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15 July 2010, Volume 31 Issue 14
Processing Technology
Optimization of Egg White Protein Enzymolysis for the Preparation of ACE Inhibitory Peptides
ZHANG Rui-dong1,CHI Yu-jie1,*,RUAN Chang-qing1,2
2010, 31(14):  1-4.  doi:10.7506/spkx1002-6630-201014001
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In order to develop an enzymatic hydrolysis procedure for the preparation of egg white protein derived angiotensin converting enzyme (ACE) inhibitory peptides, 4 proteases were used to hydrolyze egg white protein alone, and trypsin was the selected enzyme due to the largest ACE inhibitory ratio of hydrolyzed egg white protein. In order to optimize 3 parameters (namely hydrolysis time, substrate concentration and enzyme-to-substrate ratio) affecting the trypsin hydrolysis of egg white protein, central composite design was employed to establish a mathematical regression model for the ACE inhibitory ratio of hydrolyzed egg white protein with respect to the parameters, followed by employing response surface methodology (RSM) to investigate the interactive effects among the independent variables on the function. The results showed that the optimum values of the independent variables were found to be: hydrolysis time 4.87 h, substrate concentration 3.06% and enzyme-to-substrate ratio 2.91% and that the corresponding value of the function was 50.73%.

Spiral-wound Membrane Ultrafiltration of L-lactic Acid containing Fermentation Supernatant
JIANG Shao-tong,TANG Xiao-ming,LIU Mo,LUO Shui-zhong,LIU Ying-tao
2010, 31(14):  5-9.  doi:10.7506/spkx1002-6630-201014002
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The clarification of L-lactic acid containing fermentation supernatant by ultrafiltration is an important pretreatment step for the separation of L-lactic acid. In this study, spiral-wound membrane modules with molecular weight cut-offs (MWCO) of 1000 D and 3000 D were used to filtrate the L-lactic acid containing supernatant derived from Rhizopus oryzae AS3.819 fermentation, and the one with 3000 D MWCO was selected for the subsequent investigations due to larger membrane flux, in which, 4 process conditions (i.e., ultrafiltration time, operation pressure and temperature and protein concentration) affecting the membrane flux of the selected module were explored and a mathematical model was developed describing the relationship of the function with operation pressure and protein concentration. The membrane flux of the spiral-wound membrane module with 3000 D MWCO attenuated with prolonged ultrafiltration time and increasing protein concentration, but elevated with increasing operation pressure and temperature. The developed model revealed good reliability in predicting the membrane flux of the spiralwound membrane module with 3000 D MWCO.

Extraction Optimization of Pectin from Sweet Orange Peels Using Response Surface Methodology
MA Ya-qin1,2,3,SUN Zhi-gao1,2,*,WU Hou-jiu1,2,ZHOU Zhi-qin1,3
2010, 31(14):  10-13.  doi:10.7506/spkx1002-6630-201014003
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To obtain the optimal process conditions for the extraction of pectin from sweet orange peels, the effects of materialto- liquid ratio, extraction temperature, length of extraction and pH on pectin yield were investigated by single factor method and based on this, a 3-factor, 3-level Box-Behnken experimental design coupled with response surface methodology was employed to optimize extraction temperature, length of extraction and pH. The results showed that pectin yield increased with decreasing pH and increasing temperature and length of extraction and material-to-liquid ratio had positive correlation with pectin yield. The optimum values of extraction temperature, length of extraction time and pH were determined to be 90 ℃, 1.3 h and 1.1, respectively.

Effects of Extraction Conditions and Heating Time on Heat-induced Gel Properties of Salt-soluble Protein from Shark Muscle
YAN Wei-hua,DING Ning,CHEN Dan,GU Ling-fang,HE Bin-hui,YANG Wen-ge*
2010, 31(14):  14-17.  doi:10.7506/spkx1002-6630-201014004
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Salt-soluble protein was extracted from shark muscle under different levels of NaCl concentration, pH, extraction time and was then heated at 40 ℃ for different periods of time in an effort to explore the effects of these extractions and heating time on the water-holding capacity (WHC) and textural characteristics of the formed heat-induced gels. The WHC, hardness, elasticity and cohesiveness of salt-soluble protein gels from shark muscle were positively correlated with NaCl concentration. Heating for 40-60 min at 40 ℃ led to a thorough gelation of salt-soluble protein obtained after 24 h extraction at pH 6.5-7.0 and the formed gels presented optimum WHC and texture characteristics. Forty degrees Celsius was an optimum temperature for the heat-induced gelation of salt-soluble protein. However, increasing heating time led to a higher hardness and a lower WHC.

Combining BP Neural Networks and Genetic Algorithms for Optimizing the Lipase Degreasing of Brewer s Spent Grains for Insoluble Dietary Fiber Production
XIAO Lian-dong,XU Bin,ZANG Jin,LI Hui-xing
2010, 31(14):  18-21.  doi:10.7506/spkx1002-6630-201014005
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Lipase degreasing was carried out as the first step in the production of insoluble dietary fiber from brewer's spent grains. Orthogonal array design was employed to provide a basis for the establishment of a mathematical model predicting the degreasing efficiency as a function of lipase hydrolysis conditions, namely enzyme amount, hydrolysis temperature and length of hydrolysis and the subsequent genetic algorithm optimization of these conditions. The established model displayed an error of 0.0001, indicating high reliability. The optimum values of enzyme amount, hydrolysis temperature and length of hydrolysis were found to be 0.7 g (on the basis of 10 g brewer s spent grains), 39.6 ℃ and 5.6 h, respectively, and the resultant degreasing efficiency reached up to 74.1%. The swelling capacity and water retention capacity of prepared IDF were 6.05 mL/g and 318.2%, respectively.

Optimization of Incubation Conditions for Polypeptide-enriched Wheat Germ
YANG Run-qiang1,GONG Xiao-feng1,GU Zhen-xin1,*,WU Zhi-jian2
2010, 31(14):  22-25.  doi:10.7506/spkx1002-6630-201014006
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In this study, incubation conditions including incubation time, incubation temperature, initial pH and liquid-tomaterial ratio (mL/g) for the polypeptide accumulation in wheat germ were investigated. The single factor investigations indicated that all of these conditions had significant effect on the polypeptide content of wheat germ. The response surface optimization based on a 4-factor, 3-level Box-Behnken experimental design revealed that the optimal values of incubation time and temperature, initial pH and liquid-to-material ratio were determined to be 6 h, 49 ℃, 3.0 and 10:1, respectively. After the incubation under such conditions, the maximum peptide polypeptide content of wheat germ reached up to 88.46 mg/g, 2.98 times higher than before incubation.

Antioxidant Activity of Hydrolysates from Shaoxing Duck Meat
ZHAO Chuan-chuan,PAN Dao-dong*
2010, 31(14):  26-31.  doi:10.7506/spkx1002-6630-201014007
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The optimal conditions for hydrolyzing Shaoxing duck meat by papain were investigated by single factor method and Box-Behnken experimental design coupled with response surface methodology. A maximum degree of hydrolysis (DH) was obtained under the following optimized hydrolysis conditions: 56.9 ℃, pH 7.2 and substrate-to-enzyme ratio 69.9:1 (m/m). The hydrolysates obtained under such conditions were evluated for their free radical scavenging activities, and the results showed that the IC50 values for scavenging superoxide anion, hydroxyl and DPPH free radicals were 13.06, 11.96 mg/mL and 21.13 mg/mL, respectively.

Optimization of NKA-Ⅱ Macroporous Resin Purification of Polyphenols from Apple Pomace Using Response Surface Methodology
BAI Xue-lian1,YUE Tian-li1,*,ZHANG Hua-wei2,CHEN Yan1
2010, 31(14):  32-36.  doi:10.7506/spkx1002-6630-201014008
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In order to optimize the NKA-Ⅱ macroporous resin purification of polyphenols from apple pomace, Box-Behnken experimental design coupled with multiple regression analysis was employed to establish separate mathematical models stimulating the adsorption and desorption behaviors of NKA-Ⅱ resin and based on the established models, response surface methodology (RSM) was employed to analyze the respective effects of interactions among adsorption conditions and among desorption conditions on the adsorption and desorption of apple polyphenols onto NKA-Ⅱ resin. The optimum dynamic adsorption conditions were as follows: sample flow rate 1.065 mL/min, pH 3.19, sample concentration 1.421 mg/mL, and the optimum dynamic desorption conditions were as follows: desorption flow rate 0.91 mL/min, ethanol concentration 73.99% and pH 8.90. The optimized purification provided a purity of apple polyphenols of 38.45%.

Phase Separation and Extraction with n- Hexane for the Preparation of High Purity Chlorogenic Acid
HU Ju-wu,LI Xiong-hui*,XIONG Wei,JI Qing-rong,TU Zhao-xiu,LI Xiang-yang
2010, 31(14):  37-41.  doi:10.7506/spkx1002-6630-201014009
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Macroporous resin 306 adsorption followed by phase separation and extraction was used to purify the crude chlorogenic acid extract from Eucommia ulmoides leaves. Ethyl acetate was selected for the phase separation of chlorogenic acid. The individual effects of length of extraction, pH and extraction times on the yield of chlorogenic acid were investigated in the single factor experiments. Box-Behnken experimental design was employed to provide a basis for the development of a mathematical model predicting the yield of chlorogenic acid as a function of length of extraction, pH and extraction times and subsequently, the interactive effects of the independent variables on their function were analyzed using response surface methodology (RSM). The optimal values of the independent variables were found to be: extraction time 3.40 min, pH 2.97, extraction times 4. Under these optimal conditions, the maximum yield of chlorogenic acid reached up to 95.1%. Non-polar nhexane was found to be the best choice for the transfer of chlorogenic acid from ethyl acetate phase to water phase among the tested 4 solvents and its optimal amount was determined to be 40% of the volume of the ethyl acetate phase containing chlorogenic acid. As a result, 93% of chlorogenic acid was transferred to the water phase. The purity of final chlorogenic acid product reached up to 99.5% (HPLC).

Pepsin Hydrolysis of Casein for the Preparation of ACE Inhibitory Peptides
ZHANG Yan,HU Zhi-he*,YAN Xing,FAN Hua
2010, 31(14):  42-46.  doi:10.7506/spkx1002-6630-201014010
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The optimal pepsin hydrolysis of casein for preparing ACE inhibitory peptides was explored by single factor and orthogonal array design methods. The optimal hydrolysis parameters were determined to be: 37 ℃, pH 3.0, enzyme-tosubstrate ratio 1:100, and substrate concentration 7%. The optimized pepsin hydrolysis yielded a product presenting 92.5% ACE inhibition ratio and 0.24 mg/mL IC50. The correlation between hydrolysis degree of casein and ACE inhibition ratio of its hydrolysates was complicated.

Microwave Heating for the Dry Preparation of Carboxymethyl Konjac Glucomannan and Its Properties
XIA Yu-hong1,LU Ran1,ZHONG Geng1,2,*,ZHAO Ya-nan1,HE Cui-chan1
2010, 31(14):  47-52.  doi:10.7506/spkx1002-6630-201014011
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In this study, microwave heating was used for the dry preparation of carboxymethyl konjac glucomannan (CMK) and its properties were also investigated. The effects of konjac glucomannan (KGM) -to-chloroacetic acid molar ratio, konjac glucomannan-to-sodium hydroxide molar ratio, microwave heating time and temperature on the degree of substitution (DS) were studied in the single factor experiments. Based on these studies, the optimal values of chloroacetic acid/KGM/sodium hydroxide molar ratio and reaction temperature and time determined by orthogonal array design to be 1.1: 1: 2.5, 75 ℃ and 8 min, respectively. Under these optimal reaction conditions, the maximum DS was up to 0.48. The final product obtained exhibited high solubility in water, excellent transparency and good stability. In addition, increasing DS resulted in higher water-absorbing and water-holding capacities.

Optimization of Microwave-assisted Extraction of Polysaccharides from Entermorpha prolifera Using Response Surface Methodology
GUO Lei1,2,CHEN Yu1
2010, 31(14):  53-57.  doi:10.7506/spkx1002-6630-201014012
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The microwave-assisted extraction technology of polysaccharides from Entermorpha prolifera (PEP) was optimized by using response surface methodology (RSM). The optimal extraction conditions were as follows: extraction temperature 95 ℃, microwave power 800 W, microwave treatment time 32 min and liquid/material ratio (mL/g) 78:1. Under the optimal conditions, the extraction yield of polysaccharides was 4.04%.

Purification of Aucubin from the Crude Extract of Eucommia ulmoides Seeds by Silica Gel Chromatography
LI Hui1,2,WANG Lan1,PENG Yu-dan1,ZHANG Yong-kang1,2
2010, 31(14):  58-61.  doi:10.7506/spkx1002-6630-201014013
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A silica gel chromatographic method was presented for the purification of aucubin (Au) from the crude extract of the residue of Eucommia ulmoides seed meal left after linolenic acid extraction. Subsequently, the extracted product was analyzed qualitatively and quantitatively. An optimal purification of Au was achieved by using a 2-fold mass of silica gel for Au adsorption followed by desorption with a 70% methanol/chloroform/petroleum ether/ethyl acetate mixture (7:1:0.5:1.5, V/V) at a flow rate of 1.0 mL/min. The eluate fractions were harvested and subjected to vacuum condensation, crystallization, filtration and recrystallization, and a final Au product with 96.56% purity was obtained.

Isolation and Purification of Milk Basic Protein from Cheese Whey
DONG Ting,LIU Hui-ping*,HU Zan-yang
2010, 31(14):  62-66.  doi:10.7506/spkx1002-6630-201014014
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Milk basic protein (MBP) is one part of whey protein. It has been reported to suppress osteoclast-mediated bone resorption in vitro. In the present study, MBP was extracted from byproduct whey of Mozzaralla cheese making by ion exchange chromatography and the resultant crude extract was purified by polydextran gel chromatography. Four strongly acidic cation exchange resins were used to adsorb MBP, and D072 type resin was selected due to the highest adsorption capacity. Single factor and orthogonal array design methods were employed to optimize conditions (desorption flow rate, temperature and concentration of desorption solvent, phosphate buffer) for the desorption of MBP from D072 type resin. The results showed that desorption flow rate had the most significant effect on MBP desorption, followed by temperature and desorption solvent concentration. Their optimum values were found to be: desorption flow rate 2.50 mL/min, temperature 40 ℃ and desorption solvent concentration 0.04 mol/L. Under these conditions, a MBP yield of 7.55% was obtained. After the purification with Sephadex G-100 with 4000 - 150000 D separation scope, a MBP product with 83.55% purity was obtained.

Using Macroporous Resin for Enriching and Purifying Total Flavonoids from the Crude Extract of Eucommia ulmoides Oliv. Leaves
FU Gui-ming1,LUO Yang-fan2,ZHANG Ya-nan2,WAN Yin2,CHAI Jian-xin2,CHEN Yong-hui1,WU Xiao-fang1,CHEN Jian-fang1
2010, 31(14):  67-70.  doi:10.7506/spkx1002-6630-201014015
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In this study, the leaves of Eucommia ulmoides Oliv. were extracted with absolute ethanol to obtain flavonoid compounds. The crude extract was purified using 4 macroporous adsorption resins, and AB-8 was found to be the best choice due to both the highest adsorption and desorption capacity. The optimum conditions for adorption/desorption of the crude extract of the leaves of Eucommia ulmoides Oliv. were as follows: sample concentration 193.92 mg/mL at pH 2, sample flow rate 2.6 mL/min, desorption flow rate 1.6 mL/min and amount of 80% ethanol required for desorption 30 mL. After the optimized purification, the concentration of flavonoids was improved from 10.2% to 42.6%.

Optimization of Three Oat Protein Extraction Processes and Comparisons of Amino Acid Composition and Nutritional Value among the Resultant Products
ZHAO Su-bin1,ZHANG Xiao-ping2,REN Qing2,*
2010, 31(14):  71-79.  doi:10.7506/spkx1002-6630-201014016
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The optimal process conditions for alkaline extraction, ultrasonic-assisted alkaline extraction and ultrasonic waveassisted alkaline extraction combined with enzymatic hydrolysis of proteins from oat bran were explored by single factor and orthogonal array design methods. The optimized alkaline extraction, ultrasonic-assisted alkaline extraction and ultrasonic waveassisted alkaline extraction combined with enzymatic hydrolysis presented oat protein yields of 31.96%, 39.31% and 61.43%, respectively, and the isoelectric points of the resultant products were 4.6, 3.6 and 3.8, respectively, according to the solubility and precipitation ratios at varying pH conditions and the corresponding precipitation ratios 57.92%, 63.24% and 72.24% at these isoelectric points, respectively. Moreover, the amino acid composition analysis and nutritional evaluation demonstrated that all of the resultant products displayed essential amino acid composition in good agreement with the FAO/WHO pattern. The product resulting from ultrasonic wave-assisted alkaline extraction combined with enzymatic hydrolysis exhibited a higher EAAI when compared to the products resulting from alkaline extraction and ultrasonic-assisted alkaline extraction, indicating a higher nutritional value.

Extraction and Fatty Acid Composition of Seed Oil from Xanthium sibiricum Patrin Wildly Grown in Xinjiang
ABULIKEMU Abulizi,DILINUER Talipu*,ABULIMITI Abudoukadeer,AISHA Nulahong
2010, 31(14):  80-83.  doi:10.7506/spkx1002-6630-201014017
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Soxhlet extraction was used to extract oil from the seeds of Xanthium sibiricum Patrin wildly grown in Xinjiang. The effects of extraction time, solid/liquid ratio and extraction temperature on oil yield were studied by single factor and orthogonal array design methods. Besides, the fatty acid composition of the extracted oil was measured by GC-MS. The results showed that the optimal values of the above parameters affecting oil yield were determined to be: extraction time 2.5 h, solid/liquid ratio 1:10 and extraction temperature 75 ℃. Under such conditions, the oil yield was 22.14%. Xanthium sibiricum Patrin seed oil contained mainly unsaturated fatty acids, and the relative contents of linoleic acid, oleic acid, palmitic acid, stearic acid were 85.73%, 7.67%, 3.76% and 1.35%, respectively.

Ultrasonic-assisted Alcalase Hydrolysis of Soybean Protein Isolate
2010, 31(14):  84-87. 
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In this study, soybean protein isolate (SPI) was pretreated by ultrasonic prior to alcalase hydrolysis. Single factor and orthogonal array design methods were employed to deal with the effects of length of ultrasonic treatment and some hydrolysis conditions (substrate concentration, enzyme/substrate ratio, hydrolysis temperature, initial pH and hydrolysis duration) on the degree of hydrolysis (DH) of SPI. The results showed that a maximum DH of 12.21% was obtained when 5.0% SPI was first subjected to ultrasonic pretreatment for 30 min, followed by hydrolysis at pH 8.0 and 55 ℃ for 4.0 h with alcalase added at 5.0% (on the basis of substrate amount).
Extraction and Purification of Procyanidins from the Seeds of Parthenocissus tricuspidata
DONG Ai-wen,YU Hua-zhong,FENG Ying-ying
2010, 31(14):  88-92.  doi:10.7506/spkx1002-6630-201014019
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In this study, we focused on the orthogonal array optimization of ethanol extraction of Parthenocissus tricuspidata seed procyanidins, followed by the investigations on macroporous resin purification of the crude procyanidin extract. The optimum conditions for ethanol extraction of Parthenocissus tricuspidata seed procyanidins were determined to be: ethanol concentration 60% (V/V), extraction temperature 70 ℃, extraction time 90 min and solid-to-liquid ratio 1:10 (g/mL); the procyanidin yield was 1.407% under such conditions. It was showed that AB-8 resin was more suitable for procyanidin purification and that the optimum purification conditions were as follows: sample concentration, 4 mg/mL; desorption solvent, 30% ethanol; and desorption flow rate, 2.0 BV/h. The purity of the final product was determined by HPLC to be 88.0%.

Extraction and Determination of Anthocyanins from Morus nigra L. Growing in Xinjiang
JIANG Yan
2010, 31(14):  93-96.  doi:10.7506/spkx1002-6630-201014020
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Anthocyanins in Morus nigra L. growing in Xinjiang was extracted with ethanol acidified with HCl (95% ethanol plus 0.1% HCl), and determined by pH differential method. The optimum values of extraction parameters including solid-toliquid ratio, length of extraction, extraction temperature and 0.1% HCl-to-95% ethanol ratio were determined by orthogonal array design to be: 1:20, 50 ℃, 90 min and 40:60, respectively, and solid-to-liquid ratio had the most important effect on anthocyanins yield, sequentially followed by length of extraction, extraction temperature and 0.1% HCl-to-95% ethanol ratio. Under the above optimum extraction condions, the anthocyanins yield was 0.0305%. pH differential method presented high reliability in quantifying anthocyanins in Morus nigra L.

Continuous Countercurrent Extraction and Antioxidant Activity of Flavonoids from Adinandra nitida Leaves
ZHAN Yu, LIANG Min-hua
2010, 31(14):  97-100.  doi:10.7506/spkx1002-6630-201014021
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In order to optimize conditions for the continuous countercurrent extraction (CCE) of flavonoids from Adinandra nitida leaves, the effects of countercurrent extraction stage, extraction temperature, amount of added water and extraction duration on flavonoids yield were explored in this study. The optimal extraction conditions were found to be: 4 stages for countercurrent extraction, extraction temperature of 100 ℃, material/water ratio of 1:30 (g/mL) and total extraction duration of 55 min with 25, 15, 10 min and 5 min for each stage. The DPPH free radical scavenging capacity of the flavonoids extract obtained under the above conditions was obviously stronger than that of BHT, an antioxidant widely used in the food industry.

Optimization of Polysaccharides Extraction from Lotus Bee Pollen by Response Surface Methodology
LIU Jie1,2,MIAO Xiao-qing1,2,3,*
2010, 31(14):  101-105.  doi:10.7506/spkx1002-6630-201014022
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This paper reports the use of single factor method and Box-Behnken experimental design combined with response surface methodology for optimizing the water extraction yield of lotus bee pollen polysaccharides (LBPP). In the optimization, a quadratic regression model predicting LBPP yield as a function of 3 extraction conditions, i.e., solid-to-liquid ratio, length of extraction and extraction temperature was set up and the effects of these 3 extraction conditions and their pairwise interactions on LBPP yield were evaluated. All of these extraction conditions had significant effect on LBPP yield and their optimum values were determined as follows: solid-to-liquid ratio 1:9.4 (g/mL) and extraction temperature 81.6 ℃ for an extraction duration of 2.4 h repeated twice. Under such conditions, the predicted and experimental values of LBPP yield were 1.2201% and 1. 2317%, respectively.

Using Response Surface Methodology for Optimizing Pectinase Hydrolysis of Loquat Slurry
ZHANG Yao1,PU Biao1,*,LIU Yun2,LIU Xing-yan1
2010, 31(14):  106-110.  doi:10.7506/spkx1002-6630-201014023
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The goal of this study was to develop an optimum process for hydrolyzing loquat slurry. A series of single factor experiments were carried out to address the effects of enzyme concentration, hydrolysis temperature and length of hydrolysis on juice yield and transmittance. Central composite design coupled with response surface methodology was employed to optimize these 3 hydrolysis conditions. It was indicated that all of the conditions significantly influenced juice yield and transmittance and that their optimum values were determined as follows: enzyme concentration 166.05 mg/kg, hydrolysis temperature 40.60 ℃ and hydrolysis duration 5.64 h. Under these optimum conditions, the experimental values of juice yield and transmittance were 91.17% and 76.24%, respectively, presenting a relative error of less than 1% when compared with the predicted counterparts.

Macroporous Adsorption Resin Purification of Total Flavonoids from the Crude Extract of Zanthoxylum bungeanum Leaves and Their Reducing Power and Free Radical Scavenging Activity
XU Huai-de,FAN Jing-hua
2010, 31(14):  111-115.  doi:10.7506/spkx1002-6630-201014024
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In the present study, we used macroporous resin adsorption to purify total flavonoids from the crude extract of Zanthoxylum bungeanum leaves and tested the reducing power and DPPH free radical scavenging activity of the final purified product. Eight macroporous resins were measured for their adsorption/desorption capacity towards total flavonoids from Zanthoxylum bungeanum leaves, and D4020 was the selected resin considering the highest adsorption capacity and higher desorption ratio. The optimum conditions for D4020 resin adsorption/desroption were as follows: sample (at pH 5, saturated with NaCl) concentration 2.19 mg/mL, sample flow rate 2 BV/h, desorption flow rate 2 BV/h and amount of 70% ethanol used as desorption solvent 2 BV. The optimized purification resulted in an increase in the purity of the total flavonoid extract of Zanthoxylum bungeanum leaves from 3.18% to 16.92%. In the presence of NaCl, the adsorption equilibrium ould be fitted by Freundlich isotherm equation. Moreover, the adsorption capacity increased with increasing NaCl amount. The IC50 of the final purified product for scavenging DPPH free radicals was 1.8 μg/mL, much lower than 4 μg/mL of VC, indicating better DPPH free radical scavenging activity; the final purified product also presented significantly higher reducing power than VC. Thus, Zanthoxylum bungeanum leaves deserve to be exploited as a plant resource containing flavonoid compounds.

Optimization of Process Conditions for the Extraction of Water Soluble Polysaccharides from the Flesh of Prunus sibirica L.
GUO Yong-xia,WANG Li-yan,YIN Kui-de*
2010, 31(14):  116-119.  doi:10.7506/spkx1002-6630-201014025
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Objective: To achieve full utilization of the Prunus sibirica L. resource, the fruit flesh of the plant was extracted to obtain water soluble polysaccharides (WSP). Methods: Single factor and orthogonal array design methods were used for providing experimental data for the response surface optimization of WSP yield, in which a mathematical model predicting WSP yield as a function of extraction conditions was established. Results: Extraction temperature was the most import factor affecting WSP yield, followed by length of extraction time and material-to-water ratio (mg/mL). The optimum levels of these 3 extraction conditions were found to be: material-to-water ratio 1:26 and extraction temperature 94 ℃ for an extraction duration of 2.8 h and the optimized extraction provided a WSP yield of 3.44%. Conclusion: The close agreement between the observed and predicted values of WSP yield demonstrates high reliability of the established model.

Simultaneous Extraction of Flavonoids and Polysaccharides from Asparagus officinalis
DUAN Ya-qing,MO Dan,LIU Bing,PAN Si-yi*
2010, 31(14):  120-124.  doi:10.7506/spkx1002-6630-201014026
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Dried Asparagus officinalis powder with particle size of 60 mesh was subjected to reflux extraction with aqueous ethanol solution held at a certain temperature for a certain period of time and an extract containing flavonoids and polysaccharides was then obtained. The effects of extraction number and temperature, ethanol concentration, material-to-liquid ratio (g/mL) and length of extraction on flavonoid yield were examined by single factor and orthogonal array design methods to maximize flavonoid yield. The extract was deproteinized by TCA method prior to polysaccharide precipitation with ethanol. A maximum flavonoid yield was obtained by the use of 25-fold volume of 70% ethanol to twice extract the material at 80 ℃ for 2 h each time. The addition of 1.0% TCA provided an optimum deprotainization. The supertanant harvested after centrifugation was added with 3-fold volume of 95% ethanol and thoroughly mixed, and the resultant precipitate was then separated by recentrifugation and vacuum dried to obtain a crude polysaccharide product, with a yield of 1.21%.

Supercritical Carbon Dioxide Extraction of Volatile Oil from Chrysanthemum morifolium
JIN Jian-zhong,TONG Jian-ying
2010, 31(14):  125-127.  doi:10.7506/spkx1002-6630-201014027
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In this study, the supercritical carbon dioxide extraction of Chrysanthemum morifolium volatile oil was optimized by single factor and orthogonal array design methods with respect to the effects of extraction pressure and temperature, length of extraction time and carbon dioxide flow rate. The optimum extraction conditions were determined as follows: extraction pressure 20 MPa, extraction temperature 55 ℃ and carbon dioxide flow rate 10 kg/h for an extraction duration of 2 h. Under such conditions, the oil yield was 5.92%.

Purification of Equol from Degradation Products of Soybean Isoflavones Resulting from Lactobacillus delbrueckii subsp. Bulgaricus Fermentation
LI Xiao-mei,AN Jing
2010, 31(14):  128-131.  doi:10.7506/spkx1002-6630-201014028
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MRS medium fortified with soybean isoflavones was fermented by Lactobacillus delbrueckii subsp. Bulgaricus at 37 ℃. As a result, soybean isoflavones were degraded, producing equol. Polyamide resin was used for purifying the crude equol extract from the harvested fermentation broth after 48 h fermentation. The optimal adsorption/desorption conditions were determined by single factor and orthogonal array design methods to be: sample concentration 2.40 μg/mL at pH 5, adsorption duration 6 h and amount of 80% ethanol used for equol desorption at a flow rate of 0.5 mL/min 45 mL. Under such conditions, the adsorption ratio of equol was 45.36%, and the desorption raio 60.00%.

Optimization of Processing Parameters for the Preparation of Nutritional Golden Corn Rich in Resistant Starch
JI Shu-juan1,YU Zi-jun1,2,WANG Yan-hong2,LIN Gui-feng2,WANG Shi-cheng2
2010, 31(14):  132-135.  doi:10.7506/spkx1002-6630-201014029
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In order to establish an optimum process for preparing nutritional golden corn rich in resistant starch (RS) from corn, the effects of key conditions for autoclaving treatment, aging and dehydration on resistant starch content were studied. The results showed that the optimum preparation process was that 40% corn porridge was initially subjected to autoclaving treatment at 125 ℃ for 60 min, followed by aging at 4 ℃ for 6 h and dehydration 60 ℃ for 16 h. The RS content of the finished product prepared under such conditions was 10.5%.

Effect of Extraction Methods on the Physico-chemical Properties of Green Tea Polyphenols
JIANG Li,WANG Xue-mei,QUAN Xue-jun*,RAN Xiu-zhi
2010, 31(14):  136-139.  doi:10.7506/spkx1002-6630-201014030
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Green tea polyphenols (TPs) were extracted by hot water reflux extraction, combination of cellulase hydrolysis and ultrasound-assisted extraction or each of them and extraction with room temperature water, respectively, and the resultant products were measured for their physico-chemical properties. The results showed that the extraction efficiency and product purity resulting from hot water reflux extraction at 90 ℃ were higher than those resulting from other 4 methods, but the product obtained had lower hydroxyl free radical scavenging activity than that obtained at lower reflux temperatures. Ultrasoundassisted extraction at room temperature exhibited better extraction efficiency and product purity, and the hydroxyl free radical scavenging activity of the product obtained was higher than that of the products obtained by other 4 methods. Combination of ultrasound-assisted extraction and cellulase hydrolysis gave better extraction efficiency; however, the purity and hydroxyl free radical scavenging activity of the product obtained were both lower than those of the product obtain by ultrasound-assisted extraction alone.

Extraction and Ferric Reducing Antioxidant Power of Polysaccharides from Four Edible Fungi
CHEN Xin,GONG Lan,LIU Guan-hui
2010, 31(14):  140-144.  doi:10.7506/spkx1002-6630-201014031
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In this study, we optimized key conditions for the water extraction and ethanol precipitation of polysaccharides from the edible fungi, Pleurotus eryngii, Lentinula edodes, Flammulina velutipes and Boletus edulis Bull using single factor and orthogonal array design methods and compared the reducing power of the products obtained. The results showed that the optimum values of extraction temperature, material-to-water ratio (g/mL), length of extraction and ethanol concentration were 90 ℃, 1:30, 1 h and 95% for Pleurotus eryngii polysaccharide extraction, 90 ℃, 1:20, 3 h and 85% for Lentinula edodes polysaccharide extraction, 80 ℃, 1:20, 2 h and 95% for Flammulina velutipes polysaccharide extraction, and 70 ℃, 1:40, 4 h, 95% for Boletus edulis Bull polysaccharide extraction, respectively. Under these optimum conditions, the corresponding polysaccharide yields were 3.89%, 5.93%, 2.79% and 9.48%, respectively. All of these four fungal polysaccharides had reducing power positively correlated with concentration. The reducing power of Boletus edulis Bull polysaccharides was the strongest. Also, the yield of Boletus edulis Bull polysaccharides was the highest. These results demonstrate Boletus edulis Bull appear to be a promising edible fungus.

Supercritical Carbon Dioxide Extraction of Lipid-soluble Components from the Roots of Codonopsis pilosula
LIU Tong-ju1,2,MIN Jiang1,LI Shu-fen1,*
2010, 31(14):  145-147.  doi:10.7506/spkx1002-6630-201014032
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Lipid-soluble components in the roots of Codonopsis pilosula were extracted with supercritical carbon dioxide, and the effects of material particle size, extraction pressure and temperature and length of extraction on the yields of crude extract and total saponins were investigated. The optimum conditions for the extraction of lipid-soluble components were determined to be: material particle size 380-250μm, extraction pressure 30 MPa, carbon dioxide flow rate 2 L/min and length of extraction 2 h. Under these optimum conditions, the yields of crude extract and total saponins were 1.11% and 2.23‰, respectively.

Modification Optimization of Insoluble Dietary Fiber from Soybean Dregs
TIAN Cheng1,MO Kai-ju1,2,WANG Xing-ping1,2,*
2010, 31(14 ):  148-152.  doi:10.7506/spkx1002-6630-201014033
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The phosphate modification of insoluble dietary fiber (IDF) from soybean dregs was optimized by single factor and orthogonal array design methods for maximizing its water-binding capacity (WBC). Meanwhile, the structure of modified soybean IDF was observed using X-ray diffraction and scanning electron microscopy. It was found that the optimum conditions for soybean IDF modification were as follows: disodium hydrogen phosphate concentration 0.1 g/100 mL, material/liquid ratio 1:60 (g/mL) and modification temperature 50 ℃ for a modification duration of 1 h and that the WBC of modified soybean IDF under these optimum conditions was up to 11.95 g/g. After phosphate modification, the structure of soybean IDF was improved partially and the surface became slightly wrinkled and loose and displayed distinct sheeting structure. What’s more, an evenly distributed honeycomb-like surface structure of modified soybean IDF granules was observed. The X-ray diffraction pattern of modified soybean IDF showed a remarkable intensity peak at 34.76 ℃, with a crystallinity of 30.57%.

Analysis & Detection
SYBR GreenⅠReal-time Polymerase Chain Reaction for the Detection of HAV in Strawberry
MO Xue-mei1, GAO Dong-wei 2,*
2010, 31(14):  153-157.  doi:10.7506/spkx1002-6630-201014034
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A SYBR GreenⅠ real-time polymerase chain reaction (RT-PCR) method using the primers designed to encompassing the conservative region of vp3/vp1 in the HAV was developed for the detection of HAV in strawberry. The limit of detection of the method was 101 TCID50. The standard curve was Ct = -3.052 lg(TCID50 )+ 34.57, displaying good linearity over a linear range from 101 to 105 TCID50 with 0.9961 correlation coefficient. This method was specific to HAV without any cross-reaction with rotavirus, adenovirus, norovirus or astrovirus. The coefficients of variation (CV) for determining HAV standards with different titers by this method were between 0.85% and 1.71% (n = 5) in intra-assay and between 0.76% and 1.98% (n = 3) in inter-assay. Totally 45 strawberry samples were examined, and 3 of them were found positive. This method is sensitive, specific and reliable, and can be used for the rapid detection of HAV in fruits and vegetables.

Identification of Reconstituted Milk Using a Commercially Available Lactate Dehydrogenase Kit
ZHAO Yue,PANG Guang-chang*,ZHU Jian-chun
2010, 31(14):  158-160.  doi:10.7506/spkx1002-6630-201014035
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Lactate dehydrogenase exists widely in human and animal tissues and body fluids. Due to the temperature influence in different processing technologies, the activity of lactate dehydrogenase was different in pasteurized milk, ultra-high temperature- treated milk and reconstituted milk. A commercially available lactate dehydrogenase kit was used to determine the activity of lactate dehydrogenase in pasteurized milk, ultra-high temperature-treated milk and reconstituted milk for identifying reconstituted milk. Results indicated that the activity of lactate dehydrogenase of pasteurized milk was significantly higher than those of ultra-high temperature-treated milk and reconstituted milk. This method is of easy operation, rapidity and high accuracy and consequently, deserves to be popularized.

Steam Distillation or Headspace Extraction Coupled to Gas Chromatography-Mass Spectrometry for the Volatile Composition Analysis of White Pepper
QIU Li-li,RONG Rong*,ZHANG Ying,JIANG Hai-qiang,LI Feng,WANG Zhen-guo
2010, 31(14):  161-164.  doi:10.7506/spkx1002-6630-201014036
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In the present study, steam distillation and static headspace extraction were separately coupled to gas chromatography- mass spectrometry (GC-MS) to analyze the volatile composition of white pepper. The white pepper volatile oils derived from steam distillation and static headspace extraction had different chemical compositions. Totally 32 volatile components were identified in the oil derived from static headspace extraction, whereas 26 in the oil derived from steam distillation. Totally 18 were found in both the oils, but each of them exhibited different relative contents in both the oils. Moreover, both the sampling methods provided useful information about boiling point of volatile compounds so that it was feasible to establish a system for the GC-MS characterization of white pepper.

Oil Contents and Fatty Acid Composition of the Seeds of the Genus Perilla from Different Geographical Origins
HU Yan1,2,DING You-fang1,WEN Chun-xiu3,XIE Xiao-liang3,ZHOU Qiao-mei3,LIU Yu-jun1,*
2010, 31(14):  165-169.  doi:10.7506/spkx1002-6630-201014037
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Soxhlet extraction was used to extract seed oils from 10 plant samples (from different areas of China) belonging to 5 varieties of the genus Perilla, followed by the fatty acid composition analysis using GC-MS. The oil contents of these 10 Perilla seed samples ranged from 33.49% to 42.58%. The one-way analysis of variance achieved using software package SPSS 11.0 showed that there was a significant difference in oil content among these 10 Perilla seed samples. The GC-MS analysis indicated that these 10 Perilla seed samples exhibited simple fatty acid composition. Palmitic acid, linoleic acid, α-linolenic acid and stearic acid were found in all of these 10 Perilla seed samples. Oleic acid was found only in Perilla seed samples No. 1, 2, 3 and 5 and 10-octadecenoic acid only in Perilla seed samples No.4 and 6-10. The relative contents of α-linotenic acid of these 10 Perilla seed samples ranged from 71.75% to 80.06% and the content of unsaturated fatty acids from 88.80% to 92.82%.

Fatty Acid Composition and Biological and Physical Properties of Pomegranate Seed Oil
YUAN Bo,GE Qun-mei,FENG You-jian,JIANG Ji-hong *
2010, 31(14):  170-173.  doi:10.7506/spkx1002-6630-201014038
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Pomegranate seed oil (POS) was extracted with petroleum ether oil under the assistance of ultrasonic. Its fatty acid composition was analyzed by GC-MS and its biological and physical properties were also measured. POS was determined to contain 6 fatty acids, among which, the relative content of octadecanoic acid was the highest, 71.538%. From the Schaal oven test results, the antioxidant effect of POS was better than that of VE. POS had excellent DPPH scavenging activity and the scavenging rate was up to 80.61%. In addition, PSO might provide a promising rigidity agent for paint production due to its excellent drying performance.

A Biosensor for the Detection of Catalase-positive Microorganisms in Food
YAO Bing,LIU Xiao-fang,CHAI Chun-yan,LIU Guo-yan*
2010, 31(14):  174-177.  doi:10.7506/spkx1002-6630-201014039
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Objective: To develop a biosensor for detecting catalase-positive microorganisms in food. Methods: HRP was immobilized onto screen-printed electrodes (SPE) and an analytical system was established by inserting SPE into the electrode slot connected with an electrochemical workstation. Results: For most food samples from different sources, this method allowed detection of positive signals based on current change when the number of catalase-positive microorganism colonies reached up to 104 CFU/mL. The length of time required for food detection was dependent on the number of catalase-positive microorganism colonies and a period of time ranging from 1 to 3 h was enough for the detection of most food samples. Catalase-positive microorganisms contained in food samples at 0.1 CFU/mL needed to be enriched for 7 h, at the longest. Conclusion: This method is convenient, sensitive and accurate, and deserves to be popularized.

Determination of Polyphenols in Different Organic Solvent Extracts of Semen Astragali complanati
ZHANG Qing-an1,2,FAN Xue-hui3,ZHANG Zhi-qi2,MA Xue-yan1,CHEN Yu1,WANG Jun1
2010, 31(14):  178-181.  doi:10.7506/spkx1002-6630-201014040
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In order to provide an optimal Folin-Ciocalteu assay for determining polyphenols in different organic solvent (ethanol aqueous solution, acetone aqueous solution and methanol aqueous solution all at 60% cocentration) extracts of Semen Astragali complanati, some Folin-Ciocalteu assay conditions were optimized. The results indicated that the optimal conditions for the determination of polyphenols by Folin-Ciocalteu were as follows: 10-fold diluted Folin-Ciocalteu reagent amount 1.00 mL, 7.5 g/100 mL Na2CO3 amount 3 mL, reaction temperature 25 ℃, reaction time 120 min, and determination wavelength 647 nm. A good linear relationship was observed between absorbance and gallic acid concentration within the range of 10-100 μg/mL (y = 0.0081x -0.0249, R2 = 0.9996). In addition, accurate contents of polyphenols in methanol extract, ethanol extract and acetone extract of Semen Astragali complanati diluted to a concentration of 1 g/100 mL was determined by this method.

Determination of Ametryn Residue in Four Plant-derived Foods by Gas Chromatography Coupled with Solid Phase Extraction
WANG Yu-jian1,HUANG Hui-ling1,JIANG Lin-juan2,ZHUO Hai-hua1,LIU Hong-zhuan1
2010, 31(14):  182-185.  doi:10.7506/spkx1002-6630-201014041
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A method using solid phrase extraction (SPE) followed by gas chromatography with flame photometric detection (GC-FPD, S-type filter) has been developed for determining ametryn residue in 4 plant-derived foods. Samples were extracted and cleaned up on an ENVI-Carb/NH2 column using acetonitrile/toluene (7:2) as elution solvent. The quantification method employed was external standard method. Under the selected analytical conditions, the detection limit was 0.01 mg/kg. Average recovery rates for the analyte in rice, apple, banana and eggplant spiked at 3 levels ranged from 88.0% to 100.0% with relative standard deviations (RSD) from 3.71% to 11.71%. This method is sensitive, precise and reproducible and has stable recovery. These figures of merit demonstrate its good applicability.

Optimization of Precolumn Derivatization for Simultaneous Gas Chromatography-Mass Spectrometric Analysis of Non-volatile Flavor Compounds in Angeleno Plum Fruit
HU Ling,WANG You-sheng*,LI Li-ping
2010, 31(14):  186-190.  doi:10.7506/spkx1002-6630-201014042
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This paper reports the orthogonal array optimization of some conditions for precolumn derivatization of nonvolatile flavor compounds from Angeleno plum fruit prior to gas chromatography-mass spectrometric (GC-MS) analysis. An optimal derivatization was achieved by allowing 200 μL of methanol extract of Angeleno plum fruit to react with 250μL of pyridine containing 20 mg/mL of methoxyamine hydrochloride for 2-2.5 h at 30 ℃, followed by addition of 250 μL of MSTFA for reaction at 37 ℃ for another 30 min. Storage for 24 h was carried out before GC-MS analysis. This method can allow the rapid simultaneous determination of organic acids, sugars and amino acids in plum fruit with good reproducibility.

Determination of Cyclohexanediones Herbicide Residues in Foodstuffs of Animal Origin by QuEChERS-HPLC-MS/MS
YANG Chang-zhi1,CHEN Li2,LIU Yong1,KANG Qing-he1,WU Yan1,CHENG Yang1
2010, 31(14):  191-196.  doi:10.7506/spkx1002-6630-201014043
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A HPLC-MS/MS method based on QuEChERS extraction has been developed for determining cyclohexanediones herbicide residues in foodstuffs of animal origin. Cyclohexanediones herbicide residues in samples were extracted with acidic acetonitrile under the assistance of high-speed homogenization. The extract was cleaned up with N-propyl ethylenediamine (PSA), octadecylsilane (ODS) and graphitized carbon black prior to HPLC-MS/MS analysis. The calibration curves of 8 cyclohexanedione compounds developed all exhibited good linearity over a concentration range from 0.0025 to 0.1000 μg/mL, with a correlation coefficient ranging from 0.9973 to 0.9996. Average recoveries for the analytes in pork spiked at 0.005, 0.010 mg/kg and 0.050 mg/kg were between 75.68% and 106.80%, with a relative standard deviation between 6.65% and 11.04%. The detection limit was 0.005 mg/kg for all of the analytes.

Determination of Chlormequat Residues in Vegetables by High Performance Liquid Chromatography-Mass Spectrometry
ZHOU Yan-ming,HAN Yu,TIAN Hong-zhe,CHEN Bai
2010, 31(14):  197-200.  doi:10.7506/spkx1002-6630-201014044
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A analytical method using high performance liquid chromatography (HPLC) combined with electrospray ionization mass spectrometry (ESI/MS) was developed for determining chlormequat residues in vegetables. Samples were extracted with methanol/water/acetic acid, and the extract was then centrifugated. The supernatant was harvested and cleaned up on a SPE-SCX column before HPLC-ESI/MS analysis. Retention times and characteristic ions were used for qualification and external standard method for quantification. A good linear of the calibration curve developed was exhibited over a concentration range of 0.03-10 μg/mL with a correlation coefficient of 0.9991. Average recoveries for chlormequat in 5 vegetables ranged from 74.92% to 103.28% with a relative standard deviation from 2.92% to 10.48%. The quantitative limit for chlormequat was 0.02 mg/kg.

Determination of Polyphenol Content in Houttuynia cordata Thunb. by Folin-Ciocalteu Colorimetric Method
CAI Wen-guo,WU Wei*,SHAO Jin-feng,CHEN Que,WANG Yuan-biao,LIU Zheng-qiong
2010, 31(14):  201-204.  doi:10.7506/spkx1002-6630-201014045
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Objective: To establish a quantitative method to assay total polyphenols in Houttuynia cordata Thunb.. Method: Four solvents (methanol, ethanol, acetone and water) were used to extract Houttuynia cordata Thunb. with the assistance of ultrasonic in order to explore the effects of extraction solvent type and length of extraction on the extraction of total polyphenols. Subsequently, the 2 h ethanol extract was used to optimize 20% sodium carbonate amount, Folin-Ciocalteu regent amount, reaction temperature and length of reaction. Results: Methanol was the best extraction solvent, followed by ethanol, acetone and water. The optimum conditions for determining total polyphenols in Houttuynia cordata Thunb. were as follows: a mixture of 0.5 mL of methanol extract, 2.0 mL of 20% sodium carbonate and 1.5 mL of Folin-Ciocalteu reagent diluted with distilled water to 50.0 mL for incubation at 55 ℃ for 1.5 h, followed by detection at 760 nm. Conclusion: The method is simple, accurate and provides an appropriate method for measuring total polyphenols in Houttuynia cordata Thunb.

Determination of Total Amount of Sibutramine and Its Active Metabolites in Weight-reducing Food
YANG Chun-hua1,WANG Wei2,LI Gang2,*,LUO Wen-wen3
2010, 31(14):  205-208.  doi:10.7506/spkx1002-6630-201014046
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Objective: To establish a HPLC and HPLC-MS method for determining the total amount of sibutramine and its active metabolites, N-desmethyl sibutramine and N-di-desmethyl sibutramine in weight-reducing food. Methods: Samples were subjected to methylation treatment with formaldehyde and potassium borohydride in ice bath in order to convert active sibutramine metabolites into sibutramine. Results: The linear range of the method was between 10 and 200 mg/L and the regression equation was y = 89.59847x-1.05361 with a correlation coefficient of 0.9999. The detection limit was 1 mg/kg. The average recovery for the total amount of sibutramine and its active metabolites was 83% with a RSD of 4.5%. Conclusion: The established method is simple, accurate and rapid and has good selectivity. It is most suitable for determining total amount of sibutramine and its active metabolites in weight-reducing food.

Fatty Acid Composition of the Muscle of Lateolabrax japonicus (Cuvier) Grown in Seawater and Freshwater
XU Jian-he1,XU Jia-tao1,LIN Yong-jian2,LUO Gang1,BI Xiang-jing1
2010, 31(14):  209-211.  doi:10.7506/spkx1002-6630-201014047
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Lipids in the dorsal muscle of Japanese seabass Lateolabrax japonicus grown in seawater and freshwater fortified with the same feed were extracted by reflux extraction with “Folch” solvent, esterified with KOH-BF3 method and analyzed by gas chromatography. The results indicated that an obvious difference in fatty acid profile was observed between the muscles of Japanese sea basses grown in seawater and freshwater. The muscle of Japanese seabass from seawater exhibited higher contents of monounsaturated fatty acids (MUFA), n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acids (EPA, C20:5 n-3) and docosahexaenoic acids (DHA, C22:6 n-3), and lower levels of saturated fatty acids (SFA), n-6 PUFA and arachidonic acids (AA, C20:4 n-6). The ratios of n-6/n-3 fatty acids in the muscles of seawater and freshwater sea basses were 0.27 and 0.42, respectively. both significantly lower than maximum safety standard (4.0) recommended by the UK Department of Health.

RP-HPLC Determination of Water-soluble Vitamins in Functional Beverages
ZHANG Zhi-qing,BAI Qi,ZHAN Jun-wen,YAO Yan-yan
2010, 31(14):  212-215.  doi:10.7506/spkx1002-6630-201014048
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Objective: To develop an HPLC method for the simultaneous determination of several water-soluble vitamins in functional beverages. Methods: Luna C18(2) column (200 mm × 4.60 mm, 5μm) was used as stationary phase. The mobile phase was composed of 0.005 mol/mL hexanesulfonste sodium, methanol and glacial acetic acid (80: 20: 0.5) at pH 4.0. The flow rate was 1.0 mL/min. The wavelength of UV detection was set at 278 nm. Results: The standard curves developed exhibited a good linear over a range of 2.94-43.50μg/mL for VC, 6.00-90.00μg/mL for VPP, 1.70-25.50μg/mL for VB6, 1.60 -24.00μg/mL for VB2, and 2.30-43.50μg/mL for VB1. The detection limits for VC, VPP, VB6, VB2 and VB1 were 0.001, 0.362, 0.095, 0.328μg/mL and 0.619μg/mL, respectively. The average recoveries were 98.29% for VC, 98.38% for VPP and 98.51% for VB6. Conclusion: This method is simple, fast and accurate. It allows the simultaneous determination of water-soluble vitamins in functional beverage.

Effects of Processing and Storage Conditions on Selenomethionine Content in Edamame Determined by Gas Chromatography-Mass Spectrometry
ZHANG Hao1,MO Hai-zhen1,ZHOU Quan-xia1,ZHANG Min2
2010, 31(14 ):  216-220.  doi:10.7506/spkx1002-6630-201014049
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A gas chromatography-tandem mass spectrometric (GC-MS/MS) method was set up for selenomethionine determination based on the collision-induced ion fragmentation pattern of its derivatives in order to investigate the change of selenomethionine content in edamame during processing and storage. After 4 weeks of storage at 4 ℃, fresh edamame presented a selenium loss of 13% (based on the content of selenomethionine). Throughout the whole storage of 6 months at room temperature, the selenomethionine degradation of dehydrated edamame remained lower than that of edamam juice significantly increasing. This indicates that dehydration greatly contributes to selenomethionine retention. Blanching had little effect on selenomethionine loss and the percentage retention of selenomethionine still kept over 85%. Lypholization resulted in the highest percentage retention of selenomethionine, followed by vacuum drying and hot air drying and the resultant percentage retentions of selenomethionine were all over 80%. The lowest percentage retention of selenomethionine (30%-40%) was found in edamame dehydrated by spray drying. This is probably due to large contact area with air.

Changes in Volatile Compounds of Psophocarpus tetragonolobus [L.] D.C. Seeds Before and After Aspergillus oryzae Fermentation
JIANG Li-wen1,ZHENG Bing-fu1,LIAO Lu-yan1,CHEN Dong-ming2,LI Bai-yu1
2010, 31(14 ):  221-224.  doi:10.7506/spkx1002-6630-201014050
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In this study, GC-MS was used to examine the changes in the volatile compounds of the seeds of winged bean, Psophocarpus tetragonolobus [L.] D.C. before and after Aspergillus oryzae fermentation. Totally 88 compounds were identified in either fresh or fermented winged bean seeds. After Aspergillus oryzae fermentation, the volatile composition of winged bean seeds changed greatly and lots of new compounds were generated. Only phenyl acetaldehyde and 3,3,5-trimethylcyclohexanone were found in both fresh and fermented winged bean seeds. The main volatile compounds in fresh winged bean seeds were ketones, alcohols and alkenes, while in fermented winged bean seeds, those were esters, ethers and alkenes.

Determination of Sulfur Dioxide in Preserved Fruits Using Auto-Kjeldahl s Apparatus Combined with Automatic Potentiometric Titrator
XIE Yan-yun,ZHANG Ming-ming,DENG Ying-yan,SUN Yuan-ming,LIU Chun-hong*
2010, 31(14):  225-228.  doi:10.7506/spkx1002-6630-201014051
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A method using FOSS 2200 auto-Kjeldahl s apparatus coupled with Metrohm 809 automatic potentiometric titrator was developed to determine sulfur dioxide in preserved fruits. This method is simple, rapid and accurate and the whole process only needs 6 minutes. No significant difference (P > 0.05) between determination results obtained using Kjeldahl s apparatus and glass distiller for distillation was observed. The relative error of this method was lower than 0.94%. Average spike recovery rates for sulfur dioxide in 5 preserved fruits were between 90.39% and 103.40%, and the detection limit was 2.6 mg/kg. Therefore, this method is most suitable for determining sulfur dioxide in solid and liquid food samples.

Chemical Composition Analysis of the Essential Oil of Hemp Seeds by Simultaneous Distillation and Solvent Extraction Coupled with GC-MS
DAI Huang1,FANG Guo-shan1,LI Wen-feng1,WANG Xiao-wei1,LIU Fei1,MING Jian1,2,*
2010, 31(14):  229-233.  doi:10.7506/spkx1002-6630-201014052
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Hemp seed oil was extracted by simultaneous distillation and solvent extraction (SDE). The yield of oil was 0.096%. The oil was subjected to gas chromatography-mass spectrometric analysis (GC-MS). A total of 128 components were well separated, of which 95 were identified, altogether accounting for 90.88% of the total components. The main compounds identified and their relative contents were as follows: α-caryophyllene (7.59%), pentadecanoic acid (5.74%), 4-hydroxy-2-methylacetophenone (5.45%), a,a,4-trimethyl-benzenemethanol (5.38%), naphthalene and derivative (5.22%), 2(3H)-furanone (3.49%), 1-methoxy-4-(1-propenyl)-benzene (3.71%), caryophyllene oxide (3.59%), D-limonene (3.16%), benzeneacetaldehyde (3.03%), 3-methoxy-1,2-propanediol (2.97%), phenol (2.85%), humulene (2.56%), 2-cyclohexen-1-ol (2.14%), indole (1.64%), 1,3,3-trimethyl-bicycloheptan-2-ol (1.41%), hexanal (1.18%), 8-methyl-1- undecene (1.15%), tetradecane (1.07%) and citral (1.02%).

Spectrophotometric Determination of Citrulline in Wine
LIANG Xin-hong,SUN Jun-liang,ZENG Jie
2010, 31(14):  234-237.  doi:10.7506/spkx1002-6630-201014053
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Citrulline in wines spontaneously reacts with alcohol to produce ethylcarbamate, which is well known to be carcinogenic. In this paper, a method is described for colorimetric determination of citrulline in wine based on Fearon reaction. The results showed that the optimal conditions were as follows: 350 mL of sulfuric acid, 200 mL of phosphoric acid and 50 mg of ferric chloride comprising a 1 L reaction system held at 100 ℃ for 5 min, followed by cooling to room temperature in the dark and detection at 530 nm. The detection limit of the method was 5μg/L. The precision RSDs of determining two red wine and one white wine (all of them freshly brewed) ranged from 2.4% to 3.2%. Mean recoveries in these 3 wines ranged from 96.9% to 106.6%. The method descried in this paper is accurate and reliable, and it is most suitable for determination of citrulline in wine.

Isolation, Purification and Antioxidant Activity of Polysaccharides from the Fruit Body of Panus giganteus (Berk.) Corner
FU Ming-hui,CHEN Jie-qiong
2010, 31(14):  238-240.  doi:10.7506/spkx1002-6630-201014054
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The polysaccharides in the fruit body of Panus giganteus (Berk.) Corner were extracted with hot water, and precipitated with ethanol. The crude polysaccharides were then deproteinized by Sevage method, followed by DEAE 52 column chromatographic purification/fractionization. As a result, 2 fractions were obtained. Finally, fraction A, the first elution peak on DEAE 52 column was further purified by Sephadex S-200 column chromatography, and only one peak was observed in the elution profile, indicating this faction contains only a single component. It was found that fraction A could inhibit lipid peroxidation in mouse liver homogenate in vitro in a concentration-dependent way.

Determination of Resveratrol and Polydatin in Mulberry
ZHAO Kang1,2,SU Zheng-rong3,YANG Bi-wen3,TAN Feng2,DENG Jun1,*
2010, 31(14):  241-244.  doi:10.7506/spkx1002-6630-201014055
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An analytical method was established to determine the contents of resveratrol (Res) and polydatin (PD) in mulberry using HPLC with phenomenex C18 column (150 mm × 4.6 mm, 4μm) based on gradient elution with MeOH/H2O at a rate of 0.8 mL/min and detection at 305 nm. The method exhibited good linearity over concentration ranges from 0.5 to 50μg/mL for Res and from 2 to 100μg/mL for PD. The mean recoveries (n = 3) for Res and PD at 3 spike levels were 99.0% and 98.28%, respectively, with corresponding RSDs of 3.86% and 1.18%. The content of PD was always higher than that of Res throughout the whole maturation phase. Both compounds reached their separate maximum levels in mid-red period; however, a slight reduction was observed in the purple period. Meanwhile, Xinong 1 had the highest level of total Res (original Res plus Res derived from hydrolyzed PD), reaching up to 94.5μg/g. Therefore, mulberry is rich in Res and the best harvest time should be the initial period of fruit color change from red to purple.

Simultaneous UPLC-MS/MS Determination of Four Artificial Sweeteners in Luzhou Flavor Liquor and Flavoring Agents
GUO Ying-ying,QIAO Shan-lei,LI Lei*,ZHOU Jing-ping,DAI Jin-feng
2010, 31(14):  245-249.  doi:10.7506/spkx1002-6630-201014056
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Objective: To establish a UPLC-MS/MS method for the simultaneous determination of four artificial nonnutritive sweeteners, cyclamate, saccharin, acesulfame-K and aspartame in Luzhou flavor liquor and flavoring agents. Methods: The chromatographic separation was achieved on a Waters ACQUITY UPLC BEH C18 column (50 mm × 2.1 mm, 1.7μm) using acetonitrile/0.01% ammonia water as mobile phase in the gradient elution mode at a flow rate of 0.2 mL/min. Electrospray ionization (ESI) in the negative ion mode followed by triple quadrupole mass spectrometric analysis in the multiple reaction monitoring mode (MRM) was used for quantification. Results: The concentrations of these four sweeteners ranging from 10 to 1000μg/L had good linear relationship with the peak area. The limits of detection (LODs) ranged from 0.03 to 0.35μg/L. The average recoveries for them were between 75 .2% and 115.3% in Luzhou flavor liquor sample NO and between 100.3% and 116.1% in flavoring agent sample W3 and the relative standard derivations were all within 8%. The contents of cyclamate, saccharin and aspartame in 10 Luzhou flavor liquor samples and 5 flavoring agent samples tested in this study were found to range from 0 to 287 μg/L, from 0 to 67.2 μg/L and from 0 to104.8μg/L, respectively, but none of them was found to contain acesulfame-K. Conclusions: The method is of simplicity and presents lower LODs than other methods reported previously. Thus it is more suitable for simultaneous determination of trace amount of sweeteners in distillate spirit.

Content Comparisons of Six Isoflavones in Soybean Meals Fermented by Different Microorganisms
LI Yi-sheng,CHEN Jian-ping,LIN Rong-feng,HE Yao-hui,HUANG Xiao-qi,SU Zi-ren
2010, 31(14):  250-253.  doi:10.7506/spkx1002-6630-201014057
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A high-performance liquid chromatographic method was presented for the determination of the contents of six isoflavones. An Alltima C18 column (150 mm × 4.6 mm, 5μm), whose temperature was set at 35 ℃ was used for the chromatographic separation, which was achieved using methanol/water as mobile phase in the gradient elution mode. The detection wavelength was set at 254 nm. The injection amounts of six isoflavones over respective ranges displayed good linear relationship with the peak area and the correlation coefficients equaled or exceeded 0.9998. The average spike recoveries for six isoflavones ranged from 97% to 102%, with a RSD of less than 3%. There were significant differences in the contents of six isoflavones among soybean meals fermented by different microorganisms.

Pressurized Solvent Extraction and HPLC Determination of BHA and BHT in Food
LIN Tai-feng1,2,LIU Yang1,WANG Hui-qin1,2,ZHENG Da-wei1,2,LUO Yun-jing1,2,ZHANG Shu-fen1,2
2010, 31(14):  254-257.  doi:10.7506/spkx1002-6630-201014058
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The purpose of this study was to establish a method for determining butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in food using pressurized solvent extraction (PSE) and HPLC. The simultaneous PSE extraction of BHA and BHT was optimized using orthogonal array design with respect to the effects of extraction temperature and pressure, extraction solution type and length of extraction, and the optimum values of these extraction parameters for achieving the maximum sum of extraction yields of BHA and BHT were. Under the optimized PSE extraction conditions, the average spike recoveries for BHA and BHT determined by the analytical method ranged from 92.60% to 97.80% with RSDs from 0.5% to 3.1%. The developed method exhibited good linearity over the range from 1.0 to 200.0μg/mL, with a correlation coefficient of no less than 0.9997 and the detection limit was 0.05μg/mL This method is simple, fast and efficient and has good repeatability. It is most suitable for the simultaneous determination of BHA and BHT in food.

Non-destructive Measurement of Soluble Solids, Vitamin C and Titratable Acidity of Hamlin Sweet Orange using Vis/NIR Spectrometry
MAO Sha-sha1,ZENG Ming1,HE Shao-lan2,ZHENG Yong-qiang2,YI Shi-lai2,
2010, 31(14):  258-263.  doi:10.7506/spkx1002-6630-201014059
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The potential of reflectance visible/near infrared spectroscopy (VNIRS) was investigated for measuring total soluble solids (TSS), vitamin C (VC) and titratable acidity (TA) in Hamlin orange fruit (Citrus sinensis L.). VNIR spectra of Hamlin orange fruits harvested at different times were measured and related with the contents of TSS, VC and TA by partial least squares (PLS) method to establish nondestructive models for predicting the TSS, VC and TA in the fruit. Meanwhile, the effects of different spectral pretreatment methods and spectral waveband range on the performance of the established models were also investigated. The results showed that the PLS models of original spectra within the waveband range from 400 to 1000 nm gave optimal predictions for TSS, VC and TA. Through multiple scatter calibration and 5-point moving-average smoothing pretreatment, an optimal TSS prediction model was obtained, with a correlation coefficient of 0.995 and a root mean square error of calibration (RMSEC) of 0.026% for the calibration sample set and a correlation coefficient of 0.992 and a root mean square error of prediction (RMSEP) of 0.028% for the validation sample set. Multiple scatter calibration and 9-point moving-average smoothing pretreatment gave an optimal TA prediction model, with a correlation coefficient of 0.997 and a RMSEC of 0.012% for the calibration sample set and a correlation coefficient of 0.997 and a RMSEP of 0.013% for the validation sample set. An optimal VC prediction model was also obtained through multiple scatter calibration and 9-point moving-average smoothing pretreatment, with a correlation coefficient of 0.998 and a RMSEC of 0.009% for the calibration sample set and a correlation coefficient of 0.999 and a RMSEP of 0.009 for the validation sample set. These results suggest that the use of a sample set comprising Hamlin organe fruits collected at different harvesting times can improve the accuracy of a PLS prediction model.

Comparison of Three Chromatographic Methods for the Determination of Melamine in Powdered Milk
LIU Ju,ZHENG Ting,CHANG Cheng,LIU Xia,ZHANG Wei-wei,SHI Chao-ou*
2010, 31(14):  264-267.  doi:10.7506/spkx1002-6630-201014060
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Three chromatographic methods, i.e., reversed-phase ion pair chromatography, hydrophilic interaction chromatography and cation exchange chromatography, were established to determine melamine in powered milk. Before hydrophilic interaction chromatographic analysis, samples were extracted with formic acid, precipitated with acetonitrile for the removal of proteins and centrifugated. While for other two methods, the sample pretreatment was based on extraction with aqueous acetic acid solution, precipitation, centrifugation and cleanup on a RP column. The chromatographic separation was performed on a C18 column using a mobile phase composed of a buffer solution containing 10 mmol/L sodium heptanesulfonate and 10 mmolL citric acid and acetonitrile (85:15, V/V) in reversed-phase ion pair chromatographic analysis. A HILIC column and 20 mmol/L ammonium formate/acetonitrile (10:90, V/V) as mobile phase were used for hydrophilic interaction chromatographic analysis. The column and mobile phase employed for cation exchange chromatographic analysis melamine were CS17 column and 6 mmol/L of sulfuric acid. A mobile phase flow rate of 1.0 mL/min was employ for all three chromatographic methods and the detection wavelength was set at 240 nm. The results showed that the calibration curves of melamine derived from the methods were all linear within the range from 0.1 to 25.0 mg/L (r = 1.0000). The recoveries for melamine determined by reversed-phase ion pair chromatography, hydrophilic interaction chromatography and cation exchange chromatography were 95.75%, 99.96% and 93.91%, respectively. Reversed-phase ion pair chromatography had the highest response to melamine, cation exchange chromatography could detect melamine within the shortest time and while hydrophilic interaction chromatography could be used as a supplementary method for the determination of false positive samples.

Determination of Dichlorvos Residue in Dried Salted Fish by Accelerated Solvent Extraction-Gel Permeation Chromatography Purification Followed by Gas Chromatography
WANG Yao,HU Hao-guang,XIE Cui-mei,LU Wei-hua*
2010, 31(14):  268-271.  doi:10.7506/spkx1002-6630-201014061
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A novel method has been developed to determine dichlorvos residue in dried salted fish using capillary gas chromatography (GC). Samples were extracted by accelerated solvent extraction and cleaned up by gel permeation chromatography. The eluate was condensed and injected into a gas chromatograph equipped with a flame photometric detector (FPD) for the quantification of dichlorvos by external standard method. Recovery rates for dichlorvos in 9 varieties of blank dried salted fish samples spiked at 2.5 × 10-2 mg/kg and 10.0 × 10-2 mg/kg ranged from 74.4% to 96.8%. The limit of detection (LOD) of this method was 5.0×10-4 mg/kg. This method is accurate, highly automated and presents high cleanup effectiveness. It can meet the requirements of pesticide residue analysis.

Calcium Content and Dissolution Rate of Rapeseed
CAI Guang-zhi,SHEN Xiao-jun,SUN Quan-le,GUO Jin-ping,GUO Yun-long,GONG Ji-yu*
2010, 31(14):  272-274.  doi:10.7506/spkx1002-6630-201014062
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Bionic extraction followed by atomic absorption spectrometry (BE-AAS) was used to determine the content and dissolution rate of calcium in rapeseed. Turnip seeds contained higher calcium content than the seeds of cucumber, bitter gourd, Perilla, black sesame, black pumpkin, grape, Cucurbitaceae and white gourd. The dissolution rates of black pumpkin and Cucurbitaceae seeds were almost 2 times higher than those of cucumber and bitter gourd seeds. The method exhibited good linearity over the concentration range from 3 to 21μg/mL, with a correlation coefficient of 0.9997. The average recovery for calcium was 103.58%, with a RSD of 1.27%. This method can allow accurate determination of the content of dissolution rate of calcium plant seeds. The seeds of the plants tested are abundant in calcium.

Purification and Structural Identification of Chlorogenic Acid from Eucommia ulmoides Leaves
LU Qi,DUAN Jia-cai,GAO Li,CHEN Ruo-wen,FU Hong-fei,PAN Si-yi*
2010, 31(14):  275-279.  doi:10.7506/spkx1002-6630-201014063
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Eucommia ulmoides leaves were extracted with 60% aqueous ethanol under the assistance of ultrasound. The crude extract was then condensed on a rotation evaporator, added with chitosan acetic acid solution and stirred, allowed to stand at 60℃ for 60 min for precipitate sedimentation, and filtrated. The filtrate was decolorized with activated carbon prior to 5-time ethyl acetate extraction to remove flavonoids. The lower phase was collected and a chlorpgenic acid extract was obtained. Seven types of moroporous resins were used to purify the chlorpgenic acid extract, and NKA-2 was the selected resin because it exhibited good selectivity to chlorpgenic acid and the static adsorption and desorption ratios were 99.67% and 62.8%. The use of 30% acidified ethanol (pH 3) provided an optimum elution. After NKA-2 purification in the gradient elution mode, a chlorpgenic acid product with 76.3% purity was obtained. Chlorpgenic acid was confirmed by HPLC-MS analysis to be a condensation product of caffeic acid and quinic acid.

Packaging & Storage
Effects of Super-chilling Combined with Preservatives on Chemical, Biochemical and Sensory Properties of Pacific White Shrimp
LING Ping-hua,XIE Jing*
2010, 31(14):  280-284.  doi:10.7506/spkx1002-6630-201014064
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In the present study, we formulated 4-hexylresorcinol, citric acid and ascorbic acid to provide a preservative for inhibiting the darkening of Pacific white shrimps. The formulation was optimized using orthogonal array design. Pacific white shrimps treated with the optimized blend of 4-hexylresorcinol, citric acid and ascorbic acid were kept cold-stored or superchilled for 10 days and the polyphenol oxidase (PPO) activity, total volatile base nitrogen (TVB-N), pH and total bacterial count (TBC) of the shrimps were periodically measured during storage. The results showed that the temperature of super-chilling ranged from 0 to -2.2 ℃, and the temperature fluctuation of a common refrigerator met the requirements of super-chilling. A blend containing 0.01% 4-hexylresorcinol, 1.5% citric acid and 1% ascorbic acid provided an optimal inhibitory effect against the darkening of Pacific white shrimps and could effectively inactivate PPO activity. Super-chilling could make the growth of TVBN, pH and TBC slow down significantly. The combination of super-chilling with the optimized blend gave a mutual complement between them, presented a more significant inhibitory effect against the darkening of Pacific white shrimps and the growth of PPO activity, TVB-N, pH and TBC, and resulted in a 2-fold prolongation of shelf-life when compared with cold storage at (4 ± 1) ℃. These results suggest that super-chilling provides a promising technique for delaying the darkening and prolonging the shelf-life of Pacific white shrimps.

Optimization of Preservative Formulation for Kiwi Fruit Slurry by Response Surface Methodology
MA Li-zhi,LIU Xiao-yan,QIN Jin-ying,GAO Peng-ming
2010, 31(14):  285-288.  doi:10.7506/spkx1002-6630-201014065
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ε-polylysine, nisin, natamycin and R-polysaccharide were added to fresh kiwi fruit slurry for inhibiting the growth of microorganisms in it. In order to minimize the total bacterial count in kiwi fruit slurry, the amounts of these compounds were optimized using central composite design and response surface methodology. The results showed that the optimum amounts of ε-polylysine, nisin, natamycin and R-polysaccharide were 0.009514%, 0.010812%, 0.002968% and 0.140249%, respectively. Fresh kiwi fruit slurry with these compounds added at the optimum amounts was stored at 0-4 ℃ without sterilization, and after 12-month storage, the total bacterial count, mold count and coliform count were measured to be 130 CFU/g, 10 CFU/g and less than 3 MPN/100 g, respectively, no pathogenic bacteria were detected, and the titratable acidity and the contents of sugar and vitamin C were 1.14%, 8.9%, and 68 mg/100 g, respectively, indicating a good fresh-keeping effect.

Effects of Microwave Treatment Conditions on the POD Activity of Green Soybean
ZHUO Cheng-long1,2,3,SONG Jiang-feng2,3,LI Da-jing2,3,JIN Bang-quan1,LIU Chun-quan2,3,*
2010, 31(14):  289-293.  doi:10.7506/spkx1002-6630-201014066
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Green soybean was subjected to microwave treatment, and the effects of microwave power, length of treatment and material-to-water ratio on the peroxidase (POD) activity of green soybean were investigated in this study. A mathematical model was established to describe the relationship of the POD activity of green soybean with the above treatment conditions. Response surface analysis was employed to analyze the pairwise interactive effects of these treatment conditions on the POD activity of green soybean, and the results showed that the 80 s microwave treatment at 650 W and a material-water ratio of 2:1 (g/mL) could thoroughly inactivate the POD in green soybean and resulted in decreases in the losses of VC and chlorophyll by 14.02% and 11.43%, respectively, when compared with conventional hot water blanching; however, there were no significant differences in the losses of crude and protein between both treatment methods.

Formulation Optimization of a Biological Preservative for Pacific White Shrimp
ZHAO Hai-peng,XIE Jing*
2010, 31(14):  294-298.  doi:10.7506/spkx1002-6630-201014067
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In order to resolve the problem of Pacific white shrimp spoilage and food safety issues caused by chemical preservatives, a compound biological preservative composed of chitosan, tea polyphenols and Nisin was developed. The formulation of the preservative was optimized using orthogonal array design. Meanwhile, the optimized preservative formula was tested for its fresh-keeping effect on Pacific white shrimps. The optimal composition was 1.5% chitosan, 0.1% tea polyphenols and 0.02% Nisin. The total volatile basic nitrogen (TVB-N) in Pacific white shrimps treated with this biological preservative on 8th day of storage at (4 ± 1) ℃ was still less than 30 mg/100 g, the total bacterial count (TBC) was only 5 × 105 CFU/g on the 9th day, and in the first 6 days, the sensory quality kept better than that of untreated Pacific white shrimps and the shelf-life was prolonged from 4 to 7-8 days. This compound preservative has promising applications in the fresh-keeping of Pacific white shrimp due to its low cost.

Microencapsulation Optimization of Essential Oils from Four Varieties of Plants and Their Fresh-keeping Effect on Cucumbers
DAI Heng-yan,LIU Chun-mei,TAN Shu-ming*
2010, 31(14):  299-304.  doi:10.7506/spkx1002-6630-201014068
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The essential oils from clove, garlic, ginger and pepper were separately microencapsulated using a mixture of gum arabic and maltodextrin as wall material and a mixture of Span 80 and Tween 20 as emulsifier to prepare solid preservatives. The optimal ratio of Span 80 to Tween 20 was determined to be 1:2. The key process conditions including maltodextrin-to-gum Arabic ratio, emulsifier amount, core material-to-wall material ratio and CaCl2 amount for the microencapsulation of clove, garlic, ginger and pepper essential oils were optimized using orthogonal array design. Cucumbers were treated with each of four microcapsules obtained under optimized conditions, fumigated in the presence of 0.06% 1-MCP for 2 days and stored at room temperature for 30 days, and the percentage of rotten fruits, weight loss, respiratory intensity, total sugar content and chlorophyll content of cucumbers were determined at 6-day intervals during storage. It was found that microencapsulated clove, garlic, ginger and pepper essential oils all presented remarkable fresh-keeping effect on cucumbers and that the fresh-keeping effect of microencapsulated clove essential oil was the best, followed by microencapsulated pepper and garlic essential oils.

The Combined Use of Nisin, Lysozyme and Vitamin C for the Preservation of Channel Catfish (Ictalurus punctatus) Fillets
GU Ren-yong
2010, 31(14):  305-308.  doi:10.7506/spkx1002-6630-201014069
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Nisin, lysozyme and vitamin C were dissolved together in deionized water, followed by pH adjustment and channel catfish fillets was treated with the mixed solution before cold storage. The optimum final concentrations of Nisin, lysozyme and vitamin C in their mixed solution and solution pH for improved total bacterial count and TVB-N of channel catfish fillets were determined by orthogonal array design to be 0.5%, 0.3%, 3.0%, and 4.5, respectively. Along with this, the changes in total bacterial count, TVB-N, pH and sensory attributes of treated channel catfish fillets were measured during storage at (0 ± 1) ℃. The combination of treatment with the compound preservative and vacuum packing provided a 21-day shelf-life for channel catfish fillets stored at (0 ± 1) ℃.

Technology Application
Optimization of Key Technological Parameters for the Production of Cream Cheese
YANG Wei-dong1,REN Fa-zheng2,ZHANG Xiao-ying2,ZHANG Yu-xiu1,*
2010, 31(14):  309-312.  doi:10.7506/spkx1002-6630-201014070
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In order to optimize the production technology of cream cheese, Single factor and orthogonal array design methods were used to investigate the effects of key technological parameters such as calcium chloride amount, rennet amount, coagulation temperature and fat amount on the productivity, protein content, fat content, water content and sensory quality of cream cheese. The optimum values of rennet amount, coagulation temperature, fat amount and calcium chloride amount were found to be: 0.002g/mL, 32 ℃, 12% and 0.01 g/mL, respectively.

Application of Enzymatically modified Soybean Protein Isolate in Ice Cream
WU Qiong1,CHEN Li-na1,DAI Yong-gang2,CHEN Xing1,LIU Bo1
2010, 31(14):  313-315.  doi:10.7506/spkx1002-6630-201014071
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In this study, the emulsifying properties and applications of transglutaminase (TG)-modified soybean protein isolate in ice cream were explored. The formula of ice cream with modified soybean protein isolate consisted of 12% sugar, 8% milk powder, 3% butter, 3% TG-modified SPI, 0.1% CMC, 0.1% monoglycerides and 0.2% gelatin. The ice cream made from this optimal formula was found to be good in expansion rate, melting rate and sensory attributes. Compared with ordinary ice cream, TG modified SPI exhibited a decrease in the consumption of milk powder, emulsifier and stabilizer and an improvement in the nutritional value and a reduction in the production cost of ice cream.