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15 May 2010, Volume 31 Issue 10
Processing Technology
Enzymatic Preparation and Physico-chemical Characterization of Wheat Bran Starch
ZHAO Rui-chang,TIAN Yi-hua,JIANG Dong*,DAI Ting-bo,JING Qi,CAO Wei-xing
2010, 31(10):  1-5.  doi:10.7506/spkx1002-6630-201010001
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Optimal neutrase hydrolysis of wheat bran for starch preparation was investigated using orthogonal array design. Along with this, the prepared starch was characterized physicochemically. Results showed that the neutrase hydrolysis reaction for 90 min at 45 ℃ and an enzyme dosage of 3 g/L resulted in an optimal compromise between high starch yield and low protein content in the prepared starch, which reached up to 14.86 g/100 g wheat bran and 0.25%, respectively. The prepared starch contained lower contents of both protein and damaged starch and small starch granules with a volume fraction of 58.4%. Compared with wheat starch, this starch exhibited lower amylose content, pasting value and degree of crystallinity and higher swelling power.

Two-step Alkalinase Hydrolysis for Production of Casein-derived ACE Inhibitory Peptides with High Activity
LI Ya-yun,ZHAO Xin-huai*
2010, 31(10):  6-11.  doi:10.7506/spkx1002-6630-201010002
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The ACE inhibitory peptides derived from casein hydrolyzed with alkaline protease from Bacillus subtilis at 55 ℃ for 6 h exhibited an IC50 of 38.6μg/mL. To enhance their activity, they were modified via the plastein reaction catalyzed by the enzyme. Moreover, response surface methodology was employed to investigate the optimal values of plastein reaction parameters including enzyme dosage and reaction temperature and time. Results showed that after the optimal reaction for 6 h at 42.7 ℃ and an enzyme dosage of 7.7 kU/g protein, the content of free amino groups in the peptides were decreased by up to 179.72 μmol/g protein. The optimized plastein reaction resulted in an obvious enhancement of casein-derived ACE inhibitory peptides, which was related to the reaction degree and the IC50 of the modified ACE inhibitory peptides was reduced to 0.5μg/mL.

Formulation of Mill Fractions of Wheat Cultivars Shanyou 225 Blended with Xiaoyan No. 6 for Production of Instant Noodle Flour
AN Cheng-li,ZHANG Gai-sheng*,HU Jun-peng,CHEN Guang-dou,YUE Xiu-qin,LI Bi-yun, TANG Tao,YANG Ming-ming
2010, 31(10):  12-15.  doi:10.7506/spkx1002-6630-201010003
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Wheat cultivar Shanyou 225 and its blend with Xiaoyan No. 6 (45:55, m/m) were milled using a home-made 4-skin, 3-wick medium-sized flour miller and 7 mill fractions (1B to 4 B and 1M to 3M) were obtained respectively. The 7 mill fractions of wheat cultivar Shanyou 225 and their blend as well as the blend of the 7 mill fractions of wheat cultivar Shanyou 225 blended with Xiaoyan No. 6 were compared for the differences in flour properties and dough rheological properties. Results showed that both protein and wet gluten contents in skin mill fractions were higher than those in wick mill fractions. Skin mill fractions from 1B to 4B exhibited a gradual increase in both indexes; however wick mill fractions from 1M to 3M exhibited an opposite trend. A basically identical trend was observed in dough forming time and stabilizing time and tensile area rather than water absorption rate. 3B mill fraction exhibited the best dough rheological properties. The changes in instant noodle quality and overall score displayed an identical regularity to dough rheological properties. The best and the worst instant noodle quality and overall score were observed in 3B and 1B fractions obtained from skin milling and 1M and 3M fractions obtained from wick milling, respectively. Compared with the blend of 7 mill fractions of single wheat cultivar Shanyou 225, the blend of 7 mill fractions of wheat cultivar Shanyou 225 blended with Xiaoyan No. 6 exhibited an obvious improvement in flour quality and an increase of 5.0 to 6.1 in overall score of instant noodles. The main flour parameters of the blend of 6 of 7 mill fractions of wheat cultivar Shanyou 225 blended with Xiaoyan No. 6 at a blend ratio of 2B/3B/4B/1M/2M/3M of 10.5:8.5:6.5:37.0:23.0:11.0 met or even exceeded the requirements of the relevant national standards.

Isolation, Purification and Relative Molecular Mass Determination of Corn Bran Polysaccharides
ZHANG Yan-rong,YU Jun,LIU Xiang-yang,WANG Da-wei*
2010, 31(10 ):  16-19.  doi:10.7506/spkx1002-6630-201010004
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Crude corn bran polysaccharides (CBP) were obtained through microwave-assisted extraction followed by 95% alcohol precipitation, purified through D315 ion exchange resin column chromatography for the removal of protein and fractionated into 2 fractions, CBPA and CBPB, through fractional precipitation with alcohol. CBPA was further fractionated through Sephadex G-100 column chromatography into 2 subfractions, CBPA-1 and CBPA-2 of which Sephadex G-75 column elution profile exhibited a single absorption peak. Sephadex G-75 column chromatographic analysis indicated that CBPB comprised a single homogeneous composition. Neither protein nor nuclear acid characteristic absorption peaks were shown in the UV-visible spectra of CBPA-1, CBPA-2 and CBPB. The relative molecular mass of CBPA-1, CBPA-2 and CBPB were determined by the dextran gel filtration method to be 186170, 103885 and 146887 , respectively.

Protease Hydrolysis of Bovine Bone Power
TAN Bei-ni,MA Mei-hu*,WEI Tao
2010, 31(10):  20-25.  doi:10.7506/spkx1002-6630-201010005
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Pepsin, alkaline protease, trypsin, neutral protease and papain were used to hydrolyze bovine bone powder, respectively. According to the overall evaluation on degree of hydrolysis and nitrogen recovery of bovine bone powder and sensory quality of the resulting hydrolysate, papain was selected to prepare bovine bone hydrolysate. Single factor experiments were carried out to examine the effects of papain hydrolysis parameters including substrate concentration, enzyme amount, pH and hydrolysis time and temperature on degree of hydrolysis and nitrogen recovery of bovine bone powder. Based on this, a 4- variable, 5-level quadratic orthogonal rotation combination design involving 36 experiments was employed to investigate the optimal values of other 4 hydrolysis parameters except hydrolysis time. Results showed that the optimal hydrolysis of bovine bone powder with 6000 U/g papain for 3 h at 60 ℃, pH 6.5 and 1 g/100 mL substrate concentration resulted in a degree of hydrolysis of up to 26.27%. When the substrate concentration was adjusted to be 5 g/100 mL for the enhancement of solid content in bovine bone powder hydrolysate, a predicted value of degree of hydrolysis of 18.33% was obtained. Validation experiments gave an actual value range of 16.5% to 20% and a nitrogen recovery range of 84.5% to 92%.

Enzymolysis of Early Indica Rice for Production of High Purity Maltose Syrup
LIN Qin-lu1,2,XIAO Hua-xi1,YU Feng-xiang1,LIU Xing1,LI Li-hui1,2,WANG Zhan-xi3
2010, 31(10):  26-29.  doi:10.7506/spkx1002-6630-201010006
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Liquefaction with heat-stable α-amylase and combined saccharification with fungal amylase and pullulanase for the production of high purity maltose syrup from early Indica rice were studied. Results showed that the final product containing more than 85% of maltose was obtained through liquefaction resulting in DE value followed by combined saccharification for 18 h with fungal amylase at a dosage of 0.6 FAU/g dried rice starch and pullulanase at a dosage of 0.3 PUN/gdried rice starch at 59 ℃ and pH 5.5.

Reponses Surface Methodology for Optimization of Supercritical Carbon Dioxide Extraction of Black Currant Seed Oil
BAO Zhi-jie,WANG Yu,YU Dian-yu*
2010, 31(10):  30-34.  doi:10.7506/spkx1002-6630-201010007
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The present study aimed to optimize the supercritical carbon dioxide extraction of blackcurrant seed oil using response surface methodology combined with a 3-variable, 3- level Box-Benhnken central composite design (CCD) on the basis of single factor experiments. Results showed that the optimal extraction for 180 min at 33 MPa and 38 ℃ resulted in a blackcurrant seed oil yield of up to 14%.

Phosphorylation with Sodium Tripolyphosphate for Modification of Peanut Protein Isolate
XIONG Liu1,2,SUN Gao-fei2,3,WANG Jian-hua2,4,SUN Qing-jie1,2,*
2010, 31(10):  35-41.  doi:10.7506/spkx1002-6630-201010008
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Peanut protein isolate (PPI) was phosphorylated with sodium tripolyphosphate (STP) for the modification of its functionality. To maximize the nitrogen soluble index (NSI) of PPI, crucial phosphorylation reaction parameters including PPI concentration, STP amount, reaction temperature and time and pH were optimized using response surface methodology (RSM) combined with central composite design based on single factor design. Results showed that the optimal values of the above parameters were as follows: PPI concentration 6.38%, STP amount 7.77% (g/g protein), pH 8.24 and reaction temperature 44.85℃ for a reaction duration of 5.68 h. Under such conditions, a maximum NSI of PPI of 77.74% was obtained. The oil absorption, water absorption, water capacity, emulsifying capacity, emulsion stability, foam stability of PPI were all improved to different extent after the optimized phosphorylation.

Microwave-assisted Enzymatic Hydrolysis of Corn Silk for Extraction of Polysaccharides
CHEN Hong,ZHANG Yan-rong,WANG Da-wei*,LIU Ting-ting,ZHANG Bo
2010, 31(10):  42-46.  doi:10.7506/spkx1002-6630-201010009
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The present study aimed at developing an optimal procedure for the extraction of polysaccharides from corn silk hydrolyzed with a commercial cellulase preparation under microwave assistance. The optimal values of crucial technological parameters for improved polysaccharides yield were determined by one-factor-at-a-time and orthogonal array design methods as follows: microwave powder 500 W for 2 min treatment, water/material ratio 30:1 (mL/g), enzyme dosage 1.5%, pH 5.0 and hydrolysis temperature 50 ℃ for a hydrolysis duration of 40 min. Under such conditions, a maximum polysaccharides yield of up to 8.12% was obtained.

Optimization of Ultrasonic-assisted Extraction of Proanthocyanidins from Rapeseed Shell
PAN Li-jun,FAN Ting-ting,JIANG Shao-tong,CAO Li-li
2010, 31(10):  47-52.  doi:10.7506/spkx1002-6630-201010010
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To optimize proanthocyanidins yield from rapeseed shell extracted by ultrasonic-assisted extraction, single factor experiments followed by response surface analysis combined with a 4-variable quadratic orthogonal rotation combination design were carried out. Results showed that the optimal ultrasonic-assisted extraction, namely using 54% aqueous ethanol to extract the powdered material having particle size of 60 mesh at a material/liquid ratio of 1:12 (g/mL) with the assistance of 22.5 min ultrasonic treatment, resulted in a proanthocyanidins yield of up to 37.12%.

Extraction and Purification of Anthocyanins from Black Rice
HOU Zhao-hua,ZHAI Hu-qu,WAN Jian-min,REN Gui-xing*
2010, 31(10):  53-59.  doi:10.7506/spkx1002-6630-201010011
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To maximize anthocyanins yield from black rice extracted with ethanol solution, one-factor-at-a-time and orthogonal array design methods were used to examine the optimal values of 5 main technological parameters. Cyanidin-3-glucoside was served as the reference substance for the quantification of anthocyanins. Subsequently, the crude anthocyanin extract obtained was purified by macroporous resin absorption. Results showed that an optimal anthocyanins yield was achieved through extracting the material with a 10-fold (mL/g) volume of a mixture composed of absolute ethanol, water and hydrochloric acid (50: 50:0.5, V/V) for 1 h 3 times each time at 50 ℃. Among 9 macroporous resins tested, AB-8 exhibited the best compromise between high adsorption and high desorption rates so as to be used to purify the crude anthocyanin extract from black rice. In the purification, the optimal elution solvent was 80% aqueous ethanol and the optimal values of flow rate for sample loading onto AB-8 and elution solvent flow rate were 1.0 and 2.0 BV/h, respectively. The purified anthocyanin extract was determined to have 22.59% anthocyanins content (the value in the crude anthocyanin extract 3.448%) with a 6.02-fold enrichment, which demonstrated an effective purification.

Optimization of Glutathione Extraction from Saccharomyces cerevisiae Using Response Surface Methodology
ZHENG Li-xue,WANG Li-mei,MEI Yan-zhen,QI Bin*
2010, 31(10):  60-63.  doi:10.7506/spkx1002-6630-201010012
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Box-Behnken design and response surface methodology were applied to maximize the glutathione yield from Saccharomyces cerevisiae extracted with alcohol. Results showed that the optimum conditions of glutathione extraction were as follows: ethanol concentration 43.7%, amount of added ethanol 7.03 mL/ 0.1 g yeast powder and extraction time 80 min. Under such optimal conditions, a maximal glutathione yield of 9.54 mg/g were obtained.

Inhibitory Effect of Ultra-high Pressure Treatment on Polyphenol Oxidase and Peroxidase Activities in Banana Pulp
YUAN Gen-liang,YANG Gong-ming*,YU Ming,DU Bing,ZHANG Xue-ying,XIA Yu,JIANG Dong-wen
2010, 31(10):  64-68.  doi:10.7506/spkx1002-6630-201010013
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In order to minimize residual polyphenol oxidase (PPO) and peroxidase (POD) activities in banana pulp after ultrahigh pressure treatment, the effects of pressure, temperature and pressure holding time on PPO and POD inactivation in banana pulp were dealt with using single factor and quadratic orthogonal rotation combination design methods. Results showed that the above factors decreasingly affected residual PPO and POD activities in the following order: pressure>temperature>pressure hold time and temperature>pressure>pressure hold time, respectively. The optimal values of the above factors leading to 0.90% residual PPO activity and 3.26% residual POD activity were identical, 480 MPa held for 10 min and 55 ℃.

Enzymatic Production of Soybean Bioactive Peptides
LI Feng,PAN Yao,CHEN Qi
2010, 31(10):  69-74.  doi:10.7506/spkx1002-6630-201010014
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To achieve an optimal degree of hydrolysis of soybean protein isolate (SPI) enzymatically hydrolyzed for the production of soybean bioactive peptides, single factor experiments were carried out to investigate 4 hydrolysis parameters (namely pH, hydrolysis temperature, enzyme dosage and substrate concentration) affecting Alcalase and Flavourzyme hydrolysis procedures of SPI and subsequently, according to experimental results, both enzymes were used for the combined hydrolysis of SPI and the optimal values of 4 hydrolysis parameters (namely pH, Alcalase dosage, Flavourzyme dosage and hydrolysis temperature) were investigated using a 4-variable, 3-level Box-Behnken design and response surface methodology. Results showed that a maximum degree of hydrolysis of SPI was achieved through the optimal double enzymatic hydrolysis for 7 h at 56 ℃ and pH 7.7 with Alcalase at a dosage of 110 mg/g substrate and Flavourzyme at a dosage of 90 mg/g substrate. Most of the soybean bioactive peptides obtained under such hydrolysis conditions exhibited a molecular weight below 1000 D.

Preparation and Biological Activities of Zn (Ⅱ)–Tilapia Peptide Complexes
XU Qing-ling1,ZENG Qing-zhu1,*,YAN Lei2,LIN Jin-ying1,GU Cai-qin1,ZHAN Yu1,FAN Ya-ming1,HUANG Ru-qiang3
2010, 31(10):  75-80.  doi:10.7506/spkx1002-6630-201010015
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The preparation procedure of Zn (Ⅱ)–tilapia peptide complexes was investigated by single factor design method. Along with this, the complexes were structurally characterized and their biological activities were tested by measuring their effects on kidney GSH-Px and hepatic SOD activities and the percentage of macrophages engaged in phagocytosis in mice and in vitro superoxide anion free radical scavenging activity. Results showed that the optimal reaction conditions for the preparation of Zn (Ⅱ)–tilapia peptide complexes were as follows: pH 5.0 and 80 ℃ for a reaction between Zn (Ⅱ) and tilapia peptides contained in the tilapia meat hydrolysate with 15% degree of hydrolysis. Under such conditions, the yield of Zn (Ⅱ)–tilapia peptide complexes with a Zn content of 6.5 × 104 mg/kg reached up to 54% and Zn exhibited a chelation rate of 55%. Spectral characteristics demonstrated the formation of new complexes from Zn (Ⅱ) and tilapia peptides. The complexes remarkably increased the percentage of macrophages engaged in phagocytosis and hepatic SOD and kidney GSH-Px in mice and exhibited an excellent superoxide anion free radical scavenging activity.

Ultrasonic Pretreatment Followed by Enzymatic Hydrolysis for Extraction of Polysaccharides from Fermented Mycelia of Phellinus linteus
XIE Li-yuan1,2,WANG Fu-wei3,LI Hong-jun1,GAN Bing-cheng2,*,PENG Wei-hong2,TAN Wei2,HUANG Zhong-qian2
2010, 31(10):  81-85.  doi:10.7506/spkx1002-6630-201010016
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To develop an optimal procedure based on ultrasonic pretreatment followed by enzymatic hydrolysis for the extraction of polysaccharides from the fermented mycelia of Phellinus linteus, single factor and orthogonal array design methods were used to deal with the effects of crucial ultrasonic pretreatment and hydrolysis parameters on polysaccharide yield. Results showed that the optimization of ultrasonic pretreatment led to 3.356% polysaccharide yield, in which, the optimal values of ultrasonic power, pretreatment time and material/liquid ratio were determined to be 500 W, 20 min and 1:25 (g/mL), respectively. The optimization of enzymatic hydrolysis leading to 6.619% polysaccharide yield was achieved through the combinatorial use of cellulase at 2.5% dosage, pectinase at 2.5% dosage and neutral proteinase at 1% dosage for the hydrolysis for 120 min at pH 6.5 and 50 ℃. The combination of ultrasonic pretreatment and enzymatic hydrolysis may provide a good idea for the large-scale production of polysaccharides from the fermented mycelia of Phellinus linteus.

Microwave-Ultrasonic Assisted Extraction of Cordycepin from Cultured Mycelia of Cordyceps militaris
WANG Tao,LI Wen,CHEN Hong-wei,CHEN Xiao-long,DIAO Jin-jin
2010, 31(10):  86-90.  doi:10.7506/spkx1002-6630-201010017
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Single factor and orthogonal array design methods were used to investigate an optimal procedure for the extraction of cordycepin from cultured mycelia of Cordyceps militaris with the assistance of microwave combined with ultrasonic. Besides, a UV spectroscopic method was developed for the assay of cordycepin and its figures of merit were evaluated. Results showed that the optimal values of crucial technological parameters affecting cordycepin yield were as follows: ethanol concentration 70%, microwave power 200 W, material/liquid ratio 1:240 (g/mL) and extraction time 110 s. Under such conditions, a cordycepin yield of up to 9.228 mg/g was obtained. The developed analytical method exhibited mean recoveries ranging from 97.41% to 99.60% of 3 replicates for cordycepin in a real sample spiked at 3 levels and both high accuracy and precision so as to provide a convenient and cost saving method for the assay of cordycepin.

Preparation of Chloramphenicol Immunogen and Coating Antigen
LUO Shun-jing,ZHONG Han-yan,LIU Cheng-mei,CHEN Ting-ting,CHEN Fa-rong,YAN Jie-lin
2010, 31(10):  91-94.  doi:10.7506/spkx1002-6630-201010018
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Chloramphenicolsuccinate and keyhole limpet hemocyanin (KLH) were mixed at 3 initial molar ratios, namely 30:1, 20:1 and 10:1, to synthesize chloramphenicol (CAP) immunogens (hapten-KLH conjugates) with coupling ratios of 25:1, 16:1 and 8:1, respectively. Additionally, chloramphenicolsuccinate was mixed with ovalbumin (OVA) at 7 initial molar ratios, namely 40:1, 30:1, 20:1, 10:1, 7:1, 4:1 and 1:1, to synthesize CAP coating antigens (hapten-OVA conjugates) with coupling ratios determined by the UV spectrometric method of 23:1, 20:1, 14:1, 6:1, 3:1, 1:1 and 1:3, respectively. Indirect competitive enzyme linked immunosorbent assay (ic-ELISA) experiments were carried out to choose a CAP coating antigen with an optimal coupling ratio. CAP was determined with the CAP coating antigens to have IC50 values ranging from 15 to 36 ng/mL. As the coupling ratio between chloramphenicolsuccinate and OVA decreased from 26:1 to 3:1, there was a decrease in the IC50 value of CAP. When the coupling ratio was less than 3:1, the IC50 value of CAP exhibited a slight increase. These findings demonstrate that a CAP coating antigen with an optimal coupling ratio should be synthesized for the ic-ELISA assay of IC50 significantly influenced by coupling ratio.

Response Surface Analysis for Optimization of Mechanical Properties of Konjac Glucomannan Film
CHEN Wen-ping1,JIANG Gui-lin1,WANG Chao1,2,*,CHEN Shi-yong1,LU Wen-ping1,JIANG Fa-tang1,2
2010, 31(10):  95-100.  doi:10.7506/spkx1002-6630-201010019
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To achieve optimal mechanical properties of konjac glucomannan (KGM) film prepared by the solution casting method, Plackett-Burman factorial design was used to select the most important ones affecting KGM film tensile strength out of 7 technological parameters and subsequently, the optimal values of selected parameters, namely KGM concentration (X1), stirring time (X2), heating temperature (X3), standing time (X5) and drying temperature (X7), for improved KGM film tensile strength were investigated using response surface analysis based on a 5-variable, 3-level central composite design leading to 46 experiments. Results showed that the above selected parameters all had significant effects on KGM film tensile strength in the decreasing order: X1 > X3 > X2 > X7 > X5 and their optimal values were as follows: KGM concentration 2.19 g/100 mL, heating temperature 60.0 ℃ for 190 min stirring, standing time 156 min and drying temperature 51.1 ℃. The KGM film obtained under such conditions exhibited a smooth regular surface, an optimal tensile strength and good water resistance.

Processing Technology
Response Surface Methodology as an Approach to Optimization of Supercritical CO2 Extraction and Chemical Composition Analysis of Volatile Oil from Flowers of Chrysanthemum morifolium
SHEN Mao-wen,SHAO Liang-liang,HOU Fu-jing,FAN Yan-feng,GUAN Yong-fang,SU Xiu-rong*
2010, 31(10 ):  101-105.  doi:10.7506/spkx1002-6630-201010020
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The optimal conditions (namely extraction pressure, temperature and time) for the supercritical CO2 extraction of volatile oil from the flowers of Chrysanthemum morifolium were investigated using response surface methodology (RSM) based on a 3-variable, 3-level Box-Benhnken experimental design leading to 15 experiments. Meanwhile, the extracted volatile oil was analyzed for chemical composition. Computer generated response surfaces, canonical analysis and contour plot interpretation revealed that the optimal values of extraction pressure, temperature and time were 25 MPa, 74.9 ℃ and 186.3 min, respectively. Under such conditions, the experimental and predicted values of volatile oil yield was 3.464% and 3.51% and the former was 1.28% lower than the latter. Totally 44 compounds were identified by GC analysis in the extracted volatile oil and their total content was determined by the area normalization method to be 72.3%, of which, 20 exhibited a relative content of more than 1%.

Ultrasonic-assisted Extraction and in vitro Antioxidant Activity Evaluation of Polysaccharides from Chaenomeles sinensis (Thouin) Koehne
XU Huai-de,QIN Sheng-hua
2010, 31(10):  106-111.  doi:10.7506/spkx1002-6630-201010021
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The optimal conditions for the ultrasonic-assisted extraction of polysaccharides from Chaenomeles sinensis (Thouin) Koehne fruits were determined by single factor and orthogonal array design methods. Besides, the in vitro antioxidant activity of the extracted polysaccharides was evaluated. Results showed that the optimal values of extraction conditions leading to a maximum polysaccharide yield of 12.072% were as follows: ultrasonic power 600 W, material/liquid ratio 1:45 (g/mL), and extraction temperature 80 ℃ for an extraction duration of 40 min. The fact that Chaenomeles sinensis (Thouin) Koehne fruit polysaccharides exhibited strong scavenging effects against nitrate, DPPH· and hydroxyl free radicals and excellent reducing power, demonstrates good in vitro antioxidant activity of the polysaccharides.

Chemical Synthesis of Dihydro-iso-alpha-acids
LIU Yu-mei1,GAO Zhi-ming2,LUO An-qiong1
2010, 31(10):  112-116.  doi:10.7506/spkx1002-6630-201010022
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Dihydro-iso-alpha-acids are the products of isomerization followed by hydrogenation of alpha-acids as one kind of the main soft resins in flower cone of hops (Humulus lupulus L.) and show a slightly bitter taste and the best solubility among all hydrogenation products of isomerizd alpha-acids. Single factor and orthogonal array design methods were used to deal with the effects of reaction temperature and time and amounts of added NaBH4 and KOH to iso-alpha-acids on dihydro-iso-alpha-acid yield. Results indicated that the above reaction conditions all exhibited an obvious effect on dihydro-iso-alpha-acid yield in the decreasing order: reaction temperature > amount of added KOH > amount of added NaBH4 > reaction time and their optimal values were as follows: a reaction system composed of iso-alpha-acids, KOH and NaBH4 at 1:1:0.25 molar ratio left to react for 2 h at 100 ℃. Two-, 3- and 5- fold scale-up experiments carried out under such conditions all gave over 97% dihydro-iso-α- acids yields.

Extraction and Purification of Polysaccharides from Gynura divaricata (L.) DC.
QIU Xi-min1,JIANG Man-hua1,TAN Min1,LU Yan-yan1,YANG Xiao-hong1,FENG Xing1,LI Li-li2
2010, 31(10):  117-121.  doi:10.7506/spkx1002-6630-201010023
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The extraction yield of Gynura divaricata (L.) DC. polysaccharides affected by extraction temperature, time and times and solid/liquid ratio was optimized by single factor and orthogonal array design methods. In addition, the removals of protein by the Sevag method and of color with hydrogen peroxide or activated carbon from the crude polysaccharide extract obtained were investigated. The anthranone-sulphuric acid method was used for polysaccharide determination. Result showed that a maximum polysaccharide yield was achieved through the optimal twice extraction for 3.5 h each time at 100 ℃ at 1:7 solid/ liquid ratio (g/mL). The optimal solvent for the removal of protein was a mixture of chloroform and n-butanol (4:1, V/V). The addition of 0.15 g/mL activated carbon aqueous suspension for twice treatment for 45 min at 80 ℃ or the addition of 70% (V/V) hydrogen peroxide for 120 min treatment at 60 ℃ gave an optimal removal of color. The procedure proved to be simple, feasible, effective and stable so as to be most suitable for the extraction and purification of polysaccharide from Gynura divaricata (L.) DC..

Effect of Processing Parameters on Gel Properties of Catfish Ham
LIU Hui1,MA Li-zhen2,*,FU Cui-ping1,CHAI Na2,WU Hao-yue2
2010, 31(10):  122-128.  doi:10.7506/spkx1002-6630-201010024
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A procedure mainly comprising bleaching, salting, blending and cooking was designed for the processing of catfish ham. The effects of the above procedure steps on gel properties (springiness, cohesiveness, hardness, and chewiness) of catfish ham were evaluated by one-factor-at-a-time design method. Results showed that the optimal gel properties of catfish ham with 0.86 springiness and 0.66 cohesiveness were obtained by twice bleaching raw fish meat in 5-fold volume of 5 mg/mL NaCl aqueous solution (5-7 ℃), salting at 4 ℃ for 10 h with 21 mg/mL NaCl addition, chopping for 6 min at 6 ℃ kept stable through cooling with ice pieces, casting into a stainless steel mould and cooking at 85 ℃ for 2.5 h.

Pepsin Hydrolysis of Rice Protein Powder
YI Cui-ping1,2,ZHOU Su-mei3,PAN Yan-yan1
2010, 31(10):  129-132.  doi:10.7506/spkx1002-6630-201010025
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Rice protein powder was hydrolyzed with pepsin to improve its functional properties. The effects of pepsin amount, reaction time and temperature and pH on soluble protein concentration in hydrolyzed rice protein powder were studied. Results showed that the optimal hydrolysis reaction for 5 h at pH 1.5, 30 ℃ and an enzyme dosage of 7 U/g (calculated on the basis of dry protein weight) resulted in an optimal improvement in the solubility of rice protein powder and the resulting hydrolysate exhibited 0.456 min emulsifying capacity and 33.28 min emulsion stability, which were both higher than those of soybean protein powder or egg white protein powder, 25.0% and 82.4% higher foaming capacity and foam stability than unhydrolyzed rice protein powder, respectively, and 2.80 g/g water holding capacity and 3.30 g/g oil holding capacity, with 2.09- and 2.92-fold enhancement in comparison with unhydrolyzed rice protein powder, respectively.

Optimization of Extraction and Membrane Separation of Red Pigments from Garcinia mangostana L.
ZHANG Xiao-man,MA Yin-hai*,LI Yong,YAN Sheng-bo
2010, 31(10 ):  133-136.  doi:10.7506/spkx1002-6630-201010026
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A procedure based on acid extraction and membrane ultrafiltration separation was presented for the preparation of red pigments from the fruits of Garcinia mangostana L.. The optimal conditions for red pigment extraction were determined using a 3-factor, 3-level orthogonal array design to be extraction temperature 50 ℃ and material/liquid 1:8 (g/mL) for an extraction duration of 120 min. Microfiltration followed by ultrafiltration under the optimal conditions of transmembrane pressure 0.12 MPa and cross flow velocity 2500 L/h provided optimal purification of the obtained red pigment extract. The Garcinia mangostana L. red pigment product obtained after vacuum distillation and vacuum drying exhibited a color value of 22.15, which was 3.5 times higher than before purification.

Microencapsulation of Chlorogenic Acid in Yeast Cells
LU Qi,CAO Shao-qian,LU Si-yi,ZHOU Ying,GAO Li,PAN Si-yi*
2010, 31(10):  137-141.  doi:10.7506/spkx1002-6630-201010027
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Brewer's yeast (Saccharomyces cerevisiae) cells subjected to a 24 h plasmolysis treatment were used to encapsulate chlorogenic acid, a water-soluble antioxidant. The optimal encapsulation for 6 h at 40 ℃ and 3:1 core material/wall material ratio (g/g) in 6 mL of distilled water as encapsulation medium determined using orthogonal array design resulted in a maximum encapsulation efficiency of 18.9%. Infrared spectral analysis indicated the disappearance of characteristic function groups of chlorogenic acid. Fluorescence microscopic studies revealed that the microcapsules were spherical in shape and that the spontaneous fluorescence of chlorogenic acid was observed on the inner side of yeast cell wall. The similar retention time and UV-Vis profiles between unmicroencapsulated and microencapsulated chlorogenic acid were found through HPLC analysis. All these results suggested that chlorogenic acid was successfully encapsulated and no significant chemical changes occurred during the encapsulation process.

Processing Technology
Optimization of Supercritical CO2 Extraction and Analysis of Chemical Composition of Peony Seed Oil
DENG Rui-xue,LIU Zhen,QIN Lin-lin,WANG Li,LIU Xue-qin,LIU Pu*
2010, 31(10):  142-145.  doi:10.7506/spkx1002-6630-201010028
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Single factor and orthogonal array design method were used to optimize the extraction of peony seed oil using supercritical carbon dioxide (SC-CO2) with respect to the effects of extraction pressure and temperature, length of extraction. Along with this, the chemical composition of the extracted peony seed oil was analyzed by GC-MS. The results showed that the optimized SC-CO2 extraction for 2.5 h at 40 ℃, 30 MPa and a CO2 flow rate of 25 kg/h resulted in a maximum oil yield of 30.7%. The total content of unsaturated fatty acids of the extracted peony seed oil was 70.81%.

Ultrasonic Cell Disruption Followed by Isoelectric Point Precipitation for Extraction of Phycobiliprotein from Spirulina platensis
ZHU Jie1,DONG Wen-jie1,LIU Jia2
2010, 31(10):  146-150.  doi:10.7506/spkx1002-6630-201010029
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A procedure based on ultrasonic cell disruption followed by isoelectric point precipitation was considered for the extraction of phycobiliprotein from Spirulina platensis powder. The respective optimal conditions for ultrasonic cell disruption and isoelectric point precipitation were determined. Results showed that an optimal ultrasonic cell disruption was obtained through 630 W ultrasonic treatment for 20 min of 5% aqueous suspension of Spirulina platensis powder. The optimal medium was glacial acetic acid for the isoelectric point precipitation of phycobiliprotein, which was a simple and convenient operation o obtain phycobiliprotein at pH 4.0 and 4 ℃. Glacial acetic acid is easy to volatilize so that the extraction procedure is simplified. Finally, lyophilization was performed to obtain a crude protein powder. The content of phycocyanin was as high as 4.36% in the supernatant separated from ultrasonic treated 5% aqueous suspension of Spirulina platensis powder under optimized conditions, and the yield of crude protein powder from Spirulina platensis powder was 52.5%, in which, the contents of phycocyanin, allophycocyanin and phycoerythrin were 7.7%, 7.9% and 0.8%, respectively.

Optimization of Bi-enzymatic Hydrolysis of Duck Plasma Proteins for Production of Small Peptides
LIU Cheng-mei1,2,WU Bei1,ZHONG Ye-jun1,2,LIU Wei1,YANG Shui-bing1,YIN Man1
2010, 31(10 ):  151-154.  doi:10.7506/spkx1002-6630-201010030
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Response surface analysis based on a 3-variable, 5-level quadratic orthogonal rotation combination design was employed to investigate the optimal conditions for the bi-enzymatic hydrolysis with Neutrase and Flavourzyme of duck plasma proteins for the production of small peptides. In the optimization, a mathematical model describing the degree of hydrolysis of duck plasma proteins as a function of pH and hydrolysis temperature and time was established. Variance and confidence analyses demonstrated satisfactory fitting degree of the model (Root MSE = 0.488768). The optimal values of pH and hydrolysis temperature and time were determined through data analysis using SAS software to be 7.1, 50.5 ℃ and 4.8 h. The small peptides obtained under such conditions had no unpleasant smell and exhibited a slight taste, 798.5 nm average particle size, 0.82634 m2/g s specific surface area, - 8.63 mV Zeta potential, 0.4388 g/g water absorption ability and 8.323 mL/g oil adsorption ability.

Optimization of Enymolysis Conditions for Preparation of Pleurotus eryngii Protoplasts
LI Yan-li1,JIN Zhou-yu1,LI Yu2,*
2010, 31(10):  155-158.  doi:10.7506/spkx1002-6630-201010031
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The optimal conditions for the lywallzyme hydrolysis of the cultured mycelia of Pleurotus eryngii for protoplast production were investigated by single factor and orthogonal array design methods. Results showed that the optimal values of hydrolysis conditions were as follows: substrate concentration 133 mg/mL, enzyme dosage 1.0% and pH 6.0 for a hydrolysis duration of 2.5 h at 30 ℃. The hydrolysate obtained under such conditions exhibited a protoplast density of up to 6.34 × 107 cells/mL.

Use of Artificial Neural Networks for the Optimization of Preparation of Egg-white Hydrolysate with Antithrombin Activity in an Enzymatic Membrane Bioreactor
YANG Wan-gen1,2,CHENG Yun-hui3,WANG Zhang2
2010, 31(10):  159-162.  doi:10.7506/spkx1002-6630-201010032
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An enzymatic membrane reactor designed based on the combination of membrane filtration and Protease N Amanocatalyzed hydrolysis was used to prepare egg-white hydrolysate (EWH) with antithrombin activity. A L18(37×21) mixed-level orthogonal array design was used to investigate the effects of substrate concentration, enzyme dosage, pH, temperature, filtration flow rate and length of hydrolysis on the antithrombin activity of EWH. This was followed by the stimulation and predication of EW hydrolysis using back propagation (BP) neural networks to obtain the optimal values of the above parameters. The results showed that the predicted value of IC50 of EWH obtained under the following optimized conditions: substrate concentration 1%, enzyme dosage 1%, filtration flow rate 10 mL/min, and length of hydrolysis 4 h was 10.43 mg/mL, 4.03% lower then the actual value. This demonstrates good reliability of BP neural networks in optimizing egg white protein hydrolysis.

Optimization of Adsorption Capacity of Anionic Starch Microspheres Using Response Surface Methodology
XUE Bo1,LI Xin-hua1,*,ZHU Min-peng2
2010, 31(10):  163-167.  doi:10.7506/spkx1002-6630-201010033
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Response surface methodology (RSM) was used to optimize the adsorption capacity of anionic starch microspheres to arginine used as a drug model. A series of single-factor experiments was carried out to investigate the respective effects of 4 independent variables, including sodium tripolyphosphate amount, reaction temperature, length of soaking time and length of reaction time. Subsequently, a mathematical mode for the adsorption capacity as a function of the above variables was established based on a 4-variable, 5-level central composite design (CCD). Finally, the interactive effects of the independent variables on the adsorption capacity were examined using response surface analysis. The results showed that the optimal values of sodium tripolyphosphate amount, reaction temperature, length of soaking time and length of reaction time were determined to be 0.82 g, 80.52 ℃, 12 h and 1 h, respectively. Under the optimized parameters, the adsorption capacity was predicted to be 3.341 mg/g and observed to be 3.308 mg/g, 0.033 mg/g higher than the predicted value, with an increase by 95.16% than before the optimization.

Extraction and Antioxidant Activity of Polysaccharides from Acanthopanacis senticosi Leaves
MENG Fan-lei,CHEN Rui-zhan*,ZHANG Min,CHEN Rui-ping
2010, 31(10):  168-174.  doi:10.7506/spkx1002-6630-201010034
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The optimal procedure for the ultrasonic-assisted solvent extraction of Acanthopanacis senticosi polysaccharides (ASP) was investigated using orthogonal array design. The effects of different geographic origins and different harvesting times on polysaccharide content and antioxidant activity of crude ASPs from the leaves of Acanthopanacis senticosi were addressed. The phenol-sulfuric acid method was used for polysaccharide determination and the antioxidant activity of the ASP extract was tested by FRAP assay, pyrogallol autoxidation method and DPPH radical scavenging assay. The optimum conditions for the ultrasonic-assisted solvent extraction of ASP were found to be: extraction temperature 70 ℃ and ultrasonic power 500 W for 3- time extraction for 90 min each time. The polysaccharide contents of crude ASPs from different geographic origins were obviously different and decreased in the following order: Ershenchang > Dahu > Xinglong. With the harvesting time prolonged from June to August, crude ASPs from the same geographic origin exhibited an increasing trend in polysaccharide content; beyond September, an opposite pattern was observed. Antioxidant activity testing revealed that a total of 12 samples of crude ASPs from 3 geographic origins harvested during June-September, respectively were all strong antioxidants. The strongest antioxidant was the ASP extract from Ershenchang harvested in August.

Extraction of Low-methoxyl Pectin from Watermelon Peel Pretreated with Compound Phosphate
YE Hua,CAO Ling-ling
2010, 31(10):  175-178.  doi:10.7506/spkx1002-6630-201010035
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This paper reports the orthogonal array optimization of the extraction of low-methoxyl pectin (LMP) from watermelon peel pretreated with compound phosphates. The optimum procedure for LMP extraction were determined to be based on material pretreatment with compound phosphates consisting of sodium phosphate, disodium hydrogen phosphate, sodium pyrophosphate and sodium hexametaphosphate added at 2%, 0.9%, 0.3% and 0.6%, respectively and subsequent deesterification for 0.5 h at pH 10 at 15 ℃. Under the optimized conditions, the yield of LMP was 5.07% and the methoxyl content was 4.49% in the obtained LMP.

Ultrasonic-assisted Extraction of Phytic Acid from Peanut Meal
YU An,WANG Cheng-ming*
2010, 31(10):  179-183.  doi:10.7506/spkx1002-6630-201010036
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To optimize the ultrasonic-assisted extraction of phytic acid from peanut meal, response surface method (RSM) was used to investigate the interactive effects of length of ultrasonic treatment, ultrasonic powder, temperature, material/liquid ratio and concentration of hydrochloric acid on phytic acid yield. The optimum conditions for the ultrasonic-assisted extraction of phytic acid were determined as follows: using 11-fold volume (mL/g) of 0.01mol/L hydrochloric acid to extract the material with the assistance of the ultrasonic treatment for 24 min at 72 W. Under such conditions, the observed value of phytic acid yield was 1.48%, in basic agreement with the predicted value, 1.44%.

Analysis & Detection
Analysis of Taste-active Components of Autolysate of Penaeus vannamei Shrimp Head
WU Bin1,ZHANG Chao-hua1,2,*,JI Hong-wu1,2,XIE Wan-cui1,FENG Xiao-min1,FU Guang-zhong1
2010, 31(10):  184-187.  doi:10.7506/spkx1002-6630-201010037
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The shrimp heads of Penaeus vannamei were homogenize mechanically and automatically hydrolyzed by endogenous enzymes in them and the main taste-active components in the autolysate were quantified using high performance liquid chromatography, automatic amino acid analyzer or atomic absorption spectrometry. Rich free amino acids (up to 9300 mg/L) were found in the autolysate, and aspartic acid, glutamic acid, glycine and alanine, which are main amino acids responsible for umami flavor, accounted for 22.9% of the total free amino acids. The content of inosine monophosphate (IMP) greatly contributing to umami flavor was 6.12 mg/L. The contents of Na+, K+ and Cl- were 663.7, 182.1 and 417.2 mg/L, respectively. Moreover, the contents of betaine, lactic acid and succinic acid were 2400, 15.27 and 13.32 mg/L, respectively. All these components quantified contributed to umami taste, sweetness and overall taste of the autolysate.

HPLC Determination of o-Tyrosine in Irradiated Chicken Products
LIN Lin1,ZHANG Ke2,QIAN He3,*
2010, 31(10):  188-191.  doi:10.7506/spkx1002-6630-201010038
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A method using HPLC with fluorescence detection was developed for the determination of o-tyrosine in irradiated chicken products. Samples were hydrolyzed with 6 mmol/L HCl at 105 ℃ for 4 h in a vacuum environment and cleaned up on a C18 solid-phase extraction column. Three-time elution of the column with 5% actonitrile in water was carried out for the desorption of o-tyrosine. The excitation and emission wavelengths for fluorescence detection were set at 275 nm and 305 nm, respectively. The method exhibited a limit of detection of 0.1 mg/kg. The average spike recovery (6 replicates) for o-tyrosine at 1.0 mg/kg was 97.3%. Over the range of 10 to 100 kGy, irradiation dose displayed good linearity with o-tyrosine content of irritated chicken meat.

Comparison of Fatty Acid Composition among Muscles and Visceral Organs of Trachinotus ovatus
ZHANG Shao-ning,XU Ji-lin*,HOU Yun-dan,XU Shan-liang,MIAO Miao,YAN Xiao-jun
2010, 31(10):  192-195.  doi:10.7506/spkx1002-6630-201010039
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White muscle, red muscle, liver and spleen of male and female Trachinotus ovatus were analyzed for their fatty acid composition by gas chromatography mass spectrometer (GC-MS). A total of 23 fatty acids were identified. No significant differences were found in total lipid content or fatty acid composition of the same tissues between male and female fish. Among 4 tissues, the highest and lowest total lipid contents were found in liver and white muscle, respectively. Trachinotus ovatus spleen and white muscle were rich in polyunsaturated fatty acids (PUFA) and exhibited a high nutritional value. The contents of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) were higher in liver with the lowest PUFA content than in other 3 tissues. Therefore, liver is an important energy storage organ in Trachinotus ovatus.

Rapid HPLC Determination of Melamine in Beef and Mutton
LI Qiao-ling1,AN Yuan2,ZHANG Yan-chuan1,YANG Jin1
2010, 31(10):  196-199.  doi:10.7506/spkx1002-6630-201010040
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A rapid HPLC method was developed for the determination of melamine in beef and mutton. Samples were extracted with a mixture of trichloroacetic acid and acetonitrile mixture (3:1,V/V) and cleaned up on a cation exchange solid-phase extraction (SPE) column. The eluate was blown to dryness under nitrogen at 50 ℃ and then dissolved in a mixture of ion-pair buffer and acetonitrle (90:10, V/V). The analysis was carried out using HPLC with UV detector. A good linear relationship was observed for melamine within the range of 0.2-80 μg/mL and the linear correlation coefficient (R2) was 0.9999. The limit of detection was 0.05 mg/kg. For beef, average spike recoveries (6 replicates) at 3 levels ranged from 81.73% to 83.35%, with a relative standard deviation (RSD) from 0.97% to 1.95%. For mutton, average spike recoveries (6 replicates) at 3 levels ranged from 80.95% to 82.95%, with a RSD from 0.70% to 2.32%. The method proved to be rapid, accurate and reliable.

Detection of Polioviruses in Foodstuffs by Real-time RT-PCR Based on Taqman-MGB Probe
LI Xiang1,HUANG Yi1,2,PAN Liang-wen1,*,LU Zhong-shan1,ZHANG Shu-ya1, LU Rong1,LIU Yue-ming1,GAO Qin1
2010, 31(10):  200-205.  doi:10.7506/spkx1002-6630-201010041
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This study was aimed to develop three sero-specific real-time RT-PCR detection systems based on Taqman-MGB probes for the assay of polioviruses in foodstuffs. Primer and Taqman-MGB probe sets based on the 2A region of poliovirus genome were designed to detect three serotypes of polioviruses separately and simultaneously. Four artificially inoculated food samples, including oyster, blueberry, lettuce and water were analyzed based on the established standard curves using three reference molecules as calibrators. Sensitivity tests suggested that at least 2 copies of the reference molecule DNA could be stably detected both in the separate and simultaneous detection systems. Good linearity with the correlation coefficient above 0.999 and high reaction efficiency (1.01 - 1.04) were observed in four standard curves employing serially diluted reference molecule DNA as the calibrator. Three serotypes of polioviruses in four inoculated samples were successfully detected using the established real-time RT-PCR detection systems. The developed real-time RT-PCR detection systems based on Taqman-MGB probes are most suitable for polioviruses detection in foodstuffs.

HPLC Determination of Coenzyme Q10 in Queen Bee Larvae
YUE Bing1,XUE Xiao-feng1,2,WU Li-ming1,LI Yi1,ZHAO Jing1,*
2010, 31(10):  206-208.  doi:10.7506/spkx1002-6630-201010042
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A high performance liquid chromatographic (HPLC) method was established to determine coenzyme Q10 in queen bee larvae. Samples were ground and extracted with absolute ethanol under the assistance of ultrasonic and the resulting extract was then reextracted with n-hexane. The n-hexane layer was finally condensed by rotation evaporation and rediluted with absolute ethanol. The chromatographic separation was achieved on an XBridge shield RP18 column using methanol as a mobile phase prior to UV detection at 275 nm wavelength. Results showed that a good separation of coenzyme Q10 was observed within 12 min. The developed standard curve exhibited good linearity. Average recoveries for coenzyme Q10 in a real sample spiked at 3 levels, each of which was performed in 6 replicates, were within the range of 95.0% to 101.8%, with a RSD of less than 8%. The limit of detection for coenzyme Q10 was 0.23 mg/L. The analytical method proved to be simple, accurate, reliable and sensitive so as to be most suitable for the determination of coenzyme Q10 in queen bee larvae. Satisfying results from the analysis of coenzyme Q10 in some real samples by the method were obtained.

HPLC Determination of Trigonelline in Pumpkin Pulp
XU Ya-qin1,WANG Chong1,CUI Chong-shi2
2010, 31(10):  209-211.  doi:10.7506/spkx1002-6630-201010043
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A method for the determination of trigonelline in pumpkin flesh was established using high performance liquid chromatography (HPLC). Samples were defatted in a Soxhlet extractor with absolute ethyl ether as solvent and extracted with 70% aqueous ethanol with microwave assistance. An Agilent Zorbax SB-C18 column kept at ambient temperature was used for the chromatographic separation with 0.40 mmol/L aqueous solution of phosphoric acid (pH 3.2) as a mobile phase at a flow rate of 0.6 mL/min. The injection volume was 10 μL. The detection wavelength was set at 265 nm. Results showed that the developed standard curve of trigonelline exhibited good linearity over the concentration of 5.6 to 134.4 μg/mL, with a correlation coefficient of 0.9999 (n = 5). The average recovery for trigonelline in a total of 6 real samples spiked at 3 levels repeated twice each in 5 replicates was 97.09%, with a relative standard deviation of 1.02%. This method proved to be simple, accurate and of good repeatability so as to be most suitable for the determination of trigonelline in pumpkin pulp. Thirteen cultivars of pumpkin pulp were determined by the method to have very different trigonelline contents ranging between 172.5μg/g and 475.5 μg/g.

Evaluation of Measurement Uncertainty in the Enumeration of Staphylococcus aureus in Aquatic Products
WANG Li-bao,LING Yun,LIU Lu-ye,SHEN Hui,WAN Xi-he
2010, 31(10):  212-215.  doi:10.7506/spkx1002-6630-201010044
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To make an evaluation on measurement uncertainty in the enumeration of Staphylococcus aureus in aquatic products, the sources of measurement uncertainty were analyzed, each uncertainty component was modeled and an integrated uncertainty model as a function of all components was established and expanded. The expanded uncertainty was calculated to be 0.1. The evaluation is a good fit for each aquatic product sample.

Use of An Acid Meter for the Rapid Determination of β-Lactamase Residue in Milk
LIU Shan-shan1,ZHOU Zheng2,ZHOU Wei2,ZHANG Zi-de1,MA Jun-lian1,*
2010, 31(10):  216-218.  doi:10.7506/spkx1002-6630-201010045
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The principle that β-lactamase selectively decomposes β-lactam antibiotics like penicillin into acids leading to pH decline was considered to present a rapid and accurate method for the determination of β-lactamase residue in milk. β- Lactamase at a constant final concentration of 100 U/mL and penicillin were artificially added to antibiotic free milk and left to react for a certain period of time at an appropriate temperature. The optimal penicillin final concentration and reaction time and temperature were determined to be 10 mg/mL, 60 min and 33 ℃, respectively. The developed method exhibited a limit of detection of 8.92 U/mL.

Gas Chromatographic Determination of Dicofol Residue in Vegetables and Fruits
ZHOU Yan-ming,XIN Xue,HU Rui
2010, 31(10):  219-222.  doi:10.7506/spkx1002-6630-201010046
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A method using gas chromatography (GC) was established for the determination of dicofol residue in vegetables and fruits. Samples were extracted with a mixture of acetone and n-hexane. The resulting extract was then cleaned up on a Florisil column and treated with a mixture of absolute ethanol and aqueous potassium hydroxide solution. The n-hexane (upper layer) was harvested and washed with 20 g/L aqueous sodium sulfate solution twice prior to the injection into a GC system equipped with an electron capture detector. The external standard method was adopted for dicofol quantification. The figures of merit of the developed method such as sensitivity, accuracy and precision were evaluated. The limit of detection for dicofol was 0.005 mg/kg. Average recoveries for dicofol in 10 species of real samples separately spiked at 3 levels in 10 replicates each were ranged from 70.23% to 98.10%, with a RSD range between 3.21% and 10.12%. This method may satisfy the requirements of the national standards for pesticide residue determination.

Headspace Solid-phase Micro-extraction Coupled with Gas Chromatography-Mass Spectrometric Determination of Carbamate Pesticide Residues in Apples
SUN Fu-jiang1,LI Run-yan2,YUAN Xian-rui3,*,LI Hui2,WU Chun-min2,CHEN Fang4
2010, 31(10):  223-227.  doi:10.7506/spkx1002-6630-201010047
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A method was developed for the determination of MTMC, MIPC, BPMC, IPMC, furadan, pirimicarb and carbaryl carbamate residues in apples using headspace solid-phase micro-extraction (HS-SPME) coupled with gas chromatography-mass spectrometry. The respective optimal conditions for HS-SPME and GC-MS analysis were determined. All 7 analytes exhibited good linearity over a wide concentration range, with a correlation coefficient ranging between 0.996 and 0.999. The relative standard deviations of precision for 5 replicates were between 3.6% and 8.2%. The limits of detection of the method for a total of 7 analytes were between 0.00016 mg/kg and 0.0019 mg/kg. The method proved to have the advantages of rapidity, sensitivity, accuracy and less reagent consumption and meet the requirements for the determination of carbamate pesticide residues in vegetables and fruits duo to good figures of merit.

Analysis of Chemical Composition of Leaf Volatile Oils from Two Species of Ligularia Genus from Changbai Mountain
DONG Ran1,NAN Min-lun2,LIU Hong-zhang1,*
2010, 31(10):  228-230.  doi:10.7506/spkx1002-6630-201010048
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The leaves of Ligularia fischeri Turcz. and L. fischeri Turcz.f.diabolica Kitam, belonging to the Ligularia family, were used as plant materials to obtain 2 volatile oils by steam distillation method. The chemical composition of both oils was analyzed by GC-MS and the area normalization method was used for compound quantification. Results showed that 11 chromatographic peaks separated well were found in the respective GC total ion current chromatograms of both oils. Added together, 13 compounds were identified for the first time in both oils. Nine compounds accounting for 72.72% of the total volatile oil from Ligularia fischeri Turcz. leaves were identified, in which, α-farnesene, caryophyllene, A-farnesene and 3,7- dimethyl-6-octen-1-ol formate were the predominant compounds and the total content of the former 3, sesquiterenes, was 60.23%. Seven compounds were identified and accounted for 67.52% of the total volatile oil from Ligularia fischeri Turcz.f. diabolica Kitam leaves, in which, 3,7,11-trimethyl-2,6,10-dodecatrien-1-ol, phytol, caryophyllene and caryophyllene oxide were the predominant compounds and the latter 2, also belonging to the sesquiterene family exhibited a total content of 20.07%.

Analysis of Total Lipid Content, Fatty Acid Composition, Total Protein Content and Amino Acid Composition of Winged Bean (Psophocarpus tetragonolobus [L.] D.c.) Seeds
JIANG Li-wen1,ZHENG Bing-fu1,LI Bai-yu1,CHEN Dong-ming2
2010, 31(10 ):  231-234.  doi:10.7506/spkx1002-6630-201010049
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Four cultivars of winged bean seeds were analyzed for total lipid content and fatty acid composition by Soxhlet extraction coupled with gas chromatography, total protein content by the Kjeldahl method and amino acid composition on a Hitachi model L-8800 automated amino acid analyzer. Results showed that the total lipid contents of 4 cultivars of winged bean seeds varied from 20% to 22% and 28 fatty acids were identified in each winged bean oil, in which, oleic acid accounted for 90.7% of the total monounsaturated fatty acids (MUFA), the predominant polyunsaturated fatty acids consisted of linoleic acid, α-linolenic acid and EPA and the average content of saturated fatty acids was 25.76%. The total protein contents of 4 cultivars of winged bean seeds were approximately 38%. Four cultivars of winged bean seeds were all rich in essential amino acids.

Analysis of Polyphenol Composition of Different Parts of an Ear of Sweet Corn
CHEN Zhi-yi1,XU Yu-juan1,YIN Yan1, LIU Xue-ming1, LI Xiao-qin2
2010, 31(10):  235-238.  doi:10.7506/spkx1002-6630-201010050
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A HPLC method was developed for the analysis of polyphenol composition of different parts of an ear of sweet corn including kernels, cob, silk and leafy husk. The chromatographic separation was performed on an Agilent ZORBAX SB-C18 column (4.6 × 250 mm, 5μm) with a binary mobile phase composed of a mixture of 0.4% aqueous solution (phase A) of acetic acid and acetonitrile (phase B) leading to the following gradients: 0-40 min, phase A 5% + phase B 95%; 40-45 min, phase A 25% + phase B 75%; and 45-50 min followed by 5 min running, phase A 35% + phase B 65% at a flow rate of 1.0 mL/min. Column temperature was set at 30 ℃. The VWD detection was performed at a wavelength of 280 nm. Added together, 13 phenolic compounds were identified in sweet corn kernels, cob, silk and leafy husk, including gentisic acid, rutin, quercetin, picatechin, vanillic acid, benzoic acid, syringic acid, catechin, hyperoside, gallic acid, caffeic acid and ferulic acid, of which, 12 were identified in sweet cob or leafy husk and 8 in sweet silk.

Analysis & Detection
Headspace Solid-phase Microextraction Followed by GC-MS Analysis of Volatile Flavor Composition of Hami Melon
JIA Kai1,HU Xiao-song1,LIAO Xiao-jun1,ZHANG Ming-wei2,CHEN Fang1,WU Ji-hong1,*
2010, 31(10):  239-243.  doi:10.7506/spkx1002-6630-201010051
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The optimal conditions (namely NaCl amount and extraction temperature and time) for the headspace solid-phase microextraction (HS-SPME) of volatile flavor components from Jiashi muskmelon, one cultivar of Hami melon were investigated by single factor and orthogonal array design methods. The optimized HS-SPME was coupled with GC-MS to develop a method for the analysis of volatile flavor composition of Jiashi muskmelon. Results showed that the use of a PDMS/DVB/CAR fiber for the 40 min extraction at 40 ℃ of Jiashi muskmelon with NaCl added as electrolyte at 2.4 g/mL gave an optimal extraction of volatile flavor components from Jiashi muskmelon. The developed analytical method exhibited spike recoveries for ethyl 2-methylbutyrate, octanal, hexyl acetate and n-butyl acetate varying from 86.8% to 97.6%, a liner range from 8.24 to 217 ng/mL and a minimum detectable quantity of 7.21 ng/mL and demonstrated high sensitivity and reliability. Forty-two compounds were identified in Jiashi muskmelon, in which, the predominant compounds were ehyl aetate, n-popyl acetate, popanoic acid, 2-methyl-, ethyl ester, btan oic acid, ethyl ester, btanoic acid, 2-methyl-,ethyl ester, hxanoic acid, ethyl ester, aetic acid, hexyl ester and nonanal.

HPLC-MS Determination of Bromate and Perchlorate in Drinking Water
WANG Jun,HU Mei,ZHANG Hui,ZHANG Xi-qi,ZHU Jian-hua
2010, 31(10):  244-246.  doi:10.7506/spkx1002-6630-201010052
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A method for the determination of bromate and perchlorate in drinking water was established by high performance liquid chromatography coupled to electrospray ionization quadrupole mass spectrometry (HPLC/ESI-MS). The chromatographic separation column used was a Waters XterraTM C18 column, and the binary mobile phase used consisted of acetonitrile as mobile phase A and 1.5 mmol/L aqueous solution of tetrabutyl ammonium hydroxide solution as mobile phase B. Both analytes were detected in the selected ion monitoring (SIM) mode. The developed calibration curve showed good linearity over the concentration range from 1 to 200 ng/mL. The detection limit was 1 ng/mL for both bromate and perchlorate.

Determination of Total Selenium in the Fruit Body of Agaricus blazei by Hydride Generation Atomic Fluorescence Spectrometry
XIAO Hui1,WU Xiang-yang2,*,YANG Liu-qing3,ZHANG Min2,YAN Shu3,ZOU Ye2,LI Fang1
2010, 31(10):  247-249.  doi:10.7506/spkx1002-6630-201010053
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Hydride generation atomic fluorescence spectrometry was used to develop a rapid and simple method for the determination of total selenium in the fruit body of Agaricus blazei. Either wet digestion or high-pressure microwave assisted digestion was used for sample preparation before hydride generation atomic fluorescence spectrometric analysis. A 1000 μm/mL selenium standard solution was used to examine the effects of the concentration of hydrochloric acid as current carrier, sodium borohydride concentration and the concentration of hydrochloric acid as medium acid on fluorescence intensity. The method exhibited a linear range between 1.0 and 10.0 ng/mL, a limit of detection of 0.002 ng/mL, precision RSDs for 10 replicates ranging between 1.32% and 4.11% and spike recoveries (5 replicates) ranging between 92.89% and 106.49%. The method is simple and accurate, thereby providing a good method for the determination of selenium in the fruit body of Agaricus blazei.

Simultaneous Extraction and Determination of Chromium (Ⅲ) and Chromium (Ⅵ) in Milk
LI Jing,WANG Yu,CHEN Hua-bao,LIANG Li-na*
2010, 31(10):  250-253.  doi:10.7506/spkx1002-6630-201010054
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A method was developed for the simultaneous extraction and determination of chromium (Ⅲ) and chromium (Ⅵ) in milk. One pretreatment process was required for chromium (Ⅵ) extraction, the release of chromium (Ⅲ) from organic chromium, chromium (Ⅲ) pre-column derivatization and milk protein sedimentation, which exhibited simplicity, convenience and high extraction efficiency of chromium. The separation of chromium (Ⅲ) and chromium (Ⅵ) was achieved on an IonPac CS5A column within 8 min. Chromium (Ⅲ) and chromium (Ⅵ) were chleated with PDCA and DPC and were detected with a UV-Vis detector at UV and visible wavelengths, respectively. This work provides an accurate and practical method for milk quality evaluation.

HPLC Determination of Versicolorin A in Aspergillus parasiticus Contaminated Rice
TAN Hui-yong,FANG Ming-ying,WANG Heng-xin,YAO Dong-sheng,LIU Da-ling*
2010, 31(10):  254-258.  doi:10.7506/spkx1002-6630-201010055
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A HPLC method was established for the determination of versicolorin A (VA) in Aspergillus parasiticus contaminated rice using the VA prepared in our laboratory as a reference standard, which was prepared from the fermented mycelia of Aspergillus parasiticus ATCC 36537 through organic solvent extraction followed by semi-preparative HPLC purification. Samples (like rice artificially contaminated with Aspergillus parasiticus GIM 3395 in this study) were extracted with acetone, cleaned up on a silica column and analyzed using a HPLC system equipped with a UV detector at 288 nm wavelength. Results showed that the standard curve of VA exhibited good linearity over the concentration range of 100 to 1250 ng/mL with more than 0.999 correlation coefficient. Average recoveries of 3 replicates of VA in a blank rice sample spiked at 3 levels were between 84.12% and 105.12% with an average relative standard deviation of less than 7.5%. The limit of detection was 50 ng/mL. This method proved to be sensitive, stable and economical and thus is most suitable for the quantification of VA in cereal grains.

Dual-wavelength Ratio Spectrometric Determination of Carmine, Sunset Yellow and Tartrazine in Beverages
DU Jian-zhong1,LI Qing-mei1,ZHU Yi-qiang1,DING Ding2,3,TAN Yong-hui1
2010, 31(10):  259-262.  doi:10.7506/spkx1002-6630-201010056
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A dual-wavelength ratio spectrometric method was presented for the determination of carmine, sunset yellow and tartrazine in fruit-flavored carbonated beverages. According to the spectral characteristics of the pigments, the wavelengths were chosen to be 431 nm and 456 nm for tartrazine detection and 509 nm and 525nm for carmine detection under the disturbance of sunset yellow and 514 nm and 535 nm for sunset yellow detection under the disturbance of carmine. Results showed that the developed standard curves for determining carmine, sunset yellow and tartrazine all exhibited good linearity over the concentration ranges of 0.2 to 80, 0.8 to 90 mg/L and 0.1 to 60 mg/L, respectively. The mean recoveries of 5 replicates of carmine, sunset yellow and tartrazine in orange-flavored Miranda soft drink were 100.5%, 101.1% and 102.4% respectively. This method proved to be simple and convenient and thus deserves to be popularized.

RP-HPLC Analysis of Phenolic Acids in Different Varieties of Cereal Bran
HAO Jie,ZHANG Chang-hong,CAO Xue-li*
2010, 31(10):  263-267.  doi:10.7506/spkx1002-6630-201010057
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Eight phenolic acids (PAs) in different varieties of cereal bran including 3 wheat cultivars, 2 corn cultivars, 1 oat cultivar and 1 buckwheat cultivar were determined by the developed RP-HPLC method. Meanwhile, the differences in the contents of each PA and total PAs among the cereal bran materials were statistically analyzed. Results showed that the total PA contents in different varieties of cereal bran decreased in the following order: corn > wheat > buckwheat > oat. Bound PAs were the predominant PAs in the 4 varieties of cereal bran, of which, cinnamic acid exhibited a much higher content than benzoic acid. Of free and soluble covalent PAs, 4-hydroxybenzoic and vanilla acids both exhibited a higher content. Of bound PAs, the highest content of ferulic acid was observed in all the varieties of cereal bran and reached up to 6527.86 μg/g corn bran.

GC Determination of Chlorfenapyr Residue in Cucumbers and Apples
WU Di,LUO Xue-ting,PAN Hong-ji,NIE Xiang-yun,FAN Li-jia
2010, 31(10):  268-271.  doi:10.7506/spkx1002-6630-201010058
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A gas chromatographic (GC) method was established for the determination of chlorfenapyr residue in cucumbers and apples. The target analyte was extracted from samples with acetonitrile, cleaned up on a Frilisil column, and determined by GC with electron capture detector. The average recoveries of 5 replicates of chlorfenapyr at the spike levels of 0.005, 0.01 and 0.5 μg/g were 115.6%, 86.4% and 82.8% in cucumbers, with the relative standard deviations (RSDs) of 2.6%, 7.6% and 9.2% and 109.2%, 95.9% and 94.6% in apples, with the RSDs of 8.0%, 4.2% and 7.6%, respectively. Field tests gave the equations describing the degradation dynamics of chlorfenapyr residue in cucumbers and apples of y = 0.043e-0.1665x and y = 0.115e-0.0734x, with the half lives of 4.2 d and 9.4 d, respectively. The method has the advantages of high sensitivity, accuracy and precision, thereby providing a good approach for the monitoring of chlorfenapyr residue in vegetables and fruits.

Ion Chromatographic Determination of Nitrate and Nitrite in Soybean Milk Powder
LU Dai-zhu
2010, 31(10):  272-274.  doi:10.7506/spkx1002-6630-201010059
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An analytical method using ion chromatography was developed for the determination of nitrate and nitrite in soybean milk powder. Samples were extracted with deionized water and cleaned up using solid phase extraction prior to ion chromatographic analysis. The linear ranges for nitrate and nitrite were 1-50 mg/L and 1-25 mg/L, respectively. The average recovery ranges for nitrate and nitrite in 3 commercial brands of soybean milk powder were 89.3% - 98.9% and 89.6% - 102.0%, respectively. The method with the limits of detection of 0.16 mg/kg for nitrate and 0.11 mg/kg for nitrite proved to have the benefits of simplicity, high sensitivity and accuracy and good reproducibility.

HPLC Determination of Nicarbazin Residue in Chicken Tissues
XIE Shou-xin1,LIN Hai-dan2,YAO Yang-xun2,SHAO Lin-zhi2,WU Ying-xuan2
2010, 31(10):  275-278.  doi:10.7506/spkx1002-6630-201010060
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A high performance liquid chromatographic (HPLC) assay with UV detection of 4,4'- dinitrocarbanilide (DNC), the marker residue for nicarbazin, was developed for the determination of nicarbazin residue in chicken tissues. Samples were extracted with a 50% aqueous potassium hydroxide solution containing acetonitrile, and the resulting extract was then treated with n-hexane for the removal of lipids prior to HPLC analysis using a mobile phase composed of a mixture of acetonitrile and an 1% aqueous acetic acid solution at a flow rate of 1.0 mL/min with UV detection at the 350-nm wavelength. Average recoveries of 10 replicates for DNC in chicken meat, liver and eggs spiked at 3 levels (0.05, 0.20 mg/kg and 0.50 mg/kg) were within the range of 93.6%-102.0%, with a RSD ranging from 2.8% to 10.4%. The method detection limit was 0.05 mg/kg. This method, thanks its simplicity and high accuracy, is most suitable for the determination of nicrabazin residue 4,4'- dinitrocarbanilide in chicken tissues.

Gas Chromatographic Determination of Fipronil Residue in Tea
FU Xiao-fang,LIN Yan-fei,LI Jing,ZHAO Xiao-ya,WANG Peng
2010, 31(10):  279-282.  doi:10.7506/spkx1002-6630-201010061
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An analytical method based on gas chromatography (GC) was proposed for the determination of fipronil residue in tea. Samples were extracted with acetontrile and cleaned up on a Florisil (containing graphitized carbon black) column prior to HPLC analysis with μECD detection. The minimum detectable amount of fipronil was 2 × 10-12 g and the minimum detectable concentration of fipronil in tea was 2μg/kg. Average recoveries of 3 replicates for fipronil in a real sample spiked at 5 levels were within the range of 74.0%-92.0%, with a RSD ranging from 3.26% to 10.55%. The accuracy and sensitivity of the developed method both meet the requirements of pesticide residue analysis.

Correlations between Physico-chemical Properties and Aroma Quality of Different Flavors of Liquors
ZHANG Jian1,GAO Hai-yan1,ZHAO Lei2,YIN Jing-yuan1,*
2010, 31(10):  283-286.  doi:10.7506/spkx1002-6630-201010062
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Seventy-six liquor samples including 49 brands of Luzhou-flavor liquor, 7 brands of Maotai-flavor liquor, 10 brands of Fen-flavor liquor, 6 brands of rice-flavor liquor and 3 brands of Dong-flavor liquor were analyzed for physicochemical properties to evaluate the correlations between them and aroma quality assessed by 10 professional sommeliers. Total acid content exhibited a positive correlation with aroma intensity or harmony and the correlation was the strongest among the 5 physicochemical parameters tested. Some chemical parameters like total acid and total ester contents made a big difference to the aroma quality of liquor. Little effects of some physical parameters like Brix, electrical conductivity and viscosity on the aroma quality of liquor were observed.

Immunomagnetic Capture-Fluorescent PCR (IMC-FPCR) for Rapid Detection of Aspergillus flavus in Foods
SU Hui-yu1,XIE Rong-zhen2,NIU Jian-jun2
2010, 31(10 ):  287-291.  doi:10.7506/spkx1002-6630-201010063
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An immunomagnetic bead based technique combined with fluorescent PCR assay was developed for the detection of Aspergillus flavus in foods. Aspergillus flavus in foods could be captured with the immunomagnetic beads coated with goat antiserum against Aspergillus flavus without the requirement for fungal enrichment and rapidly detected by fluorescent PCR assay. The IMC-FPCR assay exhibited a limit of detection of 2 CFU/mL. Two of 12 commercial food samples were detected by the IMC-FPCR assay to contain toxin genes from carcinogenic fungal strains and the detection rate was 16.7% and one Aspergillus flavus strain was detected in peanut and Xiamen ready-to-eat noodles, respectively. This assay is most suitable for the rapid detection of Aspergillus flavus in foods.

Packaging & Storage
Effect of Harvesting Time on Volatile Composition of Ya Pears during Postharvst Storage
LIU Xiang-ping1,KOU Xiao-hong2,*,ZHANG Ping3,LI Jiang-kuo3,HUANG Yan-feng3,WANG Yi-zhou2,WU Cai-e4
2010, 31(10):  292-295.  doi:10.7506/spkx1002-6630-201010064
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The loss of volatile components is partially attributed to the flavor changes of pears during postharvest storage. As a consequence, the understanding of changing patterns of volatile composition of pears with different degree of maturity will make a vital contribution to the development of pear harvesting and storage techniques. The main volatile components of Ya pears harvested at different times (early, middle and late) were measured by SPME-GC every 2 months during 6 months of storage. The results showed that the main volatile components in Ya pears were ethyl acetate, hexanal, 1-hexanol, butanoic acid, ethyl ester, hexanoic acid and ethyl ester. A significant effect of harvesting time was observed on the volatile composition of Ya pears. Lower contents of volatile components found in early harvested pears were kept over the whole storage period. Higher contents of volatile components were observed in late harvested pears. However, there was a significant decrease in them with the extended storage period and a dramatic loss of volatiles was seen during the later stage of storage. In middle harvested pears, volatile components were gradually accumulated and exhibited a significantly higher content than those in early and late harvested pears after 6 months of storage (P < 0.05).

Prediction Model, Based on L* Value, of Lycopene Content of Mature Green Tomato
PEI Jiao-yan1,2,YANG Zhen-feng2,XU Feng1,2,ZHENG Yong-hua1,*
2010, 31(10):  296-300.  doi:10.7506/spkx1002-6630-201010065
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A kinetic model was developed to predict the lycopene content as a function of the luminosity (L) of mature green tomatoes stored at different temperatures. The L value and lycopene content of mature green tomatoes stored at 283.15, 288.15, 296.15 K or 298.15 K were determined. The kinetic models of L value and lycopene content with respect to length of storage and storage temperature were developed based on exponential function and Gomportz function, respectively. The high regression coefficients (R2 > 0.95) indicated the acceptability of the exponential function and Gomportz function for predicting the changes of L value and lycopene content in tomato fruits. Activation energies (Ea) and multiple correlation coefficients for L value and lycopene content were obtained based on the Arrhenius equation: 48.09 kJ/mol and 67.06 kJ/mol, 0.9644 and 0.9815, respectively. The average relative error between the predicted and measured values of lycopene content was 8.74% (within ± 10%). These results suggest that lycopene content in mature green tomato fruits stored at a storage temperature from 283.15 to 298.15 K may be accurately predicted based on L value.

Modeling of the Effects of Modified Atmosphere Storage Conditions on Free Fatty Acid Value Increase Rate of Wheat
SONG Wei,DING Chao,HU Huan-chong,AN Rong-rong,TAO Ting-ting
2010, 31(10):  301-303.  doi:10.7506/spkx1002-6630-201010066
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The effects of wheat moisture content, temperature and oxygen concentration on free fatty acid value increment per 10 days of wheat stored under modified atmosphere. The storage conditions exhibited significant and different effects on free fatty acid value increase rate in the decreasing order: wheat moisture > temperature > oxygen concentration. Regression analysis gave a mathematical model describing fatty acid value increase rate (y) with respect to the storage conditions, y = -10.903 + 0.08x1 + 0.681x2 + 0.05x3, R2 = 0.875, where, x1, x2 and x3 represented temperature, wheat moisture content and oxygen concentration, respectively. The model proved to be reliable in predicting fatty acid value increase rate.

Antiseptic and Preservative Effect of Sepia Ink Polysaccharide on Squid during Cold Storage
WU Jin-long1,LUO Jian-qiu1,LIU Hua-zhong2,WANG Guang1,LI Wei-dong3,XIAO Yun3,ZHONG Jie-ping3,PAN Jiang-qiu1,*
2010, 31(10):  304-307.  doi:10.7506/spkx1002-6630-201010067
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Squids were soaked for 20 min in a polysaccharide solution extracted from sepia ink (adjusted to different pH values and different concentrations) and then taken out of the solution and packaged in a tray prior to 1-day storage at 0-4 ℃ or were kept soaked in the solution throughout the entire storage period. After the completion of the storage, the squids were tested for their pH, total bacterial number, TVB-N value and sensory quality. Results showed that the polysaccharide had a good antibacterial and antiseptic effect on squids, and the optimal pH and the optimal polysaccharide concentration for improved antiseptic and preservative effect were 7.00 and 7 mg/mL, respectively. Keeping squid in the polysaccharide solution gave a better antiseptic effect than 20 min soaking followed by tray packaging. The antiseptic effect of sepia ink polysaccharide was inferior to potassium sorbet and chitosan at the same concentrations, and sepia ink polysaccharide at 7 mg/mL, potassium sorbate at 1 mg/mL, chitosan at 1 mg/mL had equivalent antiseptic effects.

Effect of Pre-harvest Salicylic Acid Spray Treatment on Fruit Quality and Antioxidant Capacity of Raspberry during Post-harvest Storage
ZHANG Fan1,WANG You-sheng1,*,LIU Xiao-yan1,GUO Xiao-min1,WANG Gui-xi2,LI Li-ping1
2010, 31(10):  308-312.  doi:10.7506/spkx1002-6630-201010068
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Raspberry fruits were sprayed with 1 mmol/L salicylic acid 1, 2 or 3 times every 3 days before harvest, harvested and stored at 1 ℃. Their sound fruit rate, contents of bioactive components, and antioxidant capacity were determined after storage for 10 or 23 days. The results showed that 2-time and 3-time pre-harvest salicylic acid spray treatments both increased significantly sound fruit rate and 2-time salicylic acid spray treated raspberry fruits revealed higher sound fruit rate than 3-time salicylic acid spray treated ones. Each pre-harvest salicylic acid spray treatment improved the contents of anthocyanins, total phenolics, total flavonoids and total antioxidant capacity, hydroxyl and DPPH radicals scavenging capacity, whereas obviously decreased the content of H2O2 of freshly harvested raspberry fruits. The most obvious changes in these parameters were observed in 2-time pre-harvest salicylic acid spray treated raspberry fruits. In addition, pre-harvest salicylic acid spray treated raspberry fruits exhibited an increase in the contents of H2O2 and total flavonoids and DPPH radical scavenging capacity and a decrease in the contents of anthocyanins, total phenolics and total antioxidant capacity and hydroxyl radical scavenging ability during postharvest storage. Pre-harvest salicylic acid spray treatment induced the generation of secondary metabolites and the enhancement. of DPPH radical scavenging capacity of raspberry fruits so that their post-harvest storage quality was improved.

Application of Tea Polyphenol and Allicin to the Coating Preservation of Chilled Pork
JIANG Shao-tong,WU Jie-fang,LIU Guo-qing,WANG Li-dan,PAN Li-jun
2010, 31(10):  313-316.  doi:10.7506/spkx1002-6630-201010069
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Tea polyphenol and allicin were added to edible film-forming solutions to prepare a novel coating for the coating preservation of chilled pork. To increase the freshness and shelf life of chilled pork, a L9(34) orthogonal array design was used to investigate the effect of coating formulation on pH value, TVB-N value, total bacterial number and sensory quality of chilled pork. The results showed that the optimal coating formula consisted of tea polyphenol 0.7%, allicin 0.4% and an edible filmforming solution consisting of soluble starch 3%, sodium alginate 0.6% and monoglyceride 0.2%. No significant sensory and physico-chemical changes were observed in chilled pork treated with the coating formula after 19 days of storage at 0—4 ℃.

Effect of Postmortem Chilling on Chicken Quality
MIN Cheng-jun,ZHU Zhi-ying,WU Hua-feng,GONG Guan-bing,WANG Chun-yi,YANG De-ming
2010, 31(10):  317-320.  doi:10.7506/spkx1002-6630-201010070
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This study aimed at investigating the effects of chilling temperature, length of chilling time and length of standing time at the segmentation workshop on water-holding capacity of chicken and investigating the effects of chilling temperature, length of chilling time and sodium hypochlorite amount on total number of bacteria and coliform bacteria on the surface of chicken carcasses by a 3-facor, 4-level orthogonal array design. The results indicated that the water-holding capacity of chicken was enhanced by controlling chilling temperature, length of chilling time and length of standing time at the segmentation workshop and the production of blood ice was reduced. An obvious reduction in total number of bacteria and coliform bacteria could be achieved by controlling chilling temperature, length of chilling time and sodium hypochlorite amount. The effects of chilling conditions on water-holding capacity and water-losing rate decreased in the following order: chilling temperature > length of chilling time >length of standing time at the segmentation workshop. The optimum chilling conditions for retaining water-holding capacity of chicken were chilling at (15, 8 ℃) for 35 min and subsequent standing for 30 min at the segmentation workshop, while chilling at (10, 4 ℃) for 30 min and subsequent standing for 40 min at the segmentation workshop were able to minimize water-losing rate. The effects of chilling conditions on the production of blood ice decreased in the order of chilling temperature>length of standing time at the segmentation workshop>length of chilling time. The optimal chilling conditions for reducing the production of blood ice were chilling at (10, 4 ℃) for 30 min and subsequent standing for 25 min at the segmentation workshop. Chilling temperature, length of chilling time and sodium hypochlorite amount exhibited different effects on total number of bacteria and coliform bacteria on the surface of chicken carcasses in the decreasing order: chilling temperature >sodium hypochlorite amount >length of chilling time. Chilling at (10, 4 ℃) for 30 min and sodium hypochlorite treatment at 80 mg/kg presented the best effect for reducing total bacteria and preventing coliform bacteria.

Effect of Chilling Injury on Storage Quality of Postharvest Eggplant Fruits
ZHAO Yun-feng1,2,ZHENG Rui-sheng3
2010, 31(10):  321-325.  doi:10.7506/spkx1002-6630-201010071
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To elucidate the quality deterioration pattern of eggplant fruit stored at low temperatures, the effect of chilling injury on storage quality of postharvest eggplant fruits was investigated. Freshly harvested eggplant fruits were stored at chilling injury temperature (4 ± 1) ℃ (4 ℃for short hereinafter) or non-chilling temperature (13 ± 1) ℃ (13 ℃ for short hereinafter) for 10 days. The quality changes were monitored periodically during storage. Browning appeared on the surface of eggplant fruits after 4 days of storage at 4 ℃. No chilling symptoms occurred within 10 days of storage at 13 ℃. Chilling injury accelerated the increases in weight loss and membrane permeability and promoted the decreases in the contents of chlorophyl, titrateble acid (TA) and VC. Chilling injury also propelled the decreases of the contents of reducing sugar, soluble protein and free amino acid in postharvest eggplant fruits during mid to late storage (4 - 10 days). In conclusion, chilling injury can accelerate the quality deterioration and play down the edible value and merchandise value of postharvest eggplant fruits.

Effect of 1-MCP Treatment on Reactive Oxygen Metabolism and Related Enzymes in Melon during Postharvest Storage
SUN Ai-ping1,ZHENG Yong-hua2,YANG Hai-yan1,LI Xue-wen1,2,*,HAN Wei1,ZHANG Xi-jun1
2010, 31(10):  326-329.  doi:10.7506/spkx1002-6630-201010072
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The fruits of Zaohuangmi melon, an early ripening melon cultivar, were treated with 1 μL/L 1-methylcyclopropene (1-MCP) for 24 h at ambient temperature (22-25 ℃) and then stored at 22 ℃. The activities of reactive oxygen species (ROS) metabolism related enzymes: SOD, POD, CAT and POD, superoxide anion radical production rate and the content of MDA in the treated melon fruits were measured periodically during 22 days of storage. The results showed that exposure of melon fruits to 1-CMP prevented the decline of CAT activity, caused the increase of SOD activity at the beginning of storage and significantly increased POD activity, reaching a peak value after 3 days. The POD activity of 1-CMP-treated melon fruits was higher than that of control fruits over the entire storage period. 1-CMP-treated melon fruits exhibited significantly lower superoxide anion radical production rate and lower MDA content and thus, the postharvest senescence of melon fruits was postponed.

Technology Application
Study on the Key Processing Technologies of Lotus Root Soup with Pork Ribs
FENG Xi,ZHANG Ke,ZHANG Ke-tian,HUANG Wen*
2010, 31(10 ):  330-335.  doi:10.7506/spkx1002-6630-201010073
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Lotus root soup with pork ribs was prepared from pork ribs and lotus root. The influences of different pretreatment methods of pork ribs, solid/liquid ratio, time point of adding salt, sterilization were investigated on sensory properties and nutrient composition as well as their correlations. The results showed that the optimal conditions for the processing of lotus root soup with pork ribs were determined to be: raw material/water ratio 1:2, the addition of salt at the end of cooking and high pressure sterilization. Different processing conditions indicated significant effects on the contents of soluble solids, IMP & GMP, soluble sugars and soluble proteins in the soup (P < 0.05). The taste quality of the soup had a positive correlation with the contents of fat or free amino acids in the soup (P < 0.05). The overall sensory quality of the soup was positively correlated with the contents of soluble solids, free amino acids or soluble sugars in the soup (P <0.05).

Optimization of Processing Conditions of Shiitake Soup
WANG Ying,ZHU Ke-xue*,ZHOU Hui-ming
2010, 31(10):  336-340.  doi:10.7506/spkx1002-6630-201010074
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Shiitake soup was made from shiitake mushrooms and porcine bone by cooking in boiling water. The processing procedure of shiitake soup was optimized by investigating the effects of cooking temperature, length of cooking time, solid-toliquid ratio and particle size of porcine bone powder on the dissolution ratios of solids and proteins using single factor and orthogonal array design methods. The optimum processing conditions were obtained as follows: cooking temperature 120 ℃ length of cooking time 30 min, solid-to-liquid ratio 1:70, and particle size of porcine bone powder less than 60 mesh. Under such conditions, the dissolution ratios of solids and proteins was 44.55% and 40.56% respectively.