Table of Content

25 April 2013, Volume 34 Issue 8
Enzymatic Acylation of Epigallocatechin Gallate (EGCG) and Antioxidant Activity of Acylated EGCG in Soybean Oil
Zhe LI Hongxin Wang
2013, 34(8):  1-5.  doi:10.7506/spkx1002-6630-201308001
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The acetylation of EGCG as a green tea polyphenol was catalyzed by lipases in a non-aqueous phase reaction system so as to increase the lipophilicity of EGCG. This study investigated the effects of solvent type, enzyme dosage, reaction temperature and vinyl acetate/EGCG molar ratio on the conversion rate of EGCG. These reaction conditions were optimized by one-factor-at-a-time method and orthogonal array design. As a result, the optimum conditions for EGCG acetylation were found to be reaction at 45 ℃ for 10 h in acetonitrile with a vinyl acetate-to-EGCG molar ratio of 0.5:1 and an enzyme dosage of 7%. In soybean oil, the antioxidant activity of acylated EGCG was higher than that of EGCG and BHT but lower than that of TBHQ at equal concentration.
Optimization of Properties of Chitoan-Kudzu Starch Blend Films
2013, 34(8):  6-11.  doi:10.7506/spkx1002-6630-201308002
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To extend the application of chitosan-kudzu starch, we developed the film by casting and studied the properties of films with different composition by Texture Analyzer, Rheometer etc. The Response Surface Method (RSM) was used to analyze and optimize the composite concentration. Besides, the effects of components of the mixture on the tensile strength, elongation of rupture, water vapor permeability (WVP) and opacity of the films were studied. According to the models generated by and Design-expert software, the edible films display the best properties with the composition of 1.5% kudzu starch, 1.29% chitosan and 24.27% glycerol. Our results provide statistical support for industrial production of chitosan-kudzu starch films.
Preparation of Conjugated Linoleic Acid glyceride by direct esterification under the condition of subcritical water
2013, 34(8):  12-15.  doi:10.7506/spkx1002-6630-201308003
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In this study, preparing conjugated linoleic acid glycerides from conjugated linoleic acid (CLA)and glycerin by direct esterification under the condition of subcritical water was sdudied,the effects of, temperature, time, reactant molar ratio(CLA:glycerin),pressure on the impact of the conversion rate of CLA was studied. Through single factor test, and on the basis of the level of the single factors,through the response surface optimization determine the optimum conditions of reaction: The temperature of reaction is 250 ℃,the time of reaction is 40min,Substrate molar ratio is 2:1, the pressure of reaction is 13Mpa,conversion rate of Conjugated linoleic acid was 96.3%,the resulting conjugated linoleic acid glycerides is yellow oily transparent liquid.
Optimization of Microwave-Assisted Extraction of β-Cryptoxanthin from Satsuma Mandarin Peel by Quadratic Orthogonal Rotation Design
SUN Zhi-gao,JIANG Guo-ling,ZHANG Meng-meng,SUN Ying,GUO Li-qiong
2013, 34(8):  16-20.  doi:10.7506/spkx1002-6630-201308004
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The microwave-assisted extraction technology was used to extract β-cryptoxanthin from satsuma mandarin peel. The experimental values were firstly selected by single-factor test and a quadratic orthogonal rotation combination design was chosen based on the results of single factor test in order to study the effects of three main technological conditions, including ratio of solvent to solid, microwave time and microwave power on yield of β-cryptoxanthin from satsuma mandarin peel. Results showed that the influence of investigated facors on yield of β-cryptoxanthin followed the decreasing order: microwave power> microwave time> ratio of solvent to solid and a maximum yield of 0.30‰ was achieved under the optimal extraction: ratio of solvent to solid 1:20, microwave time 184 s and microwave power 357 W.
Purification of 1,8-Cineole from Stock Solution of Eucalyptus Oil by Batch Vacuum Distillation
WANG Shi,JIN Lin-xi,XIE Jian-chun*,ZHENG Fu-ping,HUANG Ming-quan,SUN Bao-guo
2013, 34(8):  21-26.  doi:10.7506/spkx1002-6630-201308005
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Purification of 1,8-cineole from the stock solution produced from the industrial processing of raw eucalyptus oil was studied by batch vacuum distillation. The technique of tower packing pretreatment was selected based on effusing curves of the target 1,8-cineole as well as the main impurities of α-pinene, limonene and p-cymene in batch vacuum distillation. The effect of full-reflux time, pressure of operation system, and reflux ratio were investigated through singlefactor and response surface analysis experiments. The optimum conditions for recycling of 1,8-cineole from the stock solution were obtained as follows: (1) The tower was cleaned with ethanol, and then rinsed with water; (2) Under the pressure of 2.7 kPa, the stock solution was distilled initially in a full-reflux mode for 50 min and in a reflux ratio of 2:2. When the boiling point arrived at 60 ℃, the reflux ratio was adjusted from 2:2 to 10:1 and the fraction of 1,8-cineole was then collected within the boiling point range of 68 to 73 ℃. The purity of 1,8-cineole reached up to 85.1% confirmed by GC, and the recovery was 79.0%.
Extraction of Isothiocyanate from Radish Sprout
2013, 34(8):  27-30.  doi:10.7506/spkx1002-6630-201308006
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Total content of MTBITC and sulforaphene was considered as a parameter to evaluate extract efficiency, extraction technology of isothiocyanate from radish sprout was carried out using n-hexane and dichloromethane being extraction solvent. The optimal extraction conditions were: enzymolysis for 3 min, a liquid/solid ratio of 2 mL/g, an extraction time of 3-5 min, and n-hexane, dichloromethane, dichloromethane being extract order in turn.
Determination of Total Polyphenols in Apple Vinegar Drink by Folin-Ciocalteu Method
ZHAO Xiao-juan,LI Min-yi,HUANG Gui-ying,CHEN Yue-jiao
2013, 34(8):  31-35.  doi:10.7506/spkx1002-6630-201308007
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The optimum condition on determining total polyphenols content in apple vinegar drink by Folin-Ciocalteu method was studied. The results indicated that the optimum conditions for total polyphenols determination by Folin-Ciocalteu were as follows: 2.5 mL of Folinphenol reagent was added in 1.0 mL of sample, and then 4.0 mL of 12% sodium carbonate solution was added. After the coloration reaction was for 1.5 h at 45 ℃, the optical density was measured at 756 nm. Under the optimum conditions, the absorbance increased linearly with the concentration of gallic acid in the range of 0 to 6 μg/mL (y=0.1238x+0.0098, R2=0.9992). The average spiked recovery rate was 101.2% with the relative standard deviations of 2.8% (n=5). The method is highly precise and stable, and suitable for determining total polyphenol content in apple vinegar drink.
Optimization of Preparation Process for Nano-SiOx /Albumin Complex Film by Response Surface Methodology
ZHENG You,CHEN Hou-rong,WANG Xue-rong
2013, 34(8):  36-42.  doi:10.7506/spkx1002-6630-201308008
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Using albumin as raw material and fixing nano-SiOx addition amount, nano-composite films were achieved through casting technique. Single factor and response surface tests were used to explore the optimal preparation process of composite film. Regression models of tensile strength (TS), elongation (E) and water vapor permeability (WVP) were established using albumin content, plasticizer content, intensifier content and crosslinker content as response factors. The optimal preparation conditions were albumin content of 8 g/100 mL, plasticizer content of 3.09 g/100 mL, intensifier content of 0.55 g/100 mL and cross-linker content of 0.71 g/100 mL. Under the optimal conditions, the properties of composite films were (3.492 ± 0.183) MPa, (58.300 ± 2.415)% and (5.570 ± 0.077) g?mm/(m2?d?kPa), which were close to the predicted values.
Quality Control of Dried Noodle Processing Based on Statistical Process Control (SPC)
2013, 34(8):  43-47.  doi:10.7506/spkx1002-6630-201308009
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Mixing is the key step in dried noodle processing, thus the sufficient mixing process capability is very important for guaranteeing the stable dried noodle quality. In order to improve the quality control of mixing, quality traits of dough crumbs were monitored and measured. Control chart methods were used to determine whether the process was in a state of control or not. The factors affecting quality variance were investigated, the corresponding control methods and technical parameters were proposed, and the improvement effect was estimated. The results showed that the dough crumb moisture and dough crumb moisture uniformity fell outside the control limits when the product line was monitored for 20 days. The factors affecting quality variance mainly included excessive noodle crumbs, insufficient mixing time and inappropriate quantity of water added as well as high watering speed. The major methods to improve the process capability included choosing stable quality wheat flour suitable for noodle processing, choosing appropriate way and mixing time, limiting the weight of dried and wet noodle crumbs and making personnel standardization. When SPC was applied in quality control of mixing, the variances of dough crumb moisture and dough crumb moisture uniformity were reduced significantly, and the process capability levels were improved.
Effect of Extract from Euryale ferox Seed Shell on Quality of Pork Sausage during Storage
ZHANG Cuan,XU Xing-lian,ZHOU Guang-hong,LI Chun-bao,CAI Hua-zhen
2013, 34(8):  48-52.  doi:10.7506/spkx1002-6630-201308010
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Eruyale ferox is a kind of tonic food and its seed shell is the major by-product. One extract (Eruyale seed extract,ESE) was achieved from Eruyale ferox seed shell with 50% ethanol. The phenolic compounds in ESE were analyzed usingHPLC-UV method, and the preservative effect of ESE on pork sausage product was also investigated in the present study.The results showed that ESE was rich in total phenols that were identified as gallic acid, chlorogenic acid, epicatechin, epicatechin gallate and rutin with concentrations of 364.11, 42.31, 95.95, 3.16 mg/g and 129.21 mg/g, respectively. Furthermore, the addition of ESE (500 mg/kg) into sausage alone, lipid oxidation during storage could be significantly inhibited, but the effects on pH and color of meat products were limited. The mixture of ESE, NaNO2 and red yeast rice at the appropriate ratios was added to sausage, the good and stable color of the products was achieved and notably inhibition of lipid oxidation during storage was observed. Therefore, ESE, NaNO2 and red yeast rice can reveal a synergistic effect on the inhibition of microbial growth and lipid oxidation in sausage products.
Production of Gracilaria lemaneiformis-Based Seasoned Seaweed Sauce
YANG Xian-qing,XIA Guo-bin,QI Bo,LI Lai-hao,CHEN Sheng-jun,HAO Zhi-ming
2013, 34(8):  53-57.  doi:10.7506/spkx1002-6630-201308011
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Economic microagae Gracilaria lemaneiformis (Rhodophta) was used as the raw material to explore the optimal preparation process of seasoned seaweed sauce. On the basis of pretreatment of raw materials through high-pressure homogenization, high-pressure steaming and vacuum package, and taking protease activity and fermented meal sensory scores as the evaluation indices, the optimal fermentation conditions of Aspergillus oryzae and yeast were explored. Results indicated that the optimal fermentation conditions were 1.0% inoculation of Aspergillus oryzae and 0.8% yeasts, fermentation time of 5 days and fermentation temperature of 35 ℃. Under the optimal fermentation conditions, the protease activity was up to 6.08 g amino nitrogen per 100 g dry sauce product with a relatively high sensory evaluation score of 4.1. Four developed seaweed sauce products with different flavors are delicious, nurtitional and meet the national food quality standard.
Production of Lentinus edodes Biscuits and Analysis of Characteristic Aroma Components
GAO Yong-xin,HU Qiu-hui,YANG Wen-jian,FANG Yong,MA Ning,ZHAO Li-yan
2013, 34(8):  58-63.  doi:10.7506/spkx1002-6630-201308012
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Processing technology of Lentinus edodes biscuits was optimized by orthogonal tests. Aroma compositions of Lentinus edodes biscuits and common biscuits were analyzed to explore characteristic aroma compositions in Lentinus edodes biscuits. The results showed that the suitable baking temperature and baking time of Lentinus edodes biscuits were 205 ℃ and 10 min. The formula of Lentinus edodes biscuits was composed of 69.3 g flour, 7.7 g Lentinus edodes powder, 1.0 g salt, 20 g palm oil, 1.5 g baking powder, and 0.5 g HPMC. Totally 27 aroma components in common biscuits and 36 aroma components in Lentinus edodes biscuits were identified by SPME-GC/MS, respectively. Compared with common biscuits, the characteristic aroma components of Lentinus edodes biscuits were sulfur compounds, which included 1.46% dimethyl disulfide, 1.52% dimethyl trisulfide, 0.63% 1,2,4,5-tetrathiane and 1.74% 1,2,4-trithiolane.
Optimization of Reaction Conditions for Buckwheat Resistant Starch Preparation by Autoclaving Enzymatic Debranching Recrystallization and Its Granular Morphology
2013, 34(8):  64-69.  doi:10.7506/spkx1002-6630-201308013
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Response surface methodology was employed to study the reaction conditions for buckwheat resistant starch (RS) content by autoclaving enzymatic debranching recrystallization. Thermal-press temperature, pullulanase amount, pullulanase debranching time, cold preservation time at 4 ℃, were analyzed for their influence on the content of buckwheat resistant starch. A five-level-four-factor central composite design was used for maximizing the buckwheat RS content. The optimal reaction conditions obtained were thermal-press temperature 120.63 ℃, pullulanase debranching time 7.49 h, pullulanase amount 4.61 U/g, cold (4 ℃) preservation time 3.11 d, respectively. RS content experimentally obtained was 47.87%, in agreement with the predicted values. In addition, the physical shape of original starch and RS were investigated by scanning electron microscopy (SEM), the starch shape changed significantly, by rule smooth ball into larger transparent crystal structure.
Optimization of Hydrolysis Conditions of Soybean Meal by Response Surface Methodology
ZHAO Yan-wei,WANG Yu-sheng,CHEN Hai-hua,JI Yuan-yuan
2013, 34(8):  70-75.  doi:10.7506/spkx1002-6630-201308014
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According to the degree of hydrolysis (DH) and sensory evaluation, effects of pretreatments on soybean meal was studied and the optimum hydrolysis condition was analyzed by single factor experiments and response surface optimization. The soybean meal was pretreated by pressurization, ultrasonic treatment, microwave irradiation treatment and heating treatment, respectively. The results showed that the heating treatment, with temperature of 80 ℃ and time of 10 min, was suitable for the pretreatment of soybean meal. According to DH and sensory evaluation, the compound enzyme for soybean meal hydrolyzing was the mixture of neutral protease and protamex with ratio of 2:3. The optimal hydrolysis condition of compound enzyme was obtained by single factor experiments and response surface optimization. The results showed that optimum hydrolysis condition was as follows: pH 7.5, hydrolysis temperature of 50 ℃, hydrolyzing time of 6 h.The degree of hydrolysis was 19.25% under the above conditions. The total content of free amino acids of soybean meal was increased to 660% after hydrolysis.
Preparation and in vitro Digestibility of Cross-linked Potato Starch
2013, 34(8):  76-81.  doi:10.7506/spkx1002-6630-201308015
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Cross-linked starch was prepared with potato starch as raw material and sodium trimetaphosophate (STMP) and sodium tripolyphosphate (STPP) as cross-linking agent at the mass ratio of 99:1. Effects of cross-linking agent amount, cross-linking pH, reaction temperature and reaction time on phosphorus content were studied. Response surface methodology was employed to optimize the process parameters. The optimal reaction conditions were determined as follows: the crosslinking agent amount of 16%, reaction time of 4.5 h, cross-linking pH of 11.5 and reaction temperature of 55 ℃. A series of cross-linking starches with various phosphorus contents were prepared by changing cross-linking agent amount on the basis of optimal reaction conditions. In vitro digestibility of the cross-linked potato starch was conducted. Therefore, the amount of total resistant starch revealed an increase with the increase of phosphorus content.
Optimization of Microwave Extraction of Total Phenols from Magnolia Bark by Orthogonal Array Design
ZHONG Ping,WANG Pin-pin
2013, 34(8):  82-84.  doi:10.7506/spkx1002-6630-201308016
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Microwave radial extraction method was applied to extract total phenols from magnolia bark using extraction rate of total phenols as evaluation index. The effects of extraction conditions on extraction rate of total phenols from magnolia bark were evaluated by single factor and orthogonal tests. The optimal extraction process parameters include 70% alcohol as extraction solvent, microwave radial time of 6 min, microwave power of 40% (240 W), and material-liquid ratio of 1:20 (g/mL). Under the optimal extraction conditions, the extraction rate of total phenols was up to 6.34%.
Optimization of Supercritical CO2 Extraction and Fatty Acid Composition of Wheat Embryo Oil
HE Jiao,ZHANG Zheng-mao*,YAN Wen,WANG Tian,LIU Yu-xiu
2013, 34(8):  85-87.  doi:10.7506/spkx1002-6630-201308017
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The high, medium and low gluten wheat germs were taken as experimental material. In order to optimize the extraction of wheat germ oil, the influence of extraction pressure, time and extraction temperature on the yield of wheat germ oil were investigated by the single factor experiments. Technology parameters were optimized by orthogonal experiments design experiments. The results showed that the optimum condition for extracting the yield of wheat germ oil was: extraction pressure 30 MPa, temperature 50 ℃ and 2 hours of extraction. Under these conditions, the extraction ratio is 11.05%. Analysis of fatty acid composition in embryo oil by gas chromatograph revealed that linoleic acid accounted for higher than 58.23% of total fatty acid in embryo oil of low intensity wheat.
Optimization of Inclusion Reactions of β-Cyclodextrin and Its Derivatives with Artemisinin
DUAN You-gou,ZHU Shi-long,ZHANG Jun-sheng,LI Yong
2013, 34(8):  89-93.  doi:10.7506/spkx1002-6630-201308018
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One-factor-at-a-time method and orthogonal array design were used to establish the optimal reaction conditions for inclusion complexes of β-cyclodextrin and its derivatives with artemisinin. Formation constants for inclusion complexes of artemisinin with β-cylcodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD) and γ-cyclodextrin (γ-CD) were measured by phase solubility analysis and Gibbs free energy differences were also calculated before and after reactions. The optimal reaction conditions for artemisinin/cyclodextrin inclusion complexes were 1:1, 40 ℃, 5 h and 7 for artemisinin-to-cyclodextrin molar ratio, temperature, reaction time and medium pH, respectively. The formation constants of the inclusion complexes of artemisinin with β-CD, HP-β-CD and γ-CD were 80.06, 58.68 L/mol and 116.96 L/mol, respectively, and the corresponding Gibbs free energy differences were -11.76, -10.93 kJ/mol and -12.78 kJ/mol, respectively. In this study, we have succeeded in preparing 1:1 artemisinin/cyclodextrin inclusion complexes with improved solubility of artemisinin.
Optimization of Preparation of Collagen Polypeptide Chelated Calcium by Orthogonal Array Design
PENG Qiao-yun,SHEN Ju-quan,WEI Dong-zhi,MA Zhi-ying,SHEN Ya-ling
2013, 34(8):  94-99.  doi:10.7506/spkx1002-6630-201308019
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This work reports the application of orthogonal array design to explore the optimum chelating conditions of food-grade calciumchloride with collagen polypeptide. The optimal chelating conditions were found to be reaction at 30℃ and an initial pH of 6.0 for 30 min with a calcium-to-collagen polypeptide mass ratio of 13:100. Under the optimized conditions, the calcium-chelating efficiency of collagen polypeptides was 77.7 mg/g. FTIR analysis demonstrated that we successfully obtained collagen polypeptide chelated calcium as a new material. Moreover, the chelated calcium was found to increase bone density in animal studies.
Optimization of Enzymatic Extraction of Insoluble Dietary Fiber from Rapeseed Shells
WANG Shun-min,ZHENG Rui
2013, 34(8):  100-103.  doi:10.7506/spkx1002-6630-201308020
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The enzymatic extraction of insoluble dietary fiber (IDF) from rapeseed shells was optimized by orthogonal array design based on IDF yield. The IDF yield from rapeseed shells was 81.24% after 60 min of amylase hydrolysis at 40 ℃ and an initial pH of 5.5 with an enzyme dosage of 0.7% and a solid-to-liquid ratio of 1:20, and 77.13% after 60 min of protease hydrolysis at 40 ℃ and an initial pH of 7.5 with an enzyme dosage of 0.7% and a solid-to-liquid ratio of 1:20. In this study, we have identified main process parameters that influence IDF extraction from rapeseed shells and established the optimum process conditions.
Purification and Molecular Weight Detection of Polysaccharides from Banana Peel
LIN Zhi-chao,YU Jin-fu,PAN Yu-tian
2013, 34(8):  104-106.  doi:10.7506/spkx1002-6630-201308021
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In this study, an orthogonal array design involving 9 experiments of 3 variables at 4 levels was applied to optimize the extraction of crude polysaccharides from banana peels. Polysaccharides bpp1, bpp2 and bpp3 were obtained from the crude extract by DEAE-cellulose ion-exchange chromatography. Molecular weight determination of bpp1 was performed by HPLC. The optimum conditions for extracting polysaccharides from banana peels were found to be extraction at pH 8 and 85 ℃ for 5 h. The yield of crude polysaccharides under the optimized conditions was 2.75%. The molecular weight of bpp1 was measured to be 442068 u.
Optimization of Polysaccharide Extraction from Pumpkin by Central Composite Design/Response Surface Methodology
CHEN Li-jiang,WANG Yong-jie,LIU Yu,GAO Fei,YAN Xi-chen
2013, 34(8):  107-112.  doi:10.7506/spkx1002-6630-201308022
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Objective: Central composite design/response surface methodology was employed to optimize the extraction of polysaccharides from pumpkin and a suitable type of macroporous resin was identified for the purification of crude polysaccharides. Methods: A hot water extraction method was proposed for polysaccharide extraction from pumpkin. One-factor-at-a-time method and central composite design/response surface methodology were used to examine the effects of extraction conditions including solid-to-liquid ratio, time, temperature and repeated extraction as well as alcohol precipitation conditions on the extraction efficiency of polysaccharides. Purified polysaccharides were obtained through repeated alcohol precipitation and purification by macroporous resign chromatography. Results: The optimum extraction process of pumpkin polysaccharides was found to be three extraction cycles with a 36-fold volume of hot water at 84 ℃ for 3.2 h each followed by evaporation until one-third of the original volume and precipitation with a three-fold volume of alcohol. AB-8 resin was chosen to purify the crude polysaccharides through adsorption at 20 ℃ with an initial sample concentration of 2.84 mg/mL and a sample loading amount of 5 BV and desorption with 5 BV of 20% alcohol. The purified products contained over 60% polysaccharides. Conclusion: The optimized extraction process is simple and reliable. AB-8 resin is suitable for the purification of crude polysaccharides from pumpkin.
Process Optimization for Extruded Rice Production
WANG Hui-ran,LI Zong-jun
2013, 34(8):  113-117.  doi:10.7506/spkx1002-6630-201308023
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The production process of extruded rice was optimized to provide theoretical references for its exploitation and economic value. Several one-factor-at-a-time experiments were conducted to preliminarily explore three process parameters including extrusion die head temperature, water content, and screw speed. Thereafter, we used response surface methodology to establish the optimum process conditions based on comprehensive consideration of texture and water absorption. The optimum process parameters that met practical production conditions were 90 ℃, 25% and 180 r/min for extrusion die head temperature water content and screw speed, respectively. The comprehensive evaluation score of extruded rice obtained under these conditions was 76.67. The proposed optimum production parameters are reliable and have the potential for practical applications.
Adsorption Properties of Alpha Hydroxy Acids from Apricot Sauce
AISIKAER Ailati,HUANG Gui-dong,JI Zhong-wei,MAO Jian
2013, 34(8):  118-123.  doi:10.7506/spkx1002-6630-201308024
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Apricot sauce has excellent nutritional value. However, the sale profit of apricot sauce is very low and its market demand is unstable so that the export has to suffer restriction. To solve the problem of production and market, the adsorption properties of alpha hydroxy acids (AHAs) from apricot sauce was investigated in the present study. The results showed that ion exchange resin SQD56 was selected as the optimal resin among seven resins. The adsorption quantity reached as high as up to (135.81 ± 1.33) mg/g of SQD56 under the conditions of 16 g/L, 20 ℃ and 3 BV/h for sample solution concentration, temperature and flow rate, respectively. Meanwhile, the optimal elution conditions were found to be 4%, 40 ℃, 3 BV/h and 6 BV for ammonia concentration, temperature, flow rate and elution volume, respectively, resulting in a recovery of AHAs of (76.52 ± 1.8)%. Most of the obtained AHAs belonged to the L-type class with malic acid, lactic acid and citric acid accounting for 62.12%, 22.05% and 14.21% of the total amount, respectively.
Fermentation Performance of Crystallized Fructose and Optimization of Baking Process
2013, 34(8):  124-130.  doi:10.7506/spkx1002-6630-201308025
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In this study, we compared the ability of yeast to ferment crystallized fructose and sucrose based on yeast biomass and residual glucose concentration. Crystallized fructose was used as a sweetener to make breads, and the optimum bread formulation and fermentation conditions were established for improved sensory quality, texture and specific volume. The quality of breads was considerably improved by the addition of additives at optimum levels of 0.1%, 0.1%, 0.3%, 0.2%, 0.3% and 480 U/100 g of flour for sodium stearoyl lactylate (SSL), diacetyl tartaric acid ester of mono(di)glycerides (DATEM), sucrose ester (SE), guar gum, CMC and fungal amylase. An apparent improvement in the quality of breads was obtained when the prepared dough was fermented for 40 min and proofed for 50 min at the same temperature of 30 ℃. Breads with crystallized fructose had the same quality as those with white sugar, and maintained good quality over a storage period of 3 d at 20 ℃ and 55% relative humidity without being packaged.
Response Surface Methodology for Optimization of Wet Heat Lipoxygenase Denaturation of Dehulled Non-Soaked Soybeans
LIU Xin,CHEN Cong,ZHAO Jian-xin,FAN Da-ming,MA Zhi-gang,ZHANG Hao
2013, 34(8):  131-135.  doi:10.7506/spkx1002-6630-201308026
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In the present study, wet heating (blanching) was applied to denature liposygenase (LOX) in dehulled nonsoaked soybeans and consequently improve the flavor of soymilk. Response surface methodology was employed to optimize blanching conditions (temperature, time and pH) based on residual LOX activity and protein content of soymilk. The optimum experimental conditions for LOX denaturation in samples high in protein (3.60 g/100 g) were found to be blanching at (94 ± 2) ℃ and pH (8 ± 0.45) for 4 min.
Removal of Tannins from Quercus mongolica Fisch Acorns
CAO Hai-xia,YANG Xiao-qing
2013, 34(8):  136-139.  doi:10.7506/spkx1002-6630-201308027
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An ultrasonic-assisted solvent extraction method for the removal of tannins from acorns, Quercus mongolica Fisch, was explored in this work. Main process parameters influencing the removal efficiency of tannins were identified by one-factor-at-a-time method and optimized by orthogonal array design. Optimum removal conditions were obtained when using 40% ethanol as the extraction solvent at a solid-to-liquid ratio to extract acorn powder with particle size over 80 mesh at 55 ℃ for 60 min with an ultrasonic power of 400 W. The maximum removal efficiency of tannins observed under the optimum conditions was 69.99 mg/g.
Establishment and Application of a Multiplex PCR Assay for Simultaneous Detection of Salmonella spp. and Staphylococcus aureus in Quick-Frozen Foods
Suo Biao
2013, 34(8):  140-144.  doi:10.7506/spkx1002-6630-201308028
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A multiplex PCR assay was developed for the effective and simultaneous detection of Salmonella spp. and Staphylococcus aureus in quick-frozen foods. Optimum amplification system and genomic DNA extraction method were established. Salmonella spp. and S. aureus could be simultaneously detected with 100% specificity under the optimum conditions of 60 ℃, 200 nmol/L and 35 for annealing temperature, primer concentration and number of amplification cycles, respectively. Among three tested genomic DNA extraction methods, the highest purity of genomic DNA could be obtained by kit-based method, and the limits of detection were 31 and 26 DNA copies/reaction for both pathogens, respectively. When the mulitplex PCR assay was applied in artificially contaminated quick-frozen dumpling, both pathogens could be simultaneously detected with detection limit as low as 100 CFU/g after 4 h of bacterial enrichment. Taken together, considering specificity, sensitivity and effectiveness, the multiple PCR assay has a high potential in pollution condition investigation and effective detection of Salmonella and S. aureus in quick-frozen foods.
Application of Hyperspectral Feature Extraction to Detect Surface Damage in Red Jujubes
XIN Shi-hua,HE Jian-guo*,WANG Song-lei,HE Xiao-guang
2013, 34(8):  145-148.  doi:10.7506/spkx1002-6630-201308029
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Spectral images of red jujubes with different types of surface damage were collected by hyperspectral imaging technology over the wavelength range of 650–950 nm. Principal component analysis (PCA) was applied for dimension reduction of the spectra. The characteristic wavelengths of 715 nm and 668 nm, where samples were recognized, were proposed based on eigenvalues obtained from PCA. As a result, classification of surface damage in red jujubes achieved with an accuracy of 98.7%.
Analysis of Volatile Components of Cantharellus cibarius Fr. by GC-MS
LI Wen,GU Zhen,YANG Yan,FENG Tao,LIU Yan-fang,ZHOU Shuai,ZHANG Jin-song
2013, 34(8):  149-152.  doi:10.7506/spkx1002-6630-201308030
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Volatile components in dried fruiting bodies and steam distilled extract of Cantharellus cibarius Fr. were extracted by headspace solid-phase micro-extraction (HS-SPME) method, analyzed by gas chromatography-mass spectrometry (GC-MS) and quantified by peak area normalization method. A total of 75 volatile components were identified in dried fruiting bodies and 48 volatile components in steamed fractions, which were 76.05% and 32.05% of the total volatile components, respectively. Volatile components in dried fruiting bodies mainly included acids, ketones, alcohols and esters, whereas those in steam distilled extract mainly consisted of ketones and aldehydes. Major volatile compounds in dried fruiting bodies were hexanoic acid, isovaleric acid and 1-octen-3-ol and butanoic acid, compared to dihydro-β-ionone, (2E,4E)-2,4-decadienal and geranylacetone for steam distilled extract. Meanwhile, 15 volatile compounds with significant differences in contents were observed in both samples.
Quantitative Determination of Tea Saponin in Tea Seed Meal by High Performance Liquid Chromatography
ZHANG Hai-long,ZHANG Wei-nong,HU Zhi-xiong,QI Yu-tang,GONG Ren
2013, 34(8):  153-156.  doi:10.7506/spkx1002-6630-201308031
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In this work, tea saponin was purified by reversed-phase ODS-A column chromatography from degreased coldpressed tea seed meal for use as a reference standard in the quantitative determination of tea saponin by HPLC and identified by UV absorption spectrometry, FTIR and mass spectrometry. HPLC separation was achieved with reversed-phase ODS column and acetonitrile-water as eluent (an initial acetonitrile concentration of 20% held for 5 min, then increased to 100% in 5 min, and finally decreased back to the initial value) at a flow rate of 1.0 mL/min in gradient mode. UV detection was carried out at 215 nm. Under these conditions, symmetric peaks, desired retention time and good separation between tea saponin and impurity were observed.
Determination of Astaxanthin in Antarctic Krill Oil by C30 Reversed Phase High Performance Liquid Chromatography with Solid-Phase Extraction
SUN Lai-di,LENG Kai-liang,SUN Wei-hong,ZHAO Xian-yong,GAO Hua,XING Li-hong,LIU Kun
2013, 34(8):  157-160.  doi:10.7506/spkx1002-6630-201308032
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An HPLC method for the determination of astaxanthin isomers in Antarctic krill oil was established following solid-phase extraction (SPE). Following clean up on LC-NH2 solid-phase extraction column, saponification of the extracted compounds was achieved with NaOH-methanol. Subsequent separation was performed on YMC-Carotenoid C30 column with n-hexane-acetone-methanol (1:2:2) as eluent at a flow rate between 2 and 4 mL/min. Injection volume was set at 8 mL. Quantification was performed by external standard method. Average recovery rates of astaxanthin isomers from spiked samples varied from 86.1% to 94.3% with RSD between 0.79% and 1.91%. Our results suggest that the developed method is of high reproducibility and recovery and suitable for the analysis of astaxanthin in Antarctic krill oil.
Comparison of Three Detectors Used for HPLC Determination of Monoglycerides
FANG Min,ZHAO Mou-ming,ZHAO Qiang-zhong
2013, 34(8):  161-163.  doi:10.7506/spkx1002-6630-201308033
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High performance liquid chromatography-ultraviolet detector(HPLC-UV), high performance liquid chromatography-differential refractive index detector(HPLC-RI) and high performance liquid chromatography- evaporative light scattering detector(HPLC-ELSD) were compared to measure the content of monoglycerides in emulsions.When using UV detector, the result was seriously influenced by impurities, the signal of the samples was weak and the sensitivity was low. RI detector could had a good linear relationship only in the higher concentration range, so it was not suitable for measuring low content of monoglycerides. When using ELSD detector, the linear range of monoglycerides were between 0.040~5.000 mg/mL. The correlation coefficient of ELSD was 0.9998 , the recovery rate of monoglycerides reached 92.94%, the standard deviations was 2.24 and the variation coefficients was 2.41%. HPLC-ELSD method was sensitive, accurate and reproducible and may therefore be applicable for the determination of monoglycerides in emulsions .
Determination of Isoflavones in Soybean Products and Supplements by UPLC
YUAN Bo,ZHEN Hui-juan,JIANG Xuan,SUN Shuai-ting,XU Li,XU Hai-yan
2013, 34(8):  164-167.  doi:10.7506/spkx1002-6630-201308034
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Objective: To develop an ultra-high performance liquid chromatography (UPLC) method for the determination of four major isoflavones such as daidzin, genistin, daidzein and genistein in soybean products and supplements. Methods: The analytes were separated on an Acquity UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 μm) with a mobile phase consisting of 0.2% formic acid and acetonitrile in gradient mode, and UV detection at 254 nm. The flow rate was 0.4 mL/min. The column temperature was 30 ℃. Results: A good linear relationship within the range of 0.625 to 40.0 mg/L for daidzin (r = 1.000), 0.625 to 40.0 mg/L for genistin (r = 0.9999), 0.04 to 2.56 mg/L for daidzein (r = 0.9997) and 0.04 to 2.56 mg/L for genistein (r = 0.9996) was observed. The average recovery rates of daidzin, genistin, daidzein and genistein were 98.5%–99.8%. Conclusion: The developed method is fast, simple, sensitive, and accurate for the determination of four isoflavones in soybean products and supplements.
Determination of Cadmium, Copper, Lead and Zinc in Grains by Ultrasound-Assisted Extraction Followed by Atomic Absorption Spectrometry
GU Jia-li,ZHAO Gang,MA Zhan-ling
2013, 34(8):  168-171.  doi:10.7506/spkx1002-6630-201308035
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Determining of cadmium, copper, lead and zinc in grain using ultrasound-assisted extraction- atomic absorption spectrometry was optimized. The results indicated that 0.1 g of grain samples were treated with 5 mL of HNO3-H2O2 (2:1, V/V) followed by 10-min presonication and then transferred to ultrasound water bath (60 ℃) for 10 min. Cd, Cu, Pb, and Zn can be quantitatively recovered and the spiked recoveries ranged within 96.0%–107.5%. The results of t-test indicated that difference in the results from ultrasound-assisted extraction and conventional wet acid digestion was not significant. The relative standard deviations (RSD) were 4.9%–7.0%, the limits of detection were 0.007–0.019 mg/L.
Detection of Bifidobacteria in Fermented Dairy Products by Real-Time Fluorescent Quantitative PCR
WU Yan-tao,LIU Xiao-li,CAO Yue,WANG Li-ping
2013, 34(8):  172-175.  doi:10.7506/spkx1002-6630-201308036
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In order to develop a rapid method for the detection of bifidobacteria in fermented milk products by real-time fluorescent quantitative PCR, the extraction efficiency of DNA in fermented milk products by different extraction methods, PCR amplification efficiency of four reference strains and enumeration of bifidobacteria according to different standard curves were compared. Results indicated that enzymatic hydrolysis with pronase E was the best extraction for total DNA with DNA OD260/280 ratio of 1.80. A significant difference between CT value of reference strain and the other strains was observed, and no significant difference between different standard curves was achieved. Therefore, real-time fluorescentn quantitative PCR technique is suitable for enumerating bifidobacteria that exist in commercial probiotic yoghurts.
Determination of Carbofuran and Carbaryl Residues in Fruits and Vegetables by Nonaqueous Micellar Electrokinetic Capillary Chromatography with Online Enrichment
TONG Ming-zhu,CHEN Guan-hua*,WU Chuan-qin,GUO Dong-shan,FANG Rou,ZHANG Li
2013, 34(8):  176-181.  doi:10.7506/spkx1002-6630-201308037
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A method of nonaqueous micellar electrokinetic capillary chromatography with online enrichment was developed to determine carbofuran and carbaryl residues in fruits and vegetables. The effects of buffer composition, apparent pH, applied voltage, and injection time were systematically discussed. The optimized buffer was composed of 100 mmol/L sodium dodecyl sulfate, 30 mmol/L sodium acetate, and formamide-acetonitrile (85:15, V/V), and its apparent pH was adjusted to 9.4. The applied voltage was 20 kV and the sample injection time was 150 s. Under these optimal conditions, peak enrichment factor was 678 and 758; detection limit was 31 μg/L and 7.9 μg/L; RSD was 2.47% and 1.76%; average recovery rates of spiked samples were 80.4%–96.2% and 92.5%–104.1% for carbofuran and carbaryl residues, respectively. Therefore, this method is of high sensitivity, good repeatability and can be used in the determination of both pesticide residues in fruits and vegetables.
Determination of Dimethylpolysiloxanes in Foodstuffs by Inductively Coupled Plasma Atomic Emission Spectrometry
GAO Feng,LI Xiao-lin,FENG Qian,LIN Yuan-hui,WANG Jin-hua
2013, 34(8):  182-185.  doi:10.7506/spkx1002-6630-201308038
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An inductively coupled plasma atomic emission spectrometry (ICP-AES) method for the determination of dimethylpolysiloxanes (PDMS) in animal muscle, edible fat and oil, baking powder, and fruits and vegetables was developed. PDMS in samples were extracted with aviation kerosene, and the extract were then centrifuged and directly detected by ICPAES. The average recovery rates of PDMS at the spiked levels of 5, 10, 100 mg/kg in the muscle of chicken, beef and pork, and in cucumber and pineapple; 1, 2, 10 mg/kg in soybean oil, peanut oil and palm oil, and 2.5, 5, 10 mg/kg in baking powder ranged from 71.2% to 122.9% with relative standard deviations (RSDs) less than 15%. The linearity of the developed method was in the range of 0.1 to 50 mg/L with correlation coefficients (r) of more than 0.995. The limits of detection were approximately 5.0 mg/kg for animal muscle, and fruits and vegetables, 1.0 mg/kg for edible fat and oil, and 2.5 mg/kg for baking powder. This simple, rapid and sensitive method allows for routine qualitative and quantitative analysis of PDMS in selected foodstuffs and can be used for the test of a large number of samples.
Determination of Total Phenols from Actinidia arguta by Visible and Near-Infrared Diffuse Reflection (VIS/NIR) Spectroscopy
FU Rao,XIN Guang,LI Shu-qian,ZHANG Bo,LIU Chang-jiang,WANG Bao-gang,FENG Xiao-yuan
2013, 34(8):  186-189.  doi:10.7506/spkx1002-6630-201308039
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The objective of this study was to establish a mathematical model for quantitative determination of total phenols of Actinidia arguta using the near-infrared diffuse reflectance (NIR) spectra in the wavelength range of 570–1848 nm. The experiment was divided into three stages to set the model (harvest stage, storage of 12 days, storage of 24 days), and compared with the different modeling methods. The results showed that the partial least squares (PLS) model, with respect to the first order derivatives spectrum D1 lg(1/R) and inverse multiple scatter correction(IMSC)treatment, provided better predictive performance for total phenols in Actinidia arguta. In calibration sample set, the correlation coefficient of cross validation (RCV) was 0.8939, and root-mean-square error of cross-validation (RMSECV) was 11.6734 mg/100 g. In prediction set sample, the correlation coefficient of prediction (RP) was 0.8627, and root-mean-square error of prediction (RMSEP) was 16.7690 mg/100 g. These results confirmed that it is feasible to use the established VIS/NIR spectroscopy model for the nondestructive determination of the total phenols in Actinidia arguta. However, further investigation is needed to improve the precision of the model.
Several Factors for the Detection of Bacteria by FT-IR Spectroscopy
YANG Li-jun,WANG Jing,LI Zhao-jie,SONG Xiao-hua,CUI Feng-jie,HU Qiao-ru
2013, 34(8):  190-194.  doi:10.7506/spkx1002-6630-201308040
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A strain of Escherichia coli was used to study the application of Fourier transform infrared (FT-IR) spectroscopy combined with chemometric method for bacterial detection. We examined the effects of bacterial concentration, culture time and heat inactivation on the detection of Escherichia coli by FT-IR spectroscopy. Results indicated that bacteria with different concentrations, culture time, and heat inactivation could be differentiated by FT-IR spectroscopy, respectively. However, the concentration, culture time and heat inactivation revealed significant impact on spectral characteristics and could interfere with the analytic results. Therefore, uniform preparation of bacteria is one of the most important factors for the successful differentiation of bacteria by FT-IR spectroscopy. Meanwhile, these results provide a theoretical basis for extensive application of FT-IR spectroscopy to detect bacteria.
Principal Component Analysis and Cluster Analysis of Sensory and Nutritional Quality of Walnut
PAN Xue-jun,ZHANG Wen-e,LI Qin-qin,WANG Jian-ming,ZHANG Zheng
2013, 34(8):  195-198.  doi:10.7506/spkx1002-6630-201308041
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In order to more scientifically evaluate the nutrition quality and classify the walnut resources based on the sensory, physical and chemical indicators, the appearance quality and the contents of protein, fat and eleven mineral elements (N, P, K, S, Ca, Mg, Fe, Mn, Zn, Cu and Se) in the walnut seed were determined according to GB/T 20398—2006 and GB/T 5009—2003, and nutritional quality was analyzed by principal component analysis and cluster analysis. Five principal components accounted for 80.83% of total variances. The cumulative contribution rate of the first factor and the second components to total variances was 46.21%, suggesting physical indicators, shelling percentage, shell thickness, fruit weight, fruit diameter, and mineral elements cadmium and copper to be characteristic indicators in evaluating walnut, and cadmium and copper to be characteristic elements. Cluster analysis showed that thirteen walnut samples could be classified into three groups, thus providing an approach for the identification of genetic kinship and geographical distribution to some extent.
Identification of Drainage Oil Based on Palmitoleic Acid and Methacrolein
LI Tao,ZHU Xiao-hong,SHENG Xi-xia,LIU Hai-jing,YANG Zhi-hai
2013, 34(8):  199-201.  doi:10.7506/spkx1002-6630-201308042
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This study was conducted to find out specific indicators for discriminating drainage oil from edible oil. For this purpose, tow approaches were proposed: one was analysis of fatty acid composition following sample saponification, and the other was methyl esterification and direct enrichment by headspace sampling method and GC-MS analysis of volatile components in samples. Results revealed that palmitoleic acid and methacrolein showed strong specificity in drainage oil. In the studied samples, using palmitoleic acid alone for identification, the overall correct detection rate was 54.1%, the correct detection rate of positive samples was 100%, the false negative rate was 60.7%, and the correct detection rate of negative samples was 100%. When using methacrolein along, the overall correct detection rate was 78.4%, the correct detection rate of positive samples was 100% and the false negative rate was 28.6%, and the correct detection rate of negative samples was 100%. However, when combining palmitoleic acid and methacrolein together, the overall correct detection rate was 86.5%, the correct detection rate of positive samples was 100%, the false negative rate was 17.9% and the correct detection rate of negative samples was 100%. Therefore, the combined application of palmitoleic acid and methacrolein were proposed as specific indicators in differentiating drainage oil. The two-way methods could be mutual validated, of overall judgment, and identify the drainage oil and the edible oil more accurately.
Determination of 11 Environmental Estrogens in Food Packaging Materials by Liquid Chromatography Coupled with Mass Spectrometry
WU Zhong-ping,LU Jian*,GAO Wei,ZHANG Xiao-qiang,WANG Li
2013, 34(8):  204-207.  doi:10.7506/spkx1002-6630-201308043
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A liquid chromatography and mass spectrometry method for determination of 11 environmental estrogens in food packaging materials was developed. The samples were dissolved by dichloromethane and precipitated by methanol. The filtrates were cleaned up through C18 SPE cartridge, and then separated with liquid chromatography, detected with mass spectrometry. Average recoveries between 81.4% and 111.11% and relative standard deviations between 3.9% and 9.7% were obtained for spiked samples. The detection limits of 11 environmental estrogens were between 0.0075 mg/kg and 0.32 mg/kg.
Anthocyanin Composition and Content in Different Peach Cultivars as Determined by HPLC
ZHAO Xiu-lin,WANG Fu-rong,XU Ling-yun,HE Hua-ping,ZANG Cheng,TIAN Yi-Chao
2013, 34(8):  208-211.  doi:10.7506/spkx1002-6630-201308044
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A reverse phase HPLC method was utilized to investigate anthocyanin composition and content in different peach cultivars. The calibration curve of cyanidin-3-glucoside was linear (r=0.9992) in the range of 0.4–100 μg/mL, and the recovery rates at lower, median and higher concentration were 85.7%, 89.4%, 92.1%, respectively. Cyanindin-3-glucoside was a major anthocyanin in three different peach cultivars. The cyanidin-3-glucoside contents in blood-flesh, yellow-flesh and white-flesh peach were 103.7, 30.6, 21.5 mg/kg (fresh weight), respectively. This method is suitable for quantitative analysis of cyanidin-3-glucoside in peach.
Distribution of Heavy Metals in Soil and Tea from Yunwu Tea Area in Guizhou Province and Diffusion Characteristics of Heavy Metals in Tea Infusion
ZHANG Qing-hai,LONG Zhang-bo,LIN Shao-xia,ZHU Ping,TAN Hong,LIN Chang-hu
2013, 34(8):  212-215.  doi:10.7506/spkx1002-6630-201308045
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In order to investigate the distribution characteristics of heavy metals in tea, samples of tea and soil were collected in Yunwu tea garden in Guizhou Province. Concentrations of heavy metal in soil, tea and tea liquor were detected. Results showed the heavy contaminations of Cd, Hg and As in soils in Yunwu tea garden, the exceed rates were 80.4%, 69.6% and 8.7% over the national standard of China, respectively. However, contents of heavy metals in tea and tea liquor did not exceed the national standard. The accumulation ability of different heavy metals in tea was Cu > Cd > Hg > Pb > Cr > As. Hg was shown to have the highest diffusion rate in tea infusion followed by As, Cu, Pb, Cd and Cr. Moreover, Hg and Cu had high accumulation abilities in tea and high diffusion rates in tea infusion.
Determination of β-Agonists in Cooked Meat by HPLC-MS/MS
WANG Yuan,XING Li-jie,HAO Jia-yong,LU Li-liang,TANG Zong-gui,LUO Xiao-ling
2013, 34(8):  216-219.  doi:10.7506/spkx1002-6630-201308046
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A high performance liquid chromatography-mass/mass (HPLC-MS/MS) method was established for the determination of 3 β-agonists (clenbuterol, ractopamine and salbutamol) in cooked meat. The β-agonists were hydrolyzed by β-glucuronidase, purified by MCX, and analyzed with a methanol-0.1% formic acid-acetonitrile mobile phase. The residues of β-agonists were determined by electrospray ionization-trandem mass spectrometry, and quantified by external standard method. The calibration curve revealed an excellent linear range between peak areas and concentrations in the range of 1–100 ng/mL with correlation coefficient (R2) higher than 0.99. The limit of detection of the developed method was 0.25 μg/kg. The average recovery rate from spiked cooked meat at three concentrations of 0.5, 1, 2 μg/kg was in the range of 80%–120% with relative standard deviations of 1.0%–10.0%.
Determination and Application of Phthalic Acid Esters in Liquor Packaging
MA Li,DING Hong-yan,XUE Shao-zong,LIU Hui,ZHU Xiao-yong,HU Yong-gang,ZHANG Sheng-wan
2013, 34(8):  220-223.  doi:10.7506/spkx1002-6630-201308047
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Some plastic materials for liquor packaging were studied. Retention time (tR) of 17 phthalic acid esters (PAEs) was determined by gas chromatography-flame ionization detector (GC-FID). A model of quantitative structure retention relationship (QSRR) was established through the chemical metrology method and further applied to PAEs qualitative analysis of actual samples. The result shows that the model demonstrated good qualitative capacity. Our work provides a new way to study the migration behavior of PAEs in liquor and plastic packaging materials.
Detection for Pig-Derived Components in Foods by Real-Time Polymerase Chain Reaction
FAN Li-li,LI Pei,FU Chun-ling,DING Hong-liu,CHEN Ying
2013, 34(8):  224-227.  doi:10.7506/spkx1002-6630-201308048
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Species-specific real-time PCR (TaqMan) assay was developed for the detection of pig-derived components in foods. Primers and Taqman probe of this assay were designed with pig conservative regions of the mitochondrial cytochrome b (Cytb) gene (amplicon = 98 base pairs). The specificity was evaluated and achieved without amplification on DNA from other meats. Results showed that this method revealed a high sensitivity and could detect 1 pg of pork template DNA, while Ct (cycle threshold) values of negative samples were limited to 35 cycles. Applying this assay method, the recovery rate of DNA extracted from meat mixtures was up to 1% pork spiked in other species. Therefore, it is a potentially reliable and suitable technique in routine food analysis for the detection of pork in foods.
Simultaneous Determination of 18 Food Additives in Foods by High Performance Liquid Chromatography
LIN Hai-dan,ZOU Zhi-fei,QIN Yan,CHEN Yu-fang,LI Xiao-li,WANG Lan,LIU Zhong-yong
2013, 34(8):  228-231.  doi:10.7506/spkx1002-6630-201308049
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A high performance liquid chromatography method was developed for simultaneous determination of 18 food additives in foods. Low fat or fat free food samples were extracted and purified with n-hexane saturated acetonitrile containing ascorbyl palmitate-6 mol/L HCl solution-saturated sodium chloride solution (containing medium fat sample usingnhexane to remove fat). Oil samples were extracted with n-hexane saturated acetonitrile (containing ascorbyl palmitate)- acetonitrile saturated n-hexane. Analysis was performed using HPLC system equipped with an Ecosil C18 column (250 mm × 4.6 mm, 5 μm) and a UV detector at 280 nm with a mobile phase of acetonitrile-0.6% acetic acid solution, at a flow rate of 1.0 mL/min with gradient elution. Good linear was observed in the range of 1.0–25 mg/L with correlation coefficient of 0.99. The average recovery rate in foods was in the range of 88.9%–99.9% at three spiked levels of 10, 25 mg/kg and 50 mg/kg (n = 6), and the relative standard deviation was in the range of 2.43%–11.7%. The limit of quantification was 10 mg/kg. This method is simple, accurate and suitable for the determination of 18 food additives in foods.
Determination and Comparison of Six Active Compounds in Green Tea from Shaanxi Province
SHI Ming-ming,TANG Xin,LI Xiao,WANG Yu-tang,WU Kun,LIU Juan-juan,LIU Xue-bo
2013, 34(8):  232-235.  doi:10.7506/spkx1002-6630-201308050
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Objective: To determine and compare the contents of theanine, gallic acid (GA), CAF (CAF), epicatechin gallate (EGC), epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) in tea samples from three regions of Shaanxi province by high performance liquid chromatography (HPLC). Methods: Tea samples were extracted by hot water. The six active compounds were separated on a C18 column (250 mm × 4.6 mm, 5 μm) and examined by a photodiode array (PDA) detector at 190 nm and 280 nm with gradient elution at 25 ℃. The mobile phase was composed of trifluoroacetic acid (0.05%) and acetonitrile at the flow rate of 1 mL/min. Results: The contents of the six active compounds were in range of 0.325–47.061 mg/g. The level of GA was significantly higher (P < 0.05) in Hanzhong green tea, while the levels of other five active compounds were significantly higher (P < 0.05) in Ankang green tea.
Fast Detection of Fried Oil Quality by Electronic Nose
LI Jing,WANG Cheng-tao,LIU Guo-rong,ZHAO Lei,YANG Pei-qiang
2013, 34(8):  236-239.  doi:10.7506/spkx1002-6630-201308051
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An electronic nose (PEN3) was used to characterize the dynamic change of volatile components during the frying process of soybean salad oil without objects in oil bath at 180 ℃. Volatile components produced by soybean oil were monitored dynamically and analyzed every 6 h. Results showed that volatile components such as aromatic benzenes, nitrogen oxides, amines, alkanes, H2S and ethanol revealed an obvious increase with the prolonged frying time. In addition, nitrogen oxides, amines, alkanes, H2S and ethanol were the major factors for the deterioration of oil. Data analysis was conducted by using principal component analysis (PCA) and linear discrimination analysis (LDA). LDA was more effective than PCA to distinguish the oil with various frying time. Loading analysis was used to analyze the contribution and correlation of different sensors to the first and second principal components. The sensors Sl, S2, S3, S5, S6, S7, S8 and S9 could be used to analyze the quality of frying oil. These results will be helpful for the application of electronic nose to detect the quality of frying oil.
Determination of 2,4-Diaminotoluene in Laminated Food Packaging Bags by Gas Chromatography and Gas Chromatography-Mass Spectrometry
LI Shao-xia,HUANG Wei-xiong,Lü Fen,CHEN Ming,ZHONG Xiu-hua,HUANG Jing-chu
2013, 34(8):  240-243.  doi:10.7506/spkx1002-6630-201308052
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A gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) method has been established for the determination of 2,4-diaminotoluene in laminated food packaging bags. The samples were soaked by boiling water and the soaked solution was extracted by ethyl acetate. Finally, 2,4-diaminotoluene in ethyl acetate was derived with trifluoro-acetic anhydride and the derivative was separated by DB-1701 capillary column and analyzed by GC and GC-MS. The calibration curve of 2,4-diaminotoluene was linear in the range of 0.002–0.040 mg/L. The limit of detection was 0.001 mg/L. The average recovery rate of 2,4-diaminotoluene at the spiked level of 0.004 mg/L and 0.020 mg/L was 94% with the relative standard deviation of 3.8%–5.5%. The developed method was fast, sensitive and accurate, and was suitable for the determination of 2,4-diaminotoluene in laminated food packaging bags.
Uncertainty Evaluation for Determination of HCH and DDT in Dried Cucumber by Gas Chromatography
HUO Xiao-min
2013, 34(8):  244-248.  doi:10.7506/spkx1002-6630-201308053
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Uncertainty evaluation model was established for evaluating determination results of HCH and DDT in dried cucumber by gas chromatography. In this paper, the bias and precision of determination method was evaluated. The key factors for measurement results during the analysis process were discussed. Meanwhile, the composed and expanded uncertainties were evaluated. This uncertainty evaluation model was practical, simple and easy to understand and valuable as the reference.
Quick Identification of Five Species of Meat by PCR Assay
LI Tong,YIN Yan, WANG Hai,JIANG Yan-bin,HOU Dong-jun,YUAN Qi-peng, YU Lei
2013, 34(8):  249-252.  doi:10.7506/spkx1002-6630-201308054
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A new method was established to identify five species of meat such as beef, mutton, pork, chicken and duck through polymerase chain reaction (PCR). Using specific primers and total DNA from each species of meat as the template, fragments with sizes of 494, 716, 611, 259 bp and 350 bp were obtained, respectively. Our results were further confirmed through the digestion of restriction enzymes. In addition, mutton with 1% added beef, pork, chicken and duck was identified using the designed primers. The detection limit of this method was 1%. Quick and accurate identification of meat can be achieved using it.
Detection of Lactic Acid Bacteria in Commercial Yoghurt by PCR-DGGE Combined with Species-Specific PCR
WANG Ying,MENG Xiang-chen
2013, 34(8):  253-258.  doi:10.7506/spkx1002-6630-201308055
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Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) combined with species-specific PCR was used to detect lactic acid bacteria in commercial yoghurts. DGGE conditions were optimized and the results indicated that the optimal conditions of DGGE were 30%–60% denaturant gradient range and 300 min electrophoresis. Lactobacillus plantarum and Bifidobacterium lactis could be distinguished, while Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus acidophilus, Streptococcus thermophilus, Lactobacillus casei and Lactobacillus rhamnosus could not be distinguished. Furthermore, species-specific PCR was used to distinguish among the strains with the same migration distance in gel. Lactic acid bacteria in six commercial yoghurts were detected by PCR-DGGE combined with species-specific PCR. All yoghurts contained Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus plantarum; three kinds of yoghurts contained Lactobacillus casei; Bifidobacterium lactis stated on the label was not detected in one kind of yoghurt. Lactic acid bacteria in yoghurt were isolated and enumeratied by selective medium and the results were confirmed by previously approved technology. Therefore, PCR-DGGE coupled with speciesspecific PCR was an effective method to detect lactic acid bacteria in yoghurt.
Separation and Identification of Aroma Compounds in Yeast Extract
LIN Mei-li,XU Qian-qian,SONG Huan-lu,*,LI Pei,XIONG Jian,LI Shu-sheng
2013, 34(8):  259-262.  doi:10.7506/spkx1002-6630-201308056
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Volatile compounds from three types of yeast extract (YE) were extracted by solid phase microextract (SP-ME), analyzed by GC-O-MS and key aroma compounds in YE was identified by aroma extract dilution analysis (AEDA). Totally, 48 kinds of aroma compounds were separated and identified, which included ketones, aldehyde, acids, alcohols, furans, pyrazine, thiazole and tepenes. Flavor dilution factor (FD) of key aroma compounds including 3-methyl-butanal (chocolate), 2-methyl-5-methylthiofuran (meat) and 3-(methylthio) propionaldehyde (cooked potato) were 125, thus these aroma compounds made a significant contribution to the overall flavor characteristics of YE.
Effects of Calcium Chloride and Chitosan Coating Treatments on Citric Acid Metabolizing Enzymes and Gene Expression in Postharvest Pear
GUO Run-zi,KOU Xiao-hong,ZHANG Ying,WANG Shuang
2013, 34(8):  263-268.  doi:10.7506/spkx1002-6630-201308057
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Post-harvest Huangguan pear was treated with calcium chloride and chitosan coating and the citrate metabolic regulation mechanism and the citric acid metabolism under different treatments during cold storage were investigated. Huangguan pear was soaked with calcium chloride followed by chitosan coating treatment. The level of citric acid was determined using HPLC and the activity of citric acid metabolizing enzymes such as citrate synthase (CS), cytoplasmic aconitase (cyt-ACO) and isocitrate dehydrogenase (NADP-IDH) were also monitored. Real-time PCR was employed to analyze the relative expression levels of citric acid metabolizing enzyme genes. Statistical analysis on correlation among citric acid, metabolizing enzyme and related genes were conducted. Both treatments could significantly prevent the decline of citric acid content and improve the activity of enzymes. Calcium chloride and chitosan treatments can affect the gene expression in certain extent. CS had important influence in citric acid accumulation. The correlation analysis showed that there was a significant correlation between the content of citric acid and the activity of CS. A significant positive correlation were observed between citric acid and the activity of cyt-ACO in pulp whereas the correlation was negative in Huangguan peel. NADP-IDH showed slight effect on the metabolism of citric acid. Gene expression wasconsistent with the changes in the corresponding enzyme activity and thereby regulate the citric acid metabolism. In summary, the metabolism of citric acid in postharvest Huangguan pear was co-regulated by enzyme activity and related gene expression. Calcium chloride and chitosan coating treatments can affect the activity of the enzymes and the expression level of related genes.
Comparison of Quality Changes of Pickled Radish Treated by High Hydrostatic Pressure and Thermal Processing during Storage
ZHAO Dong,LI Xue-mei,CHEN An-jun,PU Biao
2013, 34(8):  269-273.  doi:10.7506/spkx1002-6630-201308058
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This study was carried out to evaluate the effect of high hydrostatic pressure (HHP; 200 MPa and 400 MPa for 20 min, respectively) and thermal processing (85 ℃, 20 min) on microbial population, pH, titrable acidity (TA) and color changes of pickled radish during storage time at different temperature. The results showed that HHP treatment at 400 MPa for 20 min and heat treatment maintained microbial population, efficiently delayed the decrease of pH and retarded the acidification of pickled radish, and desired results were obtained during storage at 4 ℃. Moreover, HHP treatment had no significant impact on color as compared to thermal processed samples. However, the color of HHP-treated samples declined obviously in pickled radish during storage at 20 ℃, and the color of pickled radish subjected to HHP treatment at 400 MPa declined more severely compared with those treated at 200 MPa, but the color decline in pickled radish slowed down and the color of HHP-treated samples were brighter than that of heat-treated samples during storage at 4 ℃.
Effect of H2O2 on Disease Resistance of Postharvest Tomato Fruits Infected with Botryis cinerea
WU Huan-huan,SHEN Lin,SHENG Ji-ping
2013, 34(8):  274-278.  doi:10.7506/spkx1002-6630-201308059
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The disease-resistant effect of H2O2 on post-harvest tomato fruits infected with Botryis cinerea was investigated. Freshly harvested tomato fruits were treated with 10 mmol/L H2O2. One day later, the treated fruits were subjected to establish wound models including mechanical wound and inoculation of Botryis cinerea. The wounded fruits were divided into three groups with mechanically wounded fruits as the control group, the Botryis cinerea-inoculated fruits as the inoc group, and H2O2-pretreated fruits coupled with Botryis cinerea-inoculated fruits as the inoc + H2O2 group. All fruits were stored the environment with temperature of (25 ± 1) ℃ and RH of 80%–85% for 4 days. The results showed that inoc treatment could significantly improve the incidence and lesion area of tomato fruits compared with the control group. After inoculation for 3 days, inoc + H2O2 treatment could reduce disease incidence by 35.5% and lesion area by 29.7% compared with the inoc treatment. In addition, inoc + H2O2 treatment could significantly improve the activities of disease defenserelated enzymes such as PAL and PPO during 1–2 days, GLU and CHI during 1–4 days and induce gene expression level of disease-related protein PR-1. Meanwhile, inoc + H2O2 treatment could significantly improve the relative expression level of NADPH oxidase within 1 day, thereby increasing internal H2O2 content as a signal molecule could induce the disease resistance in tomato fruits. In a word, H2O2 can improve the disease resistance of tomato fruits infected with Botryis cinerea.
Preservation of Litchi with Composite Chitosan Coating and Modified Atmosphere Packaging
YANG Sheng-ping,XIE Jing*,QIAN Yun-fang,LI Nian-wen,ZHOU Ran
2013, 34(8):  279-283.  doi:10.7506/spkx1002-6630-201308060
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Effects of three different postharvest treatments including compound coating antistaling of chitosan, modified atmosphere packaging (MAP) and their combined treatment on shelf-life of Feizixiao litchi were investigated. The coating solution in this study was composed of 1.5% chitosan + 1.0% gallic acid + 4.0% citric acid + 0.1% CaCl2. The modified atmosphere was a gas mixture of 5% CO2 + 5% O2 + 90% N2. All fruit samples treated by coating or MAP or coating with MAP were stored at (4±1)℃ with the humidity of 80%. The general quality indexes (good fruit rate and browning index) of litchi fruit, the evaluation indicators of pericarp (anthocyanin content, moisture content and color), and the quality indexes of litchi pulp (vitamin C content , soluble solid content, titratable acidity and sugar acid ratio) were used to evaluate the quality of litchi. The results showed that both the stand-alone treatment of coating and MAP could extend the preservation time of litchi. However, the results of the combined treatment could not indicate a synergic effect from two treatments. The shelf-life of litchi packaged in MAP (5% CO2 + 5% O2 + 90% N2) was the longest (42 days) among these groups, and the health fruit rate was more than 90% with a browning index of 1.52.
Preservative Effect of Four Composite Natural Coatings on Eggs
ZHANG Shuai,MA Mei-hu*,CAI Zhao-xia
2013, 34(8):  284-288.  doi:10.7506/spkx1002-6630-201308061
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The objective of this study was to explore and compare the preservative effects of different composite coatings on eggs. Four coatings were prepared from oil, emulsifying agent, antioxidant and antibacterial materials (essential oils) and their effects on the quality of eggs during 135 days of storage at 20 ℃ were examined. Results revealed that the coatings could keep eggs at level A for 30 days and keep eggs at grade B for 90 days. C-D type (soybean oil-CMC) and H-Y type (maize oil-xanthan gum) coatings had better preservative effect, which were followed by Z type (palm oil) and Y type (maize oil). The weight loss, yolk index and albumen pH of four coating groups were slightly better than those of the mineral oil group and significantly better than those of uncoated control group. The plant essential oil added to coatings had bacteriostasis, and no microorganisms were detected during preservative period. Coating eggs after cleaning can prolong their shelf life. The natural coatings have a great application prospect due to their safety.
Physiobiochemical Characteristics of Phaseolus vulgaris L. during Controlled Atmosphere Storage
WANG Li-bin,JIANG Li,SHI Yun,LUO Hai-bo,YU Zhi-fang
2013, 34(8):  289-293.  doi:10.7506/spkx1002-6630-201308062
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To explore the effect of controlled atmosphere (CA) on physio-biochemical index of Phaseolus vulgaris L., two different storage conditions such as controlled atmosphere storage (gas components: 3% O2 + 1% CO2 + 6% N2; temperature: (9.0 ± 0.5) ℃) and cold storage as a control (gas components: air; temperature: (9.0 ± 0.5) ℃) were used. The results showed that Phaseolus vulgaris L. stored in CA revealed better quality with the characteristics of higher reducing sugar content, higher chlorophyll content and less cellulose content during the storage period. Meanwhile, the higher activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and cellulose enzyme (CE) were observed in Phaseolus vulgaris L. stored in CA; in contrast, lower accumulation of superoxide anion (O2-·), hydrogen peroxide (H2O2) and malondialdehyde (MDA) was detected. Therefore, CA can maintain the quality of Phaseolus vulgaris L. during storage, and prolong its storage time.
Involvement of Nitric Oxide in Defense Response of Salicylic Acid-Induced Disease in Postharvest Tomato Fruits
LI Cui-dan,SHEN Lin,SHENG Ji-ping
2013, 34(8):  294-298.  doi:10.7506/spkx1002-6630-201308063
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Salicylic acid (SA) and nitric oxide (NO) are important signaling molecules in disease resistance of plants. Previous studies have demonstrated the NO involvement in SA pathway. In order to explore whether NO involvement in defense response of SA-induced disease in postharvest tomato fruits and corresponding mechanisms, tomato fruits (Lycopersicon esculentum cv. Lichun) were treated with methyl salicylate (MeSA) and nitric oxide synthase (NOS) inhibitor (L-NNA). The effect of L-NNA on the resistance to Botrytis cinerea, NOS activity, NO level and defensive enzyme activity was explored. Our results showed that MeSA treatment improved disease resistance and L-NNA treatment inhibited the activities of defensive enzymes including phenylalanine ammonialyase (PAL), chitinase (CHI), β-1,3-glucanase (GLU) and polyohenoloxidase (PPO). Therefore, NO was involved in defense response of SA-induced disease in postharvest tomato fruits.
Effect of Grape Seed Extract on Preservation of Shiitake Mushroom (Lentinus edoes)
WU Ning,JIN Cheng,HUANG Ju,SONG Jun,ZHANG Lei,JIANG Tian-jia,LI Jian-rong
2013, 34(8):  299-302.  doi:10.7506/spkx1002-6630-201308064
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In order to preserve fresh shiitake mushroom conveniently and environmentally, the effect of grape seed extract (GSE) of different concentrations (0, 1, 5, 10, 20 g/L) on freshly harvested shiitake mushrooms stored 4 ℃ were investigated. The results showed that GSE at concentrations of 1, 5 g/L and 10 g/L could maintain sensory quality, reduce weight loss and MDA production in shiitake mushroom; but 20 g/L GSE darkened the color of shiitake mushroom. Therefore, GSE possesses antibacterial effect, but no significant effect on total phenolics and nutrient. This study implies that GSE can effectively extend the shelf life of shiitake mushroom with an optimal concentration of 5 g/L.
Effects of Packaging Films on the Quality of Fresh Lentinus edodes
FU Hai-jiao,ZHOU Xiao-qing,YING Li-sha,ZHANG Min*
2013, 34(8):  303-307.  doi:10.7506/spkx1002-6630-201308065
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Fresh Lentinus edodes was packaged using packaging films with different gas permeability and the effects of different packaging materials on the qualities of fresh Lentinus edodes were studied by measuring changes in respiration rate, weight loss rate, soluble solid content, hardness, whiteness and ascorbic acid content during storage at 4 ℃ and 90% humidity. Results indicated fresh Lentinus edodes packaged with a 30-micron film reserved the lowest respiration rate and weight loss rate, and the highest soluble solid content compared with other packaging films. The influences of films on hardness and whiteness of Lentinus edodes were not significant (P > 0.05). In the early storage the impacts of films on the ascorbic acid content were not significant (P > 0.05), while in the late storage ascorbic acid content in Lentinus edodes packaged with a 30-micron low density polyethylene film was higher than in Lentinus edodes packaged with other films.
Effects of Micro-Vacuum Storage Conditions on the Texture of Broccoli Curd
YUE Ben-fang,LI Wen-xiang
2013, 34(8):  308-312.  doi:10.7506/spkx1002-6630-201308066
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To solve the problem of postharvest broccoli quality degradation caused by texture changes, the relationship between texture changes and activities of enzymes, which are response for broccoli cell wall metabolism, cell wall components degradation, were studied under micro-vacuum conditions. Results showed that, at the same temperature,compared with modified atmosphere packaging (MAP), micro-vacuum storage could significantly (P < 0.05) reduce the activity of cellulose (CS), polygalacturonase (PG), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD), also could delay the degradation of pectin and formation of cellulose and lignin in broccoli cell wall, and could inhibit the increase of scape strength and hardness. Correlation analyses showed that there were significantly positive correlations among scape strength, broccoli hardness and the content of cellulose, lignin, the activity of PG, PE, and there was a negatively correlated with the activity of CS,PAL,PPO and POD. It indicated that micro-vacuum storage could reduce the formation of cellulose and lignin possibly by inhibiting the activity of PAL, PPO, POD and CS, while reduction in the activity of PG could delay metabolism of pectin, and further inhibit aging of broccoli.
Effect of Exogenous Glycine Betaine on Oxidative Metabolism in Cucumber during Low-Temperature Storage
WANG Fu-gui,HAN Tao,ZHANG Hai-ying*,XU Li
2013, 34(8):  313-316.  doi:10.7506/spkx1002-6630-201308067
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The aim of this work was to investigate the effect and possible mechanism of glycine betaine (GB) treatment on the antioxidant properties of cucumber during low-temperature storage. ‘Zhongnong 8’ cucumbers were immersed in GB solutions at 0, 5, 10 mmol/L and 15 mmol/L and stored at 4 ℃. Changes in parameters related to oxidative metabolism were observed. The results showed that increasing GB concentration resulted in a decrease in lipoxygenase (LOX) activity. The activities of peroxidase (POD) and catalase (CAT) were enhanced by exogenous GB treatment. Meanwhile, the accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2) were restrained. GB at a dose of 10 mmol/L revealed the most obvious effect.
Development of Natural Matrix Standard Tea for Quality Control of Bifenthrin Residues
YU Kong-jie,YANG Fang, HUANG Jie, LI Yao-ping,JIANG Jin-bin,LI Jie,LAN Jin-chang,WANG Yan
2013, 34(8):  317-320.  doi:10.7506/spkx1002-6630-201308068
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In order to obtain quality control standard for the analysis of bifenthrin residues in tea, a methodology was explored for establishing tea natural matrix reference material containing bifenthrin. Tea plants were due to the spraying of 0.17 g/L bifenthrin solution at a dosage of 3.0 g/mu (1 mu = 666.67 m2). Daily monitoring detection was conducted after the application of bifenthrin in tea plants. After tea picking at appropriate moment, normal tea making, and milling and screening through 120 mesh, the content of bifenthrin residues in 320 tea samples with independent bags from 2 batches were determined. The homogeneity and stability of the samples were examined. The chemical constituents of the samples were certified through collaborative analysis program and uncertainty assessment. The developed standard was applied to CNAS national proficiency testing program participated by 98 laboratories.
Optimization of Emulsification Salt Formulation for Preparing Cheese by Response Surface Methodology
CHEN Ling,LIU Hui-ping
2013, 34(8):  321-325.  doi:10.7506/spkx1002-6630-201308069
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Single-factor tests, central composite design (CCD) and response surface methodology (RSM) were used to optimize the emulsification salt formulation for preparing cheese. The results of single-factor tests showed that sodium citrate, sodium polyphosphate and sodium pyrophosphate had an obvious emulsification effect on cheese preparation. Three significant factors were made by the steepest ascent design (SAD) to approach the maximum response area and then optimized by CCD and RSM. The optimal formulation was composed of 2.0% sodium citrate, 0.20% sodium polyphosphate and 0.37% sodium pyrophosphate (on the basis of the weight of natural cheese). Under the optimal formulation, the peptization coefficient was 62.15%, which was close to the predicted value. Therefore, RSM can provide a reliable process for optimizing emulsification salt formulation for preparing cheese.