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15 February 2010, Volume 31 Issue 4
Processing Technology
Extraction and Stability of Pigment from Arecanut (Areca catechu L.) Seeds
HAN Lin,ZHANG Hai-de*,WAN Jing,JIANG Lin-juan,HE Jie
2010, 31(4):  1-5.  doi:10.7506/spkx1002-6300-201004001
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In this work, arecanut seeds were used for the raw material to extract a natural red pigment by organic solvent extraction, and the stability of the pigment obtained was evaluated. Results showed that the optimum extraction process of arecanut pigment was achieved by using 70% ethanol to extract arecanut seeds for 4 h at pH 7.0 and 80 ℃ with a solid/liquid ratio of 1: 40 (g/mL). The pigment had good stability under light illumination or acidic pH value, strong reduction resistance, but poor antioxidant capacity. A hyperchromic effect of alkaline pH value and some food additives including citric acid, glucose, sodium benzoate, potassium sorbate and sodium bicarbonate on the pigment was observed. The pigment exhibited a percent loss of 13.41% when exposed to 4.0% H2O2. Some metal ions such as Na+, K+, Ca2+ and Mg2+ had little effects on the pigment and others such as Fe3+, Cu2+ and Zn2+ also had no obvious destructive effects. Characteristic color reactions preliminarily demonstrated that the pigment was one kind of anthocyanins or even flavonoids.

Orthogonal-array-design Optimization of Extraction Technologies of Polysaccharide from Soybeans
CHEN Hong,WANG Da-wei*,LI Xia,WANG Xiu-juan
2010, 31(4):  6-10.  doi:10.7506/spkx1002-6300-201004002
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Extruded soybean dregs were used as the raw material for extracting polysaccharide by hot water extraction, ultrasonicassisted extraction or microwave-assisted extraction. Optimal hot water extraction technology was investigated using single factor method, and optimal ultrasonic-assisted extraction and microwave-assisted extraction technologies using single factor method coupled to orthogonal array design for maximizing polysaccharide yield. Results showed that optimized hot water extraction, ultrasonic-assisted extraction and microwave-assisted extraction gave polysaccharide yields of 3.45%, 8.67% and 11.60%, respectively. In comparison with conventional hot water extraction, other two methods have the benefits of safety, saving energy, rapidity, high productivity, and so on.

Response Surface Optimization of Formulation of Low Sugar Litchi Jam
WU Wen-fei,YU Xiao-lin*,HU Zhuo-yan
2010, 31(4):  11-15.  doi:10.7506/spkx1002-6300-201004003
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To develop an optimal processing formula of low sugar litchi jam, central composite design combined with response surface methodology was used for examining the interactive effects of amounts of low methoxyl pectin (LMP), calcium chloride, citric acid and jelly powder on the sensory quality of litchi jam. Results showed that the optimal amounts of the above ingredients were as follows: low methoxyl pectin 0.71%, calcium chloride 0.052%, citric acid 0.48% and jelly powder 0.15%. Processed litchi jam using the optimal formula exhibited experimental sensory score of 14.6, approximating to the predicted value of 14.7, soluble solids content of 44.8%, total acidity of 0.65%, viscosity of 3.382 Pa·s and hardness of 3.35 N, and was characterized by a balanced sweet and sour taste and an exquisite and smooth mouth feeling.

Optimization of Processing Technology of Tenderized Dried Pork Slices
YAO Fang1,LIU Jing1,CHU Jie-ming2
2010, 31(4):  16-20.  doi:10.7506/spkx1002-6300-201004004
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Shearing force and sensory quality were used as the main evaluation indicators for optimizing the processing technology of tenderized dried pork slices. Single factor and orthogonal array test were conducted to deal with the effects of tenderizer formula and processing parameters on the tenderization of pork slices. Results showed that the optimal tenderizer formula consisted of papain 0.035%, sodium lactate 2%, polyphosphate 0.4% and calcium chloride 0.1%, and the optimal tenderization process consisted of 20 min mixing, 15 min standing (for enzymolysis) and 5 h drying by programmed temperature rise in a hot air oven. Under the above conditions, the productivity of tenderized dried pork slices was 55%. The product obtained contained 13.7% water and 40.8% protein, and exhibited an increase of tenderness by 136% when compared to the control.

Chloroplast for Removal of Sulfites from Foods
HUANG Guo-ping,YAO Yu-jing,CHEN Li-bin
2010, 31(4):  21-23.  doi:10.7506/spkx1002-6300-201004005
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Chloroplast extracted from fresh spinach was used for the removal of sulfites from foods in the present study. The optimal technological conditions were investigated using single factor method and central composite design coupled with response surface methodology (RSM). Results showed that the optimal sulfites removal process was based on the reaction between spinach chloroplast and NaHSO3 for 3 h at pH 8 in a proportion of 1:250 (m/m). A removal rate of sulfites of 94.85% was observed using the optimal removal process. In addition, light illumination, oxygen exposure and shake promoted the oxidation of NaHSO3.

Investigation of Strecker Degradation in Model Systems Consisting of Alpha-Dicarbonyls and L-Leucine
TIAN Hong-yu,SUN Bao-guo,ZHANG Jie,HUANG Ming-quan
2010, 31(4):  24-27.  doi:10.7506/spkx1002-6300-201004006
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As typical degradation products of carbohydrates, alpha-dicarbonyls including glyoxal, pyrualdehyde and butandione were individually used for comprising model systems with L-leucine to investigate their roles in the formation of isovaleraldehyde in the Strecker degradation of L-leucine. A high pressure vessel was used for the reaction between alphadicarbonyls and L-leucine in phosphate buffer solution and the effects of molar ratio of reactants, temperature and pH value on isovaleraldehyde yield were examined using orthogonal array design. Results showed that among three alpha-dicarbonyls, the system containing glyoxal gave the highest isovaleraldehyde yield of around 24% under the reaction conditions of 140 ℃, pH 5 and 6:1 molar ratio of glyoxal to L-leucine, while isovaleraldehyde yield was only around 14% when pyrualdehyde or butandione was used instead of glyoxal. This demonstrates the highest reactivity of glyoxal for the formation of isovaleraldehyde. Among three reaction conditions tested, pH had the most obvious effect, and an acidic condition favored the formation of isovaleraldehyde.

Extraction of Ursolic Acid from Loquat (Eriobotrya japonica (Thunb.) Lindl.) Leaves
JIAO Rong-rong1,2,SUN Yi-min1,2,*,SUN Ruo-qiong2,3,GENG Ji-hua4,SONG Wen-jia1,2,LUO Le1,2
2010, 31(4):  28-34.  doi:10.7506/spkx1002-6300-201004007
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In this study, ultrasonic-assisted extraction of ursolic acid from loquat leaves was systematically investigated. The influence of five technological parameters including ethanol concentration, extraction time, liquid/solid ratio, extraction number and material particle size on ursolic acid yield was assessed by uniform design for obtaining optimal ultrasonic-assisted extraction process. Ursolic acid was quantified by HPLC method. The optimized process was validated by 20-fold pilot scale enlargement. The optimal values of technological parameters were obtained as follows: ethanol concentration 80% - 100%, extraction time 50-65 min or 80-100 min, and extraction number 1. Visual analysis demonstrated the complicated influence of liquid/solid ratio and material particle size on ursolic acid yield.

Extraction and Dynamic Content of Total Flavonoids in Leaves of Liquidambar formosana Hance
LIU Ya-min1,LIU Yu-min1,MA Ming1,LI Chang-xiao2,LIAN Cai-xia1,CAO Shu-jun1
2010, 31(4):  35-38.  doi:10.7506/spkx1002-6300-201004008
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Leaves of Liquidambar formosana Hance were used as the raw material to extract total flavonoids and the dynamic change of total flavonoids in leaves of Liquidambar formosana Hance during growth was examined. To maximize the extraction of total flavonoids, technological parameters like ethanol concentration, temperature, extraction time and solid/liquid ratio were investigated by single factor method coupled with L9(34) orthogonal array design. Results showed that the maximum extraction of total flavonoids was obtained by using 60% ethanol to extract leaves of Liquidambar formosana Hance for 2.5 h at 80 ℃ with a solid/liquid ratio of 1:30. Total flavonoids exhibited an obvious change as leaves of Liquidambar formosana Hance grew, and a maximum content was observed in April.

Orthogonal Array Design Tests for Optimizing Ultrasound-assisted Extraction of Black Rice Pigment
ZHANG Ji-xiang1,ZHAO Wen-jing1,BAI Xia-jie1,OU Lai-liang2,*
2010, 31(4):  39-41.  doi:10.7506/spkx1002-6300-201004009
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Ethanol was used for extracting black rice pigment under ultrasound assistance. To maximize the extraction of black rice pigment, orthogonal array design was employed for investigating the effects of ethanol concentration, solid-to-liquid ratio, ultrasound power, extraction time on black rice pigment yield (represented by the absorbance at 543 nm wavelength of extract solution). Results showed that the use of 80% ethanol for extracting black rice grains at 1:32 solid-to-liquid ratio (m/V) with the assistance of 50 min ultrasound treatment at 250 W gave an optimal pigment extraction and the resulting pigment yield reached up to 4.5%, with a near 3-fold increase in comparison with the conventional Soxhlet extraction.

Microwave-assisted Extraction of Polysaccharide from Kiwifruit (Actinidia deliciosa) Roots
LI Jia-xing1,2,LI Min-li2,CHEN Jian-fu2,LIU Fei2,CHEN Shuang-ping3,WANG Xiao-yong3
2010, 31(4 ):  42-45.  doi:10.7506/spkx1002-6300-201004010
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Microwave-assisted extraction of polysaccharide from kiwifruit roots was investigated by examining the effects of material/liquid ratio, temperature, extraction time, microwave power on polysaccharide yield using single factor method coupled with orthogonal array design. Results showed that the optimal values of the above parameters were determined as follows: material/liquid ratio 1:20 (g/mL), 60 ℃, microwave power 600 W and extraction time 15 min. Under such conditions, the yield of polysaccharide was 11.34%.

Effect of Compound Food Colloid on Properties of Sweet Potato Starch Films
SHEN Xiao-li1,WU Jia-min1,ZHAO Guo-hua1,2,3,*
2010, 31(4):  46-52.  doi:10.7506/spkx1002-6300-201004011
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In the presence of glycerol, xanthan and hydroxypropyl carboxymethyl cellulose (HPCMC) were formulated for providing an enhancer for edible sweet potato starch films. To obtain optimal mechanical properties (tensile strength and tensile strain at break) and water vapor permeability, amounts of glycerol, xanthan and HPCMC were investigated by central composite design combined with response surface methodology. Results showed that better mechanical properties were obtained for sweet potato starch films prepared by adding 3.5-4.0 g of HPCMC, less than 2.0 g of glycerol and less than 2.0 g of xanthan to per 100 g of starch, and when the amounts of added HPCMC, glycerol and xanthan to per 100 g of starch were less than 2.0, more than 4.0 and less than 1.5 g, respectively, the water vapor permeability was lower. In practical production, selection of appropriate amounts of HPCMC, glycerol and xanthan should be done for optimal mechanical properties or water vapor permeability due to their different contributions to these perroperties.

Camellia chrysantha (Hu) Tuyama Leaves: Optimization of Ultrasonic-assisted Extraction and Methodological Evaluation of Phenol-Sulfuric Acid Determination of Polysaccharide
XU Zi-jing,LIAO Min-fu,CHEN Hai-yan,JIANG Yan,LIN Cui-wu*
2010, 31(4):  53-58.  doi:10.7506/spkx1002-6300-201004012
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Optimal ultrasonic-assisted extraction of polysaccharide from Camellia chrysantha (Hu) Tuyama leaves (PCCT) was investigated by single factor method and central composite design coupled with response surface methodology. In addition, a methodological evaluation was conducted for phenol-sulfuric acid determination of polysaccharide. Results showed that the optimal PCCT extraction conditions were as follows: 87 ℃ and water/material ratio 46:1 for a triplicate extraction duration of 54 min each time. Under such conditions, PCCT yield was up to 4.39%. Methodological evaluation demonstrated high precision, good repeatability and less error of developed phenol-sulfuric acid method for polysaccharide determination. Fresh Camellia chrysantha (Hu) Tuyama leaves was determined to contain 66.8 mg/g dry weight of polysaccharide by the method.

Ultrasonic-assisted Extraction and in vitro Antioxidant Evaluation of Pholiota nameko Polysaccharides
YU Shu-chi,HOU Jin-xin,LI Ming-yan,LI Peng-cheng,CHEN Ai-ping
2010, 31(4):  59-62.  doi:10.7506/spkx1002-6300-201004013
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Fruit bodies of Pholiota nameko were used as the raw material to extract Pholiota nameko polysaccharide (PNP) by ultrasonic-assisted extraction. Optimal PNP extraction process was investigated using orthogonal array design. To evaluate the antioxidant activity of PNP, total reducing power and scavenging capacity against superoxide anion or hydroxyl radicals were assayed using in vitro simulated chemical systems. Results showed that the optimum PNP extraction conditions were as follows: ultrasonic power 700 W, ultrasonic treatment time 16 min, extraction temperature 75 ℃, and solid/liquid ratio 1:30. Under the optimum conditions, PNP yield reached up to 9.17%. PNP showed strong in vitro reducing power and free radical-scavenging capacity. Thus, PNP has good potential as a natural antioxidant used in food or medicine industries.

Dehydration Characteristics of Microwave-treated Peanut and Optimization of Microwave Dehydration for Production of Dried Salted Peanut
ZHOU Qi1,2,YANG Mei2,HUANG Feng-hong2,*,HE Jiang1,2
2010, 31(4):  63-67.  doi:10.7506/spkx1002-6300-201004014
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As an alternative to conventional electronic oven heating, microwave technique was used for the dehydration of peanuts. Dehydration characteristics of peanuts during microwave treatment under different microwave powers and material loads were investigated for providing experimental evidences for the use of microwave dehydration in the production of dried salted peanuts. Microwave dehydration of peanuts was shown to consist of two stages, i.e., two dehydration peaks. The appearance time of dehydration peaks and the maximum dehydration rate were affected by material load and microwave power. Based this investigation, a Box-Benhnken central composite design involving 3 variables (microwave power, material load, microwave treatment time) at 3 levels was employed to optimize dehydration rate, unit electricity consumption and sensory quality with respect to the production of dried salted peanuts. In the optimization, Design expert 7.0.1 was used and regression models for the above indicators were developed. Results showed that significant effects of microwave power, material load, microwave treatment time on dehydration rate and unit electricity consumption were observed, and material load had a significant effect on sensory quality. The optimal values of these parameters were as follows: microwave power 800 W, material load 54.25 g, microwave treatment time 3.5 min. Under such conditions, dehydration rate, unit electricity consumption and sensory quality score were 5.79 g/min, 0.76 kW·h/kg and 9.17, respectively.

Response Surface Analysis for Optimizing Microwave-assisted Extraction of Pleurotus ostreatus Polysaccharide
ZHU Cai-ping,GAO Gui-tian,LI Jian-ke,ZHAO Yan-hong,DENG Dian-dian
2010, 31(4):  68-72.  doi:10.7506/spkx1002-6300-201004015
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To optimize the microwave-assisted extraction process of Pleurotus ostreatus polysaccharide (POP), single factor experiments involving three technological parameters including extraction time, microwave power and solvent/material ratio were done for following investigations on the interactive effects of the parameters on POP yield using central composite design (CCD) combined with response surface methodology. In the optimization, Design Expert 7.1.6 software was used to fit CCD experimental data and a quadratic polynomial regression model was developed for POP yield as a response to the above parameters. Results showed that the optimal values of technological parameters for using deionized water to extract POP were as follows: extraction time 10 min, microwave power 420 W and solvent/material ratio 40:1 (mL/g). Under such conditions, the yield of POP was up to 9.04%.

Purification of Saponin from Edible Stems of Aralia continentalis Using Macroporous Adsorption Resin
FENG Ying1,2,WU Mei-ling1,LI Tian-lai2,*,FAN Wen-li2
2010, 31(4):  73-76.  doi:10.7506/spkx1002-6300-201004016
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Static adsorption and desorption experiments were carried out to screen an optimal one from 4 types of macroporous adsorption resins for the purification of saponin from edible stems of Aralia continentalis. AB-8-type macroporous resin was shown to be an optimum candidate for saponin purification. Subsequently, dynamic adsorption and desorption experiments were performed to optimize technological conditions for saponin purification using AB-8-type macroporous resin. Results showed that the optimal adsorption conditions were obtained as follows: saponin concentration 0.2 mg/mL and sample injection amount 20-fold bed volume (BV). Two highly pure saponin fractions having strong superoxide anion radical scavenging capacity and antibacterial potential were obtained from gradient elution with 50% and 70% ethanol, respectively.

Relationship between A238nm/A440nm Value of Gardenia Yellow and Contents of Crocin and Genipin
CHEN Yang1,ZHANG Hao2,CAI Le2,LI Xi-Lan1,JIANG Li-Juan2,XU Hui-Chuan2,WANG Wen-Jun1
2010, 31(4):  77-80.  doi:10.7506/spkx1002-6300-201004017
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TLC, HPLC and UV techniques were used to investigate the relationship between OD value (defined as the ratio of maximum absorbance value at 238 nm wavelength of genipin to maximum absorbance value at 410 nm wavelength of crocins) of gardenia yellow and genipin and crocins contents in it. Compounds with high purity were isolated from gardenia yellow by gel column chromatography and then subjected to qualitative and quantitative analysis by TLC, HPLC and UV. In addition, E1cm238, E1cm440 and OD values were calculated. UV spectral data clearly indicated strong absorption of crocins at 238 nm wavelength. As a result, OD value might cause an over-estimatation of genipin content in gardenia yellow when used for quantitation. Therefore, it is inaccurate to represent genipin content in gardenia yellow by OD value. Moreover, this study implies that HPLC is a scientific and proper tool for analyzing genipin in natural pigments.

Simultaneous Color Protection and Hardening in Production of Low-sugar Preserved Apple
ZHU Mei-yun,WEI Zheng,CHEN Guang-qi
2010, 31(4):  81-84.  doi:10.7506/spkx1002-6300-201004018
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The aim of this study was to achieve optimal simultaneous color protection and hardening in the production of lowsugar preserved apples by using a solution of compound reagents to soak fresh-cut apples. The individual color protection and hardening effects of different reagents on fresh-cut apples were investigated in single factor experiments. Based on this investigation, the optimal amounts of citric acid, VC, CaCl2 and NaCl and soaking time were examined using orthogonal array design for minimizing the degree of browning (DB) of apples. Results showed that a minimum DB was obtained when 0.30% citric acid or 0.06% VC was used for soaking fresh-cut apples. The hardening treatment with a mixed solution of 1.5% CaCl2 and 1.0% NaCl gave appropriate hardness, regular appearance and good mouth feeling to preserved apples. The optimal treatment time for a minimum DB ranged from 2.0 to 3.0 h. SPSS analysis demonstrated that VC had an extremely significant color protection effect, CaCl2 had a significant effect, while no significant effects of citric acid, NaCl and treatment time were observed. The optimum conditions for simultaneous color protection and hardening were determined as follows: citric acid 0.30%, VC 0.08%, CaCl2 1.5%, NaCl 1.2%, and soaking time 3.0 h. Under such conditions, DB reached minimum, and an appropriate hardness of preserved apples was obtained.

Cellulase Hydrolysis Followed by Microwave-assisted Extraction for Extracting Hesperidin from Navel Orange Peels
ZENG Bai-quan,ZHOU Xiao-qin,XIE Xi-yu
2010, 31(4):  85-89.  doi:10.7506/spkx1002-6300-201004019
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Cellulase hydrolysis, microwave-assisted extraction and cellulase hydrolysis followed by microwave-assisted extraction were investigated individually for the optimal extraction of hesperidin from“ Bingtang” sweet orange (Citrus sinensis L. Osbeck) peels. Results showed that the optimal hesperidin extraction was based on 90 min cellulase hydrolysis at 45 ℃ and pH 5.5 with an enzyme dose of 3% (calculated on the basis of dry weight of material) followed by extraction with 80% ethanol at a solid/ liquid ratio of 1:50 under the assistance of microwave treatment for 25 s at 560 W power. In three replicate extractions using the above process, the average yield of hesperidin was as high as 6.130%, and the relative standard deviation was 0.28%, which demonstrates the applicability of the process for extracting hesperidin from “Bingtang” sweet orange peels.

Response Surface Methodology for Optimization of Germination of Selenium-enriched Brown Rice
JIANG Hu1,FU Jin-heng1,2,*,SU Hu3,YU Bo1,OUYANG Wu-jun1,FANG Lan-kun1
2010, 31(4):  90-94.  doi:10.7506/spkx1002-6300-201004020
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To obtain both optimal germination rate and γ-aminobutyric acid content, germination conditions such as sodium selenite concentration in soaking solution, germination time and germination temperature were investigated using Box-Behnken central composite design (CCD) combined with response surface methodology. Box-Behnken CCD experimental data were fitted to establish a mathematical model for germination rate or γ-aminobutyric acid content as a function of the above variables. Results showed that the optimal production process of Se-enriched germinated brown rice was achieved by soaking for 9 h in 5 mg/L sodium selenite solution at 28 ℃ followed by cultivation for 21 h at 31.5℃. Under these conditions, germination rate was 77.67% and the contents of γ-aminobutyric acid and Se in germinated brown rice were 330 mg/kg and 0.5 mg/kg, respectively.

Orthogonal Array Design Tests for Optimizing Color Protection of Fresh-cut Burdock Shreds
CHEN Xue-hong,QIN Wei-dong,QIN Jie,SHI Dong-jing
2010, 31(4):  95-98.  doi:10.7506/spkx1002-6300-201004021
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As polypenol oxidase (PPO) is a key enzyme for enzymatic browning in burdock, crude PPO was extracted from burdock and characterized enzymlogically to provide experimental evidences for browning control in the production of fresh-cut burdock shreds. Based on this investigation, citric acid in color protection solution, soaking time and bleaching time were optimized using orthogonal array design for maximizing overall sensory quality score of fresh-cut burdock shreds. Results showed that the optimal reaction temperature and pH of burdock PPO were within the ranges of 30 - 40 ℃ and 6.5 - 7.5, respectively. VC presented higher inhibitory effect against this enzyme when compared to sodium bisulfite and EDTA. The optimal color protection was achieved for fresh-cut burdock slices by soaking for 30 min followed by bleaching in a mixed solution containing 0.5% VC, 1.0% citric acid and 0.5% CaCl2. After cooling, fresh-cut burdock slices were shredded and stored at (4 ± 1)℃. Neither change in color nor unfavorable odor was perceived after 14 days of storage.

Investigation on Ethanol Precipitation of Lentinans
GENG An-jing,CHEN Jian
2010, 31(4):  99-102.  doi:10.7506/spkx1002-6300-201004022
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A commercial sample of lentinans was refined and subjected to ethanol fractionations in two different ways: way No.1, use of ethanol concentration gradients of 10%, 20%, 30% to 90%, respectively, and way No.2, adjustment of ethanol concentration in supernatant to 10%, 20%, 30% to 90% to understand molecular weight distribution by gel filtration chromatography. Results showed that precipitation time had no notable effect on the precipitation mass of lentinans and precipitation rate exhibited a gradual decrease with prolonged precipitation time. A maximum precipitation mass of lentinans was obtained at 30% ethanol concentration in way No. 2 precipitation. With increasing ethanol concentration, the precipitation mass of lentinans progressively increased in way No.1 precipitation and then trended nearly stable after reaching a high level. The peak molecular weight (Mp) of lentinans obtained at the ethanol concentrations of 30%, 50% and 80% were 22671, 18649 D and 6011D, respectively. In summary, both ethanol concentration and precipitation way had significantly effects on the precipitation mass and molecular weight distribution of lentinans

Optimization of Millard Reaction for Preparation of Food Flavors from Hydrolyzed Soybean Protein
ZHAO Yan-yan,JIANG Shao-tong,KANG Hai-chao
2010, 31(4):  103-105.  doi:10.7506/spkx1002-6300-201004023
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To provide a main reactant for the formation of meat flavor in the Millard reaction, soybean was used as the raw material to prepare hydrolyzed vegetable protein (HVP) by acid hydrolysis. The optimal HVP preparation process and Millard reaction were both investigated using orthogonal array design. Results showed that the optimal technological parameters for soybean protein hydrolysis were as follows: sulfuric acid concentration 25% (V/V), solid/liquid ratio 1:7 (g/mL), and hydrolysis time 7 h, and the degree of hydrolysis (DH) obtained using the above hydrolysis process reached up to 65.26%. The optimum Maillard reaction conditions were as follows: pH 7.0, D-xylose amount 0.4 g/mL, and L-cysteine hydrochloride amount 0.05 g/mL.

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WANG Ming-yan,ZHANG Xiao-jie,WANG Tao,MA Wei-xing,XU Xing-you
2010, 31(4):  106-110.  doi:10.7506/spkx1002-6300-201004024
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Response Surface Methodology as An Approach for Optimization of Extraction of Water-soluble Polysaccharides from Schisandra chinensis (Turcz.) Baill
MENG Xian-jun,LI Dong-nan*,WANG Yan-qun,LIU Xiao-ming,LIU Ju,LI Bin
2010, 31(4):  111-115.  doi:10.7506/spkx1002-6300-201004025
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Response surface methodology (RSM) based on a central composite design (CCD) was applied for the optimization of extraction process of crude polysaccharides from Schisandra chinensis (Turcz.) Baill. In RSM analysis, the pairwise interactive effects of solid/liquid ratio, extraction temperature and extraction time on the yield of crude polysaccharides were examined. Results showed that the optimal values of the above parameters were determined as follows: solid/liquid ratio 1:40 (m/V), extraction temperature 90.3 ℃, and extraction time 5 h. Under the optimized conditions, the experimental value of yield of crude polysaccharides was (10.994 ± 0.332)% and was in good agreement with the predicted value.

Macroporous Resin Purification and Structural Characterization of Soybean Saponins
GUAN Hai-ning1,DIAO Xiao-qin1,SHI Bo-lin2,*,MA Song-yan1
2010, 31(4 ):  116-119.  doi:10.7506/spkx1002-6300-201004026
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To screen an optimal adsorbent for the purification of soybean saponins from low-temperature defatted soybean meal, four types of macroporous resin were compared for the differences in dynamic and static adsorption and desorption performances. AB-8-type macroporous resin was shown to have optimal adsorption and desorption capacities towards soybean saponins. The optimal desorption parameters for the purification of soybean saponins using AB-8-type macroporous resin were investigated, and the structure of purified soybean saponins was characterized by infrared (IR) spectroscopy. Results showed that the optimal elution of soybean saponins from AB-8-type macroporous resin was achieved by washing the resin with 2 BV deionized water followed by eluting with 70% ethanol at a flow rate of 0.5 BV/h. The eluate was concentrated by reduced pressure distillation and vacuum freeze dried and purified soybean saponins with 87.07% purity and 1.19% yield were obtained. In addition, the structure of purified product was confirmed by IR spectroscopy to be consistent with the known structure of soybean saponins.

Extraction and Stability of Red Pigment from Sweet Cherry Fruits
YANG Qing-zhen,WANG Feng,SUN Yuan-lin
2010, 31(4):  120-122.  doi:10.7506/spkx1002-6300-201004027
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Ethanol was used to extract natural red pigment from sweet cherry fruits under the assistance of ultrasonic. The optimal extraction process was investigated using orthogonal array design. Along with this, the stability of pigment product obtained was dealt with. Results showed that using 90% ethanol to extract raw material in 50 ℃ water bath under the assistance of ultrasonic treatment for 5 min gave an optimal red pigment extraction. The pigment was easy to dissolve in water, and had poor resistance to indoor natural light, heat and oxidation. Except Al3+ and Fe3+, other metal ions including Mg2+, Ca2+, Cu2+, Zn2+, Na+, and K+ had no obvious effects on the pigment. In acidic medium or in the presence of reductants or common food additives, the pigment exhibited good stability. Therefore, the pigment as a natural plant-derived pigment can be extensively used in food, medicine industries, and so on.

Membrane Filtration for Separation of Polysaccharides from Fermentation Broth of Ganoderma lucidum
MAO Jian1,2,MA Hai-le1,*
2010, 31(4):  123-126.  doi:10.7506/spkx1002-6300-201004028
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Ultrafiltration was used for the separation of polysaccharides from the fermentation broth of Ganoderma lucidum to simulate industrial production. Meanwhile, the molecular weight distribution of the fermentation broth and its filtrate and retentate was investigated by AcA44 gel chromatography. Results showed that ultrafilitration resulted in the removal of parts of small molecule weight polysaccharides, the increase of proportion of big molecule weight ones and the obvious improvement of quality of products resulting from the following ethanol precipitation.

Analysis & Detection
High Performance Liquid Chromatography-Tandem Mass Spectrometry for Determination of Perfluorinated Compounds in Animal Visceral and Muscle Tissues
WANG Jie-ming1,WANG Li2,FENG Yu-jing2,PAN Yuan-yuan1,SHI Ya-li1,CAI Ya-qi1,*
2010, 31(4):  127-131.  doi:10.7506/spkx1002-6300-201004029
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A high performance liquid chromatography-electrospray ionization-tandem mass spectrometric (HPLC-ESI-MS/MS) method was proposed for the determination of 11 perfluorinated compounds (PFCs) including 9 common PFCs, 2-perfluorooctyl ethanoic acid (FOEA) and 2H-Perfluoro-2-decenoic acid (FOUEA) in animal visceral (pork heart, pork liver, pork kidney, chicken heart and chicken liver) and muscle (pork tenderloin and chicken breast) tissues. WAX and MAX SPE cartridges were compared for the difference in recovery of 11 PFCs and WAX SPE cartridge was selected. Ion-pair liquid-liquid extraction and alkaline digestion were determined to be optimal methods for sample pretreatment of visceral and muscle tissues, respectively. In the determinations of real samples including pork liver, etc purchased from a local farmers market, the developed method exhibited low spike recoveries of PFTA, FOEA and FOUEA, while the spike recoveries of other 8 PFCs were found to be in the range of 80%-120%. The limit of detection of the method ranged from 0.002 to 0.032 ng/g.

Electronic Nose for Odor Analysis of Radix Peucedani with Different Growth Time
HAN Bang-xing1,2,CHEN Nai-fu2,*,ZHOU Xiao-kun1,WANG Sheng1
2010, 31(4):  132-134.  doi:10.7506/spkx1002-6300-201004030
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Electronic nose was used for the detection of odor fingerprint change of Radix Peucedani before and after blossom  and the applicability of electronic nose in the quality evaluation of traditional Chinese medicinal herbs was discussed. Response values of electronic nose for detecting odor of preblossom and postblossom Radix Peucedani were subjected to principal component analysis and discriminant factor analysis (DFA) to establish characteristic fingerprints. In addition, statistical quality control analysis (SQC) was conducted. Results showed that electronic nose could make a sensitive response to odor change of Radix Peucedani before and after blossom for distinguishing preblossom and postblossom Radix Peucedani. Consequently, this technique can be applied to the odor identification of traditional Chinese medicinal herbs.

HPLC Determination of Chlorfluazuron Residue in Cabbage (Brassica oleracea L.)
GE Xin,HUA Ri-mao*,TANG Feng,LI Xue-de,CAO Hai-qun,WU Xiang-wei,TANG Jun
2010, 31(4):  135-138.  doi:10.7506/spkx1002-6300-201004031
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A HPLC method was developed for the determination of chlorfluazuron residue in cabbage. Samples were extracted with ethyl acetate and cleaned up on Florisil column prior to HPLC analysis. The limit of detection of the method was 1.2 ng. At three spike levels (0.05, 0.5, 2 mg/kg), the recoveries of chlorfluazuron ranged from 81.95% to 100%, with coefficients of variation ranging from 2.37% to 6.21%. The figures of merit of this method can meet the requirements of pesticide residue analysis and therefore benefit its application in the determination of chlorfluazuron residue in cabbage.

Comparative Analysis of Nucleotides between Fruiting Body of Cordyceps militaris (L. ex Fr.) Link and Cultured Medium
LIU Yan-fang1,2,TANG Qing-jiu2,*,YANG Yan2,ZHANG Jing-song2,HAO Rui-xia2,TANG Chuan-hong2,WEI Dong-zhi1,SHI Guo-ping2
2010, 31(4):  139-142.  doi:10.7506/spkx1002-6300-201004032
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A high performance liquid chromatographic (HPLC) method was developed for the determination of nucleotides. Meanwhile, a comparative analysis of nucleotides between fruiting body of Cordyceps militaris (L. ex Fr.) Link and cultured medium was conducted by the developed method. YMC-Polyamine column (5 μm, 250 mm × 4.6 mm) was used for the chromatographic separation. A mobile phase composed of acetonitrile and double distilled water at a flow rate of 1 mL/min was used for gradient elution and the elution program was as follows: acetonitrile/water (90:10, V/V) for 15 min → (86.5:13.5) for 20 min→(75:25) for 30 min → (70:30) for 35 min. Other chromatographic conditions were set as follows: column temperature 30 ℃, detection wavelength 259 nm, and injection volume 10 μL. Results showed that a good separation of thymine, cordycepin, uracil, adenosine, adenine, uridine, guanine and hypoxanthine was achieved. This method was stable, precise and reproducible and was successfully applied to the determination of nucleosides in commercial Cordyceps militaris (L. ex Fr.) Link samples. HPLC analysis revealed that a basic similarity of nucleotide kind was observed in various commercial samples of fruiting body of Cordyceps militaris (L. ex Fr.) Link. But the contents of nucleotides exhibited significant differences. A high content of cordycepin was found in cultured medium and solid fermentation products, but other nucleotides had a low content. These results demonstrate the excellence of cultured medium and solid fermentation products as a source of cordycepin.

Quality Assessment of Semen Ziziphi Spinosae by HPLC Fingerprinting and Quantitative Analysis
LI You1,LIANG Zong-suo1,2,*,ZHOU Zi-yun1,2,YANG Dong-feng1,2
2010, 31(4):  143-149.  doi:10.7506/spkx1002-6300-201004033
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This study was aimed to establish a HPLC fingerprinting approach for the effective quality assessment of Semen Ziziphi Spinosae. In HPLC analysis, the chromatographic separation was achieved on an UltimateTM C18 column (250 mm×4.6 mm, 5 μm) with a mobile phase composed of acetonitrile and ultrapure wate at a flow rate of 1.0 mL/min. In addition, detection wavelength and column temperature were set at 210 nm and 30 ℃, respectively. Vector cosine and correlation coefficient methods were used to calculate similarities of 17 samples of Semen Ziziphi Spinosae and cluster analysis was made for them. Results showed that 10 common fingerprint peaks were identified in the samples by HPLC-ELSD while HPLC-UV detection gave 12 common fingerprint peaks. Cluster analysis revealed that the samples were classified into 3 main categories: geographic origins for superior, medium and inferior quality. Samples of Semen Ziziphi Spinosae with superior quality all exhibited a similarity higher than 0.9239 and a jujuboside A content range of 0.8123 to 1.1109 mg/g. It can be concluded that HPLC fingerprinting combined with quantitative analysis of indicator components can provide experimental data for the quality assessment of Semen Ziziphi Spinosae.

Ionization Extraction-Spectrophotometric Determination of Gallic Acid in Tea
GUO Jun-ling1,4,LI Cheng-liang2,ZHENG Yi-meng3,KOU Peng-qi2,QING Yu2,DU Xiao1,2,*
2010, 31(4):  150-155.  doi:10.7506/spkx1002-6300-201004034
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In this study, gallic acid and catechin were separated by ionization extraction for the visible spectrophotometric determination of gallic acid content in tea. Simulated experiments were conducted to determine the optimal amount of ionization agent and environmental pH value, and the reliability of ionization extraction was validated. The developed method has some advantages over other methods, like simplicity, low cost and less instrumental requirements. In five replicate determinations, a commercial sample of Ya an Tibetan tea was determined by the method to have a gallic acid content of (1.326 ± 0.018)%, with 1.36% relative standard derivation. This result is very close to previously reported values.

Simultaneous Determination of Phenolphthalein and Sibutramine Illegally Added to Weight Loss Functional Foods
MA Wei1,2,WANG Hai-bo2,MA Qiang3,FU Li4,LI Li3,TANG Ying-zhang3,*
2010, 31(4):  156-160.  doi:10.7506/spkx1002-6300-201004035
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A simple and rapid method using high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was developed for the simultaneous determination of phenolphthalein and sibutramine illegally added to weigh loss functional foods. Along with this, mass spectral fragmentation pathways of the above analytes were elucidated. In the method, various samples, including weight loss coffee, tea, capsule and albumin as well as apple vinegar chewing tablets were extracted for 15 minutes using methanol with the assistance of ultrasonic. Qualitative and quantitative analysis was carried out for 20 samples in the MRM mode following chromatographic separation on a Waters Atlantis T3 (150 mm × 2.1 mm, 3μm) column. Linear ranges for phenolphthalein and sibutramine detected by the method were 2.5 - 500μg/L and 0.15 - 500μg/L, and corresponding correlation coefficients 0.9992 and 0.9996, respectively. Mean recoveries for both analytes in aforementioned 5 types of weight loss functional foods at three spike levels (low, medium and high) were within the range of 82.3%-103.6% (n = 6), with intraday precision RSDs less than 5% and inter-day precision RSDs less than 8%. Sibutramine was detected in 13 of 20 samples, and namely the detection ratio was 65%. Phenolphthalein was detected in 9 of 20 samples and namely the detection ratio was 45%. This method is characterized by rapidity, high sensitivity and recovery, and good reliability, thereby providing a robust approach for the determination of phenolphthalein and sibutramine illegally added to weight loss functional foods.

Liquid Chromatography Coupled with Tandem Mass Spectrometric Analysis of Four Dipyrone Metabolites in Milk
SHEN Jin-can1,XIAO Chen-gui1,XIE Li-qi1,XIONG Bei-bei1,LIN Yan-kui1,PANG Guo-fang2
2010, 31(4):  161-165.  doi:10.7506/spkx1002-6300-201004036
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A liquid chromatography coupled with tandem mass spectrometric (LC-MS/MS) method was proposed for the determination of four dipyrone metabolites in milk, i.e., 4-methylaminoantipyrine (MAA), 4-formylaminoantipyrine (FAA), 4- aminoantipyrine (AA), 4-acetylaminoantipyrine (AAA). Samples were extracted with acetonitrile, and the resulting extract was then cleaned up/defatted with acetonitrile-saturated n-hexane and concentrated by rotary evaporation prior to LC-MS/MS with positive electrospray ionization (ESI) in the multiple reaction monitoring (MRM) mode. FAA, AAA and AA were quantified by the external standard method, while MAA by the internal standard method. The limits of detection of FAA, AAA, AA and MAA by the method were 0.24, 0.20, 0.59μg/kg and 0.61μg/kg, respectively. Mean recoveries in blank samples at three spike levels (5, 10, 20μg/kg) ranged between 80.4% and 97.9%, with relative standard deviations less than 9% (n = 10).

Analysis of Volatile Composition of Pixian Bean Sauces with Different Fermentation Time
ZHANG Yu-yu1,SUN Bao-guo1,FENG Jun2,HUANG Ming-quan1,*
2010, 31(4):  166-170.  doi:10.7506/spkx1002-6300-201004037
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With the aim to understand the effect of fermentation time on volatile composition of Pixian bean sauce, two raw materials, namely fermented chili and raw beans, and Pixian bean sauces fermented for 3, 1 years or 3 months were analyzed for volatile composition by headspace solid-phase microextraction (HS-SPME) coupled to GC-MS. Added together, 66 compounds were identified in both materials of Pixian bean sauce, including alcohols (5), esters (24), acids (2), aldehydes (5), hydrocarbons (23), phenols (4), furans (1), and nitrogen-containing compounds (2). Added together, 88 compounds were identified in Pixian bean sauces with different fermentation time, including alcohols (7), esters (20), acids (3), aldehydes (9), hydrocarbons (35), phenols (6), ketones (4), and nitrogen-containing compounds (3). The compounds simultaneously found in the above 5 samples were benzaldehyde, benzeneacetaldehyde, (Z)-3,7-dimethyl- 1,3,6- octatriene, 3,7-dimethyl-1,6-octadien- 3-ol, 2,6,6-trimethyl-2-cyclohexene-1,4-dione, 4-ethylguaiacol, ethyl hexadecanoate, and so on. These results can offer valuable reference for the study of fermentation process and flavoring preparation of Pixian bean sauce.

GC-MS Analysis of Aromatic Composition of Blueberry Wine Fermented with Different Species of Yeast Strains
GAI Yu-han1,XIN Xiu-lan2,YANG Guo-wei2,LI Ya-dong1,*
2010, 31(4):  171-174.  doi:10.7506/spkx1002-6300-201004038
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In an effort to provide experimental evidence for yeast strain selection in blueberry wine making, aromatic components in blueberry wines fermented with three different species of yeast strains, namely alcohol active dry yeast, wine active dry yeast and Saccharomyces cerevisia 1203 were analyzed by headspace solid-phase microextraction (HS-SPME) coupled to GC-MS. Added together, 76 aromatic compounds were identified in blueberry wines fermented with the above yeast strains, respectively, including 56, 50 and 47 individually found in alcohol active dry yeast-, wine active dry yeast- and Saccharomyces cerevisia 1203- fermented blueberry wines, respectively and 30 simultaneously found in the three blueberry wines. The main aromatic compound in alcohol active dry yeast- or Saccharomyces cerevisia 1203-fermented blueberry wines was 1-buten-ol-3-methyl, with relative contents of 18.98% and 37.64%, respectively. The main aromatic compound in wine active dry yeast-blueberry wine, however, was ethyl octanoate, accounting for 18.68% of total aromatic compounds.

Liquid Chromatography-Tandem Mass Spectrometric Determination of Metalaxyl Residue in Animal-derived and Plant-derived Foods
XU Juan,CHEN Jie,LIN Feng,WANG Lan,SHAO Lin-zhi,WU Ying-xuan,JIAO Hong
2010, 31(4):  175-178.  doi:10.7506/spkx1002-6300-201004039
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An analytical method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was presented for the determination of metalaxyl residue in 2 animal-derived foods, namely pigeon meat and duck kidney and 6 plant-derived foods, namely multiple vegetable juice, apple, sweet orange, grape, lemon and kiwifruit. The analyte was quantified by the external standard method. Mean spike recoveries of metalaxyl ranged from 95.9% to 102.0% for animal-derived foods (represented by duck kidney), and 116.4% and 141.0% for plant-derived foods (represented by sweet orange), with relative standard deviations ranging from 2.13% to 12.7% for duck kidney and from 0.37% to 4.09% for sweet orange. The limits of detection of the method for duck kidney and apple were 0.002 mg/kg and 0.001 mg/kg, respectively.

Analysis & Detection
Determination of Polyphenols in Apple Pomace by Folin-Ciocalteu Colorimetry
HAN Ju,WEI Fu-xiang
2010, 31(4):  179-182.  doi:10.7506/spkx1002-6300-201004040
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Folin-Ciocalteu colorimetric assay for polyphenols extracted from apple pomace by supercritical CO2 extraction using gallic acid as reference substance was systematically investigated for developing an optimal colorimetric method for the determination of polyphenols in apple pomace. The optimum colorimetric conditions were determined as follows: 0.3 mL of Folin- Ciocalteu reagent, 1.5 mL of saturated Na2CO3 solution, 20 min of reaction time and 25-35 ℃ of reaction temperature. The calibration curve for quantifying polyphenols exhibited a good linearity in the range of 1-10 μg/mL (r = 0.9994). The average recoveries of gallic acid at high, medium and low spike levels were 99.66%, 98.79% and 98.20% (n = 5), respectively, which were reaveraged at 98.82%, with a RSD of 1.93%. The proposed method demonstrates the advantages of rapidity as well as high accuracy and reproducibility.

GC-MS Determination of Di-2-ethylhexyl Phthalate in Fruits of Benincasa hispida
WANG Jia-wen,DU Qi-zhen*,XIA Hui-long,FU Xiao-wei
2010, 31(4):  183-186.  doi:10.7506/spkx1002-6300-201004041
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Benincasa hispida exhibits strong accumulation capacity towards di-2-ethylhexyl phthalate (DEPH), which proves to be carcinogenic. In the present study, a gas chromatography coupled with mass spectrometric method (GC-MS) was proposed for the determination of DEPH in fruits of Benincasa hispida, based on optimal DEPH extraction process. The developed standard curve of DEPH exhibited a good linearity over the range of 0.0001 to 1.0 mg/mL. The limit of detection (RS/N = 3) was 2.65×10-3 mg/kg. The recoveries for DEPH at 5 spike levels were between 87.69% and 96.85%, with an average RSD of 3.16%. The proposed method, thanks to its high accuracy, good selectivity and less interference, meets the requirements for the analysis of DEHP in fruits of Benincasa hispida so as to have a great application prospect.

Clustering Analysis of Volatile Aroma Compounds in Dried Chilli (Capsicum annum L.)
YANG Yong-juan,DING Zhu-hong
2010, 31(4):  187-189.  doi:10.7506/spkx1002-6300-201004042
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Five different methods were used to dry the same variety of chilli. In addition, the natural drying method was used to dry five varieties of chilli. Volatile aroma composition in the dried chilies was analyzed by GC-MS, and the analytical data were subjected to clustering analysis based on the whole consideration for kind and content of the common components. Results showed that: 1) the same variety of chilli dried by different methods revealed different volatile aroma compositions resulting in difference in aromatic smell. When the five drying methods were divided into three categories, the maximum value of λ could be 0.97108. 2) the five varieties of natural dried chilies also revealed different volatile aroma compositions, and smelled different aromas. When these varieties were divided into four categories, the maximum value of λ could be 0.943.

Dual-column Gas Chromatographic Analysis of Organophosphorus Pesticide Multi-residues in Fruit Juice
GAO Wei,LU Jian,WU Zhong-ping,GENG Ning
2010, 31(4 ):  190-193.  doi:10.7506/spkx1002-6300-201004043
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A dual-column gas chromatographic method was developed for the multi-residue determination of organophosphorus pesticides in fruit juice. Samples were extracted with acetone, and the resulting extract was cleaned up on Carb/NH2 SPE cartridge. The chromatographic separation was achieved on DB-1701 and DB-35ms capillary columns. Analytes were detected with FPD. The average recoveries of 6 replicates for analytes in blank samples spiked at 3 levels ranged between 75.23% and 98.53%, with relative standard deviations between 0.97% and 8.16%. The limits of detection were within the range of 10-60 μg/kg.

Preparation, Testing and Certification of Reference Materials for Benzo(a)pyrene in Pepper Oil
GUO Cui1,WANG Jian-hua2,1,*,DU Heng-qing2,CHEN Shi-shan2,ZE Xiang-jun2,SUI Yu-zhu1
2010, 31(4):  194-197.  doi:10.7506/spkx1002-6300-201004044
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A methodology regarding preparation and certification of the reference material for Benzo(a)pyrene in pepper oil was presented. Spiked pepper oil was packed in 100 bottles after homogenization and 10 of these 100 bottles were selected to test the homogeneity of the sample. Two batches of 10 samples from these 100 bottles were kept at 4 ℃ and 20 ℃, respectively. The stabilities of 20 bottles were analyzed e once a week for 8 consecutive weeks. Test results demonstrate the homogeneity and stability of that the pepper oil sample. Benzo(a)pyrene was determined by gas chromatography-mass spectrometry, based on isotope dilution. Uncertainty components, combined standard uncertainty and expanded uncertainty were also calculated, and the concentration of the sample was certified as (9.98 ± 0.914 )μg/kg, k = 2. The reference material is intended for use in the methodological validation and quality control for benzo(a)pyrene in edible vegetable oils

HPLC Determination of Gossypol in Cotton Seed Kernel
LUAN Shu1,MENG Lei2,SUN Lian1,YAO Jun1,*
2010, 31(4):  198-200.  doi:10.7506/spkx1002-6300-201004045
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A HPLC method was developed for the determination of gossypol in cotton seed kernel. The chromatographic separation was carried out on a ODS-C18 column (4.6 mm × 200 mm, 5 μm) with a mobile phase composed of methanol and 1% phosphoric acid aqueous solution (85:15, V/V) at a flow rate of 1.0 mL/min. The detected wavelength was set at 235 nm. Results showed that a good linear relationship between HPLC peak area and gossypol concentration was obtained over the range of 1.9-34.9 μg/mL. Mean spike recoveries of gossypol at three levels were 97.8%-100.3%, with RSDs ranging from 0.4% to 1.2%. The method provides the benefits of simplicity, rapidity, sensitivity and accuracy, and therefore is applicable to the determination of gossypol in cotton seed kernel.

Silylation Followed by GC-MS Determination of Melamine and Its Analogues in Rice Protein Powder
ZUO Hai-gen
2010, 31(4):  201-205.  doi:10.7506/spkx1002-6300-201004046
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A GC-MS method was developed for the determination of melamine and its analogues in rice protein powder, like ammeline, ammelide and cyanuric acid. Samples were extracted with a mixture composed of diethylamine, water and acetonitrile (1:4:5, V/V) for 30 min, and the resulting extract was blown to dryness under dry nitrogen atmosphere at 70 ℃. Subsequently, the residue left was dissolved in pyridine and silylated for 40 min at 70 ℃ prior to GC-MS analysis. The internal standard method was used for quantification. Melamine and its analogues all exhibited a good linear curve over the concentration range of 20-1000 μg/L (r≥0.9989). The limit of detection (LOD) of the developed method was 0.5 mg/kg. Mean recoveries of melamine and its analogues at three spike levels of 1.0, 2.0 mg/kg and 5.0 mg/kg were between 72.01%-96.45%, with relative standard deviations (RSDs) not more than 6.3%. These figures of merit of this method demonstrate its good applicability to the determination of melamine and its analogues in rice protein powder.

Evaluation of Uncertainty in Spectrophotometric Determination of Titanium Dioxide in Foodstuffs
LU Mei-bin,WANG Bu-jun
2010, 31(4):  206-209.  doi:10.7506/spkx1002-6300-201004047
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The source of uncertainty in the spectrophotometric determination of titanium dioxide in foodstuffs were investigated by analyzing the whole determination procedure. Each uncertainty component was modelled, synthesized and expanded to develop a method for the evaluation of uncertainty in spectrophotometric determination of titanium dioxide in foodstuffs. Results showed that the titanium dioxide content in a commercial flour was determined to be (122.48 ± 4.63) mg/kg, K = 2. The main uncertainties were attributed to four sources, namely measurement repeatability, solution determination, sample dilution and sampling in decreasing order of uncertainty contribution. This method is applicable to the evaluation of uncertainty in routine determinations by spectrophotometry, atomic fluorescence spectroscopy (AFS), atomic absorption spectroscopy (AAS), gas chromatography (GC), liquid chromatography (LC), and so on.

Comparative Study of HPLC-FLD and HPLC-APCI-MS/MS Determination of Amitorle Residue in Plant-derived Foodstuffs
LI Jin-qiang1,FU Jian2,YIN Da-lu1,LI Xiao-yu1
2010, 31(4):  210-213.  doi:10.7506/spkx1002-6300-201004048
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High-performance liquid chromatography with fluorescence detection (HPLC-FLD) and high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (HPLC-APCI-MS/MS) were used for analyzing amitorle residue in plant-derived foodstuffs. In HPLC-FLD analysis, the excitation wavelength and emission wavelength were set at 380 and 484 nm, respectively. HPLC-APCI-MS/MS analysis was carried out in the MRM mode under the conditions as follows: parent ion, m/z 85; quantitative daughter ion, m/z 43; qualitative daughter ion, m/z 57; collision energy, m/z 85 > m/z 57 to 56.9/11 eV, m/z 85 > m/z 43 to 58.1/11 eV; and cracking voltage, 100 V. Limit of detection was 0.01 mg/kg for HPLCFLD method and 0.005 mg/kg for HPLC-APCI-MS/MS method. Both methods demonstrate the advantages of simplicity, rapidity, accuracy and reliability and are alternatives to each other for the determination the determination of amitorle residue in plant-derived foodstuffs.

Fatty Acid and Amino Acid Composition of Eucommia ulmoides Oliver Seeds
DUAN Xiao-hua1,2,DENG Ze-yuan2,*,ZHU Du1
2010, 31(4):  214-217.  doi:10.7506/spkx1002-6300-201004049
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Fatty acid and amino acid composition of Eucommia ulmoides Oliver seeds were analyzed using Soxhlet extraction followed by GC-MS and automatic amino acid analyzer, respectively. Eucommia ulmoides Oliver seeds comprised 35.5% oil and 11 fatty acids were identified in the oil, mainly including linolic acid (10.66%), oleic acid (16.9%), palmitic acid (6.03%), stearic acid (1.96%), and linolenic acid (63.15%), among which, unsaturated fatty acids were dominant with relative content as high as 91.26% and linolenic acid exhibited the highest content. A total of 25% protein was contained in Eucommia ulmoides Oliver seeds and the amino acid composition consisted of Asp, Glu, Ser, Arg, Gly, Thr, Pro, Ala, Val, Met, Ile, Leu, Phe, His, Lys, Tyr and Cys-Cys, among which, the contents of essential amino acids and semi-essential amino acids were higher, accounting for 33.6% and 11.2% of total amino acids, respectively. These results reveal a high utilization value of Eucommia ulmoides Oliver seeds as an exploitable source abundant in protein and unsaturated fatty acids.

Construction and Application of Liquid Chromatography-Tandem Mass Spectral Database of Pesticides in Agricultural Products
TIAN Hong-zhe,ZHOU Yan-ming,LIU Wen-e
2010, 31(4):  218-222.  doi:10.7506/spkx1002-6300-201004050
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In order to assess and maintain the quality safety of agricultural products, a liquid chromatography-tandem mass spectral database was constructed for more than 50 pesticides using ion-trap mass spectrometry, which was helpful to rapid selection and qualification of unknown pesticides in agricultural products by database searching. The qualification of unknown pesticides could be achieved by aligning their retention time, MS/MS extracted ion current chromatogram, UV absorption spectrum with those of standard substances. The developed database was successfully used for the qualification of unknown pesticides in real samples. This demonstrates its good applicability.

HPLC-MS/MS Determination of Rhodamine B Residue in Chinese Preserved Sausages
CHENG Hui,LI Bing,ZHAN Chun-rui
2010, 31(4):  223-225.  doi:10.7506/spkx1002-6300-201004051
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A high-performance liquid chromatography-tandem mass spectrometric (HPLC-MS/MS) method was developed for the determination of rhodamine B residue in Chinese preserved sausages. The whole determination procedure consisted of extraction with a mixture of ethyl acetate and cyclohexane (1:1, V/V), cleanup with an Accuprep gel filtration chromatographic system, rotary evaporation concentration, filtration through 0.22 μm membrane, HPLC-MS/MS analysis, and quantitation by external standard method. The developed method showed a good linearity over the wide range of 5-100 ng/mL. Average recoveries of rhodamine B in spiked samples at three levels varied from 79.8% to 110.3%, with relative standard deviations between 10.0% and 10.3%. The limit of detection was 5 μg/kg. Therefore, this method, thanks to its simplicity and rapidity, has a good applicability to the determination of rhodamine B residue in Chinese preserved sausages.

Liquid-liquid Extraction or Simultaneous Distillation-Extraction Coupled with GC-MS Analysis of Flavor Composition of Home-made Brands of Vinegar
YUAN Zhong1,MA Qi-yun2,YANG Ji-yuan1
2010, 31(4):  226-229.  doi:10.7506/spkx1002-6300-201004052
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Qualitative and quantitative analysis was carried out for examining flavor composition of three home-made brands of vinegar using liquid-liquid extraction (LLE) or simultaneous distillation-extraction (SDE) coupled with gas chromatographymass spectrometry (GC-MS). Results showed that more low boiling point compounds were identified using SDE than using LEE and LEE made it more sensitive to detect high boiling point compounds. There was a significant difference in flavor composition of three home-made brands of vinegar. Among them, the most acid kind was observed in Shanxi mature vinegar, Zhenjiang Hengshun vinegar contained the highest contents of low boiling point compounds, while the contents of high boiling point compounds in Shanxi hypolipidemic vinegar were much higher than those in other two brands.

High-performance Liquid Chromatography Coupled with Tandem Mass Spectrometric Determination of Steroid Hormone Multi-Residues in Pork
NIU Jin-yang,SUN Huan,LI Ying-ying
2010, 31(4 ):  230-232.  doi:10.7506/spkx1002-6300-201004053
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A method using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) was proposed for the determination of steroid hormone multi-residues in pork. Analytes were extracted from samples with methanol and cleaned up using a solid-phase extraction cartridge prior to HPLC-MS/MS analysis. The proposed method exhibited a good linearity for 10 steroid hormones over the range of 0.5-100μg/kg and a limit of detection ranging from 0.2 to 2μg/kg. Mean recoveries for 10 steroid hormones in blank pork samples spiked at low, medium and high concentrations were between 71% and 88%, with relative standard deviations below 10%. The method is characteristic of rapidity, simplicity, good selectivity and high sensitivity, and therefore has a great popularization potential.

Spectrophotometric Determination of Vanillin in Oatmeal
ZHANG Yong,LIN Guo-wei,XIA Jin-hua,KE Wei-zhong,WANG Ai-bin,TAN Cheng-hai
2010, 31(4):  233-235.  doi:10.7506/spkx1002-6300-201004054
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Vanillin in oatmeal was determined by spectrophotometric method, which is based on the reaction between vanillin and thiobarbituric acid in hydrochloric acid solution. The detection wavelength was set at 436.0 nm. A linear regression equation for absorbance (y) at 436.0 nm wavelength as a function of vanillin concentration (x) was established as follows: y = 2.8939x + 0.009 (r = 0.9990), with a linear range from 0.0304 to 0.3652 g/L. The detection limit of the method was 2.2206 × 10-2 g/L. The average spike recovery of vanillin was 101.8%, with 0.44% relative standard deviation. This method is characteristic of simplicity, rapidity, accuracy and good reproducibility.

HPLC Determination of Ursolic Acid in Leaves of Sinojackia sarcocarpa L.Q.Luo
LIU Su-jun,ZHOU Ze-bin,TANG Mei
2010, 31(4):  236-238.  doi:10.7506/spkx1002-6300-201004055
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A HPLC method was developed for the determination of ursolic acid in leaves of Sinojackia sarcocarpa L.Q.Luo. The chromatographic separation was achieved on a Shim-pack VP-ODS C18 column using a mobile phase composed of H2O and H3PO4 (850:147:3, V/V) at a flow rate of 1 mL/min, and the detection wavelength was set at 210 nm. A good linearity of the standard curve for peak area versus ursolic acid concentration was obtained over the range of 0.124-2.48μg/μL (R2 = 0.9971). The average spike recovery of ursolic acid at three levels was 100.5% (n = 3), with 0.91% RSD. In sample preparation, ultrasonic extraction resulted in higher efficiency when compared to reflux extraction and percolation extraction. This method reveals the characteristics of good stability and repeatability, simplicity, and easy operation.

Development of A Colloidal Gold Strip for Rapid Detection of Listeria monocytogenes in Foods
CUI Huan-zhong1,ZHANG Hui1,WANG Xing-long2
2010, 31(4):  239-242.  doi:10.7506/spkx1002-6300-201004056
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In the present study, a specific monoclonal antibody against Listeria monocytogenes (Lm) was prepared to develop a rapid immune colloidal gold strip for detecting Lm in foods. The developed colloidal gold strip had high specificity, no crossreactivity with L.ivanovii, L.innocua, Escherichia coli, Salmonella, Bacillus subtilis, Staphylococcus aureus and Streptococcus, a sensitivity of 3.9×105 CFU/mL in detecting Lm pure culture and simulated samples of tap water, milk, raw meat products, vegetables, frozen shrimp and bread, and more than 120-day expiration date at 4 ℃. The merits of rapidity, sensitivity, and specificity demonstrate a good applicability of this strip to the detection of Lm in foods.

Determination of Chloramphenicol Residues in Meat by HPLC-MS
FENG Lei,YIN Li-zhu,SUN Wen-tong,LI Bo,MA Xue-tao
2010, 31(4):  243-245.  doi:10.7506/spkx1002-6300-201004057
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A new analytical approach using HPLC-MS was developed for the determination of chloramphenicol residue in meat. Samples were extracted with ethyl acetate, and the resulting extract was blown to dryness under nitrogen. Subsequently, the residue left was dissolved in water, defatted with n-hexan. Finally, the water phase was harvested and filtrated through 0.2μm membrane for HPLC-MS analysis. The chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetronitrile and 0.1% acetate. ESI(-)-SIM mode was adopted for the detection of chloramphenicol. The developed approach is characterized by short time consumption for chromatographic separation, high sensitivity and good reliability so as to meet the requirements for rapid analysis of large-batch samples.

Development of An Indirect ELISA Kit for Detecting Chlorpyrifos Residue in Plant-derived Foods
WEI Song-hong1,LIU Bing1,JI Ming-shan1,GU Zu-min1,WANG Ying-zi1
2010, 31(4):  246-249.  doi:10.7506/spkx1002-6300-201004058
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Based on the investigations of artificial coating antigen for chlorpyrifos and polycolonal antibody against chlorpyrifos, an indirect ELISA kit was developed for detecting chlorpyrifos residue in plant-derived foods. In addition, the developed kit was evaluated for sensitivity, specificity, precision, accuracy and expiration date. Results indicated that the limit of detection of the kit was 0.5μg/L and the linear range was between 1.8μg/L and 1000 μg/L. Both intra-assay and inter-assay coefficients of variation were less than 8%. Mean spike recoveries of chlorpyrifos in tap water, lettuce, apple and rice were all more than 85%. The kit stored at 4 ℃ or -20 ℃ exhibited more than 6-month expiration date.

Uncertainty Evaluation of HPLC Determination of Melamine in Milk Powderchromatography
YANG Yang,XU Chun-xiang,CHE Wen-jun
2010, 31(4):  250-253.  doi:10.7506/spkx1002-6300-201004059
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The sources of uncertainty in high performance liquid chromatographic (HPLC) determination of melamine in milk powder were fully analyzed according to the calculation formula of melamine. Each uncertainty component was modeled. Uncertainty evaluation was conducted for fitting of standard curve of melamine and less measurement times by least square method and extreme deviation method, respectively. HPLC determination with uncertainty evaluation by the method gave the (2.00 ± 0.088) mg/kg melamine content in a randomly inspected commercial milk powder (weighed 2.00 mg). This method proves to be applicable to the uncertainty evaluation of HPLC determination of melamine in milk powder.

Ascorbic Acid-molybdenum Blue Spectrophotometric Determination of Phosphate in Beer
WANG Jian-gang
2010, 31(4):  254-256.  doi:10.7506/spkx1002-6300-201004060
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Ascorbic acid-molybdenum blue spectrophotometric method was used for the determination of phosphate in beer. In order to obtain optimal determination results, 4 crucial determination parameters, including detection wavelength, color development time and amounts of chromogenic reagent and sulfuric acid were investigated. Results showed that the optimal values of the above parameters were as follows: detection wavelength 820 nm, sulfuric acid (9.58 mol/L) amount 2.00 mL, ammonium molybdate solution (60 g/L) 2.00 mL, ascorbic acid amount 1.00 mL, and color development time in 70 ℃ water bath 20 min. Under these conditions, a good linear relationship between absorbance (A) and phosphate concentration (c) was observed, which could be expressed as A = 0.2001c+ 0.0225 (r = 0.9996). Mean recoveries of phosphate in Harbin wheat beer varied from 94.04% to 102.03%, with a mean RSD of 1.14%. The method has the merits of omitted sample pretreatment and easy operation, and therefore is applicable to the quality control in beer production.

Packaging & Storage
Modeling of Gas Exchange in Modified Atmosphere Packaging with Perforated Film
LI Fang1,LU Li-xin1,2,*
2010, 31(4):  257-259.  doi:10.7506/spkx1002-6300-201004061
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According to the basic theory of gas mass transfer, a mathematical model based on Fick’s law for gas exchanges in modified atmosphere packaging (MAP) with perforated film was developed. The effects of different perforation parameters on the change of gas concentration inside an empty package were analyzed. In addition, the developed model was validated. Results showed that perforation diameter and number had significant effects on the change of gas concentration, while no significant effect of film thickness on the change of gas concentration was seen. High agreement between predicted and experimental values demonstrates a good reliability of this model in predicting the change of gas concentration.

Fresh-keeping Effect of 1-Methylcyclopropene on Post-harvest Hottuynia cordata Thunb
XU Li,XIAO Feng,YUE Cai-yan
2010, 31(4):  260-263.  doi:10.7506/spkx1002-6300-201004062
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Freshly harvested Hottuynia cordata Thunb was treated with different concentrations of 1-methylcyclopropene (1- MCP) for 18 h, packed with polyethylene bags of 0.04 mm in thickness and stored at 4 ℃ and relative humidity ranging 80% -90%, and edible rate, weight loss, decay rate, respiration rate, reducing sugar content, vitamin C content, polyphenol oxidase (PPO) activity, peroxidase (POD) activity, phenylalanine ammonia-lyase (PAL) activity of treated Hottuynia cordata Thunb were determined at proposed intervals of 4 ℃ storage. Results showed that 1-MCP treatment exhibited a good fresh-keeping effect on Houttuynia cordata Thunb, inhibited its respiration rate and the activities of PPO, POD and PAL, retarded the reductions of VC and reducing sugar, and obviously prolonged the storage and shelf life of Hottuymia cordata Thunb. 1-MCP treatment at 2000 nL/L dose revealed the best fresh-keeping effect on Hottuynia cordata Thunb, and the edible rate of treated Hottuymia cordata was still as high as 88.3% after 60 days of storage.

Effect of Different Color Polyethylene Food Packaging Bags on Greening and Steriodal Glycoalkaloids Content of Potatoes
LI Mei1,TIAN Shi-long1,*,XIE Min-hua1,LI Shou-qiang1,FENG Huan-de1,LIU Gang2
2010, 31(4):  264-267.  doi:10.7506/spkx1002-6300-201004063
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Changes in greening and steriodal glycoalkaloids content of potatoes packaged with different color polyethylene (PE) food packaging bags were investigated during storage under the conditions of 18-22 ℃, 40%-60% relative humidity, and even and gentle natural light illumination. Potatoes directly exposed to air were served as control group. Results showed that under natural light condition, the greening speed and steriodal glycoaloid content of control potatoes increased rapidly with prolonged storage time. Different color PE bags could effectively inhibit the greening speed and the increase in steriodal glycoaloid content of potatoes, among which, black and green bags provided the best inhibitory effect and resulted in decreases of chlorophyll content by 53.97% and 65.89% and decreases of steriodal glycoalkaloids content in potatoes stored for 45 d by 80.71% and 75.89%, respectively, when compared to direct exposure to air.

Effect of Microwave Treatment on Shelf-life Quality of Pomegranate Fruits
ZHANG Li-hua1,2,YANG Xue-mei1,ZHANG Yuan-hu1,*
2010, 31(4):  268-271.  doi:10.7506/spkx1002-6300-201004064
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Freshly harvest pomegranate fruits with above 90% maturity degree were irradiated in a microwave oven, preserved at 4-8 ℃ for 3 months, and stored at 20 ℃, a simulated shelf-life condition. Physicochemical indexes of microwave-irradiated pomegranate fruits were measured at regular intervals of 3 d during shelf storage to examine the effect of microwave treatment on shelf-life quality of pomegranate fruits. Results showed that microwave irradiation for a transient period of 10-20 s inhibited peel polyphenol oxidase (PPO) activity and browning of pomegranate fruits, delayed the decreases of peel polyphenols and titratable acid (TA), and increased soluble solid content (SSC). However, serious browning associated with heat injury appeared when microwave irradiation time was over 20 s. Thus, 10-20 s should be appropriate time for microwave irradiation.

Effect of Postharvest 1-Hexanol Treatment on Active Oxygen Metabolism and Senescence of Strawberry Fruits
LI Ying-hua1,YUAN Hai-ying2,*,ZHANG Hui1,WANG Lei1,HU Xiu-lan2
2010, 31(4):  272-275.  doi:10.7506/spkx1002-6300-201004065
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Postharvest strawberry (Fragaria ananassa Duch cv. Darselect) fruits were treated with 0.05% or 0.1% and the changes of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities, superoxide (O2·) production rate, hydrogen peroxide (H2O2) accumulation, VC content and respiration rate in treated fruits were investigated during storage at 4 ℃. Results indicated that both 0.05% and 0.1% 1-hexanol treatments significantly inhibited the respiration rate of strawberry fruits, maintained high levels of SOD, CAT, APX activities and VC content, reduced the production rate of O2· and the accumulation of H2O2, and thus the fruit senescence was delayed. Comprehensive evaluation demonstrates obvious superiority of 0.05% 1-hexanol treatment over 0.1% 1-hexanol treatment.

Effect of Salicylic Acid Treatment on Physiology of Cold-stored Fruits of Chestnut (Castanea mollissima Blume) during Shelf-life
LU Zhou-min,CHI Ming,ZHANG Zhong-liang
2010, 31(4):  276-279.  doi:10.7506/spkx1002-6300-201004066
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To explore the effect and mechanism of salicylic acid (SA) treatment on physiological indexes of cold-stored chestnut fruits during shelf-life, Zhen’an chestnut fruits were immersed in various concentrations (1, 3.5, 7.5 mmol/ L) of SA solution, respectively for 10 hours and stored under the conditions of (0 ± 1) ℃ and 65%-80% relative humidity (RH) for 220 days, the treated chestnut fruits were then placed under the simulated shelf-life conditions of 17-26 ℃ and 37%-46% RH, and the changes in rotten rate, respiratory intensity, moisture, weight loss rate, the activities of antioxidant related enzymes (SOD, CAT, POD) and malondialdehyde (MDA) content of SA-treated, cold-stored fruits were measured at regular intervals of 3 days during shelf-life. Results showed that SA treatment resulted in a significant reduction of percentage of rotten fruits and delaying of respiration peak occurrence during shelf-life. The decrease of moisture and the increase of weight loss rate and MDA content were effectively inhibited by both 1 and 3.5 mmol/ L SA treatments. SA treatment at 3.5 mmol/L concentration enhanced SOD activity at a late stage of shelf-life, effectively postponed the occurrence of CAT activity peak, and maintained a high level of POD activity throughout shelf-life. In conclusion, a good maintenance for physiological characteristics of chestnut fruits during shelf-life can be achieved using 1-3.5 mmol/L SA treatment.

Technology Application
Preparation of Soy Protein Isolate-based Food Packaging Films
ZHANG Hua-jiang,CHI Yu-jie,SUN Bo,WANG Xi-Bo,XIA Ning
2010, 31(4):  280-285.  doi:10.7506/spkx1002-6300-201004067
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Soy protein isolate (SPI) was used as the main raw material to prepare food packaging films by the covalent crosslinking reaction with a plasticizer and a reductant under appropriate conditions. The optimal film-forming formula and conditions were investigated using single factor method coupled to orthogonal array design. Meanwhile, SPI films obtained were analyzed for physiochemical properties and microstructure. Results showed that the optimal film formation process was achieved by using casting mold of acrylic material and drying for 2 h at 60 ℃, and the optimal film-forming formula consisted of soy protein isolate 4.0 g/100 mL, glycerin 2.0 g/100 mL, and sodium sulfite 0.1 g/100 mL. Under the above conditions, SPI films with 61.892 N tensile strength, 0.313 mg/cm2·d oxygen permeability, 2.899 mg/cm2·d carbon dioxide permeability were obtained, which are an attractive alternative to parts of plastic products for food packaging due to alleviated environment pollution and have promising development prospect as a green packaging material.

Liquid-state Fermentation of Orange-flavored Vinegar
2010, 31(4):  286-289.  doi:10.7506/spkx1002-6300-201004068
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Xuefeng sweet oranges and Se-rich rice bran were used as the raw materials to develop an orange-flavored vinegar by liquid-sate fermentation. Orthogonal array design was employed to obtain optimal alcohol and acetic acid fermentations. Additionally, fermented vinegar product was evaluated for sensory quality and physicochemical hygiene indicators. Results showed that the optimal alcohol fermentation parameters were determined as follows: ratio of rice bran hydrolysate to orange juice 7:3, yeast inoculation amount 8%, and temperature 30 ℃ for a fermentation period of 96 h, and the optimal acetic acid fermentation was achieved by fermentation at 35 ℃ for 84 h with an acetic acid bacteria inoculation amount of 5%. Vinegar obtained under the optimized conditions contained contents of acetic acid Se of 4.98 g/100 mL and more than 12 μg/100 mL, respectively.