The changes in the expression levels of mitochondrial membrane potential and mitochondrial genes indicate that patulin may cause HEK293 apoptosis through mitochondrial pathways.

4 The Hepatoprotective Effect of Polyphenols from Sphallerocarpus gracilis Stem Leaves against CCl4-induced Acute Hepatic Damage in Mice

KANG Li-na , MA Ting-ting , ZHAO Pei , ZHENG Cui-ping , QUAN Mei-ping , SUN Xiang-yu , TIAN Cheng-rui

2015, 31(3):18-23. DOI: 10.13982/j.mfst.1673-9078.2015.3.004

[Abstract](1117) [HTML](0) [PDF 869.93 K](1008)

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The aim of this study was to investigate the protective effect of polyphenols from Sphallerocarpus gracilis stem leaves on carbon tetrachloride (CCl4)-induced hepatic injuries, and to identify its effective dosage. The mice in the treatment group were administrated with the polyphenols from Sphallerocarpus gracilis stem leaves at doses of 150, 300, and 600 mg/kg body weight (BW)/day for 21 consecutive days. The liver injury model was established by intraperitoneal injection of 3 mL 1% CCl4 rapeseed oil (V/V). The alanine transaminase (ALT), aspartate transaminase (AST), total cholesterol (TC), total triglyceride (TG), total bilirubin (TBIL) contents in serum, and superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) levels in liver were measured. Meanwhile, a hepatic pathological examination was conducted. The results of this study showed that the polyphenols from Sphallerocarpus gracilis stem leaves could, to some extent, protect mice from CCl4-induced liver injury. In addition, these polyphenols significantly prevent the increase in liver index spleen index, serum ALT, AST, TBIL, and liver MDA levels, caused by CCl4 in mice. These polyphenols could also markedly increase the activities of liver SOD and CAT. Among the tested doses, 300 mg/kg BW/day showed the best effect. Histopathological examinations further confirmed these results.

5 Antioxidant, Antimutagenic and in vitro Anticancer Effects of Crude Polyphenols in Insect Tea Made from Kuding Tea Leaves

ZHAO Xin , WANG Qiang

2015, 31(3):24-28. DOI: 10.13982/j.mfst.1673-9078.2015.3.005

[Abstract](973) [HTML](0) [PDF 850.66 K](1292)

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In this study, the antioxidant, antimutagenic and in vitro anticancer effects of crude polyphenols in insect tea made from Kuding tea leaves (KMICP) on human hepatoma cells SMMC-7721 were investigated. The DPPH radical scavenging activity after treatment using 25, 50, 75, and 100 μg/mL KMICP was 27.8%, 46.6%, 85.9%, and 99.8%, respectively. KMICP at concentrations of 1.25 and 2.5 mg/plate showed antimutagenic effects on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced mutation (49.5% and 78.1%, respectively) and aflatoxin B1 (AFB1)-induced mutation (54.8% and 76.4%, respectively). KMICP also showed significant inhibitory activity on SMMC-7721 cells in vitro, while the growth of cancer cells was completely inhibited at 150 μg/mL concentration. By reverse-transcription polymerase chain reaction (RT-PCR) conducted on KMICP-treated SMMC-7721 cells, it was found that Bax, IκB-α, TIMP-1, and TIMP-2 gene expression in cancer cells was increased, Bcl-2 and NF-κB gene expression was decreased, and the effect of high-concentration KMICP was more significant than that of low-concentration KMICP. These results demonstrate that KMICP shows good in vitro antioxidant, antimutagenic, and anticancer properties.

6 Structural Analysis of Polysaccharides from Pleurotus ferulae Lenzi

CHEN Shuai , XU Cheng-jian , LI Ying-biao , LIU Bing , WANG Xue-ming , HE Yan

2015, 31(3):29-37. DOI: 10.13982/j.mfst.1673-9078.2015.3.006

[Abstract](1388) [HTML](0) [PDF 840.32 K](1329)

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The Pleurotus ferulae Lenzi polysaccharide (PFLP) was isolated and purified to study its components and structure. The relative molecular mass and distribution of PFLP were analyzed by high-performance gel filtration chromatography. The structure was analyzed by gas chromatography (GC), partial acid hydrolysis, periodate oxidation, Smith degradation, methylation, infrared spectroscopy (IR), 1HNMR, Congo red experiment, and iodine-potassium experiment. Two components, PFLP1 and PFLP2, were obtained through extraction and purification. The result indicated that the relative molecular mass and distribution of PFLP1 was 9400~9900 u. PFLP1 was composed of rhamnose, mannose, glucose, and galactose with a molar ration of 1:1.54:18.6:3.64. The relative molecular mass and distribution of PFLP2 was 9700–10400 u. PFLP2 was composed of rhamnose, xylose, mannose, glucose, and galactose with a molar ration of 1:1.08:0.65:6.76:4.28. Both PFLP1 and PFLP2 contained glycosidic bond of (1→2), (1→3), (1→6), and (1→4). PFLP1 and PFLP2 possessed typical infrared absorptions of polysaccharides, and the sugar chains were mainly pyranoside with β-configuration and contained a type of protein glycoconjugate. PFLP1 and PFLP2 possessed triple helical structures containing long side chains and branches.

7 Cloning, Expression, and Characterization of a Phosphoglucomutase from Paenibacillus mucilaginosus

TANG Jia-yi , LAN Dong-ming , WANG Yong-hua , YANG Bo

2015, 31(3):38-42. DOI: 10.13982/j.mfst.1673-9078.2015.3.007

[Abstract](1121) [HTML](0) [PDF 840.32 K](1210)

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Exopolysaccharides produced by Paenibacillus mucilaginous as flocculants have attracted much attention from wastewater treatment in the food industry because of their better performance over traditional industrial flocculants. Phosphoglucomutase (PGM, EC 5.4.2.2), which is responsible for the transformation of glucose 6-phosphate (G6P) into glucose 1-phosphate (G1P), was considered to be the key enzyme involved in the biosynthesis of polysaccharides. In this article, a pgm gene encoding PGM from P. mucilaginous GIM1.16 was cloned. Sequence analysis showed that the pgm contained a 1710 bp open reading frame (ORF). Subsequently, the pgm gene was expressed in Escherichia coli, and SDS-PAGE analysis demonstrated that the molecular weight of the recombined protein was 63 kDa. The optimum temperature for the recombined PGM activity was 40 ℃, but the enzyme became inactive once the incubation temperature exceeded 55 ℃. The recombined PGM showed low activity in acidic conditions (pH 4.0~6.0) and alkaline conditions (pH 8.5~10.0), and the optimum pH for the activity of this enzyme was 7.5. The Kcat and Km values of PGM were 684 min-1 and 0.24 mM-1 on G1P, respectively. This work lays a solid foundation for the construction of genetically engineered strains and metabolic engineering research.

8 Cloning and Bioinformatics Analysis of Fe-SOD Gene in Alicyclobacillus acidoterrestris

JIAO Ling-xia , HUA Cheng-wei , XU Xi-xi , WANG Jun-jie , ZHAO Rui-xiang

2015, 31(3):43-49. DOI: 10.13982/j.mfst.1673-9078.2015.3.008

[Abstract](1423) [HTML](0) [PDF 798.92 K](1194)

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Alicyclobacillus acidoterrestris, a genus of acidophilic and thermophilic resistant bacteria, is an important microbial resource of heat and acid resistant enzymes, a variety of enzymes isolated from which have acid and thermal stability. Superoxide dismutase (SOD) is widely used in food, clinical treatment, and cosmetic industry for its important physiological functions. In order to deeply explore the molecular properties of SOD gene in Alicyclobacillus acidoterrestris, the Fe-SOD gene was cloned, sequenced and analysed using homologous cloning, thermal asymmetric interlaced PCR and bioinformatics. The results showed that Fe-SOD gene(GenBank accession number: JN614998) contains a complete ORF of 606 bp, encoding 202 amino acid, the deduced amino acid sequence shared the highest homology with Fe-SOD from A. acidocaldarius DSM 446 (78%). A. acidoterrestris Fe-SOD is composed of five motifs and the active site of SOD contains the residues of His27, His82, Asp164, and His168, which has characteristics of protein structures of Fe/Mn SODs family. Cloning and bioinformatics analysis of A. acidoterrestris Fe-SOD will provide information for constructing prokaryotic expression vector and obtaining the gene engineering bacteria strains of producing heat and acid resistant SOD.

9 The Isolation and Identification of Deep-sea Bacteria That Produce Salt-tolerant Proteases

ZHAO Mou-ming , SHU Hui , CUI Chun , LEI Fen-fen , TANG Xue-lu

2015, 31(3):50-54. DOI: 10.13982/j.mfst.1673-9078.2015.3.009

[Abstract](1496) [HTML](0) [PDF 613.74 K](1348)

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This study was aimed at screening deep-sea bacteria that produce salt-tolerant proteases from deep-sea mud samples based on high-salt accumulation, fermentation rescreening, and salt-tolerant stability tests. Twenty-five strains of deep-sea marine microorganisms were selected, 14 of which demonstrated an increase in hydrolysis cycles on casein plates. A strain with high enzyme activity and salt stability was obtained based on fermentation rescreening and a salt-tolerance test, and was labeled as SWJSS3. Strain SWJSS3 was identified using 16S rDNA and a preliminary study on the effects of salt concentration on its protease yield and stability was conducted. The strain was able to grow in medium with salt concentrations between 0% and 10% and an OD600 of the bacterial suspension ranging from 0.08 to 1.98. The activity of proteases produced by SWJSS3 was maximal for a 1% salt concentration in the fermentation rescreening (233.56 ± 2 U/mL). After treatment with 15% (final concentration) sodium chloride solution at 4 °C for 1 h, the enzyme activity decreased to 40.70 ± 2.06% of the initial enzyme activity, but remained stable for up to 9 h. strain SWJSS3 was identified as Pseudomonas aeruginosa, exhibiting 99% 16S rDNA sequence similarity to P. aeruginosa RP28.

10 Effect of Fish Skin Collagen Peptides on Cell Viability of Human Skin Keratinocytes

CHEN Jun , YE Yan-jun , WANG Bao-zhou , WENG Wu-yin

2015, 31(3):55-59. DOI: 10.13982/j.mfst.1673-9078.2015.3.010

[Abstract](1357) [HTML](0) [PDF 535.87 K](1004)

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This study investigated the effects of shark skin collagen hydrolysates (SH), tilapia skin collagen hydrolysates (TH), and their isolated fractions on the viability of human skin keratinocyte (HaCat). The HaCat cell viability, determined with the MTT method, was increased notably with the addition of 0.05 mg/mL or 0.20 mg/mL SH during the exponential growth phase. However, when the concentration of the added SH was increased to 1.00 mg/mL, no significant proliferation of HaCat was observed. The HaCat cell viability with the addition of TH was higher than that of the control (without the addition of TH), but TH concentrations did not significantly influence the viability. On the other hand, the HaCat cell viability with addition of the fractions, which were isolated from SH or TH by Sephadex G-15, was much higher than that with the addition of dipeptide (Gly-Tyr) or Tyr. Compared to the sample with added GSH, the MDA content was lower and the SOD activity was higher with the added isolated fractions irrespective of fish skin collagen hydrolysates. Based on these results, it was concluded that the fractions isolated from fish skin collagen hydrolysates by Sephadex G-15, can effectively promote the proliferation of HaCat and have great potential to replace GSH as antioxidative peptides in the cosmetics industry.

11 Effect of Heat-moisture Treatment on the Physicochemical Properties and Digestibility of Starches with Different Crystal Structures

GAO Qun-yu , YE Ying , WANG Lin

2015, 31(3):60-65. DOI: 10.13982/j.mfst.1673-9078.2015.3.011

[Abstract](1677) [HTML](0) [PDF 833.49 K](1883)

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In this study, three types of starch, each with a different crystal structure [corn starch (A-type), potato starch (B-type) and pea starch (C-type)] were treated using heat at 120°C for 13 h in the presence of 25% moisture content. The effect of heat-moisture treatment was studied in terms of physicochemical properties and digestibility of starch. The results showed that, compared with native starch, the crystal structures of all three starches changed after heat-moisture treatment. The original A-type structure of corn starch changed to (A+V)-type, while both, B- and C-type structures present in potato and pea starches changed to A-type. The starch granules showed different degrees of damage on the surface, while some showed a decrease in the central intensity of the Maltese cross. The temperature required for gelatinization increased and the enthalpy values decreased in A- and B-type starches but increased in C-type. The content of resistant starch component was elevated and the anti-peptic activity was significantly enhanced. The changes in C-type starch were observed as most significant.

12 Microflora Analysis and Preliminary Identification of Dominant Spoilage Bacteria in Vacuum-packed Harbin Red Sausage

YU Long-hao , HE Wang-lin , LI Jing-jing , YU Hong , MA Hong-yan

2015, 31(3):66-70. DOI: 10.13982/j.mfst.1673-9078.2015.3.012

[Abstract](1367) [HTML](0) [PDF 594.73 K](1173)

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The aim of this study was to effectively monitor the spoilage of Harbin red sausage. Selective media were used to study the microflora of vacuum-packed Harbin red sausage stored at 4 ℃ and preliminarily identify bacteria causing spoilage at the end of the storage period. The microflora of Harbin red sausage varied significantly during storage period at 4 ℃: at the start of the storage period (0 to 4 d), logarithm values of the colony count of Brochothrix thermosphacta (0.00%), lactic acid bacteria (44.30%), Pseudomonas (23.40%), cocci (32.30%), Bacillus subtilis (0.00%), molds and yeasts (0.00%) were 0.01, 2.27, 2.11, 2.36, 0.01, and 0.01 log CFU/g, respectively. However, during spoilage, logarithm values of the colony count of Brochothrix thermosphacta (0.00%) lactic acid bacteria (60.0%), Pseudomonas (0.00%), cocci (16.30%), Bacillus subtilis (23.70%), molds and yeasts (0.00%) were 2.30, 6.74, 0.01, 6.52, 6.66, and 3.00 log CFU/g, respectively. At the end of the spoilage experiment, 14 strains were isolated, with specific morphological characteristics and preliminary identification was carried out using molecular biology methods. The isolates included six strains of genus Bacillus (7.70%) and Bacillus cereus (16.00%), five strains of Staphylococcus xylosus (3.80%) and Staphylococcus equorum (12.50%), one strain of Brochothrix thermosphacta (0.00%), and two strains of Lactobacillus sake (60.00%). Therefore, the dominant spoilage bacteria in vacuum-packed Harbin red sausage were identified as Lactobacillus sake, Bacillus cereus, and Staphylococcus equorum.

13 Characteristics of the Dynamic Spectral Response of Korla Pear

XU Hu-bo , WU Jie , WANG Zhao-peng , GAO Yong-mao , WANG Zhi-peng , ZHAO Zheng-qiang

2015, 31(3):71-76. DOI: 10.13982/j.mfst.1673-9078.2015.3.013

[Abstract](1191) [HTML](0) [PDF 1.08 M](1079)

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In this study, Korla pear was exposed to pulse excitation to determine the characteristics of its dynamic spectral response, and the frequency spectrum method was used to test its internal quality. The effect of different window functions on the dynamic spectral response curve of the pear was analyzed. Further, the influence of different excitation points, excitation forces, excitation materials as well as the mass, shape, and firmness of the fruit on the characteristics of dynamic spectral response of the Korla pear was determined. The results showed that during analysis of the dynamic signal of the pear, the exponential window function was more suitable to truncate the signal since the processed signal had high signal to noise ratio and less information leakage. Signals from a single excitation and dynamic signals from different excitation points on the equatorial region of the Korla pear were studied. The signal stability was strong and the responses of dynamic spectrum were generally consistent. Changes in excitation material and forces had no significant effect on the dominant response frequency. When a rubber head hammer was used and the excitation force was in the range of 9 to 12 N, the dynamic signal was strong. The dominant response frequency that showed a larger difference in terms of amplitude with the second response frequency was obtained, thus the dynamic signal could be analyzed easily. The mass, shape, and firmness of the fruit showed good linear correlation with the dominant response frequency.

14 Cloning, Prokaryotic Expression, and Purification of the Mincle Receptor Protein

YAN Ping , ZHU Xi-mei , LI Lu , LIN Wen-hua , ZHAN Ruo-ting , TANG Yu-qian

2015, 31(3):77-83. DOI: 10.13982/j.mfst.1673-9078.2015.3.014

[Abstract](1321) [HTML](0) [PDF 935.53 K](1232)

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In this study, genetic engineering techniques were used to construct the recombinant prokaryotic expression vector pET14b-Mincle, which was then transformed into Escherichia coli host strain BL21 (DE3) to induce the expression of the target protein Mincle. The expression product was purified, verified, and refolded using dialysis. Mincle coding sequence fragments were amplified by reverse transcript polymerase chain reaction (RT-PCR), and cloned into the carrier pMD18-T and the prokaryotic expression vector pET14b which containing His-tag. The constructed vector, verified by restriction endonuclease digestion and DNA sequence comparisons, was then transformed into E. coli host strain BL21 (DE3) and expression was induced using IPTG. A recombinant fusion protein with a molecular weight of approximately 22 kDa was expressed under optimized induction conditions with 1 mmol/L IPTG at 37 ℃ for 5 h. The specificity of the recombinant protein was confirmed using SDS-PAGE, western blots, and ELISA. Mincle was expressed in the host in the form of inclusion bodies, and was purified using a Ni2 + affinity column and refolded by biofilm dialysis. The purified and dialyzed protein was verified by western blotting and ELISA, and its activity was examined with inactivated whole cells of Candida albicans (SC5314). The specific binding with C. albicans showed that the Mincle recombinant fusion protein was biologically active. Thus, this method produced active protein and forms a basis for future studies.

15 Synthesis and Antibacterial Activity of Lauric Acid Derivatives

LIANG Zhun-cheng , YANG Ji-guo , LIU Dong-qi , NING Zheng-xiang

2015, 31(3):84-90. DOI: 10.13982/j.mfst.1673-9078.2015.3.015

[Abstract](1508) [HTML](0) [PDF 904.70 K](1792)

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In this study, lauric acid derivatives including glycerol monolaurin (GML), mixture of glycerol dilaurin and glycerol trilaurin (GDL+GTL), as well as polyglycerol monolaurin (PGML) were synthesized and those with optimum application properties, in terms of antibacterial activity and skin sensitization reactions were identified. The esterification of lauric acid derivatives was carried out under the following optimal reaction conditions: NaHSO4 at 0.3% of the weight of lauric acid, substrate molar ratio of 1:2, 200 ℃ and 5 h in vacuo with solid acid salt catalyst and the products were purified by molecular distillation. GML and PGML were obtained with relatively high purity. The minimum inhibitory concentration (MIC) was estimated by plate count method formed on the culture plate. The result showed that lauric acid, GML, and PGML showed high antibacterial activity towards both, gram-positive and gram-negative bacteria. The individual activities of lauric acid and GML were higher than that of PGML under the same conditions, while GDL+GTL combination showed no antibacterial activity. It was also confirmed via skin-sensitization tests that lauric derivatives did not induce skin allergy.

16 Angiotensin-converting Enzyme Inhibition By Rice Protein Hydrolysate

CHEN Qian-qian , TONG Li-tao , ZHONG Kui , LIU Li-ya , ZHOU Su-mei , QIAN Hai-feng

2015, 31(3):91-96. DOI: 10.13982/j.mfst.1673-9078.2015.3.016

[Abstract](1166) [HTML](0) [PDF 684.16 K](1086)

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In this study, the production of peptides with angiotensin-converting enzyme (ACE) inhibition activity was investigated from simulated in vitro digestion of four rice proteins, namely albumin, globulin, prolamin, and glutelin. The proteins were extracted from rice using the Osborne method. Production and ACE inhibiting activity, the degree of hydrolysis, and the molecular weight distribution of the proteolysis products were investigated. The results revealed that ACE inhibition activity of individual products obtained after proteolysis of the proteins, was high after 30 min of pepsin digestion. The activity decreased upon subsequent digestion with trypsin. The hydrolysates of rice albumin, globulin, prolamin, and glutelin after 4-hour digestion showed half-inhibition concentration (IC50) of 1.45, 0.91, 1.19, and 0.75 mg/mL, respectively, and their molecular weight was < 1000 u, which means they can be easily absorbed by the human body. At the same time, undigested proteins had almost no ACE inhibition activity. The result also showed the products of in vitro protein proteolysis had different ACE inhibition activities and that rice glutelin proteolysis product showed the highest ACE inhibition activity. Therefore, the gastrointestinal digestion of regularly consumed rice can produce ACE-inhibiting peptides that can be absorbed by the human body.

17 Properties of Chondroitinase Using Polyacrylamide Gel Electrophoresis

WANG Ying , WANG Feng-wu , ZHAO Xue

2015, 31(3):97-102. DOI: 10.13982/j.mfst.1673-9078.2015.3.017

[Abstract](1178) [HTML](0) [PDF 648.34 K](1173)

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In this study, polyacrylamide gel electrophoresis (PAGE) was used to explore the enzymatic properties of chondroitinase A (CSAase) produced by strain RC3. A crude solution of intracellular chondroitinase was obtained by ultrasonication of the microbial cells, which was then mixed with an equal volume of chondroitin sulfate A (CSA) and incubated. The effect of various culture conditions on enzyme activity was studied using PAGE. The results showed that the optimal temperature and pH value for fermentation of CSAase were 20 ℃ to 40 ℃ and 8.0, respectively. Magnesium ion was found to activate CSAase, while copper and zinc ions were strong inhibitors. Potassium, calcium, sodium, manganese, and barium ions did not significantly affect enzyme activity. Magnesium ions at a concentration of 10 mM showed the strongest activating effect on CSAase. Copper and zinc ions showed strong inhibitory effect on the enzyme activity at a concentration of 5 mM. Under the above optimal conditions, the low-molecular-weight products that were obtained after a 4-hour hydrolysis reaction using this enzyme, showed a higher antioxidant activity than that of CSA, which is a macromolecule. This study suggests the potential applicability of CSAase.

18 Effect of 11S Globulin on the Properties of Chicken Myosin Gel

ZHANG Qiu-hui , LI Miao-yun , GAO Xiao-ping , ZHANG Jian-wei , ZHAO Gai-ming , YUE Xi-qing

2015, 31(3):103-107. DOI: 10.13982/j.mfst.1673-9078.2015.3.018

[Abstract](976) [HTML](0) [PDF 676.65 K](1051)

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In order to reveal more accurately the role of soybean protein in meat processing and to provide the theoretical basis for minced meat processing, important proteins such as myosin and 11S globulin (high abundant in meat and soybean proteins) were extracted from chicken breast muscle and soybean, respectively, for this study. SDS-PAGE was used to determine the purity of myosin and 11S globulin. The effect of 11S globulin on the properties of chicken myosin gel was investigated by modern biotechnological methods, including texture analysis, low-field NMR, and SEM. The results showed that the purity of the two extracted proteins exceeded 90%. Low concentrations of 11S globulin improved the water holding capacity (WHC) of the myosin gel, but at high concentrations, the WHC decreased significantly. 11S globulin had little effect on the strength of the myosin gel. Higher concentrations of 11S globulin promoted inhomogeneous microstructures with larger holes in the myosin gel. Collectively, the desired quality of the myosin gel was obtained with the 11S globulin content of 4%.

19 Physicochemical Properties of Low Moisture Potato Starch and Their Effects on Surimi products

HUANG Jie , ZHAO Jian-xin , HUANG Jian-lian , FAN Da-ming , ZHANG Wen-hai , LIAN Hui-zhang , CHEN Wei , ZHANG Hao

2015, 31(3):108-114. DOI: 10.13982/j.mfst.1673-9078.2015.3.019

[Abstract](1722) [HTML](0) [PDF 687.47 K](1302)

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In this study, the physicochemical properties such as morphology, microscopic morphology, crystal structure, pasting properties, freeze-thaw stability, and swelling power of ultra-dry potato starch and their effects on surimi seafood were investigated. The results indicated that the water content of ultra-dry potato starch did not exceed 8%. With shrinkage and crack observed on the surface of the starch granule, the ultra-dry potato starch had a larger amorphous region and smaller crystallinity. It formed a gel more easily at a low initial temperature of gelatinization (To, 57.16 ℃) and transition enthalpy (ΔH, 16.26 J/g). Compared to native potato starch, ultra-dry starch exhibited better freeze-thaw stability, higher swelling power (18.83 g/g), and lower gel consistency (80.43 mm), indicating its better physicochemical properties. According to the study, both native and ultra-dry potato starch can improve the gel properties of silver carp surimi products, and the latter showed more significant effects. The optimum addition level of the starch is about 8%.

20 The Effect of Polysaccharides Extracted from Porphyra on the Quality of Prawns Subjected to Cold Storage

LI Ying-chang , WANG Ya-li , LV Yan-fang , MA Chun-ying , LI Jian-rong

2015, 31(3):115-120. DOI: 10.13982/j.mfst.1673-9078.2015.3.020

[Abstract](1024) [HTML](0) [PDF 735.48 K](1190)

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Prawns are nutritious, but are susceptible to spoilage. The aim of this study was to investigate the effect of polysaccharides extracted from Porphyra on the quality of prawns during cold storage, in order to prolong the shelf life of cold-stored prawns. The prawns treated with 0.8% polysaccharides from Porphyra, and those from the control group were stored in a refrigerator at 4 ± 1 ℃ for 8 days. The sensory quality of the prawns was assessed on days 0, 2, 4, 6, 7, and 8. The biological index (total bacterial count) and chemical indices (pH value, total volatile basic nitrogen [TVB-N], thiobarbituric acid [TBA], and K value) were measured, and a sensory evaluation performed in order to assess the change in the quality of prawns during cold storage. The results of these analyses showed that prawns treated with polysaccharides from Porphyra had significantly lower total viable count, pH, TVB-N, TBA, K value, and sensory scores, compared to the control group. Polysaccharides from Porphyra extended the shelf life of prawns by 3 to 4 days than that of the control group, during cold storage. Hence, polysaccharides extracted from Porphyra effectively inhibited the propagation of bacteria and slowed the anti-oxidation of fat, thereby prolonging the shelf life of prawns. Therefore, this method could be applied for the preservation of prawns during cold storage.

21 The Difference in Pericarp Browning between Harvested ‘Wuye’ and ‘Lanzhu’ Litchis

LIN Fu-xing , LIN Yi-xiong , LIU Mu-shui , LIN Yi-fen , CHEN Yi-hui , LIN He-tong

2015, 31(3):121-125. DOI: 10.13982/j.mfst.1673-9078.2015.3.021

[Abstract](1063) [HTML](0) [PDF 644.28 K](1083)

Abstract:
Harvested litchi (Litchi chinensis Sonn.) fruit is susceptible to pericarp browning, which is the most important factor affecting the quality and shelf-life of this fruit. The difference in the pericarp browning between harvested ‘Wuye’ and ‘Lanzhu’ litchis was investigated during storage at 8 ± 1℃ in relation to phenolics metabolism . The results showed that as compared with ‘Lanzhu’ litchis, ‘Wuye’ litchis tended to be less susceptible to pericarp browning, and the browning index in the pericarp of ‘Wuye’ litchis during storage was remarkably lower than that of ‘Lanzhu’ litchis. There were higher contents of anthocyanin, total phenolics, and flavonoid in the pericarp of harvested ‘Wuye’ litchis than those of ‘Lanzhu’ litchis, whereas the activities of polyphenol oxidase (PPO) and peroxidase (POD) were lower as compared with ‘Lanzhu’ litchis. During storage, the contents of anthocyanin, total phenolics, and flavonoid as well as PPO activity in the pericarp of harvested ‘Wuye’ litchis and ‘Lanzhu’ litchis decreased continuously, while POD activity showed a continuous increase. However, during the same storage time, there were higher contents of anthocyanin, total phenolics, and flavonoid as well as lower activities of PPO and POD in the pericarp of ‘Wuye’ litchis than those in ‘Lanzhu’ litchis. From the results, it can be concluded that, ‘Wuye’ litchis tend to be less susceptible to pericarp browning, which is related to low PPO activity and decrease in anthocyanin, total phenolics, and flavonoid contents.

22 Mechanism of Amylose-flavor Molecule-inclusion Compound Formation Simulated By Molecular Dynamics

FENG Tao , LIU Fang-fang , RONG Zhi-wei , ZHUANG Hai-ning , LIU Yi

2015, 31(3):126-132. DOI: 10.13982/j.mfst.1673-9078.2015.3.022

[Abstract](1337) [HTML](0) [PDF 1.13 M](1607)

Abstract:
In this study, glucose molecular force field and Gromacs software were used to simulate the molecular conformation of amylose, its folding in aqueous solution, and the process of formation of inclusion compounds with three small alcohol molecules, n-hexanol, n-heptanol, and n-octanol. The results were compared with previous experimental characterization to clarify the mechanism of formation of the V-shaped amylose inclusion compounds and the interactions between amylose and guest molecules contributing flavor. Amylose exhibits a free stretch of spiral coil configuration in aqueous solution, which is more obvious with a decrease of water content within a certain range. In the stimulated formation of inclusion compounds with alcohol molecules, the changing trends of root mean square deviation (RMSD) were similar, showing a corresponding increase with a rise in temperature. This shows that the inclusion compound system had a consistent macro appearance; however, the number of hydrogen bonds, the cutting process distribution of intermolecular forces, system electric potential, and so on varied between target molecules. Putting all the parameters together, the molecular dynamics simulation can provide strong evidence to predict the possibility of inclusion formation at a molecular level. It also confirms that amylose combines with other molecules to form relatively stable inclusion configurations.

23 Preparation and Adsorption Characteristic of Magnetic Molecular Imprinted Polymers for Di(2-ethylhexyl) Phthalate

XU Xiao-yan , XU Li , HUANG Meng-ling , LIN Yong-shi , LEI Qian-yun

2015, 31(3):133-137. DOI: 10.13982/j.mfst.1673-9078.2015.3.023

[Abstract](1351) [HTML](0) [PDF 790.98 K](1069)

Abstract:
Novel magnetic molecularly imprinted polymers (M-MIPs) with specific recognition were prepared using Fe3O4@SiO2 modified by 3-(trimethoxysilyl)propylmethacrylate (MPS) as magnetic carrier, di(2-ethylhexyl) phthalate(DEHP) template molecule, methacrylic acid (MAA) as functional monomer, and ethylene glycol dimethyl acrylate (EGDMA) as cross-linker. TEM graph reveals the M-MIPs owned a core-shell structure. VSM measurement manifests the M-MIPs were superparamagnetic, this feature provided the M-MIPs with easy separation in an external magnetic field. The static equilibrium adsorption experiment and the Scatchard analysis showed that there were two kinds of binding sites between the imprinted polymers and template molecule. The dissociation constants were 0.26 mmol/L and 0.071 mmol/L, and the corresponding apparent maximum number were 28.23 mg/g and 13.09 mg/g. selective experiment showed the M-MIPs exhibited excellent recognition and selection properties toward template molecule, compared with its analogues The as-prepared M-MIPs could be further employed for the separation and enrichment of DEHP from food.

24 Domestication of Chlorella protothecoides for High Tolerance to Sugarcane Bagasse Hydrolysate Using a Fibrous-bed Bioreactor

WEI Dong , CHEN Jiao-min , OU Ying-shi

2015, 31(3):138-143. DOI: 10.13982/j.mfst.1673-9078.2015.3.024

[Abstract](1008) [HTML](0) [PDF 851.79 K](1055)

Abstract:
Chlorella protothecoides can rapidly utilize fermentable sugars in sugarcane bagasse hydrolysate (SCBH), but its cell growth is inhibited by by-products in the hydrolysate. In this study, to enhance the heterotrophic growth capability in high-concentration SCBH, C. protothecoides was cultured in a fibrous-bed bioreactor (FBB). The preparation and components of SCBH, seed culture by batch-fed fermentation, cell immobilization in FBB, and cell domestication in SCBH medium in an FBB were systemically studied. The results showed that after acid hydrolysis and enzymolysis, the main components of SCBH were glucose, xylose, acetic acid, cellobiose, and arabinose with concentrations of 18.40, 16.17, 6.13, 5.10, and 2.29 g/L, respectively. The cell density was up to 12.37 g/L for batch-fed cultures in Basal medium after 117 hours in a fermenter. The immobilized cell bed formed when the medium was recycled for 33 hours after connecting the fermenter with the FBB. Then, the Basal medium was replaced with SCBH medium, and the concentration of the SCBH medium was gradually increased to domesticate the immobilized cells. A highly tolerant strain, which grew heterotrophically in SCBH medium containing 35 g/L glucose, was isolated from the fibrous bed, while the wild-type strain was unable to grow.

25 Self-association Conditions and Hydration Kinetics of Spine Grape Anthocyanins

DENG Jie-hong , WEI Jia-jing , LIU Yong-hong , WANG Wei-qian , WEI Yi-zhi

2015, 31(3):144-150. DOI: 10.13982/j.mfst.1673-9078.2015.3.025

[Abstract](969) [HTML](0) [PDF 887.32 K](1247)

Abstract:
Self-association of anthocyanins is important for stability. The effects of anthocyanin concentration, pH, temperature, time, purity, and solvent system on the self-association of spine grape anthocyanins (SGA) were studied. The results showed that the optimum conditions for self-association of SGA crude extracts were pH 3, 60 min, 20 ℃, and an anthocyanin concentration of greater than 0.240 mmol/L. Under these conditions, the degree of self-association reached 50.5433. For three SGAs that differed in purity, a higher purity resulted in molecules that could self-associate more easily and more strongly, indicating a common mechanism underlying self-association and copigmentation for anthocyanin. Solution systems were established by simulating grape wine and grape juice. The strength of self-association of crude extracts containing SGA in an alcohol solvent was greater than that in an aqueous solvent, and the initial anthocyanin concentrations that resulted in self-association in the two solvent systems were 0.03 mmol/L and 0.06 mmol/L, respectively. The anthocyanin hydration kinetics were also analyzed. As the anthocyanin concentration increased, the apparent hydration coefficient k decreased and the dissociation constant pK increased, indicating that self-association strengthened the hydrophobic properties and reduced the dissociation of anthocyanins, and therefore improved its stability.

26 High-density Culture and Potential Aquatic Remediation Activity of Bacillus subtilis H001

LIU Dong-mei , LUO Tong-hui , LI Xin-rui , WU Hui , LI Li , XIAO Xing-long , YUAN Kun , LAI Fu-rao

2015, 31(3):151-157. DOI: 10.13982/j.mfst.1673-9078.2015.3.026

[Abstract](1253) [HTML](0) [PDF 947.93 K](1201)

Abstract:
The increase in scale and degree of intensification of aquaculture has led to several environmental issues, such as eutrophication, excessive nitrite content, and presence of pathogenic microorganisms, in the water bodies used for aquaculture. Introduction of probiotics into such water bodies can help prevent and control these critical issues. Bacillus subtilis strain H001 was selected from among ten screened strains as it showed higher amylase (36.7 U/mL) and protease (35.6 U/mL) activities. The medium components were varied in order to optimize the medium for H001 growth, and the effect was investigated in terms of the logarithm of total colony number [log(TCN)]. Highest log(TCN) values for H001 were obtained for 40 g/L bran-based broth, 15g/L corn-based broth, and 20 g/L soybean meal, at 12.1, 12.1, and 14.0, respectively. The log(TCN) was approximately 15 when the mass ratio of corn-based broth (or bran-based broth) to soybean meal was 2:1. The rate of nitrite degradation by H001 in the simulated water body was 94.5%, 95.0%, 84.1%, 68.6%, 48.5%, and 44.4% when the initial nitrite concentration was 5.0, 10.0, 20.0, 30.0, 40.0, and 50.0 mg/L, respectively. In summary, the TCN of Bacillus subtilis H001 with higher amylase and protease activities increased to 1.6 × 1015 CFU/mL after the medium was optimized. This optimized medium was economical and suitable for high-density culture of H001. Strain H001 is presented as a potential aquatic bioremediation agent for water bodies used in aquaculture.

27 Extraction of Phenolic Acids and Flavonoids from Nidus Vespae Using Silica-supported Ionic Liquid-based Matrix Solid-phase Dispersion

WANG Zhi-bing , ZHAO Yang , XIN Nan , ZHANG Sheng-yu , QIU Fang-ping

2015, 31(3):158-164. DOI: 10.13982/j.mfst.1673-9078.2015.3.027

[Abstract](1164) [HTML](0) [PDF 1016.38 K](1225)

Abstract:
In this study, a new kind of silica-supported ionic liquid (S-SIL) was prepared by impregnation and employed as the dispersion adsorbent for matrix solid-phase dispersion (MSPD). This system was used for the simultaneous extraction of caffeic acid, ferulic acid, morin, chrysin, and kaempferide from Nidus Vespae (honeycomb). High-performance liquid chromatography (HPLC) was used to separate and identify the analytes. The experimental conditions for S-SIL-based MSPD were optimized. S-SIL containing 10% [C6MIM]Cl was used as dispersant, 20 mL n-hexane was used as washing solvent, and 15 mL methanol was used as the eluent. The mass ratio of sample to S-SIL was set as 1:4. The calibration curve of each target compound showed a good linear relationship within the linear range (r > 0.9995). The limits of detection and quantification were in the range of 0.05 to 0.18 μg/mL and 0.17 to 0.59 μg/mL, respectively. The relative standard deviations (RSDs) of intra-day and inter-day precision were lower than 5.48% and 6.60%, respectively. The recoveries were between 83.73% and 95.32%. Thus, a novel method of S-SIL-based MSPD combined with HPLC was developed in this study, to identify five phenolic acids and flavonoids in Nidus Vespae. Compared with other extraction methods, this method required less extraction time, sample, and organic solvent, because it combined the advantages of ionic liquid and MSPD. This method could be widely applied for the extraction of phenolic acids and flavonoids from medicinal plants and animals.

28 Preparation and Characterization of Modified Bamboo Cellulose Hydrogel and Analysis of Its Adsorption Capacity to Methylene Blue

LUO Wen-chao , LIU Shu-min , HUANG Hui-hua

2015, 31(3):165-171. DOI: 10.13982/j.mfst.1673-9078.2015.3.028

[Abstract](1222) [HTML](0) [PDF 1001.82 K](1199)

Abstract:
A composite hydrogel displaying pH sensitivity was successfully prepared from bamboo cellulose extracted from bamboo off-cuts, with added κ-carrageenan (κ-CN) by inverse suspension polymerization, and using epichlorohydrin (ECH) as a crosslinking agent. The prepared composite hydrogels and their swelling kinetics were characterized by Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis, and scanning electron microscopy. In addition, methylene blue was used as a model drug molecule to study the effects of different initial concentrations and initial pH values on the adsorption capacity of the hydrogel. The results of these analyses showed that modified bamboo cellulose and κ-CN underwent chemical cross-linking, forming a hydrogel with a three-dimensional network structure with a fixed decomposition temperature. The hydrogel showed pH-sensitive swelling behavior, caused by the variations in electrostatic repulsion exhibited by its negatively-charged side chain groups in solutions with varying pH. The initial swelling phase complied with the Fickian diffusion model, while the entire swelling process complied with the Schott model. The hydrogel was porous and displayed swelling capacity, which enabled it to express high adsorption capacity. The adsorption test showed it had a high adsorption capacity to the model drug (methylene blue). Therefore, this composite hydrogel could potentially be applied to facilitate drug adsorption and sustained release.

29 Preparation and Characterization of Cellulose Nanocrystals from Peanut Shells

LIU Xiao , DONG Hai-zhou , HOU Han-xue

2015, 31(3):172-176. DOI: 10.13982/j.mfst.1673-9078.2015.3.029

[Abstract](1685) [HTML](0) [PDF 728.41 K](1344)

Abstract:
In this study, cellulose nanocrystals were prepared from peanut shells via pretreatments including alkali hydrolysis with sodium hydroxide, bleaching with sodium chlorite, and sulfuric acid hydrolysis. The obtained cellulose nanocrystals were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. The results showed that extensive amounts of hemicellulose and lignin from peanut shells were removed by alkali hydrolysis and bleaching, so that the content of cellulose increased from 43.84% to 86.56% and the molecular diameter of cellulose was between 10 and 30 μm. The nanocrystals were rod-shaped, between 90 and 210 nm long, with a diameter ranging from 5 to 25 nm. The molecular cellulose type I crystalline structure remained intact while the crystallinity gradually increased to 74.71% during the preparation of cellulose nanocrystals. The initial decomposition temperature of cellulose nanocrystals was low, when the temperature reached 500°C, the residue weight of cellulose nanocrystals was more than 30%. The cellulose nanocrystals prepared from peanut shells have potential application in biodegradable composites.

30 Evaluation and Establishment of Shelf Life Prediction Model for Cold-chain Lettuce Dish

LI Bian-sheng , HUANG Zhi-jun , ZHANG Xiao-yin , RUAN Zheng

2015, 31(3):177-183. DOI: 10.13982/j.mfst.1673-9078.2015.3.030

[Abstract](895) [HTML](0) [PDF 903.68 K](1114)

Abstract:
The quality variation rules of cold-chain lettuce dish under refrigeration at 0 ℃, 4 ℃ and 10 ℃ were researched in this paper, and its shelf life prediction model under refrigeration at 0 ℃~10 ℃ was established at the same time with blanching cooking lettuce dish after vacuum cooling as research object. The results showed that the total bacterial count, nitrite content and a* value of lettuce dish were rising with the refrigerated time, while the hardness showed a downward trend. The higher the refrigeration temperature, the greater the quality indicators change. The nitrite content of lettuce dish was closely related to the total number of colonies, but its end of shelf life was later than that of total bacterial count, and refrigeration temperature and time had a little influence on the hardness, so both are not suitable for the evaluation index of shelf life prediction model for cold-chain lettuce dish. The established first-order kinetic model and Arrhenius equation of a* value had high regression coefficients (R2>0.97). Besides, the growth dynamic of total bacterial count of cold-chain lettuce dish under refrigeration at 0 ℃~10 ℃ can well described by Logistic model (R2>0.99). The relative error between predicted value obtained from the developed color or total bacterial count growth prediction model and its observed shelf life was less than 10% respectively. Among them, the requirement for shelf life with a* value as the evaluation index was highest. In addition, color protection can increase the color shelf life of cold-chain lettuce dish.

31 Physical and Chemical Properties of Carboxymethyl Indica Rice Starch and Use in Ice Cream

LIU Zhong-yi , PENG Li , BAO Hao , CHEN Ting , QIAO Li-juan

2015, 31(3):184-189. DOI: 10.13982/j.mfst.1673-9078.2015.3.031

[Abstract](1155) [HTML](0) [PDF 698.64 K](1156)

Abstract:
In this study, the solubility, expansion rate, freeze-thaw stability, dynamic rheological property, static rheological property, and texture properties of carboxymethyl indica rice starch (DS=0.49), which was prepared in the laboratory, were studied. The applicability of carboxymethyl indica rice starch as a thickening stabilizer in ice cream was investigated by comparing the expansion rate, melting rate, and sensory evaluation of ice cream. The result showed that the solubility and expansion rate of indica rice starch significantly increased after carboxymethylation and its freeze-thaw stability also improved. The static rheological curve showed that carboxymethyl starch had better apparent viscosity and gel stability. The dynamic rheological curve showed that the pasting temperature of carboxymethyl starch decreased, while anti-aging ability was improved. Textural data indicated that carboxymethyl starch gel had relatively low strength. Thus, carboxymethyl indica rice starch can significantly improve the quality characteristics of ice cream when used as a thickening stabilizer. When carboxymethyl starch was added in a 0.3% proportion, the expansion rate of ice cream was greater than 90% and the product exhibited enhanced anti-melting capacity, appearance, and texture.

32 Effect on Volatile Flavor Compounds in Broad Bean Sauce Fermented in Four Different Ways

LIU Ying , HU Mao-feng , LIU Su-chun

2015, 31(3):190-196. DOI: 10.13982/j.mfst.1673-9078.2015.3.032

[Abstract](1116) [HTML](0) [PDF 753.42 K](1087)

Abstract:
Four different fungus including Aspergillus oryzae, Aspergillus niger, Mucor, and Rhizopus were used in the fermentation process to produce broad bean sauce. The volatile flavor compounds in the four different types of broad bean sauce, secondary-fermented for 15 and 40 days, were analyzed by HS-SPME combined with GC-MS. The results showed that the volatile flavor compounds were changeable, and the type of flavors in the broad bean sauce became enriched during the fermentation process. In the initial stages of fermentation, the major volatile flavor compounds in the four products were alcohols and acids. Aldehydes, esters, and other heterocyclic content were enhanced with the progress of fermentation, but ketones and acid content declined. The major volatile flavor compounds simultaneously found in the above four products were 2,3-butanediol, 1-butanol, 3-methyl-, 1-butanol, 2-methyl, linalool, phenethanol, benzaldehyde, hyacinthin, succinic acid-3,4-dimethyl phenyl heptyl ester, and trimethyl pyrazine. The volatile flavor compounds in the Aspergillus oryzae-fermented broad bean sauce were most abundant, indicating that Aspergillus oryzae was a great fungus to be used for the fermentation of broad bean sauce.

33 The Effect of Polyphenol Oxidase on the Pile-fermentation Process and Quality of Pu-erh Tea

FU Ying-xuan , LIU Tong-xun

2015, 31(3):197-201. DOI: 10.13982/j.mfst.1673-9078.2015.3.033

[Abstract](1409) [HTML](0) [PDF 645.47 K](1243)

Abstract:
The change in the physical and chemical properties and sensory quality of Pu-erh tea was investigated during the pile-fermentation process, facilitated by the addition of different concentrations of polyphenol oxidase (PPO). The results showed significant changes in some quality components (p < 0.01) during the pile-fermentation process after treatment with PPO. The average pile-fermentation temperature was observed to be higher in the treatment group, compared to the control group. In addition, the change rates in polyphenols and catechins accelerated in the treatment group, and were negatively correlated with PPO concentration. Theaflavin accumulation was faster during the early stage of pile-fermentation, and the transformation occurring rapidly during the late stage of pile-fermentation. On the other hand, the accumulation of theabrownins was observed to be faster during the pile-fermentation process. Pile-fermentation for 18 days with added PPO conferred good organoleptic properties (associated with sensory qualities) to the Pu-erh tea, including tea stripe, color of tea soup, taste and aroma, as well as tea leaf. 1.6 U/g and 3.2 U/g PPO groups were observed to attain properties of aged Pu-erh tea, with a red and glow liquor color, pure and mellow taste, and full-bodied aroma. This study provides new ideas and methods to reduce the pile-fermentation period and improve the quality of Pu-erh tea.

34 The Influence of Various Processing Mmethods on the Elimination of Chloramphenicol Residues in Prawns

HUANG He , TAO Xin-chen , LIAO Jian-meng , GAO Ping , LUO Lin

2015, 31(3):202-206. DOI: 10.13982/j.mfst.1673-9078.2015.3.034

[Abstract](917) [HTML](0) [PDF 615.09 K](1177)

Abstract:
The influence of five processing methods, including steaming, boiling, roasting, deep frying, and microwaving, on the elimination of residues of chloramphenicol (CAP), thiamphenicol (TAP), and florfenicol (FF) in prawns was investigated. Blank prawn meat was mixed with 2.0 μg/g each of CAP, TAP, and FF in standard solutions; this meat was used to prepare 5 g meatballs. These meatballs were cooked separately by steaming, boiling, roasting, deep frying, and microwaving. The CAP, TAP, and FF content in the cooked meatballs was determined by high performance liquid chromatography-ultraviolet detection (HPLC-UVD). Cooking of prawn meatballs by steaming and boiling for 8 min led to a 41.99~44.50% and 53.93~56.19% decrease in CAP, TAP, and FF content, respectively; roasting and deep-frying for 4 min and microwaving for 2 min led to a decrease of 93.31~95.47%, 93.30~94%, and 29.37~41.86% in the CAP, TAP, and FF content, respectively. Among the five processing methods, the time required to reduce the contents of CAP, TAP, and FF to below the maximum residue limit (MRL) was lowest for roasting and deep frying, followed by microwaving; steaming and boiling took the longest time to reduce the CAP, TAP, and FF content to below MRL. Therefore, roasting and deep frying were discovered to be the most effective ways to reduce CAP, TAP, and FF residues in prawn meat.

35 Factors Influencing the Stability of Goat Milk Proteins

WANG Cun-fang , SHI Yong-cui , LI Yu , LOU Xin-man

2015, 31(3):207-212. DOI: 10.13982/j.mfst.1673-9078.2015.3.035

[Abstract](1121) [HTML](0) [PDF 862.25 K](1404)

Abstract:
This study examined the effects of various factors on protein stability in the colostrum and mature milk of Laoshan dairy goats. The centrifugal sedimentation rate of goat milk proteins was analyzed under various conditions, including a range of temperatures and pH values, citric acid, calcium ion, sucrose, and ultra-high pressure, to evaluate the stability of the milk proteins. The results showed that colostrum was the most sensitive to heat during the first 1~3 days. On the first day, milk samples became extremely thick when heated up to 65 ℃ for 15 min, and both first-day and second-day milk samples caked and solidified when heated up to 70 ℃ for 15 min. The third-day milk samples caked and solidified when heated up to 85 ℃ for 15 min, and milk at 4~7 days did not cake or solidify when heated at 95 ℃. Therefore, as the lactation period was extended, the thermal stability of goat milk increased gradually. The goat milk had the highest stability at pH 6.9. When less than 1.0 mg/100 mL sucrose was added, the stability of the emulsion containing milk proteins was reduced, and when greater than 1.0 mg/100 mL was added, the milk stability increased with an increasing sucrose concentration, and the stability of milk casein micelles increased. The stability of goat milk protein decreased with increases in the citric acid and calcium ion concentrations. There was little effect of ultra-high-pressure processing at 300 MPa on the protein precipitation rate. At 500 MPa, the sedimentation rate significantly increased, reaching a maximal value of 7.35% after treatment for 15 min. Treatment with greater than 500 MPa caused a significant reduction in protein stability.

36 Effect of Physical and Chemical Properties of Lotus Seed Starch by Microwave Treatment

CHEN Bin-yan , GUO Ze-bin , XU Li-bing , ZHANG Shuai , ZHENG Bao-dong , ZENG Shao-xiao

2015, 31(3):213-219. DOI: 10.13982/j.mfst.1673-9078.2015.3.036

[Abstract](1268) [HTML](0) [PDF 1.04 M](1143)

Abstract:
In this study, physical and chemical properties of lotus seed starch by microwave treatment was investigated. Lotus seed starch paste (30%) was heated in a microwave station and changes in starch particle shape, the amount of dissolution, and rheological properties of amylose during gelatinization were observed. The result showed that after treatment with different microwave intensities, no apparent change in the shape of starch particles was observed, where the granules remained smooth and oval. However, apparent aggregation of starch particles was observed with the increase in microwave intensity, with maximum average particle diameter at 26.37 μm, which was 2.15 times that of untreated starch. Additionally, the proportion of crystalline starch particles increased and the 995/1024 absorption peak ratio increased as well, from 0.89 to 0.99. Lotus seed starch treated by microwaves showed a decrease in amylose dissolution from 120 to 87.89 mg/g. Moreover, the thixotropic, rheology viscosity, and elasticity modulus of the starch paste also decreased. These indicate that microwave treatment could encourage tighter crystalline regions in the lotus seed starch and shows certain inhibition of swelling of the starch particles during subsequent gelatinization. This leads to a reduction in the amount of dissolution of amylose and changes in the rheological properties of starch.

37 The Effect of Fish Skin Collagen Extraction Method on Restructured Fish Products

ZHAO Li , WEN Hui-fang , YUAN Mei-lan , CHEN Li-li , SU Wei , JIANG Yong , LIU Hua

2015, 31(3):220-227. DOI: 10.13982/j.mfst.1673-9078.2015.3.037

[Abstract](1133) [HTML](0) [PDF 714.69 K](1274)

Abstract:
To improve the quality of minced freshwater fish products, restructured fish products were prepared using grass carp as a raw material, and the effects of extraction method, and particularly of salt, acid, and alkaline solutions, were examined. Gel strength, textural characteristics (hardness and chewiness), syneresis rate, and change in whiteness of the restructured fish were examined to comprehensively evaluate the effects of extraction method on collagen properties and the quality of restructured fish. Furthermore, the chemical bonding force, trichloroacetic acid (TCA) soluble peptide content, paraffin tissue sections, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to study the collagen properties of restructured fish. The quality of restructured meat with respect to collagen quality was optimal for extraction with the alkaline solution, intermediate for acid, and lowest for the salt solution. Furthermore, alkali-soluble collagen not only formed disulfide bonds during the gelation of minced fish, but also formed non-disulfide bonds via the activation of endogenous transglutaminase (TG), strengthening the gel network structure. Acid-soluble collagen formed disulfide bonds during the gelation of minced fish and had increased gelation force. Salt-soluble collagen formed more macromolecules, thus enhancing the gel network.

38 Analyzing the Effect of Cassia Extracts on the Decrease in Nitrosamine Content of Harbin Dry Sausages

LI Mu-chun , KONG Bao-hua , SUN Fang-da , HAN Qi

2015, 31(3):228-234. DOI: 10.13982/j.mfst.1673-9078.2015.3.038

[Abstract](1287) [HTML](0) [PDF 965.99 K](1218)

Abstract:
In this study, cassia extracts were added to Harbin dry sausages. The nitrosamine content and related physicochemical properties, such as the pH value, nitrite residue content, peroxide value (POV), thiobarbituric acid (TBARS) content, and total volatile basic nitrogen (TVB-N) content in the sausages was determined 0, 2, 4, 6, 8, and 10 days after addition of extracts, by high performance liquid chromatography, in order to determine their relationship with the inhibition of nitrosamine production. The results of these analyses revealed that cassia extract exerted a significant inhibitory effect (P < 0.05) on a number of nitrosamines in the dried sausages. This effect was observed to be more significant with the increase in the quantity of extract added. The rate of inhibition of nitrosodimethylamine (NDMA), nitroso piperidine (NPIP), nitroso-propylamine (NDPA), nitroso amide (NDBA), and nitroso diphenylamine (NDphA) was determined to be 26%, 63%, 50%, 59%, and 55%, respectively, in the group treated with 0.3 g/kg cassia extracts on day 10. The inhibitory effect of cassia extract on nitrosamines was not affected by the pH value. The cassia extract significantly (P < 0.05) reduced the TBARS, POV, and TVB-N values and nitrite residue in Harbin dry sausages. This showed that the lipid oxidation, amine content, and nitrite residue content was closely linked with nitrosamine formation.

39 Effect of Ultrafiltration Product of Cantonese Sausage on the Preservation of Ground Beef

ZHANG Da-lei , JIANG Ai-min , XIA Lie , LI Jun-guang , CHEN Wei-wei

2015, 31(3):235-241. DOI: 10.13982/j.mfst.1673-9078.2015.3.039

[Abstract](957) [HTML](0) [PDF 843.72 K](1172)

Abstract:
The aim of the current investigation was to examine the inclusion of the peptide fraction of Cantonese sausage (PFCS) and its effect on the shelf-life and sensory characteristics of ground beef. First, the antioxidant properties of PFCS (MW < 5 ku) were studied using four different antioxidant assays (DPPH and ABTS+ radical-scavenging activity, Fe2+ chelating activity, and liposome oxidation inhibition rate). Next, the changes in TBARS value, pH, carbonyl and metmyoglobin content, as well as psychrophilic and mesophilic microorganisms in ground beef with different levels of added PFCS were determined during refrigerated storage at 4°C for up to 7 days. Finally, the sensory quality of beef patties was evaluated. The results indicated that the PFCS (MW < 5 ku) had very good radical scavenging activity, Fe2+ chelating activity, and protection against oxidation in the liposome model system. The addition of PFCS to ground beef could delay oxidation reactions and reduced microorganisms than that in the control, and the effect showed a dose-dependent response. Furthermore, the sensory quality was also improved when ground beef patties were treated with PFCS. Addition of 0.6% PFCS resulted in the highest quality in terms of overall acceptance. Therefore, this study provided evidence that PFCS has great potential to inhibit the oxidation of ground beef.

40 Comparison of Volatile Components in Commercial Vegetable Oils and Gutter Oils from Hunan Cuisine

LI Xiao-feng , WANG Chao , WANG Yong , HUANG Xiao-lan , LIN Xiao-shan , WU Hui-qin

2015, 31(3):242-248. DOI: 10.13982/j.mfst.1673-9078.2015.3.040

[Abstract](1677) [HTML](0) [PDF 1.08 M](1274)

Abstract:
Solid phase micro-extraction coupled with gas chromatography-mass spectrometry (SPME/GC-MS) was applied to analyze the volatile components in 25 commercial vegetable oils and 41 gutter oils from the interceptor sewers of Hunan cuisine restaurants in Guangzhou. In total, 113 types of volatile components were detected in gutter oils, and 71 types were found in vegetable oils. Aldehydes and alkenes were the most abundant components of gutter oils, while vegetable oils contained mainly aldehydes and other volatile components. Acid components were most abundant in gutter oils, and vegetable oils contained only trace amounts of acids. Ethers and aromatics were detected in gutter oils but not in vegetable oils. Gutter oils generally contained limonene, which were not detected in vegetable oils. In addition, allicin was detected in gutter oils but not in vegetable oils. Therefore, large amounts of acids, ethers, aromatics, limonene, and allicin can be used as indicators for gutter oils. This provides a strong basis for the identification of gutter oils and adulterated vegetable oils.

41 Studies on the Inductive Methodology for Evaluating the Soluble Solid Content of Watermelon

YANG Na , JIN Ya-mei , BIN Yong-lin , ZHAO Juan-juan , JIN Zheng-yu , XU Xue-ming

2015, 31(3):249-254. DOI: 10.13982/j.mfst.1673-9078.2015.3.041

[Abstract](1054) [HTML](0) [PDF 965.41 K](1101)

Abstract:
Current rapid detection methods based on electrical properties usually use electromagnetic waves or external electrical fields to stimulate food materials. However, the electrical property of fruit juice containing diverse electrolytes, based on transformers, has not been reported. It was suggested that the measurements of the terminal voltage of juices, which acts as the secondary winding (constrained by thin, non-conductive tubing) in alternating magnetic flux, may be a novel method to assess qualitative changes. In the present research, a measurement system based on the principle of electromagnetic induction has been established to simulate the basic structure of the step-down transformer, which is able to assess the electrical properties of watermelons with different soluble solid contents (SSC). All measurements were conducted at a temperature of 22 ℃, and the test conditions were as follows: the applied voltage on the primary coil was 5~20 V; the operating frequency range was 50~400 Hz. The results showed that the values of terminal voltage and λ were maintaining at a stable level as the frequency increased, but the increasing SSC of watermelon triggered a decrease in the terminal voltage or an increase in λvalue. Simultaneously, the values of terminal voltage were observed to increase along with increasing values of excitation voltage. The effects of eight different combinations of operating frequencies (50, 120, 200, and 400 Hz) and excitation voltage levels (10 and 20 V) on the estimation of the soluble solid content was also analyzed, resulting in a significant level (a ≤ 0.01). The highest linear correlation between the terminal voltage and the SSC values was obtained at 50 Hz and 10 V (R2 = 0.969). The validation models for the SSC of 60 samples had a bias of -0.238 Brix%, and those for the SEP had a bias of 0.893 Brix%. These results encourage the industrial application of this technique for the rapid assessment of the quality parameters in liquid food products.

42 Rapid Quality Analysis of Chinese Rice Wine by Raman Spectroscopy and Support Vector Machines

WANG Wei-qin , WANG Li , YU Hai-yan

2015, 31(3):255-259. DOI: 10.13982/j.mfst.1673-9078.2015.3.042

[Abstract](1357) [HTML](0) [PDF 800.04 K](1332)

Abstract:
In this study, Raman spectra analysis technology was used to rapidly and accurately evaluate various Chinese rice wines. Fingerprint information was collected from Chinese rice wine samples from different sources and of different ages, followed by a comparison of the prediction performances of quality evaluation models established by discriminant analysis (DA) and least-squares support vector machine (LS-SVM) in order to select the optimal model. Principal component analysis was used in the entire wavelength range to reduce the dimension of Raman spectroscopy data. The Mahalanobis distance between reduced-dimension spectra was calculated and discrimination analysis models were established based on ward’s calculation. The entire wavelength range was used as the input of LS-SVM, to select a kernel radial basis function (RBF) that could alleviate non-linear issues. The kernel RBF was optimized at the same time via interactive authentication. The LS-SVM discrimination model was established based on the optimized kernel RBF function. The result showed that Raman spectroscopy coupled with LS-SVM could 100% accurately identify both production origin and wine age. The correction rates of Raman spectroscopy coupled with DA to discriminate Chinese rice wines from among Jiashan, Shaoxing, and Shanghai origins were 100%, 80%, and 80%, respectively, while that to determine wine age was 100% for all samples. Thus, the LX-SVM model was superior to the DA model. It was concluded that Raman spectroscopy in combination with chemometrics could be used for the rapid and accurate evaluation of Chinese rice wines.

43 Rapid Detection of Adulterate Starch in Chocolate by Near-infrared Spectroscopy

LIU Jia , ZHAO Qiu-shuang , LI Ming-qi , CHEN Jia , ZHAO Guo-hua

2015, 31(3):260-265. DOI: 10.13982/j.mfst.1673-9078.2015.3.043

[Abstract](1517) [HTML](0) [PDF 692.58 K](1444)

Abstract:
Chocolates are a popular snack due to their exquisite taste and unique flavor. Nevertheless, instances of chocolate adulteration are on the rise and have recently caught consumer attention, the most common being adulteration with low-cost starch. In this study, near-infrared (NIR) spectroscopy was used for the rapid detection of adulterate sweet potato or potato starch in chocolate. A correction model was established using principal component regression (PCR) and partial least squares (PLS). The effects of spectral range, spectral preprocessing method, and the number of parameters were studied. The result indicated that the highest prediction rate was achieved using PLS for modeling with eight parameters, within a spectral range of 7000 to 4200 cm-1 and first derivative (7 pts) pretreatment. The values for root mean square error of prediction (RMSEP) and the coefficient of determination (Rp2) obtained with this model were 1.7% and 0.9426, respectively. The recovery rates, intraday RSD and interday RSD of samples with varied adulterated proportions were 94.2% to 105.6%, 4.7% to 8.9%, and 5.1% to 11.3%, respectively. The results indicate that NIR spectroscopy can be used as a method to rapidly detect adulterate starch in chocolate.

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Volume 31,Issue 3,2015 Table of Contents