Table of Content

15 January 2010, Volume 31 Issue 2
Preparation and Characterization of Microencapsulated Vitamin E
MA Yun-biao,ZHOU Hui-ming*,ZHU Ke-xue
2010, 31(2):  1-5.  doi:10.7506/spkx1002-6630-201002001
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Chitosan and maltodextrin were used as wall materials to prepare vitamin E microcapsules by spray drying. The encapsulation efficiency and retention ratio of vitamin E and the moisture content of microcapsules were 89.02%, 91.73% and 2.67%, respectively. Fine surface and internal structure of microcapsules were observed under scanning electron microscopy (SEM). The values of Tg and Tm of microencapsulated vitamin E were determined by DSC to be 41.579 ℃ and 199.483 ℃, respectively, indicating good storage stability and broad application range. In addition, the retention ratio of microencapsulated vitamin E was measured at different relative humidity and modeled as a function of storage temperature using Avrami’s equation. Results showed that releasing rate of vitamin E at 75% relative humidity was even faster than that at 32% or 50%.

Spray-drying Preparation of Red Pigment Powder from Parthenocissus tricuspidata
DONG Ai-wen,BU Xiao-ying,LI Yue-feng
2010, 31(2):  6-9.  doi:10.7506/spkx1002-6630-201002002
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Parthenocissus tricuspidata red pigment powder was prepared through sequential steps of extraction with aqueous acid solution, vacuum concentration and spray drying. In the present study, the vacuum concentration process was optimized using orthogonal array design for obtaining maximum pigment concentration, and subsequently the optimal spray-drying process was investigated using uniform design for reaching a good compromise moisture among content, dissolving rate, water dissolubility and moisture absorption capacity of pigment powder. Results showed that the optimum conditions for vacuum concentration in a rotary evaporator were as follows: temperature (40 ± 1) ℃, rotation speed (40 ± 2) r/min and time 30 min; the optimum spray-drying process was that after being adjusted to 10%- 13% of soluble solid content by adding 2% (g/g) soluble starch, the pigment concentrate was spray dried under the following conditions: feeding rate 3 mL/min, input air temperature 175 -180 ℃, output air temperature 60-70 ℃, air flow 0.35-0.37 m3/min, and atomizing pressure 100 kPa. Under such conditions, no wall sticking phenomenon was observed during spray drying process, and the quality of red pigment powder completely reached the desired goal.

Optimization of GABA Accumulation during Cowpea Germination by Response Surface Methodology
SHEN Ying-bin,FAN Zi-jian,MA Hao*
2010, 31(2):  10-16.  doi:10.7506/spkx1002-6630-201002003
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In an attempt to optimize cowpea germination conditions for gamma-aminobutyric acid (GABA) accumulation, the individual effects of soaking temperature and time as well as germination temperature and time on GABA accumulation in germinated cowpea were investigated by single factor method and subsequently, based on central composite design, interactive effects of the germination parameters were evaluated by response surface methodology. The optimum conditions for cowpea germination were obtained as follows: soaking temperature 34 ℃, soaking time 25 h, germination temperature 33 ℃ and germination time 24 h. Under the optimal conditions, the GABA content in germinated cowpea reached 203.53 mg/100 g, which was 7.48 times higher than that in dried cowpea. In addition, a quadratic polynomial model was established for GABA content in germinated cowpea as a function of the above variables, which exhibited good reliability in predicting GABA content during cowpea germination.

Extraction and Stability of Pigment from Wild Grown Parthenocissus heterophylla (Bl.) Merr
BU Xiao-ying1,CHEN Xiao-hua2,MA Ming-you1
2010, 31(2):  17-21.  doi:10.7506/spkx1002-6630-201002004
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Organic solvent extraction technique was employed to extract pigment from wild grown Parthenocissus heterophylla (Bl.) Merr. Single factor method combined with orthogonal array design was used to analyze the effects of four crucial parameters (namely material/liquid ratio, temperature, extraction time and extraction solvent type) on Parthenocissus heterophylla (Bl.) Merr pigment extraction. Subsequently, the extracted pigment was spray dried and tested for physiochemical properties and meanwhile, its stability was also evaluated. Results showed that the yield of the pigment (expressed as the absorbance at 512 nm) was affected significantly by extraction temperature and material/liquid ratio, whereas extraction solvent type and extraction time had no significant effects. Red Parthenocissus heterophylla (Bl.) Merr pigment powder was obtained after spray drying. Lower contents of harmful heavy metal elements were observed in the pigment, which exhibited poor pH stability and was soluble in water, acidic ethanol and methanol but not soluble in chloroform and ethyl acetate. The thermal stability of the pigment at acidic pH was stronger than at neutral or alkaline pH. Hyperchromic effects of Mg2+, Ca2+, Cu2+, VC, sodium benzoate and potassium sorbate were observed, while the color of the pigment was changed with the existence of Fe2+, and the existence of Na+ exhibited no effect on the color of the pigment.

Preparation and Structure Characterization of Octenyl Succinate Anhydride-modified Potato Starch
HU Yu-sen1,PU Lu-mei1,ZHANG Hong-li2,KANG Ji-min2,HAN Shun-yu2,*
2010, 31(2):  22-24.  doi:10.7506/spkx1002-6630-201002005
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Octenyl succinate anhydride (OSA)-modified potato starch was synthesized by base-catalyzed reaction of octenyl succinate anhydride with granular starch in aqueous suspension using Tween-20 as dispersing agent. An orthogonal array design involving 4 factors (starch concentration, OSA concentration, reaction temperature, pH value) at 3 levels was employed to optimize the reaction conditions. The structure of OSA potato starch was characterized with fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Optimum degree of substitution (DS) was obtained when the reaction was performed between 40% potato starch slurry and 5% OSA at 30 ℃, pH 7.5-8.0. FT-IR spectrum of OSA starch showed the intensified absorption peaks at 1651 cm-1 and 573 cm-1, and characteristic absorption peaks of RCOO- at 1558 cm-1 and >C=O at 1730 cm-1, which suggest the formation of ester. SEM image showed that OSA potato starch granular had rougher surface than native potato starch, and thus had higher specific surface area.

Orthogonal-array-design Optimization of Ultra High Pressure Extraction of Lycopene from Tomato Skin
JIN Xue-yuan1,LI Xiao2,QIN Xia1,LIU Hong1
2010, 31(2 ):  25-27.  doi:10.7506/spkx1002-6630-201002006
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As a novel technique which helps achieve the extraction of bioactive substances from botanic materials under room temperature, ultra high pressure (UHP) extraction is an attractive alternative to conventional techniques that include microwave extraction, ultrasonic extraction, supercritical extraction, etc due to time saving, low energy consumption and impurity dissolution, and high extraction efficiency. Therefore, this technique was also applied to the extraction of lycopene from tomato skin in this study. The optimal UHP extraction process was investigated for maximizing lycopene yield using orthogonal array design based on single factor experiments, where the effects of UHP pressure level, holding time, solid/liquid ratio and extraction number on lycopene yield were examined. Results showed that a maximum lycopene yield of 83.2% was obtained through the triplicate extraction at a solid/liquid ratio of 1:10 (g/mL) enhanced by UHP treatment at 300 MPa pressure level held for 5 min.

Optimization of Solar Drying of Fresh Apple Slices by Orthogonal Array Design
GAO Xing-hai1,ZHANG Yong-mao2,*,HAN Shun-yu1,HUANG Zheng2,ZHANG Hai-yan2,ZHANG Fang2,PANG Zhong-cun2
2010, 31(2):  28-31.  doi:10.7506/spkx1002-6630-201002007
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The drying process of fresh apple slices with solar energy combined with abundant dry air resource in northwest China was investigated. The effects of apple slices thickness and loadage as well as air flow rate on water loss rate in apple slices were analyzed in single factor experiments. Based on this, the optimal value of three parameters were determined using orthogonal array design for reaching a good compromise between drying rate and productivity. Results indicated that both thickness and loadage of apple slices gave a significant influence on drying rate and productivity, whereas no significant influence of air flow rate was observed. As expected, a good compromise between drying rate and productivity was reached under the optimum drying conditions as follows: apple slice thickness 5 mm, loadage 5 kg/m2, and air flow rate 1.5 m/s. Totally 44.3 kg of dried apple slices containing 15% water were obtained from 500 kg of fresh ones after 84 hours of drying under such conditions. Compared with conventional hot air drying, this method consumed lower energy with 69.2% reduction.

Response Surface Optimization of Separation of A- and B-type Starch Granules
TIAN Yi-hua,ZHANG Chuan-hui,JIANG Dong*,DAI Ting-bo,CAO Wei-xing
2010, 31(2):  32-36.  doi:10.7506/spkx1002-6630-201002008
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In this study, flour of wheat cultivar Yangmai 158 was used as the raw material for investigating the optimal separation process of A- and B-type starch granules in it using response surface methodology. A series of D-optimal response surface design experiments was carried out, and the experimental data were fit by a mathematical regression model for the difference between maximum particle size of B-type starch granules and minimum particle size of A-type starch granules (Bmax-Amin) as a function of 4 independent variables (i.e. temperature, sedimentation time, wheat flour suspension volume and sedimentation number). Results revealed that a maximum Bmax-Amin value was obtained using the optimum sedimentation process of 9 replicate sedimentation for 12.84 mL of suspension volume at 21.3 ℃ for 0.96 h each time.

Response Surface Optimization of Cooking Process for Porcine Hipbone Powder Production and Its Nutritional Analysis
LI Ke,YANG Xiu-hua,HU Lin,LI Zong-jun*
2010, 31(2):  37-41.  doi:10.7506/spkx1002-6630-201002009
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For producing porcine hipbone powder with small particle size (below 140 mesh) and high protein content, the optimal cooking process of hipbone was investigated using single factor method and Box-Behnken central composite design combined with response surface methodology. Results showed that the optimal cooking process was based on twice cooking at 118 ℃ with a mass ratio of material to water of 1:1.1 for 21 min each time. After drying and ultrafine comminution, bone powder which was good in flavor and exhibited particle sizes below 140 mesh (90% distribution) was obtained. Nutritional analysis revealed that the contents of proteins, fat, ash, calcium and phosphorus were high in the processed bone powder, however, soluble and watersoluble calcium showed a bit low contents. The dominant amino acids were glycine, glutamate, aspartate and praline.

Optimization of SF-CO2 Extraction of Essential Oil from Seeds of Evening Primrose (Oenothera biennis) Grown in West Hunan Province by Response Surface Methodology
OUYANG Hui1,YU Ji2,CHEN Xiao-yuan2,ZHANG Yong-kang1
2010, 31(2):  42-45.  doi:10.7506/spkx1002-6630-201002010
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Seeds of evening primrose variety Laer Mountain No. 1 grown in west Hunan province were used as the raw material to extract essential oil in a supercritical fluid supercritical CO2 extraction apparatus. A series of central composite design experiments was conducted for developing a mathematical regression model for oil yield as a response of four variables (namely extractionpressure, extraction temperature, separation temperature, and extraction time). Besides, based on this, response surface and contour plots were drawn for analyzing the interactive effects of the above variables on oil yield. Results indicated that the optimal extraction process was obtained as follows: 39 MPa of extraction pressure, extraction temperature of 43 ℃, separation temperature of 40 ℃, 70 min of extraction time, which resulted in a maximum oil yield of 20.07%.

Optimization of Extraction Technology of Polysaccharides from Petasites tricholobus Roots by Response Surface Analysis
WANG Hong,DENG Ze-yuan*,LIU Rong,FAN Ya-wei,LI Jing
2010, 31(2):  46-50.  doi:10.7506/spkx1002-6630-201002011
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Crude polysaccharides were prepared from the residue of Petasites tricholobus roots after flavonoids extraction. According to single-factor experiments, three levels of the factors including extraction temperature, extraction time and liquid/solid ratio were selected for the central composite design to establish a quadric regression equation for predicting the yield of polysaccharides. By response surface analysis, the optimum extraction conditions were obtained as follows: extraction temperature 70 ℃, extraction time 2.3 h and liquid/solid ratio 45:1, which led to estimated and observed values of maximal yield of polysaccharides of 35.04% and 34.74%, respectively.

Preparation and Physico-chemical Properties of Quercetin-phosphatidylcholine Compound
GUAN Ming1,REN Xiao-jia2,LI Yin-ping1,KULISONG Hayierbieke1
2010, 31(2):  51-53.  doi:10.7506/spkx1002-6630-201002012
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A quercetin-phosphatidylcholine compound was prepared in a non-proton solvent, and its melting point, ultraviolet and infrared spectrum and solubility in water or n-octanol were obtained. Results showed that the prepared compound had better solubility in water or n-octanol than quercetin and its physical mixture with phosphatidylcholine.

Optimization of Processing Parameters of Extruded Nutritional Engineering Cereals with Reduced Adhesiveness
CHEN Hou-rong1,2,KAN Jian-quan1,2,*,ZHANG Fu-sheng3
2010, 31(2):  54-59.  doi:10.7506/spkx1002-6630-201002013
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The adhesiveness of extruded cereals is an important affecting factor of their edible quality, which is greatly affected by processing parameters. The individual and interactive effects of water content, extruding screw rolling speed and three barrel temperature distribution on the adhesiveness of extruded cereals were examined using single factor method and general rotation orthogonal combination design combined with response surface analysis, respectively. Results showed that the optimal parameters were as follows: water content 22.6%, extruding screw rolling speed 32.6 r/min, and three barrel temperature distribution 109.3, 119.3 followed by 129.3 ℃. Under the optimal parameters, the predicted value of adhesiveness of extruded cereals was - 375.278178 g·s, which approximated the experimental value of 378.365 g·s and the value of commercial extruded konjac flour (-346.487 g ·s) and was lower than that of commercial extruded rice (- 394.678 g·s, a lower value represents better adhesiveness). Organoleptic examination demonstrated that the extruded cereal products obtained approximated commercial extruded rice and was superior to commercial extruded konjac flour in edible quality.

Optimization of Hot Ethanol Reflux Extraction of Capsium Oleoresin for Compromise among Higher Yield and Relative Contents of Capsaicin and Capsanthin
ZHANG Jing,SHI Lei-ling,LI Hui-ping,JIA Hong-ling
2010, 31(2):  60-62.  doi:10.7506/spkx1002-6630-201002014
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The optimal hot ethanol reflux extraction process of capsicum oleoresin from powdered Chaotianjiao chili variety was investigated using orthogonal array design for achieving the compromise among higher yield and relative contents of capsaicin and capsanthin in it. Results showed that an optimal compromise was obtained using three-times reflux extraction with 95% ethanol at 70 ℃ and 1:10 liquid/solid ratio (g/mL) for 5 h each time. In addition, the effect of particle size of chili powder on the above indexes was examined.

Optimization of Enzymatic Extraction of Protein from Grape Seeds
WU Yu-zhou,FENG Cui-ping*
2010, 31(2):  63-66.  doi:10.7506/spkx1002-6630-201002015
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Enzymatic extraction was used for protein production from grape seeds as a byproduct of grape wine making. The optimal values of theological parameters including extraction temperature, liquid/solid ratio, pH value and extraction time were investigated using single factor method combined with orthogonal array design. Results showed that the above parameters had different effects on protein extraction in the following order of solid/liquid ratio > alcalase concentration > time > temperature and a significant effect of solid/liquid ratio was observed. A maximum protein yield of 94% was obtained under the optimal values of extraction parameter as follows: alcalase concentration 60 U/g, extraction temperature 40 ℃, solid/liquid ratio 1:30, extraction time 8 0 min, and pH 7.5. The protein obtained was characterized by pI 3.8.

Optimization of Ultrasonic-assisted Extraction of Red Raspberry Seed Oil by Orthogonal Array Design
ZHANG Bai-qing,GONG Pu
2010, 31(2):  67-69.  doi:10.7506/spkx1002-6630-201002016
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A new technology for red raspberry seed oil extraction was proposed using ultrasonic-assisted organic solvent extraction method. The optimal extraction parameters were investigated using single factor method combined with orthogonal array design. Results revealed that the optimized values of extraction parameters were obtained as follows: ultrasonic power 100 W, ultrasonic treatment temperature 30 ℃, ultrasonic treatment time 25 min, and liquid/solid ratio 11:1 (mL/g). This optimization led to an oil yield of 12.97%.

Effects of Drying Methods on Formaldehyde Content and Quality of Edible Mushroom Lentinula edodes
DIAO En-jie1,DING Xiao-wen2,*,ZHANG Dao-ming2
2010, 31(2):  70-73.  doi:10.7506/spkx1002-6630-201002017
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Edible mushroom Lentinula edodes (shiitake mushroom) was treated with hot-air drying, vacuum drying and vacuum freeze drying respectively, and their effects on formaldehyde content and quality of the edible fungus were studied. Results showed that the formaldehyde content in shiitake mushroom subjected to enzyme inactivation followed by each of these drying treatments was reduced to below 35 mg/kg, and vacuum freeze dried shiitake mushroom exhibited the best sensory quality and the highest rehydration rate. The optimum production process of dried shiitake mushroom was based on vacuum drying for 5 h after 2 min microwave treatment for enzyme inactivation followed by freeze treatment at - 30 ℃ for 10 h. The product obtained using the optimal process exhibited a mushroom formaldehyde content reduced to 20.18 mg/kg and a rehydration rate up to 8.29 g/g dry basis, and was good in sensory quality.

Extraction of Water Insoluble Dietary Fiber from Peanut Hull
YU Li-na,YANG Qing-li,YU Shan-lin*,BI Jie,ZHANG Chu-shu
2010, 31(2):  74-78.  doi:10.7506/spkx1002-6630-201002018
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In order to propel the value-added utilization of peanut hull as a byproduct of peanut processing, the optimal extraction technology of water insoluble dietary fiber (IDF) from the material based on sequential treatment with alkaline followed by acid was investigated using single factor method combined with orthogonal array design. Results showed that the optimal technological process for extracting IDF from powdered peanut hull with particle size below 50 mesh were based on 30 min hot water bath (40 ℃) treatment of a mixture consisting of 60 mL of 4% aqueous NaOH solution and 3 g of raw material followed by 90 min hot water bath (60 ℃) treatment of a mixture composed of 60 mL of 0.01 mol/L HCl and the residue left after alkaline treatment. The target product with an extraction yield of 86.44%, purity of 91.13% and their weighed score (weight ratio 2:1) of 88.01 was obtained using this optimal process.

Ultrasonic-assisted Extraction of Chondroitin Sulfate from Porcine Pipes
TIAN Jia-chun,HAN Ling*,YANG Xiao-li
2010, 31(2):  79-81.  doi:10.7506/spkx1002-6630-201002019
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Porcine pipes were used as the raw material to extract chondroitin sulfate based on ultrasonic-assisted alkaline treatment followed by papain hydrolysis for removing residual protein. The optimal ultrasonic-assisted alkaline treatment and papain hydrolysis processes were explored using response surface methodology and orthogonal array design, respectively. Results indicated that the optimal extraction process of chondroitin sulfate was based on ultrasonic-assisted treatment for 139 min at 491 W power followed by papain hydrolysis for 1 h at pH 6.8 and 45 ℃ with an enzyme dose of 1.3:1000 (mg/mL). After drying in an oven set at 55-60 ℃, chondroitin sulfate obtained using the optimal process was characterized by white color, 23.15% extraction yield, 0.038 clarity, 2.48% protein content, 86.06% purity, 6.32% moisture content and pH 6.7. All quality indicators completely reach the requirements of relevant national standards for chondroitin sulfate.

Enzymatic Modification of Eggshell Membrane and Characterization of Its Hydrolyzates
WANG Bao-huan,WANG Ming-mei,YANG Na,XU Xue-ming*
2010, 31(2):  82-86.  doi:10.7506/spkx1002-6630-201002020
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Based on the goal of broadening the purpose of eggshell membrane (ESM) that is abundant in collagen and keratin, this study was carried out for investigating the effect of enzymatic treatment on ESM solubility and characterizing its hydrolysates. The optimal conditions for enzymolysis were obtained by single factor analysis as follows: alcalase concentration 0.2 g/100 mL, substrate concentration 5.0 g/100 mL, pH 9.5 and temperature 65 ℃ for a reaction duration of 2 h with stirring. The optimized process led to a trichloroacetic acid nitrogen solubility index (TCA-NSI) of 43.80% and a degree of hydrolysis of 11.54%. Furthermore, compared with unmodified egg membrane, the water absorption capacity, emulsifying capacity and the foaming capacity of modified egg membrane were improved by 1.30-3.03, 2.69-2.88 and 1.21-2.56 times, respectively.

Extraction and Characterization of TypeⅠCollagen from Bovine Bone
LIU Li-li1,2,MA Mei-hu1,*,YANG Xie-li2
2010, 31(2):  87-91.  doi:10.7506/spkx1002-6630-201002021
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In the present study, critical process steps for extracting type Ⅰ collagen from bovine bone, such as defatting, decalcification and extraction medium selection were optimized. Along with this, purified collagen was analyzed through SDSPAGE, UV, FT-IR and DSC, and compared with the standard of calf-tendon type I collagen. Results indicated that the optimal extraction process was based on low-temperature ethyl ether reflux defatting and decalcification of bovine bone powder with a particle size of 5 × 10 mm using 0.48% hydrochloric acid, followed by extraction using a mixed solution simultaneously containing 1% citric acid and 1% pepsin. The extracted collagen was identified as type I collagen and the purity reached electrophoretic grade. Furthermore, the unique triple helical structure of type I collagen remained very well.

Quadratic Orthogonal Rotation Combination Design-based Optimization of Enzymatic Production of Polypeptides from Soluble Eggshell Membrane Protein
ZHOU Yan-hua,MA Mei-hu*,CAI Zhao-xia,LI Tao,LI Feng-ling
2010, 31(2):  92-97.  doi:10.7506/spkx1002-6630-201002022
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In this study, eggshell membrane was used as the raw material to prepare polypeptides by enzymatic hydrolysis. In order to maximize degree of hydrolysis (DH) and nitrogen yield, the optimal hydrolysis mode of eggshell membrane was selected from hydrolysis with pairwise combination (used sequentially or simultaneously) of alkaline protease, papaya protease and trypsin that resulted in higher degree of hydrolysis and nitrogen yield than neutral protease and pepsin, or each of them. Meanwhile, based on this, the optimal values of crucial technological parameters, including temperature, hydrolysis time, pH and total enzyme dose, were determined by the method of quadratic orthogonal rotation combination design. Results showed that the optimal enzymatic production process was based on sequential hydrolysis at 50 ℃ with alkaline protease for 2 h at pH 9.0 followed by papaya protease for 1 h at pH 5.5 using a mixture of alkaline protease and papaya protease at 8:2 activity ratio with 16000 U/g total enzyme dose, which gave 46.12% DH and 85.56% nitrogen yield.

Extraction of Protein and Speciation Analysis of Zinc in Zingiber striolatum
LUO Xing-wu1,ZHOU Da-zhai2,ZHU Yu-chang2,WAN Li-xiu1
2010, 31(2 ):  98-101.  doi:10.7506/spkx1002-6630-201002023
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The optimal extraction process of protein from Zingiber striolatum determined using single factor method coupled with orthogonal array design was that Zingiber striolatum powder was extracted with PBS (pH 9.0) at 60 ℃ for 60 minutes with a solid-to-solvent ratio of 1:40 (g/mL). Additionally, speciation analysis of zinc in Zingiber striolatum was carried out. Results revealed that organic zinc constituted a major fraction in Zingiber striolatum, which accounted for above 80% of total zinc and comprised above 65% protein-binding zinc.

Preparation of A Nano-structural ZnO/LDPE Antimicrobial Food Packaging Material
GAO Yan-ling1,JIANG Guo-wei2,ZHANG Shao-hui1GAO Yan-ling1,JIANG Guo-wei2,ZHANG Shao-hui1
2010, 31(2):  102-105.  doi:10.7506/spkx1002-6630-201002024
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A nano-structural ZnO/LDPE antimicrobial food packaging material was developed through the following steps: in the first step, activated nano-structural ZnO was dispersed into low density polyethylene (LDPE), a matrix material, by dissolving-melting-blending technique; in the second step, the resulted particulate polymer composite was blown into film by sequential treatment with a single screw extruder followed by a plastic film blowing machine; and finally the target product was obtained. Six species of common food-contaminating bacteria including Escherichia coliform, Bacillus subtilis, Staphylococcus aureus, Salmonella aertrycke, Listeria monocytogenes and Pseudomonas aeruginosa were used for testing the antimicrobial capability of the material under different illumination conditions: energy-saving lamp light (5 W, (37 ± 1) ℃), darkness (37 ± 1) ℃ and sunlight (20 ± 1) ℃. Results showed that the material had a significant antimicrobial activity against four of the 6 species of food-contaminating bacteria, which was stronger under sunlight than under other illumination conditions. Of all the tested bacterial species, the strongest inhibitory effect against Bacillus subtilis was observed, with a maximum inhibitory rate as high as 99.99% under sunlight illumination and a minimum value of 95.01% in darkness.

Effects of Spray Drying Conditions on the Instant Solubility of Chestnut Powder
WANG Lei,LAN Yu-qian,LIN Qi*
2010, 31(2):  106-109.  doi:10.7506/spkx1002-6630-201002025
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For the goal of obtaining the optimal instant solubility of chestnut powder, the optimal spray drying process of chestnut was investigated using single factor method combined with orthogonal array design. Single factor experiments were conducted for investigating technological parameters including dry matter content of material, air inlet temperature, spray flow rate and feed flow rate. Based on this, except dry matter content of material, other three parameters that had the most important effect on chestnut spray drying were further investigated using orthogonal array design. Results revealed that the three parameters had different effects on weighed score of wettability, dispersibility and solubility of chestnut powder in a decreasing order of air inlet temperature > feed flow rate > spray flow rate and their optimal values were obtained as follows: air inlet temperature 195 ℃, feed flow rate 50 mL/min, and spray flow rate 500 L/h. The chestnut powder obtained under such conditions was the best in color, flavor and instant solubility.

GC-MS Analysis of Essential Oil Composition of White Pepper
ZHENG Jiong1,2,CHEN Jing-xia1,YU Jing1,KAN Jian-quan1,2,*
2010, 31(2):  110-112.  doi:10.7506/spkx1002-6630-201002026
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Direct distillation extraction method (DDE) or simultaneous distillation extraction method (SDE) coupled to GSMS was employed to analyze essential oil composition of white pepper. Results demonstrated that DDE and SDE gave essential oil yields of 2.15% and 2.86%, respectively. Added together, 32 chemical components were identified in white pepper essential oils extracted by both methods, of which, 28 were contained in essential oil extracted by DDE and 30 in essential oil extracted by SDE. The major compounds in white pepper essential oil were 3-carene, limonene, β-pinene, caryophyllene, α- pinene, 1-methoxy-4-(1-propenyl)-benzene and α-phellandrene. Besides, all the identified chemical components were quantified. In conclusion, the combination of both extraction methods can help obtain a more comprehensive composition analysis for white pepper essential oil.

HPLC Determination of Sodium Cyclamate in Food Flavors and Fragrances
DONG Feng-qiang1,LI Zu-guang1,*,ZHOU Guo-jun2,JIANG Jian2
2010, 31(2):  113-116.  doi:10.7506/spkx1002-6630-201002027
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Objective: To establish a method for rapid determination of sodium cyclamate in food flavors and fragrances that are very complex substances. Methods: Samples were subjected to precolumn derivatization. The chromatographic separation was achieved on a C18 column with a mobile phase consisting of a mixture of acetonitrile and water (70:30, V/V) and the analyte was detected with a DAD detector set at 314 nm. Results: The analytical method developed was shown to result in an effective elimination of false positive detection for sodium cyclamate in food flavors and fragrances. A good linear relationship was observed between HPLC peak area and sodium cyclamate concentration in the range of 2.5 - 250 mg/L with the correlative coefficient of 0.9992, and the average recoveries were in the range of 94.22%-97.19%. Conclusion: This method is simple, rapid, accurate and repeatable, and applicable for qualification and quantification of sodium cyclamate in food flavors and fragrances.

GC-MS Determination of Inositol in Milk Powder
LUO Hai-ying,XIAN Yan-ping,GUO Xin-dong*,DU Zhi-feng,PENG Ying,WU Yu-luan
2010, 31(2):  117-119.  doi:10.7506/spkx1002-6630-201002028
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A GC-MS method was developed for determining inositol in milk powder. Samples were dissolved in water, silylated, and extracted with n-hexane. The extract obtained was cleaned up using a Florisil column before GC-MS analysis. At fortification levels ranging 1.0-10.0 mg/kg, the recoveries of inositol ranged from 88.4% to 102.5%, and the coefficients of variation were between 2.7% and 4.7%. The limit of detection was calculated to be 0.5 mg/kg (RSN = 3). This method, thanks to its simpleness as well as high sensitivity and accuracy, can meet the requirements for qualification and quantification of inositol in milk powder.

Simultaneous Determination of 21 Sulfonamide Residues in Aquatic Products by Ultra Performance Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry
SUN Yu-zeng,XU Ying-jiang,LIU Hui-hui,ZHANG Shi-juan,QIN Hua-wei,GAO Ji-qing
2010, 31(2):  120-123.  doi:10.7506/spkx1002-6630-201002029
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An ultra performance liquid chromatography-electrospray ionization tandem mass spectrometric (UPLC-MS/MS) method has been developed for the simultaneous determination of 21 sulfonamide residues in aquatic products. Samples were extracted with ethyl acetate, cleaned up using an HLB SPE cartridge and blown to dryness under nitrogen, and the residues were then dissolved in 1 mL of mobile phase. The 21 analytes were separated on ACQUITYTM BEH C18 column with a mobile phase composed of methanol and 5 mmol/L aqueous ammonium acetate solution (containing 0.1% formic acid). The limits for qualitative detection and quantitative determination were 0.01-0.20μg/kg and 0.03-0.67 μg/kg, respectively. The average recoveries at three spike levels ranged 68%-82%, with RSDs ranging 4.1%-11.8%. All these figures of merit demonstrate a good suitability of this method for the simultaneous determination of sulfonamide residues in aquatic products.

Element Analysis Stable Isotope Ratio Mass Spectrometric Differentiation of Cane Sugar and Beet Sugar
ZHANG Lin,CAI Yan,YUE Ai-shan,WU Shuang-min
2010, 31(2):  124-126.  doi:10.7506/spkx1002-6630-201002030
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An EA-IRMS method was developed for determination of element analysis stable isotope ratios of δ13C in cane sugar and beet sugar using liquid introduction. Results showed that this method was able to differentiate cane sugar from beet sugar according to their characteristic δ13C values. The δ13C values for beet sugar and cane sugar were between -25.48‰ and -24.05‰ and -11.87‰, respectively. The proposed method presented the benefits of accuracy and easy operation and the results were satisfactory.

A Rapid High-performance Liquid Chromatography-Tandem Mass Spectrometric Method for Determination of 4 Fluoroquinolones Residues in Fish Meat
HUANG You-sheng,LIU Bo-ping,ZHU Xiao-ling,LI Gui-sheng
2010, 31(2):  127-130.  doi:10.7506/spkx1002-6300-201002031
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A high-performance liquid chromatography-tandem mass spectrometric (HPLC-MS/MS) method was developed for the simultaneous determination of 4 fluoroquinolone antibiotic residues in fish meat. In the method, analytes were extracted with acidified acetonitrile, cleaned up with n-hexane, concentrated to dryness under nitrogen, redissolved in 1 mL of mixed solution of acetonitrile and 1% formic acid (1:9, V/V), separated on a RP-HPLC column, detected by HPLC-MS/MS with positive electrospray ionization (ESI+) in multiple reaction monitoring (MRM) mode, and quantified using an external standard method. The standard curves for all analytes exhibited good linearity over the concentration range of 2 - 40 μg/kg with correlation coefficients (r2) beyond 0.997. The recoveries of 4 fluoroquinolone antibiotics in fish meat samples spiked at concentration levels of 4, 10 μg/kg and 20 μg/kg ranged from 79.9% to 98.1%, with relative standard deviations between 2.7% and 8.7%. The limits of detection (LOD) and limits of quantification (LOQ) of the developed method were in the ranges of 0.1-0.4μg/kg and 0.3- 1.0 μg/kg, respectively. This method is characterized by simplicity, rapidity, high sensitivity, good reproducibility and better selectivity, and therefore can be used for identification and determination of fluoroquinolones in fish meat.

High Performance Capillary Electrophoresis for Determination of Melamine in Dairy Products
LI Zhi-wei,HUO Yun-xia,LIU Jia,YU Yi-feng
2010, 31(2):  131-133.  doi:10.7506/spkx1002-6300-201002032
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A method using high performance capillary electrophoresis (HPCE) was presented for determination of melamine in dairy products. An HPCE apparatus equipped with an untreated fused-silica capillary (75 μm × 78 cm, 70 cm effective length) was used. Mobile phase was 30 mmol/L phosphate buffer at pH 5.0. UV detection wavelength was set at 240 nm and separation voltage at 10 kV. The regression curve for peak area versus melamine concentration revealed a good linearity in the range of 10.0-50.0μg/mL, with a correlation coefficient of 0.9992. The spike recovery was averaged at 97.04%, with a relative standard deviation (RSD) of 1.24% (n = 3). The method exhibits characteristics of simplicity, rapidity and good repeatability, and consequently can be used for melamine determination in dairy products.

Supercritical Fluid Carbon Dioxide Extraction and GC-MS Analysis of Essential Oil from Chimonanthus praecox Flowers
SI Hui-qing,SHEN Qiang,PANG Xiao-li*
2010, 31(2):  134-137.  doi:10.7506/spkx1002-6300-201002033
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The optimum supercritical fluid CO2 (SFE-CO2) extraction process of essential oil from Chimonanthus praecox flowers that maximizes oil yield was investigated using orthogonal array design and the essential oil obtained was analyzed for chemical composition by gas chromatography and mass spectrometry (GC-MS). Results showed the optimal values of SFE-CO2 extraction parameters were as follows: extraction for 3 h at 30 MPa pressure level, 40 ℃, and 25 kg/h CO2 flow rate and the optimized conditions resulted in a maximal oil yield of (1.18 ± 0.02)%. A total of 57 components were identified and the dominant compounds were alcohol, ester and terpene, accounting for 67.30%, 15.19% and 10.90% of total essential oil, respectively. Based on the above test and analysis, it is speculated that the fragrance of Chimonanthus praecox flowers might be attributed to those compounds in essential oil including acetic acid, phenylmethyl eser, bornyl acetate and dibutyl phthalate.

Rapid HPLC Determination of Amygdalin in Dried Nuts Grown in Xinjiang
ZHANG Fan1,2,LI Zhen1,HAMULATI Wufuer2,GAO Fu-chun1
2010, 31(2):  138-140.  doi:10.7506/spkx1002-6300-201002034
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A rapid high performance liquid chromatographic (HPLC) method was presented for determining amygdalin in Semen Armeniacae Amarum, bitter almond and Semen Persicae. The chromatographic separation was performed on a Shim-pack VPODS column (150 mm × 4.6 mm, 5 μm) with a mobile phase composed of methanol and water (20:80, V/V) at a flow rate of 1 mL/min, the column temperature was set at 40 ℃, and the analyte was detected at 215 nm wavelength. Results showed that mygdalin was separated well and analyzed effectively by the method. There was a good linearity between relative peak area (X) and amygdalin concentration (Y), and the linear regression equation was Y = 4.86244 × 10-6X -0.0129273. Methodological investigations demonstrated the advantages of this method, including good repeatability and high precision, which benefit its application to rapid online determination of amygdalin in dried nuts.

HPLC Profile Analysis of Fructus Mori
YOU Yuan-yuan1,WAN De-guang2,*,YANG Wen-yu3,PEI Jin2
2010, 31(2):  141-144.  doi:10.7506/spkx1002-6300-201002035
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Sixteen Fructus Mori samples of different origins and habitats were compared for quality difference according to their characteristic HPLC profiles and subjected to hierarchical cluster analysis. Besides, the optimal chromatographic conditions were discussed. A low similarity in HPLC profile and remarkable differences in content and chemical composition were observed among the 16 samples. There was no obvious correlation between quality and habitat of Fructus Mori. Samples from half-bred mulberry varieties displayed larger peak area than those stipulated in the Chinese pharmacopoeia. Commercial Fructus Mori products differed greatly in quality. All these results reveal that Fructus Mori quality is closely associated with mulberry variety, processing and storage.

Uncertainty Evaluation for Determination of Evaporation Residue of Polypropyrene Products in Contact with Foodstuffs
ZHU Xiao-yan,CAO Guo-zhou*,LIU Zai-mei,YUAN Wei-wei
2010, 31(2):  145-147.  doi:10.7506/spkx1002-6300-201002036
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Sample pretreatment and analysis were performed according to GB/T 5009.60 — 2003 Hygienic standard for polypropyrene products used as food containers and tablewares in the determination of evaporation residue of polypropyrene products in contact with foodstuffs. Based on analytical data, mathematical models were developed for uncertainty evaluation for the determination. Each uncertainty component was calculated by analyzing the source of uncertainty generated during the determination steps. When the evaporation residue content (n-hexane) was 30.1 mg/L, the relative standard uncertainty was 1.99 mg/L, and the expanded uncertainty was 4.0 mg/L (k = 2).

Ion Chromatography Coupled with Tandem Mass Spectrometric Determination of Bromate in Flour
GUO Xin-dong,DU Zhi-feng,LUO Hai-ying
2010, 31(2):  148-150.  doi:10.7506/spkx1002-6300-201002037
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An analytical method using ion chromatography coupled with tandem mass spectrometry (IC-MS/MS) was developed for the determination of bromate in flour. Samples were dispersed in water, extracted with sonication, and cleaned up with a pre-activated C18 solid-phase extraction cartridge before IC-MS/MS analysis. Recoveries of bromate in flour spiked within the range of 10.0-50.0 μg/kg ranged from 82.1% to 86.6%, with coefficients of variation between 4.5% and 7.3%. The limit of detection was 3μg/kg (RSN = 3). These results suggest that this method is simple, sensitive and precise, and therefore can be used for qualification and quantification of bromate in flour.

Uncertainty Analysis of GC Determination of Ethyl Acetate in Distilled Spirit
ZHANG Su-juan
2010, 31(2):  151-153.  doi:10.7506/spkx1002-6300-201002038
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The whole procedure of GC determination of ethyl acetate in distilled spirit was traced to systematically analyze the source of determination uncertainty and subsequently assess and synthesize each component of uncertainty. Results show that the 1 mL outflow graduated pipette was a major source of determination uncertainty. When the content of ethyl acetate was determined to be 1.556 g/L, the uncertainty was consequently extended to 0.032 g/L. An expression of uncertainty was proposed as C = (1.556 ± 0.032) g/L, k = 2, P = 95%.

LC-MS/MS Determination of Glucocorticoids Residues in Quick-Frozen Meat Products
LI Fei1,2,GU Li-li1,2,ZHANG Yan2,ZHAO Bao-hua1,*
2010, 31(2):  154-156.  doi:10.7506/spkx1002-6300-201002039
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A liquid chromatography coupled with tandem mass spectrometric (LC-MS/MS) method was established for the determination of 7 glucocorticoids residues in quick-frozen meat products. Samples were extracted with ethyl acetate, cleaned up with a silica solid-phase extraction (SPE) cartridge and diluted with acetonitrile prior to LC-MS/MS analysis. Glucocorticoids were quantified with external standard method. The limit of detection (LOD) and limit of quantification (LOQ) were 0.2, 0.5 μg/kg respectively for prednisone, prednisolone, dexamethasone, betamethasone, 0.5 μg/kg and 1.0 μg/kg respectively for beclomethasone and fludrocortisone, and 1.0, 2.0 μg/kg respectively for hydrocortisone. Spike recoveries for the seven glucocorticoids ranged from 85.0% to 96.4% with a relative standard deviation within the range of 2.3%-6.1%.

Identification of Five Stearate Salts Served as Common Food Additives
HUANG Jie,YU Kong-jie,YANG Fang,CHEN Xiang-ming
2010, 31(2):  157-160.  doi:10.7506/spkx1002-6300-201002040
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A method using combined techniques of heating test, chemical precipitation of metal ions, gas chromatography and infrared (IR) spectroscopy was proposed for the identification of five stearates including stearate acid, calcium stearate, magnesium stearate, sodium stearate and potassium stearate that are commonly used as food additives. In this method, metal ions in stearate salts were identified using chemical precipitation methods, and fatty acids were identified according to gas and IR spectra.

Liquid-phase Microextraction Coupled to High Performance Liquid Chromatographic Determination of Melamine in Dairy Products
HUANG Yan-hong,DING Jian-hua*,QIU Chang-fu,XIE Xiao-li,ZHANG Hui,LIU Shu-juan,LIU Yan
2010, 31(2):  161-164.  doi:10.7506/spkx1002-6300-201002041
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A method using liquid-phase microextraction coupled to high performance liquid chromatography (LPME-HPLC) was proposed for the determination of melamine in dairy products. LPME was achieved with polypropylene hollow fiber for 30 min at 1000 r/min string rate using tributyl phosphate (TBP) as extraction solvent and 0.02 mol/L ammonium sulfate solution at pH 5.0 (pH 8.0 of donor phase) as acceptor phase. An Agilent C18 (4.6 mm × 250 mm, 5μm) column was used for chromatographic separation and the analyte was detected under optimized conditions. The proposed method provided a linear range of 0.01-100 μg/mL with R2 = 0.9987, detection limit of 2.5 ng/mL (RSN = 3), RSD<4.4% (n = 5) and spike recovery ranging 92.1%- 102.4%. Less than 34 min is needed for single sample analysis with little organic solvent consumption. Moreover, this method has the advantages of high sensitivity and extraction efficient and good reliability, thereby benefiting the rapid determination of low content of melamine in complex dairy product matrices.

HPLC Determination of Lactoferrin in Dairy Products
XIA Ming1,2,YING Tie-jin1,*
2010, 31(2):  165-167.  doi:10.7506/spkx1002-6300-201002042
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A HPLC method was developed for the determination of lactoferrin in dairy products. Lactoferrin was easier to precipitate by the introduction of additional ferrous ion and 60% ethanol solution was added to precipitate proteins for removing carbohydrates. The precipitate, whose main composition was lactoferrin, was extracted with acetic acid buffer to remove casein impurity prior to HPLC analysis. The chromatographic separation was achieved on a LiChrosorb RP-C18 column using single 0.1 g/100 mL TFA as mobile phase A and a mixture of 98% methanol and 0.1 g/100 mL TFA as mobile phase B and linear gradient elution mode was used. This method exhibited a good linearity over the concentration range of 0.4 to 2 mg/mL for lactoferrin in dairy products (R2 = 0.9980), and the average recovery for lactoferrin at five spike levels was 95.4%.

Extraction and GC-MS Analysis of Volatile Oil from Fruits of Artocarpus heterophyllus Lam Grown in Hainan Island
GUO Fei-yan,JI Ming-hui*,SHU Huo-ming,CHEN Jing,CHEN Yi-nan
2010, 31(2):  168-170.  doi:10.7506/spkx1002-6300-201002043
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Fruit flesh of Artocarpus heterophyllus Lam grown in Hainan island was used as the raw material to extract volatile oil with steam distillation, ether extraction or resin adsorption and analyze chemical composition of the obtained volatile oils by GC-MS. Totally 38, 22 and 14 peaks were detected respectively in the above 3 volatile oils, among which 37, 21 and 13 compounds were identified respectively, representing 99.47%, 99.36% and 99.63% of total peak area. Totally 5 compounds, i.e., butyl acetate, propyl valerate, butyl butyrate, 3-methyl-butyl butyrate and 9-octadecenoic acid, were present simultaneously in the 3 oils.

SPME-GC-MS Analysis of Volatile Composition of Bitter Melon Fruits
2010, 31(2):  171-174.  doi:10.7506/spkx1002-6300-201002044
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Freshly harvested fruits of bitter melon grown in Gansu province were analyzed for volatile composition by SPMEGC- MS. A total of 83 volatile components were identified and aldehydes, alcohols, alkenes and alkanes were the dominant volatile constituents. Totally 18 of aldehydes, 15 of alcohols, 11 of alkenes and 8 of alkanes were identified, accounting for 37.46%, 37.16%, 7.02% and 2.92% of total volatile components, respectively.

GC-MS Analysis of Peel Volatile Oils of Three Hybrid Cultivars of Citrus
SHANG Xue-bo,ZHANG Ju-hua,SHAN Yang,PAN Zhao-ping,LIU Yang
2010, 31(2):  175-178.  doi:10.7506/spkx1002-6300-201002045
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The chemical composition of peel essential oils of three hybrid cultivars of citrus (Rose Bergamot, JoJo and Red Xiangshan) was investigated by GC-MS to probe into the merit of new citrus cultivars and provide experimental evidences for screening and processing of new citrus cultivars and full utilization of peel residues. Citrus peel oil was extracted by steam distillation prior to GC-MS analysis and the relative contents of chemical components in it were quantified by the method of peak area normalization. Results showed that 66, 68 and 61 components were identified in peel essential oils from Rose Bergamotwere, JoJo and Red Xiangshan, respectively, accounting for 99.37%, 99.18% and 97.42% of total peak area. Totally 36 compounds were found simultaneously in the 3 cultivars and the dominant compounds were D-linmonene, β-myrcene, linalool, α-terpineol and α-pinene. Differences in chemical composition of peel essential oils of various cultivars could be used to identify the quality of citrus fruits.

Comparative Analysis of Water-soluble Vitamins in Fruit Powders of Nitraria, Wolfberry and Seabuckthorn Grown in Qinghai-Tibetan Plateau
ZHANG Feng-ping1,2,3,ZHAO Yan2,LIU Yao-min2,SUO You-rui1,*
2010, 31(2):  179-182.  doi:10.7506/spkx1002-6300-201002046
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The contents of 7 water-soluble vitamins in fruit powders of Nitraria, wolfberry and weabuckthorn grown in Qinghai- Tibetan Plateau were determined by high performance liquid chromatography (HPLC). Results showed that the contents of 7 water-soluble vitamins were successfully determined simultaneously by sequential treatment of extraction followed by chromatographic separation and the recoveries for spiked standards and the relative standard deviations were 88.0%-113.4% and 1.1% - 9.0%, respectively. Significant differences in the contents of VC, VB1 and VB2 were observed among the three fruit powders. The contents of VC and VB1 were decreased in the following order: seabuckthorn> Nitraria > wolfberry, and wolfberry > Nitraria > seabuckthorn, respectively. However, higher VB2 was exhibited in Nitraria fruit powder than in wolfberry powder, whereas no VB2 was detected in seabuckthorn powder. Moreover, fruit powders of seabuckthorn and Nitraria were abundant in VC with contents of (18266.4 ± 201.1) mg/kg and (1468.5 ± 24.6) mg/kg, respectively. In additions, no other water-soluble vitamins like nicotinic acid, pyridoxine hydrochloride, folic acid and vitamin B12 were also detected in the three fruit powders.

A Comparative Study of Post-column Derivatization HPLC and LC-MS/MS Determination of Carbamate Pesticide Residues in Vegetables
HAO Xue-fei,DONG Xiao-hai,ZHONG Hong-jian
2010, 31(2):  183-186.  doi:10.7506/spkx1002-6300-201002047
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In the present study, 7 carbamate pesticides in vegetables were determined using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), and this method was compared with commonly used HPLC with post-column derivatization method. Results showed that the analytes were well separated using both methods, which had good figures of merit. HPLC with post-column derivatization method is considered as a classical method having the advantage of good repeatability and the disadvantages of time-consuming operation, expensive derivative reagent cost and poor stability; in contrast, LCMS/MS, thanks to its short retention time, high sensitivity, simple and easy operation, and rapidity, is more competitive for determination of carbamate pesticides in vegetables.

Simultaneous Determination of Nitrite and Nitrate in Cooked Meat by On-line Dialysis-ion Chromatography
YAO Jing1,2,HANG Yi-ping1,*,ZHONG Zhi-xiong2,CHEN Ming2,LI Min2
2010, 31(2):  187-190.  doi:10.7506/spkx1002-6300-201002048
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A new method based on the combination of on-line dialysis and ion chromatography was established for measuring nitrite and nitrate in cooked meat. Samples were suspended in water, extracted in ultrasonic bath and centrifuged. The resulted supernatant was then subjected to on-line treatment with dialysis before being injected into Ag column. Nitrite and nitrate were separated on a Metrosep A Supp 4 anion exchange column using an eluent composed of a mixed aqueous solution of 1.8 mmol/L Na2CO3 and 1.7 mmol/L NaHCO3 and monitored using suppressed conductivity detector. The limits of detection of this method for nitrite and nitrate were 0.004 mg/L and 0.005 mg/L, respectively. The average recoveries were in the range of 88%-105%. This method presents the benefits of rapidity, high sensitivity and precision and easy performance, thereby providing a promising approach for simultaneous determination of nitrite and nitrate in cooked meat.

Development of A One-step Immunochromatographic Strip Test for Rapid Detection of Chlortetracycline Residue in Food
FU Yun-jie,LIU Zhi-guo*,WU Yu-xiang
2010, 31(2):  191-194.  doi:10.7506/spkx1002-6300-201002049
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An immunochromatographic strip test was developed to detect chlortetracycline residue in food using immune colloidal gold technique. Chlortetracycline immuno-antigen (CTC-BSA) was prepared by conjugating chlortetracycline to bovine serum albumin via glutaraldehyde, and injected into rabbits to prepare anti-CTC polyclonal antibody. The resulted anti- CTC antibody was purified, and its titer and specificity was determined by indirect enzyme-linked immunosorbent assay (ELISA). Subsequently, colloidal gold particles 15 nm in size were prepared by the method of trisodium citrate reduction. The purified anti-CTC antibody was finally conjugated to colloidal gold particles served as a detection reagent to pack the immunochromatographic (IC) strip. A positive reaction gave a visual color to assess the residue level of CTC. Results suggested that the limit of quantification of CTC was 0.7 μg/mL. Cross-reactivity could not be observed till the concentration of tetracycline was higher than 1 μg/mL. Chlortetracycline content obtained with the IC strips provided a positive correlation with that obtained by HPLC method. Using this method, the analysis of CTC in food could be completed within less than 5 min.

Rapid Determination of Sixteen Kinds of Food Additives in Beverages by Ultra Performance Liquid Chromatography
WANG Jun,HU Mei,ZHANG Hui,ZHANG Xi-qi,ZHU Jian-hua
2010, 31(2):  195-198.  doi:10.7506/spkx1002-6300-201002050
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An ultra performance liquid chromatographic (UPLC) method was presented for the rapid determination of 16 kinds of food additives in beverages. The method was based on extraction with methanol mixed with water, separation on an ACQUITY UPLC BEH C18 column and detection with diode-array detector. All the sixteen kinds of food additives were well separated within 5.5 minutes. The limits of detection for them were more than 1.0 mg/kg, and the recoveries at three spike levels were 91.6% - 100.3%, RSD was 0.66% — 2.20%.

Application of Acoustic Resonance Analysis to Eggshell Crack Detection
LIN Hao,ZHAO Jie-wen*,CHEN Quan-sheng,CAI Jian-rong,ZHOU Ping
2010, 31(2):  199-202.  doi:10.7506/spkx1002-6300-201002051
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A system based on acoustic resonance was developed for eggshell crack detection. It was achieved by analysis of the acoustic frequency response of eggshell excited with a light mechanical. Least mean square (LMS) adaptive filtering were attempted to remove the noise from the response signal. Some characteristics were extracted from excitation resonant frequency and served as input vectors of discrimination model. Back propagation artificial neural network (BP-ANN) model was employed to discriminate intact eggs and cracked eggs. This method allows a crack detection level of 97% in calibration and prediction set respectively. This work shows that acoustic resonance system combined with adaptive filters has a significant potential in cracked eggs detection.

Chemometric Resolution of Common Volatile Oil Composition of Seeds and Leaves of Perilla frutescens (L.) Britt
XIONG Yun-hai1,WANG Mei2
2010, 31(2):  203-207.  doi:10.7506/spkx1002-6300-201002052
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The volatile oil composition of seeds (SPF) and leaves (LPF) of Perilla frutescens (L.) Britt. was investigated by two-dimensional gas chromatography-mass spectrometry (GC-MS). The overlapped spectral data of SPF and LPF volatile oils were resolved by chemometric method into a pure chromatogram and a mass spectrum of each compound, which was qualified by mass spectral library search. In total, 85 volatile chemical components from SPF and 74 from LPF were identified, which accounted for 97.92% and 98.56% of total volatile oil, respectively. Forty-five volatile components were observed in both SPF and LPF, occupying 52.94% and 60.81% of total numbers of volatile oil components identified in SPF and LPF, occupying 84.30% and 66.38% of total contents, respectively. The dominant common volatile chemical components in SPF and LPF were D-Limonene, bicyclo[7.2.0]undec-4-ene,4,11,11-trimethyl-8-methylene-Bicyclo[3.1.1]hept-2-ene, 2,6-dimethyl-6-(4-methyl- 3-pentenyl)-, caryophyllene oxide, 1-pentanone, 1-(2-furanyl)- and tricyclo[,4)]hexane,3,6-diethyl-3,6-dimethyl-.

Solid Phase Microextraction Followed by GC-MS Analysis of Volatile Flavor Compounds in Fresh Pumpkin and Pumpkin Juice
2010, 31(2):  208-210.  doi:10.7506/spkx1002-6300-201002053
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A comparative study was conducted for analyzing the difference in volatile flavor compound profile in fresh pumpkin and pumpkin juice using solid phase microextraction (SPME) followed by GC-MS method. Results indicated that 44 and 53 kinds of volatile compounds were identified in fresh pumpkin and pumpkin juice, respectively, and the main components were alcohol, aldehyde and ketone. Processed pumpkin juice from fresh pumpkin retained its characteristic aroma. However, cooking aromas such as furfural, pyridine and furan in pumpkin juice, and carotenoids degradation products, such as aldehyde, ketone and ionone, were also found in pumpkin and pumpkin juice due to heat treatment.

Synthesis of Rhodamine 123 Artificial Antigen and ELISA Determination of Rhodamine B
WANG Ting-xin,ZHAO Zhi-lei,LI Xiao-ting
2010, 31(2):  211-213.  doi:10.7506/spkx1002-6300-201002054
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For establishing an enzyme-linked immunosorbent assay (ELISA) method for rhodamine B determination, a complete antigen R123-BSA and a coating antigen R123-OVA were prepared by coupling rhodamine123 with the carrier proteins of bovine serum albumin (BSA) and ovalbumin (OVA) using glutaraldehyde method, respectively. The synthesis of rhodamine123 artificial antigens was confirmed by animal experiments. A novel anti-rhodamine123 polyclonal antibody was prepared, which was successfully applied to the determination of rhodamine B in food with a limit of detection of 0.001 ng/mL. The development of anti-rhodamine123 antibody will provide a valuable tool for the determination of rhodamine B in food seasoning products.

Identification of Animal Species by Terminal Restriction Fragment Length Polymorphism (T-RFLP) of Mitochondrial 12S rRNA Gene
WANG Qi1,ZHANG Xin1,ZHAO Da-he2,MA Hai-ping2,CHEN Guang-quan1,ZHANG Hui-yuan1
2010, 31(2):  214-219.  doi:10.7506/spkx1002-6300-201002055
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An accurate and reliable method was developed to identify ten animal species (pig, dog, cattle, goat, sheep, horse, chicken, mouse, salmon and deer) by terminal restriction fragment length analysis based on mitochondrial 12S rRNA gene. Universal primers for the 12S rRNA gene were labeled with FAM and the specific fragments of 450 bp were obtained using polymerase chain reaction. The PCR products obtained using a set of unlabeled forward and labeled reverse primers were digested by AluⅠ, and those obtained using another set of labeled forward and unlabeled reverse primers by Tru9Ⅰ. The resulted restriction fragments were loaded on ABI prism 3100 genetic analyzer to perform capillary electrophoresis. Peak Scanner Software 1.0 was used to analyze the electrophoresis data. Results showed that chicken, horse, pig and salmon had different Alu Ⅰ restriction pattern while the same pattern was observed among deer and cattle, goat and sheep, mouse and dog, which, however, could be differentiated by Tru9 Ⅰ restriction pattern. Each species had a unique characteristic and reproducible pattern of restriction fragments while different individuals of the same species had the same and repeatable patterns and no intraspecies polymorphism appeared. In most cases, the difference between observed and expected restriction fragment length was only 2– 5 bp. In summary, this T-RFLP method is demonstrated to be accurate and easy-operating and therefore suitable for animal species identification.

GC-MS Analysis of Volatile Components of Mango (Mangifera indica L. var Zihua) Fruits
WEI Chang-bin,XING Shan-shan,LIU Sheng-hui,WU Hong-xia,WANG Song-biao,
2010, 31(2):  220-223.  doi:10.7506/spkx1002-6300-201002056
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The volatile components in ripening fruit peel and pulp of mango (Mangifera indica L. var Zihua) were extracted with 100 μm PDMS or 75 μm Carboxen/ PDMS fibres prior to GC-MS analysis. Twenty-six volatile components were identified in mango peel extracted with 75μm Carboxen/ PDMS fibre, accounting for 98.71% of total volatile components. Terpenes contributed to 98.49% of identified components, among which terpinolene constituted a major fraction, accounting for 44.20%. Totally 21 components were detected in mango pulp, occupying 99.29% of total volatile components. Terpenes made a contribution of 97.82%, in which p-cymene was a dominant compound (55.45%). However, only 22 volatile components were identified in mango peel extracted with 100 μm PDMS fibre, which accounted for 98.51% of total volatile components, comprising 98.14% of terpenes and the content of terpinolene was 68.45%. Fifteen volatile components were found in mango pulp, the total relative content 97.68%, and the content of terpenes 96.69% with the dominant terpinolene of 79.18%. Therefore, 75 μm Carboxen/ PDMS fibre provides a much more suitable tool for the extraction of volatile components in mango fruits and the peel seems to contain more volatile components than the pulp in quantity, and the main volatile is terpenes.

Reversed-Phase High Performance Liquid Chromatographic Determination of Chlorogenic Acid in Yacon Leaves
CHEN Hong-hui1,2,PENG Guang-hua3
2010, 31(2):  224-227.  doi:10.7506/spkx1002-6300-201002057
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A method using reversed-phase high performance liquid chromatography was developed for the determination of chlorogenic acid in yacon leaves, an active substance. The chromatographic separation was achieved on a Hypersil ODS column (4.6 mm × 300 mm, 5 μm) using a mobile phase composed of acetonitrile and 0.5% phosphoric acid (8:92, V/V) at a flow rate of 1.0 mL/min. The detection wavelength and the column temperature were set at 325 nm and 25 ℃, respectively. There was a good linear relationship between peak area and chlorogenic acid concentration over the range of 10-100 μg/mL (r = 0.9999), and the average spike recovery for chlorogenic acid was 97.0% with a relative standard deviation (RSD) of 1.10%. The developed method presents the benefits of rapidity, simplicity, high accuracy and good separation.

Differences in Sensory Quality and Chemical Composition of Fuzhuan Tea of Different Storage Ages
HUANG Ya-hui1,2,CHEN Jian-hua1,*,ZHOU Yun2,CHEN Xiao-yang3
2010, 31(2):  228-232.  doi:10.7506/spkx1002-6300-201002058
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Fuzhuan brick-tea is a popular Chinese dark tea fermented by Eurotium cristatum, which contributes its typical fungal aroma. Samples of Fuzhuan tea of different storage ages (produced in 2008, 1985 and 1952) were analyzed for sensory quality and main chemical components such as tea polyphenols, amino acids, caffeine, procyanidins, water-soluble sugar, pectin, anthocyanins, TF, TR and TB. Results showed that after aging, Fuzhuan tea exhibited a decrease in the contents of water extract, tea polyphenols, amino acids, TF and TR and an increase in the content of pectin, water-soluble sugars, anthocyanins and TB, whereas no obvious change in caffeine content was observed. Sensory quality evaluation demonstrated that appropriate aging made a contribution to the conversion of internal substances in Fuzhuan tea and its pleasant aroma and mellow and heavy taste, while Fuzhuan tea exhibited exhausted aroma, offensive stale odor and plain and thin taste after excessive aging. Based on sensory attributes and chemical composition profile of Fuzhuan tea, two approaches to the identification of aging time of this tea were put forward. Moreover, the correlation between aging time and TB/tea polyphenols ratio was preliminarily analyzed.

Effect of Acetaldehyde Fumigation on Fresh-cut Chinese Water Chestnut Quality during Room Temperature Storage
DENG Li-li1,MING Jian1,2,TIAN Wei-na1,ZENG Kai-fang1,2,*
2010, 31(2):  233-236.  doi:10.7506/spkx1002-6300-201002059
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Postharvest Chinese water chestnuts were exposed to 0, 0.1%, 0.5% or 1.0% acetaldehyde vapor for 4 h in a wellsealed container and, thereafter, stored in a cool, dry and ventilative place for 2 days. Following being peeled and sliced, the resulted Chinese water chestnut slices were stored in a plastic container covered with fresh-keeping film at ambient temperature (12 ℃) and were evaluated for color, nutrients and weight loss at intervals of 2 days. Results showed that acetaldehyde treatment at 0.1%, 0.5% or 1.0% levels resulted in an effective delay of browning and a significant reduction of water loss in fresh-cut Chinese water chestnuts. The best browning-delaying effect was seen in 0.5% acetaldehyde-treated group, and 0.1% acetaldehyde treatment significantly increased the soluble solids content and decreased the titratable acidity. However, the degradation of reduced ascorbic acid was accelerated due to acetaldehyde treatment.

Effect of Storage Temperature on Rancidity of Raw Trichosanthes kirilowii Seed Oil
ZHOU Yong-jun,GAO Hai-yan*,CHEN Hang-jun,SONG Li-li,MAO Jin-lin,CHEN Wen-xuan
2010, 31(2):  237-240.  doi:10.7506/spkx1002-6300-201002060
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To examine the effect of storage temperature on the rancidity of raw Trichosanthes kirilowii oil, the oil stored at different temperatures (0, 5, 15, 25 ℃) was analyzed for acid value, lipase activity, peroxide value, TBA value and VE retention rate according to relevant national standards for edible oils at intervals of 1 month. Results showed that the stability of Trichosanthes kirilow oil was affected notably by environmental temperature and higher storage temperatures resulted in the fast quality change. However, storage temperatures of 0 ℃and 5 ℃ significantly inhibited lipase activity, delayed the elevation of acid value, peroxide value and TBA value, and reduced the loss of vitamin E, thereby obviously delaying the rancidification of raw Trichosanthes kirilowii oil.

Effect of Chitosan Coating on Strawberry Preservation
KUANG Yin-jin1,LONG Jing1,XU Dong-sheng1,QIN Cai-qin1,2,*
2010, 31(2):  241-244.  doi:10.7506/spkx1002-6300-201002061
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Seven different molecular weight chitosans were tested for antimicrobial effect against Botrytis cinerea by spread plate method. Along with this, the effect of chitosan coating on hardness and soluble solids, VC and reducing sugar contents of strawberry stored at ambient temperature was investigated. Results showed that of the 7 chitosans, 6 water insoluble ones dissolved in acetic acid exhibited a higher inhibitory effect against B. cinerea, especially medium weight molecular chitosans (7.8×104, 4.8×104), whereas chitooligomer exhibited a poorer inhibitory effect. Exposure to water insoluble chitosans dissolved in acetic acid for 30 d significantly protected strawberry from Botrytis cinerea invasion, inhibited fruit softening and delayed the decreases in contents of reducing sugar and VC, thereby providing a good preservation effect. However, no significant preservation effect of chitooligomer was observed. According to experiments, within the concentration range of 5-10 g/L, chitosans with molecular weight between 5 × 104 and 20 × 104 demonstrated a better preservation effect on strawberry.

Intermittent Warming Effects on Enzymatic Browning of Plum Fruits during Postharvest Cold Storage
WANG Yan-ying,HU Wen-zhong*,LIU Cheng-hui,TIAN Mi-xia,JIANG Ai-li
2010, 31(2):  245-249.  doi:10.7506/spkx1002-6300-201002062
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Fresh plum fruits were subjected to prestorage treatment by intermittent warming and the effect of intermittent warming on enzymatic browning of plum fruits was examined during postharvest cold storage (at 0 ℃). Results showed that after 20 d of storage, chilling injury in plum fruits started to appear, the content of polyphenol and the activity of polyphenol oxidase (PPO) were decreased gradually, the index of chilling injury was increased significantly, and the normal fruit postripening was blocked. Meanwhile, the activity of superoxide dismutase (SOD) was induced by low temperature, and the activities of peroxidase (POD) and catalase (CAT) were stimulated by chilling injury. These results demonstrate the synergistic effect of antioxidant enzyme system against environmental stress. With prolonged storage time, the content of malondialdehyde (MDA) was increased gradually and chilling injury and browning were aggravated. Intermittent warming led to increased activities of SOD, POD and CAT, inhibited accumulation of reactive oxygen species and reduced level of lipid peroxidation and thereby delayed the occurrence of chilling injury. An intermittent warming to 18 ℃ significantly inhibited chilling injury and promoted fruit postripening, thereby delaying fruit aging. Despite alleviated chilling injury during the early storage, plum fruits subjected to intermittent warming to 10 ℃ exhibited accelerated postripening and aging and poor resistance to low temperature during the late storage so that chilling injury was aggravated and severe browning was observed.

Effects of Storage Temperature and Duration on Quality Properties of Cooked Wuchang Rice
YU Shi-feng,MA Ying*
2010, 31(2):  250-254.  doi:10.7506/spkx1002-6300-201002063
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Cooked rice was prepared from Wuchang rice harvested from Heilongjiang province. The quality properties of cooked rice: moisture content, enthalpy change (Δ Hr), textural attributes and sensory quality were monitored at intervals of 1 day during 14 days of storage at different temperatures (-18, 0, 4, 10 ℃ and 22 ℃). Results showed that storage temperature had little effect on the moisture content of cooked rice, which exhibited no significant change over the whole storage at the same temperature. However, both storage temperature and time significantly affected the enthalpy change, hardness and stickness of cooked rice. A continuous increase in enthalpy change and hardness was observed in cooked rice stored at 0, 4 or 10 ℃ and a maximum value was obtained for both indexes on the 14th day. The stickness continued to decrease with prolonged storage time and reached a minimum value on the 14th day. Cooked rice stored at -18 ℃ exhibited slowly increased enthalpy change and hardness and slowly decreased stickness, whereas no significant change was observed in sensory quality. Storage at 22 ℃ led to little changes in the above three indexes, but after 2 days, cooked rice completely spoiled. Therefore, the optimum storage temperature for cooked rice was 0-4 ℃, and lower temperature (-18 ℃) can inhibit starch retrogradation.

Relationship between Harvest Maturity and Lignification of Loquat Fruits during Cold Storage
WU Jin-cheng,LIANG Jie,CHEN Jian-qin,CAO Lian-huang,XU Xin,GUAN Ling,CHEN Li-ping
2010, 31(2):  255-259.  doi:10.7506/spkx1002-6300-201002064
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Flesh leatheriness is a major problem during cold storage of loquat fruits. In order to identify the optimal maturity level of loquat fruits for cold storage so as to retard flesh leatheriness and extend the storage life of loquat fruits, Jiefangzhong loquat (Eriobotrya japonica Lindl. cv. Jiefangzhong) fruits with 70%, 80% or 90% maturity levels were selected as the experimental subjects to measure the changes of quality indexes and lignification related enzyme activities of loquat fruits stored at 4 ℃. Results showed that loquat fruits higher maturity level exhibited more severe lignification. When loquat fruits were stored for 35 d, there was no significant difference in lignin content between loquat fruits at 70% maturity and those at 80% maturity (P > 0.05). The total sugar and total soluble solids content of loquat fruits at 80% maturity was significantly higher than those at 70% or 90% maturity (P < 0.05). There were no significant differences in titrable acid (TA) content and cinnamyl alcohol dehydrogenase (CAD, EC 1. 1. 1. 195.), polyamine oxidase (PAO, EC, peroxidase (POD, EC, 4- coumarate coenzyme A ligase (4CL, EC 6. 2. 1. 12.) activities of refrigerated loquat fruits with different maturity. Significantly higher phenylalanine ammonia lyase (PAL, EC activity was observed fruits with 90% maturity than those with 70% or 80% maturity (P < 0.05). A significant positive correlation was found between PAL activity and lignin content (r = 0.89). In conclusion, PAL activity is closely associated with lignification of loquat fruits during cold storage and the optimal maturity level of loquat fruits for storage at 4 ℃ is 80%.

A Comparative Study of Use of Coating Agents for Preservation of Eggs
FU Xing,MA Mei-hu*,CAI Zhao-xia,XIONG Wei,CHEN Miao
2010, 31(2):  260-263.  doi:10.7506/spkx1002-6300-201002065
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Eggs were subjected to coating treatment with chitosan, starch, polyvinyl alcohol or alcohol ethoxylate (AEO) and were subsequently stored for 28 d at 28 ℃ and 80% relative humidity. The effect of such treatments on the interior quality and consumer perception of eggs were studied. Results showed that after 28 day storage, the weight loss in AEO-coated eggs was 4.22% (6.52% in uncoated eggs), the relative density dropped from 1.095 to 1.064 (1.01 in uncoated eggs), the yolk index from 0.43 to 0.37, the haugh unit from 88.7 to 56.32 (B grade level), and the pH value remained below 9.01. The above indexes in AEOcoated eggs were significantly better than those in uncoated ones and slightly better than those in polyvinyl alcohol- or chitosancoated ones, while no significant preservation effect was found in starch-coated ones. AEO coating results in significantly prolonged shelf life as well as good interior quality and consumer acceptability, thereby having a promising potential as a coating agent used for the preservation of eggs.

Effect of Cutting Injury on Post-ripening, Softening and Ethylene Biosynthesis in Nectarine (Prunus persica (L.) Batsch var. nucipersica (Suckow) C. Schneider) Fruits
JIANG Ai-li1,2,MA Yan2,HU Wen-zhong1,2,*,TIAN Mi-xia1,2,LIU Cheng-hui1,2
2010, 31(2):  264-268.  doi:10.7506/spkx1002-6300-201002066
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Changes in activities of enzymes related with cell wall polysaccharides degradation or membrane lipid peroxidation, ethylene production and ACC oxidase (ACO) and ACC synthase (ACS) activities were measured during 10 ℃ storage of freshcut nectarine fruits to probe into mechanism for ethylene production and its relationship with fruit softening. Results showed that the appearance of ethylene production peak, ACO and ACS activity peak, which appeared on the second day of storage, were earlier than that of polygalacturonase or lipoxygenase activity. These phenomena indicate that increased ethylene production induced by cutting injury triggers the process of cell wall hydrolysis and membrane lipid peroxidation. Cell wall hydrolysis and membrane lipid peroxidation were more serious in upper layer of cutting area than in other layers. After 2 days, the protopectin content in upper layer was decreased by 83.7% and the malondialdehyde (MDA) content by 57%, compared with control nectarine fruits.

Color Changes of Fresh Orange Juice during Refrigerated Storage
HAN Yan,WU Hou-jiu*,DOU Hua-ting
2010, 31(2):  269-272.  doi:10.7506/spkx1002-6300-201002067
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Orange juices derived from 3 orange cultivars were stored at 4 ℃ for 12 weeks, and their color, carotenoids and vitamin C contents were determined at intervals of 2 weeks. Color changes of the orange juices and their possible relationships with the changes of carotenoids and ascorbic acid contents were investigated. Results showed that during storage, CIE1976 a* value (redgreen) and OJ value decreased and CIE1976 L* value (brightness), b* value (yellow-blue), C* and Hue values increased, and overall color change (ΔE*) increased significantly (P < 0.05). Simultaneously, the content of carotenoids and vitamin C decreased and browning index increased. The color of orange juice was significantly positively correlated with the content of carotenoids and vitamin C, and significantly negatively correlated with the browning index. From the viewpoint of color, the expiration time of the orange juices is 7-9 weeks.

Edible Quality of Ice-stored Yellowfin Tuna (Thunnus albacares) Dorsal Sashimi
LIU Yuan,WANG Xi-chang*,LUO Yin
2010, 31(2 ):  273-276.  doi:10.7506/spkx1002-6300-201002068
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Dorsal sashimi of yellowfin tuna (Thunnus albacares) from Fiji island was processed under simulated freshnesskeeping conditions used in sushi shops (ice storage), and its edible quality was evaluated according to biochemical [pH value, color, drip loss, total volatile base nitrogen (TVB-N), K value], sensory and microbiological attributes. Results showed that ice-stored yellowfin tuna sashimi well kept its edible quality within 0-4 h. Within 0-1 h, the sashimi exhibited fresh red color, fishy aroma and delicious taste, and therefore was edible. Within the next 3 hours, the color gradually became dark and the aroma and taste were lost, revealing the decrease in edible quality. Beyond 4 hours, the sashimi was no longer fresh and completely lost its inherent mouthfeel and color and, consequently, became commercially valueless.

Single and Combined Inhibitory Effects of Inhibitors against Polyphenol Oxidase from Pingguoli Pear (Pyrus bretchneideri Rehd cv Pingguoli) Fruits
ZHAO Jian-hua1,ZHENG Yu-shu2,LI Guan-hao1,QUAN Wu-rong1,*
2010, 31(2 ):  277-279.  doi:10.7506/spkx1002-6300-201002069
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Crude polyphenol oxidase (PPO) in Pingguoli pear fruits was prepared through sequential steps of homogenization followed by extraction with acetone. The single inhibitory effects of glutathione, cysteine and sodium sulfite against the enzyme were evaluated according to residue enzyme activity. Subsequently, to obtain the optimal inhibitory effect, the above inhibitors were compounded and the optimal formulation was investigated using orthogonal array design. Results showed that glutathione exhibited a good inhibitory effect against this enzyme with half-inhibitory concentration of 300μmol/L and maximal inhibitory concentration of 500 μ mol/L, which was stronger than that of other two inhibitors.

Processing Technology of Beijing Traditional Food“Douzhi”
DING Yu-zhen1,ZHANG Shao-ying1,2,*,LIANG Jin-yi3,LIU Peng2
2010, 31(2):  280-283.  doi:10.7506/spkx1002-6300-201002070
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To enhance the product quality of Beijing traditional food “Douzhi”, the microbiological, chemical and biochemical changes during its processing were studied. Lactic acid producing bacteria were confirmed accounting for the natural acidification of mung bean milk during sedimentation. The main fermenting bacteria came from two species: Lactococcus lactis and Leuconostoc citreum, which accounted for 72% and 26% of the total, respectively. Soaking brought little change in starch content, but caused a significant reduction in crude protein and sugars and an increased level in soluble proteins and free amino acids content. This suggests that a high metabolic activity is induced during steeping. Fermentation caused a rapid reduction in soluble proteins, soluble sugars and reducing sugars and a significant accumulation in free amino acids. Mung bean endogenous protease and amylase activity dropped significantly during fermentation, while the activity of microbial protease enhanced during the latter part.

Synthesis and Application of Edible Flavor 3-Heptanol
LIU Yu-ping1,2,YIN De-cai2,HUANG Ming-quan2,SUN Bao-guo2,*
2010, 31(2):  284-286.  doi:10.7506/spkx1002-6300-201002071
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3-Heptanol, an edible flavor, was synthesized through a nucleophilic addition reaction of ethylmagnesium bromide with n-pentanal. Factors influencing 3-heptanol yield, such as molar ratio of raw materials, refluxing time in preparing ethylmagnesium bromide and refluxing time in its addition reaction with n-pentanal were discussed. The optimal reaction conditions were obtained as follows: mole ratio of n-pentanal, monobromoethane and magnesium 1.0:1.2:1.5, refluxing time in preparing ethylmagnesium bromide 45 min, and refluxing time in preparing 3-heptanol 30 min. The yield of 3-heptanol under such conditions was 87.3%. The target product obtained was subjected to structure characterization by means of GC, IR GC-MS and 1H NMR and its characteristic aroma was evaluated. In addition, this flavor was successfully used in commercial banana essence.