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Table of Content

25 March 2013, Volume 34 Issue 6
Effects of Cooking Time and Drying Time on Texture and Color of Salty Chicken Wing
2013, 34(6):  1-5.  doi:10.7506/spkx1002-6630-201306001
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In order to obtain optimal cooking and drying time of salty chicken wings, chicken wings were cooked at 80 ℃ for different lengths of time (10, 20, 30, 40 min), and drying at 60 ℃ for different lengths of time (20, 40, 60, 80, 100, 120 min) to observe changes in water loss rate, salt content, color and texture. Results showed that drying time had a significant impact on water loss rate, salt content, water content and color (L*, a* and b*) (P<0.0001), while cooking time did not exhibit a significant impact. Chicken wings subjected to cooking for 40 min and drying for 40 min had the minimum hardness, the best chewiness and better resilience. In conclusion, the optimal processing parameters of salty chicken wings include cooking for 40 min and drying for 40 min.
Processing Quality and Oleoresin Composition of Ginger at Different Growth Periods
2013, 34(6):  6-9.  doi:10.7506/spkx1002-6630-201306002
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In order to determine the characteristics of raw ginger processing, the change of major compositions in ginger rhizome at different growth and storage periods was studied. Results showed that the contents of dry materials, soluble sugar, soluble starch, crude fiber and oleoresin revealed an obvious increase as the extension of growth and storage periods, while the contents of soluble protein and free amino acids were higher in the early growth stage, but lower or no significant change in the later growth and storage periods. During the growth of ginger, chemical compositions of ginger oleoresin exhibited an increasing trend. Although new compounds were synthesized during ginger storage period, 14 trace volatile compounds such as β-terpineol, neral and bornyl acetate disappeared after prolonged storage, while the major chemical compositions of ginger oleoresin maintained a stable level during different periods. Higher production, lower dry materials and ginger oleoresin, lighter spicy taste, and less crude fiber were observed in ginger at the age of four or five months so that ginger was suitable for pickling processing. After storage for 60 days, dry material content, soluble starch and ginger oleoresin in ginger rhizome remained stable, which was suitable for ginger dehydration, starch processing and ginger oleoresin extraction.
Preparation of β-Cryptoxanthin from Paprika
2013, 34(6):  10-13.  doi:10.7506/spkx1002-6630-201306003
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In order to establish a method for the separation and preparation of β-cryptoxanthin from paprika, the crude β-cryptoxanthin was extracted by ultrasonic acetone extraction, saponificated and separated by silica gel column chromatography. Preparative high performance liquid chromatography was used to refine and purify β-cryptoxanthin. The structure of β-cryptoxanthin was identified by UV, ESI-MS, 1H-NMR and 13C-NMR. The purity of β-cryptoxanthin was determined by analytical HPLC. The results indicated that complete saponification of chili pigment extract was achieved when saponifying its dispersion in 45 mL of isopropanol (9 g/mL) with 6.5 mL of 20% KOH methanol solution for 24 h at room temperature. During the rough separation by silica gel column chromatography using petroleum ether and acetone as elution solvents, β-cryptoxanthin could be better enriched at a volume ratio of 10:1. The preparative high performance liquid chromatography required acetone and water at a ratio of 95:5 (V/V) and a flow rate of 5 mL/min. Under these optimized conditions, β-cryptoxanthin with a purity of 99.0% could be obtained. This developed method is simple, rapid, reproductive, and suitable for the preparation of β-cryptoxanthin with high purity.
Preparation and Application of Hydrogen Dioxide Biosensor Based on Microelectrode Array of SiO2 Cavity
2013, 34(6):  14-18.  doi:10.7506/spkx1002-6630-201306004
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A new biosensor for the detection of H2O2 was prepared by immobilizing microperoxidase-11 (MP-11) onto silicon dioxide (SiO2) cavity array directly. Polystyrene (PS) particle array was constructed on indium-tin oxide (ITO) electrode surface by Langmuir-Blodgett technique. The silicon dioxide cavity array was prepared by Langmuir-Blodgett technique using PS particle array as the template. Using MP-11 as a model protein, MP-11/SiO2 cavity array-ITO electrode was prepared by adsorbing MP-11 into SiO2 cavity. The fast response of the biosensor against H2O2 was observed. A linear relationship between current response and H2O2 concentration ranging from 7.06 × 10-6 to 4.02 × 10-2 mol/L was achieved with a detection limit of 3.0 × 10-7 mol/L. The apparent Michaelis-Menten constant was 0.916 mmol/L. This established method is satisfactory for the determination of hydrogen peroxide in food samples with a recovery rate varying from 94% to 97%.
Optimized Synthesis of Glucose Palmitate by Immobilized Lipase from Candida sp. with Response Surface Methodology
2013, 34(6):  19-26.  doi:10.7506/spkx1002-6630-201306005
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The effects of lipase addition amount, substrate concentration, palmitic acid-glucose ratio, reaction temperature, reaction time, and 4 ? molecular sieve amount on the esterification of glucose were studied. The optimal ranges of independent variables were selected on the basis of single-factor tests. Response surface methodology and central composite rotatable design were adopted to evaluate the effects of synthesis variables on the degree of esterification. The results showed that reaction time was the most important parameter. The optimal conditions for esterification were lipase addition amount of 14.67 U, substrate concentration of 1.31 mol/L, palmitic acid-glucose ratio of 3.03:1, reaction time of 6.63 h, 4 ? molecular sieve amount of 0.71 g, and reaction temperature of 45 ℃. The actual degree of esterification was 89.72%, which was close to the predicted value of 94.55%. After seventh repeated use, the residual activity of immobilized lipase remained 40%.
Large-Scale Isolation and Preparation of Soybean Saponin by High-Speed Countercurrent Chromatography Combined with Preparative HPLC
2013, 34(6):  27-32.  doi:10.7506/spkx1002-6630-201306006
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The objective of this study is to isolate and purify soybean saponin from soybean germs by high-speed countercurrent chromatography (HSCCC) combined with preparative HPLC. The isoflavonoids were removed from crude extract by HSCCC first. The pure soybean saponin was then obtained by preparative HPLC with acetic acid or trifluoroacetic acid (TFA) as mobile phase in a gradient elution mode. The optimal conditions for preparative HPLC were dual mobile phases composed of acetonitrile containing 0.01% (V/V) TFA and millipore water at a flow rate of 10 mL/min for gradient elution. Five compounds in group A and two compounds in group B and 3 kinds of 2,3-dihydro-2,5-dinydroxy-6-methyl-4H-pyran-4-one (DDMP)- conjugated soybean saponins with high purity were prepared and their structures were elucidated by mass spectrum (MS) and nuclear magnetic resonance (NMR). Therefore, the developed method can be used to separate partially and fully acetylated soybean saponins as well as DDMP-conjugated and unconjugated soybean saponins in the original sample.
Preparation, Isolation and Purification of Dairy Ingredients with Antioxidant Activity from Milk Casein
TONG Wei,LI Zhi-cheng*,XIONG Qing-quan,ZHENG Xiao-ying,SU Jin-wen,REN Jiao
2013, 34(6):  33-36.  doi:10.7506/spkx1002-6630-201306007
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The dairy ingredients with low allergenic reaction and antioxidant activity were prepared from milk casein. The optimal preparation process parameters were explored to achieve the strong hydroxyl radical scavenging activity. Milk casein hydrolysates (MCH) were isolated and purified by macroporous adsorption resin and gel filtration chromatography. The results indicated that: (1) MCH obtained from hydrolysis by trypsin and neutral protease for 6 h had higher degree of hydrolysis (36.80%) and better antioxidant activity. IC50 of MCH for scavenging hydroxyl free radicals 3.12 mg/mL. (2) The elution fraction from 75% ethanol purified by macroporous adsorption resin had higher antioxidant activity with IC50 of 0.14 mg/mL. (3) The elution fraction from 75% ethanol by gel filtration chromatography with molecular weight in the range of 355.38–854.89 D had higher antioxidant activity with IC50 of 0.09219 mg/mL, which revealed a 33.84-fold increase compared with MCH. The contents of peptides with molecular weight less than 3238.05 D were accounted for 60.32% of total purified peptides, and 30.09% peptides were oligopeptides with 2–8 amino acid residues. This preparation process not only increased antioxidant activity, but also reduced anaphylaxis of dairy ingredients from milk casein. In addition, the spray drying was also better for the preparation of dairy ingredients.
Optimization of coagulation process of " Qula" rennet casein using response surface methodology
JI Yin-li1,HE Xiao1,GAO Wei-dong1,SONG Li1,GE Jing-wei1,SU Yan-ping1,XIE Xiao-dong2,*
2013, 34(6):  37-41.  doi:10.7506/spkx1002-6630-201306008
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In this study, Qula was selected as the raw material and Pusillus mucor chymosin was used as the coagulant to prepare Qula rennet casein. Based on the single factor tests, response surface design was used to optimize the coagulation process of Qula rennet casein. Results indicated that the order for affecting the yield of Qula rennet casein was curd pH, chymosin addition amount, CaCl2 addition amount, and curd temperature. The optimal curd conditions included pH 6.2, chymosin addition amount of 0.05 g/kg, CaCl2 addition amount of 2.5% and curd temperature of 42 ℃. Under these optimal conditions, the maximum predicted yield was 75.23% compared to 73.54% in the validation experiments.
Effects of Different Color Inhibitors on Color and Polyphenols of Litchi Puree
CHENG Li-na1,2,XU Yu-juan1,TANG Dao-bang1,XIAO Geng-sheng1,2,*,WU Ji-jun1,LI Jun1
2013, 34(6):  42-46.  doi:10.7506/spkx1002-6630-201306009
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In order to optimize the formula of litchi puree browning inhibitor, litchi puree was treated by citric acid, D-sodium erythorbate and sodium pyrosulfite with various concentrations and dried at 60 ℃ for 24 h to observe the effect on color preserving and polyphenols. The results of orthogonal tests showed that the higher retention of polyphenols resulted in the higher lightness value and the better color preserving effect. Among these inhibitors, the inhibition order was sodium pyrosulfite, D-sodium erythorbate and citric acid. The best formula was composed of 0.1% citric acid, 0.075 g/L D-sodium erythorbate and 0.25 g/L sodium pyrosulfite. A highly significant correlation between changes in polyphenol retention and lightness was observed for litchi puree treated with the optimized blend of three browning inhibitors during 60 h of heat treatment.
Simultaneous Extraction of Flavonoids and Polysaccharides by Ultrasonic-assisted Extraction from Chaenomeles sinensis (Thouin) Koehne
2013, 34(6):  47-51.  doi:10.7506/spkx1002-6630-201306010
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Objective: To make comprehensive utilization of Chaenomeles sinensis (Thouin) Koehne. Methods: Box-Behnken experimental design and response surface methodology were used to optimize ultrasonic-assisted extraction conditions of simultaneous extraction for flavonoids and polysaccharides from Chaenomeles sinensis (Thouin) Koehne. Results: The optimal extraction conditions were ultrasonic power of 480 W, extraction time of 35 min, extraction temperature of 73 ℃ and materialliquid ratio of 1:90 (g/mL). Under these optimal conditions, the total yield of flavonoids and polysaccharides was up to 15.62%, an increase of 21.46% when compared with hot water extraction. Conclusion: The total yield of flavonoids and polysaccharides during the simultaneous extraction from Chaenomeles sinensis (Thouin) Koehne is improved by ultrasonic-assisted extraction.
Synthesis of Laurate Starch Using Immobilized Lipase
XIN Jia-ying1, 2,LIU Tie1,WANG Yan1,CHEN Lin-lin1
2013, 34(6):  52-55.  doi:10.7506/spkx1002-6630-201306011
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Laurate starch was synthesized by immobilized lipase Novozym 435 as the biocatalyst in the solvent-free system. The effects of water activity, reaction temperature, reaction time and lipase-substrate ratio on esterification of laurate starch were explored. The results showed that the optimal reaction conditions included reaction time of 24 h, reaction temperature of 60 ℃, lauric acid-starch ratio of 4:1 and lipase-starch ratio of 3:100. Under the optimal reaction conditions, the degree of substitution was 0.1339. The structure of the product was confirmed by FT-IR.
Research on Water-holding Capacity of Sea Bass with two kinds of methods of Ultra High Pressure Processing and Adding Compound Phosphate
SHANG Xiao-lan,LIU An-jun
2013, 34(6):  56-59.  doi:10.7506/spkx1002-6630-201306012
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The effects of ultra high pressure treatment and compound phosphate on cooking loss of sea bass were studied. The muscle tissue of sea bass subjected to different processing treatments was observed to explore water retention mechanism of sea bass. The results showed addition of 1.0 g/kg trisodium phosphate, 2.0 g/kg tripolyphosphate, 1.0 g/kg pyrophosphate and 1.5 g/kg hexametaphosphate resulted in minimal cooking loss of 25.34%. In addition, high-pressure treatment at 400 MPa provided a cooking loss of 24.53%. The increased sarcomere length of sea bass due to the highpressure treatment resulted in network space between muscle fibers, thus facilitating water retention.
Preparation of microencapsulation of Thymus oil and determination of controlled-release properties
WANG Di,XU Hui,WANG Zhang-gui,XIE Hai-wei,CAO Ke-ke,REN Mao-sheng,TIAN Chang-cheng
2013, 34(6):  60-63.  doi:10.7506/spkx1002-6630-201306013
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Microcapsules of thymus oil were prepared by using beer yeast cells as wall materials. The effects of essential oil-yeast ratio, encapsulating temperature and encapsulating time were investigated. The optimal microencapsulating conditions included essential oil-yeast ratio of 2:1, encapsulating temperature of 60 ℃ and encapsulating time of 10 h. Under these conditions, the maximum yield of essential oil encapsulated in yeast-based microcapsule was 86.71%. After heating at 100 ℃ for 30 h, the releasing rate of volatile components in microcapsules was only 15.8%. Meanwhile, microcapsules also revealed more stable antioxidant activity. Therefore, microencapsulation can reduce the releasing rate and oxidation process of volatile components, thus prolonging the life of essential oil.
Optimization by Orthogonal Array Design of Extraction of Chlorogenic Acid from Burdock Root Peels
2013, 34(6):  64-67.  doi:10.7506/spkx1002-6630-201306014
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Objective: To optimize extraction process of chlorogenic acid in burdock root peels by cellulose methods. Methods: The effects of enzyme dosage, material-liquid ratio, extraction temperature, extraction duration and extraction pH on the yield of chlorogenic acid from burdock root peels by single factor and orthogonal tests were explored. Results: The optimal extraction process included cellulose addition amount of 4 mL, extraction temperature of 60 ℃, extraction time of 1.5 h, extraction pH 6.0, and material-liquid ratio of 1:20. Under the optimal extraction conditions, the maximum yield of chlorogenic acid was 1.45%.
Use of Macroporous Adsorption Resin for the Enrichment of Esterified Catechin
2013, 34(6):  68-72.  doi:10.7506/spkx1002-6630-201306015
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Macroporous adsorption resin was used for the enrichment of esterified catechin from green tea powder. LX-16 was selected from four macroporous adsorption resins by evaluating adsorption and desorption capacity, and investigating velocity curve of static adsorption, adsorption isotherm, dynamic adsorption and alcohol gradient elution. The results showed that LX-16 revealed better adsorption selectivity for esterified catechins. When the loading amount of esterified catechin was 17 mg/g, the purity of purified esterified catechin was 65.2% as opposed to 7.3% for crude esterified catechin, and a recovery rate of 80% was obtained.
Optimization of RFLP-PCR Reaction System for cpDNA in Tea Plants
CHEN Sheng-xiang,QI Gui-nian*,LI Huan
2013, 34(6):  73-76.  doi:10.7506/spkx1002-6630-201306016
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Optimal reaction system of PCR-restriction fragment length polymorphism (RFLP) for cpDNA in tea plants was investigated by orthogonal array design. Results showed that the optimal amplification system was 100 ng DNA template, 200 μmol/L dNTPs, 1.5 mmol/L MgCl2, 50 ng primer, 3U Taq DNA polymerase, and addition of ddH2O up to total volume of 25 μL. The optimal digestion system included 6 μL amplified product, 2 U endonuclease, 1 × endonuclease buffer in digestion solution, digestion time of 6 h and digestion temperature of 37 ℃, and addition of ddH2O up to total volume of 15 μL. Under the optimal reaction system, 30 camellia cultivars were analyzed and polymorphic digestion maps were obtained.
Optimizing the extraction of tea polyphenols and theanine from summer green tea by using response surface methodology
2013, 34(6):  77-82.  doi:10.7506/spkx1002-6630-201306017
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The response surface methodology was used to optimize the extraction of tea polyphenols and theanine from summer green tea by hot water. Three parameters including extraction temperature, extraction time and ratio (v/w) of water to raw material were optimized based on tea polyphenols content, theanine content and antioxidant activity of the extracts. The optimal extraction conditions were extraction temperature 96.12 ℃, extraction time 40.32 min and ratio of water to raw material 15.91 mL/g for tea polyphenols (133.68 mg gallic acid/g), 98.55 ℃, 40.97 min and 12.61 mL/g for theanine (4.11 mg/g), and the extraction conditions that provided optimum IC50 value for DPPH free radical scavenging activity (722.17 ?g/mL) were 96.34 ℃, 40.27 min and 16.09 mL/g. Under the extraction conditions (96 ℃, 40 min and 16 mL/g), the predicted yields for tea polyphenols and theanine were 99.99 and 96.68% of their corresponding predicted values under their optimal extraction conditions, respectively. The results suggested that the regression models were accurate and adequate for the extraction of tea polyphenols and theanine from summer green tea.
Optimization of Preparation of Seafood Flavor Essence from Mussel Hydrolysate by Response Surface Methodology
2013, 34(6):  83-87.  doi:10.7506/spkx1002-6630-201306018
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The optimal process conditions for producing seafood flavor essence from mussel hydrolysate by Maillard reaction were studied and the developed product was subjected to sensory evaluation and GC-MS analysis. The results showed that the optimal model system for preparing seafood flavor essence included 0.5% alanine/proline mixture at a ratio of 2:3, 8% glucose/xylose mixture at a ratio of 1:3, pH 6.2, and reaction at 100 ℃ for 25 min. By GC-MS analysis, 29 volatile compounds were identified as carboxylic acids, pyrazine, esters, aldehydes, ketones, alcohols and sulfur compounds. Among these compounds, benzothiazole, 3-(methylthio)propionaldehyde, pyrazine and other compounds contributed to seafood flavor essence.
Preparation and Properties of Dietary Fiber from Pineapple Pomace
2013, 34(6):  88-92.  doi:10.7506/spkx1002-6630-201306019
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The soluble and insoluble dietary fibers were prepared with acid hydrolysis and alkali hydrolysis from pineapple pomace and their properties were also compared. The extraction process was optimized by orthogonal tests. The results showed that the optimal extraction conditions for insoluble dietary fiber required reaction temperature of 60 ℃, reaction time of 60 min and hydrolysis pH of 2.0 during acid hydrolysis; NaOH concentration of 1%, material-liquid ratio of 1:15, reaction temperature of 50 ℃ and reaction time of 40 min during alkali hydrolysis. The optimal extraction condition for soluble dietary fiber required reaction temperature of 90 ℃, hydrolysis pH of 1.0, hydrolysis duration of 90 min and material-liquid ratio of 1:10 during acid hydrolysis. The maximum yield of soluble and insoluble dietary fiber by acid hydrolysis could reach 8.1% and 24.4%, respectively, and the maximum yield of insoluble dietary fiber by alkali hydrolysis was 62.80%. The waterholding capacity, swelling capacity, oil-holding capacity and cation exchange capacity (CEC) of water insoluble dietary fiber from both hydrolysis methods were 5.85 g/g and 3.82 g/g, 9.25 mL/g and 10.66 mL/g, 1.35 g/g and 1.75 g/g, and 0.21 mmol/g and 0.27 mmol/g, respectively. Therefore, higher maximum yield and better properties of dietary fibers were achieved during alkali hydrolysis.
Purification of Glycyrrhizic Acid from Glycyrrhiza Using Macroporous Resin
2013, 34(6):  93-97.  doi:10.7506/spkx1002-6630-201306020
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The purification of glycyrrhizic acid from glycyrrhiza using macroporous resin was study. Static absorption and desorption experiments were carried out to screen the optimal resin from macroporous resins DA201-C and AB-8. AB-8 was found to have better performance than DA201-C. In static adsorption and desorption experiments, the optimal purification conditions of glycyrrhizic acid by resin AB-8 were sample pH 6.0, 5.89 mg/mL sample concentration, and 50% ethanol as the desorption solvent. In addition, the purity of purified glycyrrhizic acid was determined by HPLC to be 52.3%, and was increased to 76.0% after recrystallization.
Optimization of Ultrasound-Assisted Extraction of Allicin Using Response Surface Methodology
HE Li,GU Yun,LIU Gui-zhen,WANG Qing-zhang*,YAN Shou-lei,LI Jie
2013, 34(6):  98-101.  doi:10.7506/spkx1002-6630-201306021
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The allicin extraction by low intensity ultrasound method was explored in this article. The effects of ultrasonic spower, ultrasonic temperature and ultrasonic duration on extraction rate of allicin were investigated using single factor and response surface tests. The results showed that the optimal extraction conditions were material/liquid ratio of 1:7 (g/mL), ultrasonic power of 48 W, ultrasonic temperature of 35 ℃ and ultrasonic duration of 32 min. Under these conditions, theactual maximum yield of allicin was 2.897 mg/g, which was close to the predicted value of 2.893 mg/g.
Variation of Trans-Fatty Acid Contents in Pure Milk Subjected to Different Heat Treatments and Optimization of Sterilization Process
LIU Jiao1,GE Wu-peng1,*,GU Chen1,LIU Zhi-hong2,CHEN Ying3,ZHANG Xiao-jun4
2013, 34(6):  102-105.  doi:10.7506/spkx1002-6630-201306022
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Objective: To explore the change rule of the TFA during the processing of pure milk under different heat treatments and to provide a theoretical reference for optimal process parameters. Methods: Trans-fatty acids are extracted with ethanol and petroleum ether from milk, and then methyl-esterificated and analyzed by GC. Results: These results showed that TFA contents revealed an increase as the extension of heating time at 85 ℃ (P<0.05). The sterilization temperature under UHT (T>133 ℃) condition during the same heating time did not reveal an obvious effect (P>0.05). TFA revealed an obvious increase with increasing heating time (P<0.05). Conclusion: The process parameters for controlling the content of TFA required heating temperature of 85 ℃ and heating duration of 15, and industrial pasteurization temperature of (137 ± 2) ℃, heating duration of 4 s under the UHT conditions.
Microwave-Assisted Extraction and Characterization of Potato Starch
LIU Ting-ting,SONG Chun-chun,WANG Da-wei*
2013, 34(6):  106-111.  doi:10.7506/spkx1002-6630-201306023
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Potato starch was obtained by microwave-assisted extraction, and its chemical components and properties were also analyzed. The optimal extraction process parameters including microwave power, microwave treatment time, particle size and material-liquid ratio of potato starch were explored using extraction rate of potato starch as the evaluation index by single factor and orthogonal tests. All factors had obvious effect on extraction rate of potato starch. The optimal extraction process parameters included microwave power of 500 W, microwave treatment duration of 4 min, particle size of 0.246 mm and material-liquid ratio of 1:1 (g/mL). Under the optimal extraction conditions, the extraction rate of potato starch was 93.85%, which revealed an improvement by 3.85% when compared with the traditional method. The contents of protein and amylase in potato starch were 0.13% and 34.60%, respectively. The granule shape was shell or rotundity, and the average granule size was 23.1 μm. The peak viscosity of potato starch was 1332 BU. The solubility, swelling power and transparency revealed a decreasing trend whereas the sedimentation revealed an increasing trend.
Orthogonal Array Design for the Optimization of Pectin Extraction from Hawthorn Pulp by Hydrochloric Acid Treatment, Microwave Heating and Salting Out
TANG Xia1,LIU Yue-ying2,ZHANG Zi-de1
2013, 34(6):  112-115.  doi:10.7506/spkx1002-6630-201306024
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Hawthorn pulp was used as the raw material to explore the effects of hydrochloric acid concentration, microwave power, microwave treatment time, saturated aluminum sulfate amount and material/liquid ratio on the extraction efficiency of pectin by one-factor-at-a-time method and orthogonal array design. The results indicated that the effect of microwave power revealed the strongest impact on extraction rate of pectin followed by material/liquid ratio, saturated aluminum sulfate amount, hydrochloric acid concentration and microwave treatment time. The optimal parameters for pectin extraction from hawthorn pulp were hydrochloric acid concentration of 0.05 mol/L, microwave power of 800 W, microwave treatment time of 50 s, material/liquid ratio of 1:15 and 7 mL of saturated aluminum sulfate. Under the optimal extraction conditions, the yield of pectin was 5.87%.
Separation of 10-Hydroxy-2-Decenoic Acid from Royal Jelly by Use of Macroporous Resin
2013, 34(6):  116-119.  doi:10.7506/spkx1002-6630-201306025
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10-Hydroxy-2-decenoic acid (HDA), a special bioactive component in royal jelly, has many physiological functions. In this study, we investigated the adsorption and desorption properties of HDA from royal jelly on macroporous resin and explored the optimal elution solution. X-5 resin had the best adsorption and desorption capacity for HDA and its saturated absorption capacity was 9.7 mg/g. The optimal elution solution was 90% alcohol, resulting in a dynamic desorption rate of 91.7%. The final product prepared by vacuum freeze-drying was white power with a purity of 80.4% as analyzed by HPLC.
Optimization by Orthogonal Array Design of Decolorization of Hydrolyzed Apricot Sauce
2013, 34(6):  120-123.  doi:10.7506/spkx1002-6630-201306026
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This study aimed to explore the decolorization effect of eight agents on hydrolyzed apricot sauce. Active carbon was identified as the optimal decolorizing agent based on decolorization rate and organic acid loss rate. The decolorization of hydrolyzed apricot sauce using active carbon was optimized by one-factor-at-a-time method and orthogonal array design. The optimal process parameters were active carbon amount of 1.2 g/100 mL, decolorization temperature of 70 ℃ and decolorization time of 60 min. Under these conditions, the decolorization rate of hydrolyzed apricot sauce was 93.01% and the organic acid loss rate was 5.89%.
Total Flavonoids from Mentha haplocalyx Briq. Leaves: Optimization of Extraction Process by Response Surface Methodology and Antioxidant Activity
HOU Xue-min,LI Lin-xia,ZHANG Zhi-feng,YAN Gui-qin*
2013, 34(6):  124-128.  doi:10.7506/spkx1002-6630-201306027
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Objective: To explore the optimal ultrasonic-assisted extraction conditions of total flavonoids from Mentha haplocalyx Briq. leaves and evaluate the antioxidant activity. Methods: Based on the single-factor tests, the ultrasonic extraction conditions of total flavonoids from Mentha haplocalyx Briq. leaves were optimized by response surface methodology in order to increase the extraction rate of total flavonoids. Meanwhile, the antioxidant activity of total flavonoids was assessed by scavenging assays of hydroxyl and superoxide anion free radicals. Results: The optimal extraction conditions of total flavonoids were ethanol concentration of 80%, material-liquid ratio of 1:40, extraction time of 118 min and extraction temperature of 62 ℃. Under the optimal conditions, the maximum extraction rate of total flavonoids was 6.11%. Extracted total flavonoids had strong scavenging capacity on hydroxyl and superoxide anion free radicals in a dose-dependent manner. Conclusion: Response surface methodology is applicable for the optimization of ultrasonic extraction of total flavonoids from Mentha haplocalyx Briq. leaves. The total flavonoids from Mentha haplocalyx Briq. leaves have strong antioxidant capacity. These investigations will be theoretical reference for further development and utilization of Mentha haplocalyx Briq..
Process Optimization by Response Surface Methodology for the Extraction of Water Soluble Flavonoids from Coreopsis tinctoria Flowers
2013, 34(6):  129-133.  doi:10.7506/spkx1002-6630-201306028
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Response surface methodology (RSM) was applied to optimize the extractions of water soluble flavonoids from Coreopsis tinctoria flowers using water as the extraction solvent. The effects of extraction temperature, material/liquid ratio, particle size and extraction time on the extraction efficiency of water soluble flavonoids were investigated. The optimal extraction conditions were extraction temperature of 90 ℃, material/liquid ratio of 1:90, extraction time of 60 min and raw material particle size of 40 mesh. The actual extraction rate of flavonoids from Coreopsis tinctoria under the optimal extraction conditions was 24.85%, which was close to the predicted value.
Establishment of Immunoassay Method for Allergy-Inducing Proteins in Eggs
2013, 34(6):  134-138.  doi:10.7506/spkx1002-6630-201306029
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Allergy-inducing proteins in eggs were isolated and purified by ammonium sulfate precipitation and ion exchange chromatography. Polyclonal antibody was generated by inoculated rabbits. A rapid, sensitive and specific ELISA method was developed and optimized for the detection of egg allergy proteins. Under the optimal experimental conditions, a good linear relationship between allergy-inducing proteins and inhibitory rate in the range of 1 × 10-4–10 μg/mL was observed. The regression equation was y = 0.74145+0.21692 × lgC (r = 0.9971). IC50 and IC10 were 77.076 ng/mL and 1.104 ng/mL, respectively. The recovery rate of the ELISA method was 70.1%-117.8%. The developed method had cross-reactivity with the proteins from turkey, duck and goose eggs, despite having no cross-reactivity with the proteins from peanut or milk. The variation coefficients of intraassay and inter-assay were 4.63% and 5.49%, respectively. The shelf life of the prepared immunoassay kit was 6 months during the storage at 4 ℃ and met the requirements for the analysis of egg allergy proteins with fast operation and high sensitivity.
Multiplex PCR for detection of Transgenic Rice with Bar and Bt gene
2013, 34(6):  139-142.  doi:10.7506/spkx1002-6630-201306030
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Based on the DNA sequences of rice endogenous SPS gene and exogenous Bar, Bt, CaMV35S promoter, Ubiquitin promoter and NOS terminator genes, specific primers were selected to establish a multiplex polymerase chain reaction (PCR) detection system for transgenic rice with Bar and Bt genes. This multiplex PCR system could allow accurate and rapid detection of six target genes, and the sensitivity was 0.9%.
Identification of Lateolabrax japonicus Freshness by Electronic Nose
2013, 34(6):  143-147.  doi:10.7506/spkx1002-6630-201306031
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The flavor change in the gill and flesh of Lateolabrax japonicus during different storage periods was evaluated by electronic nose. An electronic nose technology for evaluating the freshness of Lateolabrax japonicus was established through principal component analysis (PCA), linear discriminant analysis (LDA) and loadings analysis coupled with sensory evaluation and TVB-N as well as total bacterial counts. The results showed that the flavor in the gill and flesh of Lateolabrax japonicus was changed with the extension of storage period. The response of electronic nose revealed a gradual increase, and the second sensor played an important role in the first principal component. The response of electronic nose to the gill was stronger than that to the flesh. The analytical results of electronic nose were consistent with the results from sensory evaluation, TVB-N analysis and total bacterial count determination. Therefore, electronic nose can be used to identify the freshness of Lateolabrax japonicus and has a better discrimination in the flavor of the gill than that of the flesh.
Establishment of Determination Method for Flavonoids in Honey and Distribution of Flavonoids in 5 Kinds of Characteristic Honey from Yunan
2013, 34(6):  148-151.  doi:10.7506/spkx1002-6630-201306032
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A method for the determination of flavonoids in honey by SPE/HPLC was developed. The sample was extracted with acidified water (pH 2) and centrifuged, then enriched and cleaned-up by oasis HLB. The chromatographic separation was conducted on a VP-ODS (150 mm × 4.6 mm, 5 μm) column at the detection wavelength of 270 nm. The elution was completed by the mobile phase composed of methanol and water (pH 3) at the ratio of 60:40 (V/V) at the flow rate of 0.7 mL/min. The detection limits were 0.05 mg/kg for rutin and myricetin, and 0.04 mg/kg for quercetin and kaempferol, respectively. The recovery rates of rutin, myricetin, quercetin and kaempferol were 91%–92%, 82%–85%, 84%–86% and 86%–89%, respectively. Five kinds of characteristic honey from Yunnan were detected to reveal a significant difference in flavonoids. Therefore, flavonoids may be as the markers for the identification of honey.
Rapid Determination of 52 Pesticide Residues in Citrus by Gas Chromatography-Tandem Mass Spectrometry Coupled with QuEChER
ZHANG Xue-lian1,ZHANG Yao-hai2,JIAO Bi-ning1,2,3,*
2013, 34(6):  152-155.  doi:10.7506/spkx1002-6630-201306033
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In this study, an analytical method was established for the determination of 52 pesticide residues in citrus fruits using QuEChERS cleanup and gas chromatography-tandem mass spectrometry (GC-MS/MS). The pesticide residues in citrus fruit samples were extracted into acetonitrile and salted out by anhydrous MgSO4 and NaCl. Then, the pesticide residues in the supernatant after clean-up on the sorbents of N-propyl ethylene diamine (PSA) were subjected to GC-MS/MS analysis under multi-reaction monitoring (MRM) mode. The limit of detection (RSN = 3) of the established method were in the range of 0.07–5.7 μg/kg, and the average recovery rates for 52 pesticide residues in a blank sample were 77.3%–117.8% with a relative standard deviation (RSD) less than 13.8%. Therefore, this method is simple, quick, safe, cheap and reproducible so that it is suitable for the detection of multiple pesticide residues in citrus fruit samples.
Determination of Trace Aluminum in Foods by Ionic Liquid Sensitized Sepctrophotometic Method
2013, 34(6):  156-159.  doi:10.7506/spkx1002-6630-201306034
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A new ionic liquid sensitized sepctrophotometic method was developed on the basis of the Al(Ⅲ)-chromeazurol S (CAS)-1-n-tetradecyl-3-methylimidazolium (C14minBr) system. In the presence of Britton-Robinson buffer solution at pH 4.8, the color reaction of Al(Ⅲ) with chromeazurol S (CAS) could be sensitized by the addition of ionic liquid, C14minBr. The maximum absorption wavelength of the stationary ternary complex Al(Ⅲ)-CAS-C14minBr was 621 nm and the apparent molar absorption coefficient of the complex was 1.942 × 105 L/(mol?cm). Beer’s law was obeyed for Al(Ⅲ) in the range of 0.001–0.150 μg/mL. The developed method was used for the determination of vermicelli and could result in the consistent results from flame atomic absorption spectrophotometry. The recovery rates in the spiked samples were in the range of 97.8%–101.8%.
Chemical Composition Analysis of Volatile Components in Newhall Navel Oranges
2013, 34(6):  160-163.  doi:10.7506/spkx1002-6630-201306035
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Volatile aroma components in Newhall navel oranges were analyzed by gas chromatography-mass spectrometry (GC-MS) coupled with a pre-condensation system. Totally 42 volatile compounds were detected, which included limonene (46.33%), ethanol (17.41%), β-myrcene (11.73%), sabinene (7.60%), α-pinene (5.29%), acetaldehyde (3.56%) and Δ-3-carene (2.59%).
Determination of Anthocyanins in Fruits of Lycium ruthenicum Murr. by HPLC
2013, 34(6):  164-166.  doi:10.7506/spkx1002-6630-201306036
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Objective: A HPLC method for the determination of anthocyanins in fruits of Lycium ruthenicum Murr. was developed. Methods: A Kromasil C18 (4.6 mm × 250 mm, 5 μm) column was used as the chromatographic column and a mixture of 0.2% HCOOH-H2O and acetonitrile (98:2) was used as the mobile phase at a flow rate of 1 mL/min for gradient elution. UV detection wavelength was set up at 520 nm. MAL standards were used for calibration. Results: An excellent linear relationship was achieved in the range of 43–935 μg/mL with correlation coefficient of 0.9994 and RSD of 2.73%. The recovery rate of in spiked samples was 101.01% with RSD (n = 6) of 2.12%. Conclusion: This developed method is simple, stable, fast, and reproducible and without the interference of impurities, so that it can be used for determining the content of anthocyanins in fruits of Lycium ruthenicum Murr..
Tracing Geographical Origin of Peanuts by Near Infrared Spectroscopy
2013, 34(6):  167-170.  doi:10.7506/spkx1002-6630-201306037
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Near infrared spectroscopy combined with chemometrics was used to trace geographical origin of peanuts from different provinces of China. The original spectra were subjected to noise reduction by standard normal variate (SNV) and de-trend (DT) transformation (SNV+DT), and dimension reduction by principal component analysis; wavelet transform (WT) was also used for noise reduction and data compression. The extracted features were processed with linear discriminant analysis, Bayes discriminant analysis and k-nearest neighbors to discriminate the geographical origin of peanuts produced in different provinces of China. The results showed that WT and k-nearest neighbors present the best classification. Approximately 100.0% samples were correctly classified in original test, and 55.9% samples were correctly classified in cross-validation test. As a result, the geographical origin of peanuts from different provinces of China was discriminated. However, the performance of the discrimination models still needs to be improved.
Optimization of Testing Conditions for TPA Analysis of Rice Dumplings
ZHU Jin-jin,PAN Zhi-li,XIE Xin-hua,SUO Biao,YUE Zong-yang,AI Zhi-lu*
2013, 34(6):  171-174.  doi:10.7506/spkx1002-6630-201306038
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The optimal testing conditions of textural property analysis (TPA) for rice dumplings were explored. Testing speed and compression ratio were selected as research objects. The results showed that compression ratio had a significant impact on textural parameters. Quadratic models were fitted for hardness and resilience, which revealed a statistically significant difference. The ideal testing conditions were testing rate of 1 mm/s and compression ratio of 60%.
Analysis of Aroma Components from Peels of Different Lemon Varieties by GC-MS
2013, 34(6):  175-179.  doi:10.7506/spkx1002-6630-201306039
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The aroma components from lemon peels of different varieties such as rough lemon, eureka lemon and meyer lemon grown in same condition were detected and analyzed by solid phase micro-extraction (SPME) coupled with GCMS. Semi-quantitative evaluation of aroma components were carried out by comparing peak area of each compound and its internal standard. The results showed that 67, 65 and 65 flavor compounds were identified in the peels of eureka lemon, meyer lemon and rough lemon, respectively. Volatile compounds mainly included sesquiterpene hydrocarbons, alcohols, aldehydes, esters and ketones. The difference of aroma compounds in lemon was determined by genotype. Therefore, eureka lemon has higher sensory quality than meyer lemon and rough lemon.
Effects of Different Smoking Methods on Volatile Flavor Compounds in Bacon
2013, 34(6):  180-187.  doi:10.7506/spkx1002-6630-201306040
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The effects of traditional wood smoking and modern fluid smoking on the volatile flavor compounds in bacon were studied in order to provide a theoretical support for the improvement of modern liquid smoked products. The characteristic flavor of both types of smoked products was evaluated by determining volatile flavor compounds by GCMS. The results demonstrated that the variety and quantity of volatile flavor compounds were significantly higher in traditional wood smoked products when compared with modern liquid smoked products. Totally, 130 kinds of volatile flavor compounds were detected from traditional wood smoked products while only 121 kinds of volatile flavor compounds were detected from modern liquid smoked products. Furthermore, the content of characteristic volatile flavor compounds, namely phenolic compounds including 15 phenols in the traditional wood smoked products reached 22.85%; in contrast, 14 kinds of phenolic compounds with a total content of only 7.87% were found in modern liquid smoked products. Therefore, the traditional wood smoking process remains superior for the flavor of smoked products.
Determination of Paraquat in Edible Fungi by Microwave Extraction-High Performance Liquid Chromatography
TANG Jun1,2,QI Zhong-hua1,SHI Tao-zhong1,2,WU Xiang-wei1,2,CAO Hai-qun1,2,HUA Ri-mao1,2,TANG feng3,YUE Yong-de3,*
2013, 34(6):  188-191.  doi:10.7506/spkx1002-6630-201306041
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An HPLC method was established for the determination of paraquat residues in edible fungi. Samples were extracted with 10 mL of hydrochloric acid solution by microwave digestion extraction at 120 ℃ for 30 min, cleanedup by strong cation exchange (SCX) solid-phase extraction (SPE) column and eluted by saturated ammonium chloride. HPLC separation was carried out by reverse phase chromatography on Atlantis HILIC silica column with a mobile phase composed of acetonitrile and actyl sulfonate at the ratio of 40:60. Paraquat was detected by ultraviolet detector at 259 nm. The limit of quantification (LOQ) based on 10 times signal-to-noise was 1.0 μg/kg. The recovery rate was in the range of 82.33%–96.99% with the relative standard deviations (RSD) of 1.23%–3.90%. This established method is satisfactory for the determination of paraquat residues in edible fungi.
Quantitative Structure-Property Relationship of Volatile Components in Mentha hapioealyx Briq.
2013, 34(6):  192-194.  doi:10.7506/spkx1002-6630-201306042
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In order to predict retention index (RI) and accurate mass (M) of volatile compounds in Mentha hapioealyx Briq. the advantage conformations of 65 volatile compounds in Mentha hapioealyx Briq. were obtained with AM1 method and Kier’s index and E-State were calculated on the basis of molecular topological theory. The quantitative structureproperty relationship (QSPR) model that can be used to predict accurately the retention index and accurate mass of volatile compounds in Mentha hapioealyx Briq. were obtained by multiple regression method. The correlation coefficients of regression equations were 0.986 and 0.998, respectively. The model of retention index was tested by jackknifed methods with the jackknifed regression correlation of 0.986 and the model of accurate mass was tested with relatively average error of 1.43%. These results showed that two models have preferable stability, correlation and good predictability.
Determination of Total Flavonoids in Leaves of Glycyrrhiza glabra L. by Spectrophotometry
2013, 34(6):  195-198.  doi:10.7506/spkx1002-6630-201306043
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Four coloration methods were applied for the determination of total flavonoids in leaves of Glycyrrhiza glabra L. from Xinjiang. Two absorption wavelengths were selected in terms of wavelength scanning of 80% ethanol extract from the leaves and standard controls including rutin, quercetin and liquiritin. Standard curves for three standard controls by four coloration methods were established. The accuracy, stability, repeatability and recovery rates of four coloration methods were also determined. The content of total flavonoids were determined using AlCl3-CH4O coloration at 314 nm and quercetin as the control. The RSD for accuracy, stability, repeatability and recovery rate were 0.92%, 0.87%, 2.15% and (105.02 ± 1.11)%, respectively.
Rapid Detection of Staphylococcus aureus in Aquatic Products by Duplex PCR-DHPLC
2013, 34(6):  199-203.  doi:10.7506/spkx1002-6630-201306044
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Staphylococcus aureus is an important pathogen that can cause food poisoning. Two pairs of specific primers were designed according to the sequences of the sea gene (staphylococcal enterotoxin A) and the nuc gene from Staphylococcus aureus for the development of a duplex polymerase chain reaction-denaturing high performance liquid chromatography (PCRDHPLC) to detect Staphylococcus aureus strains in aquatic products. The positive and negative detection using this duplex PCR-DHPLC method was observed in 8 and 22 out of 30 strains, respectively. This method had high sensitivity with the detection limit of 50 CFU/mL, which revealed an improvement by 10 fold compared with the ordinary gel electrophoresis. Based on the duplex PCR-DHPLC method, 240 aquatic products were analyzed and showed a positive detection rate of 9.2% for Staphylococcus aureus contamination, which did not exhibit significant difference in positive detection rate from national standard approach. Therefore, duplex PCR-DHPLC can be used for specific, sensitive, rapid and high throughput detection of Staphylococcus aureus in aquatic products, and also can be used to determine the strength of pathogenicity of Staphylococcus aureus through analysis of the staphylococcal enterotoxin gene.
Analysis of Aroma Components in Flowers of Three Kinds of Camellia by HS-SPME/GC-MS
2013, 34(6):  204-207.  doi:10.7506/spkx1002-6630-201306045
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The aroma components in flowers of three kinds of Camellia (C. japonica Linn., C. oleifera Abel., C. sinensis (L.) O. Kuntze) were analyzed by HS-SPME/GC-MS. Significant differences in aroma components and their relative amounts in the flowers from three kinds of Camellia were observed. Totally 26, 36 and 48 aroma compounds were identified from C. japonica Linn., C. oleifera Abel. and C. sinensis (L.) O. Kuntze, which accounted for 94.53%, 96.43% and 98.76% of the total aroma components, respectively. 1-hexanol, 1-phenyl-ethanone, linalool, trans-anethole, dehydrogeosmin, germacrene D, butylhydroxytoluene and δ-cadinene were identified in flowers from three kinds of Camellia, but their relative contents showed a considerable difference. In addition, unique aroma components in the flowers of each kind of Camellia were also detected. Eugenol and decylacetate were the characteristic compounds in C. japonica Linn.; dihydro-3-methyl-2(3H)-furanone and myrcene were the characteristic compounds in C. oleifera Abel.; 6,10,14-trimethyl-2-pentadecanone and citral were the characteristic compounds in C. sinensis (L.) O. Kuntze.
Evaluation of Uncertainty in Spectrophotometric Determination of Nitrite in Chinese Cabbage
2013, 34(6):  208-210.  doi:10.7506/spkx1002-6630-201306046
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The sources of uncertainty in the spectrophotometric determination of nitrite in Chinese cabbage were investigated by analyzing whole determination procedure. Each uncertainty component was modeled, synthesized and developed a method for the evaluation of uncertainty in spectrophotometric determination of nitrite in Chinese cabbage. The uncertainty was attributed to four sources. The order of their impacts was measurement repeatability, nitrite mass determined by standard curve, sample dilution and sample weighting. The results of uncertainty evaluation showed the nitrite content to be (12.3 ± 1.08) mg/kg (k = 2).
Determination of Fatty Acid Profiles in Fifteen Kinds of Edible Vegetable Oil by Gas Chromatography-Mass Spectrometry
2013, 34(6):  211-214.  doi:10.7506/spkx1002-6630-201306047
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A gas chromatography-mass spectrometry (GC-MS) method for rapid determination of fatty acids in vegetable oil was developed. The vegetable oil samples were derived by sodium hydroxide-methanol solution. The analysis was completed on a polar capillary column with split ratio of 20:1. The cluster analysis was applied for the classification of 15 vegetable oil samples through SPSS software. Results showed that major fatty acids were palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2) and the content of unsaturated fatty acids in these edible oil samples was more than 75%, which was much higher than that of saturated fatty acids.
Determination of 36 Artificial Pigments in Foods by Ultra High Performance Liquid Chromatography and Time-of-Fight Mass Spectrometry
2013, 34(6):  215-218.  doi:10.7506/spkx1002-6630-201306048
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An ultra high performance liquid chromatography and time-of-flight mass spectrometry (UPLC-TOF-MS) method for the determination of 36 artificial pigments in foods was established. Samples were extracted with hot water and purified with polyamide powder, and the extract was separated on C18 column (1.8 μm) using methanol-5 mmol/L ammonium acetate as the mobile phrase through gradient elution and analyzed by UPLC-TOF-MS coupled with electrospray ionization (ESI) resource in a negative ion mode. An excellent linear relationship for pigments was observed in the concentration range of 0.01–1 μg/mL and the detection limit was 0.0072–0.94 mg/kg. The recovery rate of spiked samples was in the range of 80%–106% with relative standard deviation of 1.8%–9.7%.
Determination of Neomycin in Milk with Acidic Fuchsin-B-R System by Resonance Light Scattering Method
GAO Xiang-yang1,2,XU Ya-li2,ZHANG Na1,KONG Xin-xin1
2013, 34(6):  219-222.  doi:10.7506/spkx1002-6630-201306049
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In order to explore a novel method for the rapid determination of neomycin residues in milk, ultra high temperature (UHT)-sterilized pure milk from supermarket was used as the sample to determine neomycin residues in milk on basis of the reaction between neomycin and acidic fuchsin in Britton-Robinson buffer at pH 5.50 through resonance light scattering (RLS) technology. Results indicated that the maximum RLS peak was observed at 625 nm. A good liner relationship (r = 0.9978) was observed in chlorpyrifos concentration range of 0.00–2.50 μg/mL and the detection limit of neomycin was 0.013 μg/mL. The relative standard deviations (RSD) of the precision tests for 5 repeated determinations of all samples were less than 2.5%. The recovery rate of this developed method was in the range of 84.0%–96.7%. Due to simple operation, rapid determination and high sensitivity, this developed method is suitable for the determination of neomycin residues in milk.
Analysis of Volatile Compounds in Rosa davurica Pall. Fruits by Head Space Solid Phase Microextraction and Gas Chromatography Mass Spectrometry
2013, 34(6):  223-226.  doi:10.7506/spkx1002-6630-201306050
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Volatile compounds in dry and fresh fruits of Rosa davurica Pall. were extracted and analyzed by head space solid phase micro-extraction and gas chromatography mass spectrometry (HS-SPME-GC-MS). The relative contents of volatile compounds were determined using area normalization method. Totally 61 volatile compounds were identified in dry fruits of Rosa davurica Pall. The relative content of ethanol (28.00%) was the highest, followed by 4-terpineol (8.17%). Totally 23 volatile compounds were identified in fresh fruits of Rosa davurica Pall., among which 1-heptanol (37.08%) was the most predominant followed by ethylbenzene (15.20%). This study can provide an experimental basis for the further development and utilization of fruits of Rosa davurica Pall. as a natural resource.
Identification of Off-Flavor Components in Frozen Strawberry Juice
2013, 34(6):  227-230.  doi:10.7506/spkx1002-6630-201306051
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In order to evaluate the major off-flavor components in frozen strawberry juice after ultra-high pressure (UHP) treatment, strawberry juice was subjected to UHP treatment at 400 MPa for 15 min, and then stored at -60, -18 ℃ and -5 ℃ for 4 weeks, respectively. Solid phase micro-extraction (SPME) with different fiber coatings and gas chromatographymass spectrometry (GC-MS) were used to analyze and identify the major off-flavor components. The results showed that volatile flavor components of strawberry juice after frozen storage revealed an obvious change and unpleasant off-flavor was observed. Compared with unfrozen strawberry juice, hydrogen sulfide and isooctyl alcohol were detected in frozen strawberry juice as the major off-flavor sources.
Nutritional Analysis of Minerals and Fatty Acids in Bohu Mushroom
YANG Qin1,DU Shuang-tian2,*,ZHANG Gui-xiang1
2013, 34(6):  231-233.  doi:10.7506/spkx1002-6630-201306052
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In this paper, minerals and fatty acids of pileus and stipe of Bohu mushroom were determined and compared with other mushroom species such as Agaricus brunnescens, Lentinus edodes, Flammulina velutiper and Pleurotus rhodophyllus. High contents of minerals such as calcium, magnesium, iron and selenium in the pileus and stipe of Bohu mushroom was determined, which were higher than other edible mushroom species. Bohu mushroom was rich in fatty acids, which included 12 fatty acids in pileus and 11 fatty acids in stipe. Linolic acid and palmitic acid were prominent fatty acids in Bohu mushroom with the contents of 71.12% and 75.75%, respectively. Although both fatty acids were slightly lower than those in Lentinus edodes, they were higher than those in others mushroom species. The pileus and stipe in Bohu mushroom were characteristics of unsaturated fatty acids with concentrations of 74.84% and 79.74%, respectively. In addition, the content of unsaturated fatty acids in stipe was much higher than that in other mushroom species. These features offered Bohu mushroom good taste and health benefits as well as great utilization value.
SPME/GC-MS Analysis of Aroma Compounds in Ready-to-eat Rice
LIU Mei-yan1,ZHANG Zi-pei1,ZHAO Guo-hua1,2,*
2013, 34(6):  234-237.  doi:10.7506/spkx1002-6630-201306053
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In order to analyze and identify aroma compounds in ready-to-eat rice prepared by enzymatic method, headspace solid-phase micro-extraction and gas chromatography-mass spectrometry were used in this study. Volatile compounds from atmosphere-cooked rice and pressure-cooked rice were compared. Totally 66 compounds were detected in enzymatically prepared ready-to-eat rice, while 69 and 84 were detected in atmosphere-cooked rice and pressure-cooked rice, respectively. The common aroma compounds between ready-to-eat rice and pressure-cooked rice were also detected. Therefore, the process of ready-to-eat rice can bring a small amount of new volatile compounds and result in a loss of some compounds.
Analysis and Evaluation of Nutritional Components in Fruit Body of Pholiota nameko
XIANG Ying,CHEN Jian*
2013, 34(6):  238-242.  doi:10.7506/spkx1002-6630-201306054
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Objective:To systematically determine and analyze nutritional components in Pholiota nameko. Methods:The contents of nutritional components were determined using national standards and common methods. Results:The contents of crude protein, total polysaccharides, crude fat, crude fiber, ash and water in dry samples were 24.98%, 57.12%, 3.21%, 5.06%, 6.38% and 12.29%, respectively. After being decolorized and deproteinization through DEAE-52 column, two polysaccharides with the same molecular weight of 21394 u were obtained. The total content of 17 amino acids was 12.50%, and of which 28.1% were essential amino acids. Amino acid score (AAS), chemical score (CS), essential amino acid index (EAAI), biological value (BV), nutritional index (NI) were 19.98, 24.38, 44.50, 36.80 and 7.56, respectively. Conclusion: Pholiota nameko has high protein, low fat and low fiber and reveals excellent pharmacological effects so that it is a kind of mushroom with high nutritive and economic values.
Dynamics of Fat Oxidation in Grass Carp Fillets during Cooling Storage
2013, 34(6):  243-246.  doi:10.7506/spkx1002-6630-201306055
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Sensory evaluation and corresponding physiochemical indices were investigated to explore the dynamics of fat oxidation in freshwater fish fillets during cooling storage. During cooling storage period, dynamic changes in total fat, water content and peroxide value of fish fillets with four days storage were not obvious, but a significant change was observed between the 5th and 6th days. A relatively low change in carbonyl value was observed, however, a rapid increase was observed on the 6th day. According to dynamic change of TBARS value, the fat in grass carp was heavily oxidized on the 8th day during the cooling storage with the TBARS value of 1 mg/kg so that the fillets became inedible. Sensory evaluation score was positively correlated with total fat and water content, but negatively correlated with POV, COV and TBARS. Water-holding capacity and the inhibition of lipid oxidation play an importance role in the preservation of freshwater fish fillets.
Effect of Gradient Cooling on Membrane Lipid Peroxidation and Browning of Yali Pear Flesh after Harvest
2013, 34(6):  247-252.  doi:10.7506/spkx1002-6630-201306056
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The effect of gradient cooling (storage at 12 ℃ and cooling them to (0 ± 1) ℃ over 30 days at a gradual interval of 1 ℃ every 2.5 days) on membrane lipid peroxidation and browning of Yali pear flesh with different maturity was explored. The results showed that flesh-browning index had significantly positive correlation with MDA and radical content, and significantly negative correlation with reducing substance and protective enzyme. Gradient cooling improved the activities of SOD, CAT and POD, delayed the decrease of vitamin C and GSH contents to a certain extent, inhibited the accumulation of H2O2, O2 -? free radicals, reduced MDA content and membrane permeability, and retarded flesh browning of Yali pears at the early stage after harvest. In contrast, the contents of vitamin C and GSH in the flesh of Yali pears at the late stage after harvest were obvious higher and revealed a fast decrease during storage. Meanwhile, higher contents of O2 -·, H2O2 and MDA, and lower activities of SOD and POD were also determined. Therefore, gradient cooling can accelerate membrane lipid peroxidation and flesh browning of Yali pears at the late stage after harvest. Timely harvesting combined with gradient cooling can efficiently inhibit the flesh browning of Yali pears during storage.
Effect of Enhanced Freshness Formulation and Calcium Nitrate on Aroma Compounds in Postharvest Oriental Sweet Melons (Cucumis melo var. makuwa Makino) during Storage Period
2013, 34(6):  253-259.  doi:10.7506/spkx1002-6630-201306057
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Oriental sweet melons ‘Yumeiren’ and ‘Japanese Tianbao’ were immersed in the blended solution (2% EFF and 0.5% calcium nitrate) for 3 min before storage in incubators with temperature of 15 ℃ and a relative humidity of 85% for 21 days. Melons were immersed in plain water (CK1) or 0.5% calcium nitrate solution (CK2) as the controls. The change in relative physiological indexes and aroma compounds were measured during storage period. Compared with both controls, the blended solution treatment alleviated the decrease of fruit weight, firmness, water content and soluble solid content. Alcohols and aldehydes were the major compounds during the early stage of storage period, and then decreased gradually. Meanwhile, the contents of esters revealed an increasing trend. Among esters, acetic esters were the major compounds, which followed by oxalic acid esters and other esters. The concentrations of hexanal and other 4 aldehydes in melons with blended solution treatment were significantly higher (P < 0.05) than those in two controls. In addition, the content of total aroma compounds in both cultivars was higher and the appearance of aroma peak was later than that in two controls. Compared with both cultivars, ‘Japanese Tianbao’ had a longer shelf-life. Taken together, these results indicate that the blended solution (2% EFF and 0.5% calcium nitrate) is more effective than calcium nitrate solution on maintaining fruit quality, decreasing the loss of aroma compounds and delaying the ripening and senescence of oriental sweet melons.
Effect of Methyl Jasmonate Treatment on Synthesis and Antioxidant Activity of Phenolic Acids in Grape Berries and Corresponding Mechanisms
2013, 34(6):  260-265.  doi:10.7506/spkx1002-6630-201306058
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In the present study, the effect of 10 μmol/L MeJA (methyl jasmonate) treatment on the synthesis and antioxidant activity of phenolic acids in grape berries (Vitis vinifera L. × V. labrusca L. cv. ‘Kyoho’) during storage at 1 ℃ was investigated and the corresponding mechanisms were also explored based on phenylpropnaoid metabolism. The results showed that MeJA treatment could significantly inhibit the decay rate and abscission rate of grape berries, induce the increase in activities of key enzymes involved in phenylpropnaoid metabolism including phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H) and chalcone synthase (CHS) and delay the decrease in 4-CL activity. Meanwhile, a remarkable enhancement of phenolic acids (gallic acid, caffeic acid, protocatechuic acid, syringic acid, p-coumaric acid) and total phenolics was observed, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and reducing power of grape berries during storage was maintained. These results implied that MeJA treatment markedly promoted the synthesis of phenolic acids and maintained antioxidant activity through the regulation of phenylpropanoid-related enzymes, thus finally improving the edible and nutritional quality of postharvest grape berries.
Browning Mechanism of Laiyang Pears during Micro-vacuum Storage
2013, 34(6):  266-270.  doi:10.7506/spkx1002-6630-201306059
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The changes of CAT, SOD, POD, LOX and PPO activities, H2O2, MDA and polyphenol contents, O2- production rate, membrane permeability and pulp browning index in Laiyang pears during micro-vacuum storage at pressure levels between 500 torr and 600 torr and temperature of (3 ± 1) ℃ were analyzed. The results showed the micro-vacuum storage could significantly improve the activities of SOD, CAT and POD, reduce the activities of LOX and PPO, attenuate the release rate of O2-, decline the contents of H2O2 and MDA, slow down the increase of relative electric conductivity and delay pulp browning, when compared with the atmospheric pressure storage at same temperature (P<0.05). Similarly, microvacuum storage could reduce reactive oxygen species and lipid peroxidation, maintain membrane structure and function, and delay pulp browning of Laiyang pears by improving endogenous antioxidant enzyme activity and reducing LOX activity. On the other hand, it also could inhibit the metabolism of phenolic substances, and reduce PPO activity and oxygen content in the storage environment, thus delaying pulp browning of Laiyang pears.
Effect of Storage Temperature on Quality and Antioxidant Activity of Ready-to-eat Pomegranate Seeds
WANG Min,KOU Li-ping*
2013, 34(6):  271-275.  doi:10.7506/spkx1002-6630-201306060
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The overall quality, functional components and antioxidant activity of ready-to-eat pomegranate seeds stored at different temperatures (0, 5, 10 ℃ and room temperature) were investigated. The results indicated that lower temperatures (0 ℃ and 5 ℃) reduced the respiration rate, maintained a significantly lower relative conductivity and weight loss rate, improved the antioxidant activity and prolonged the shelf-life of pomegranate seeds when compared with those stored at 10 ℃ and room temperature. At the end of storage, ready-to-eat pomegranate seeds stored at 0 ℃ exhibited higher total soluble solids and anthocyanins than those stored at 5 ℃ and 10 ℃ as well as room temperature. Our findings suggest that ready-toeat pomegranate seeds should be stored at 0 ℃ to maintain optimal quality and maximal shelf life.
Effect of Vacuum Pre-cooling Treatment on Storage Quality of Sweet Broad Pea
2013, 34(6):  276-279.  doi:10.7506/spkx1002-6630-201306061
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Vacuum pre-cooling treatment that can immediately remove the respiration heat from postharvest vegetables, extending the shelf life and improving the storage quality of sweet broad pea. In order to explore the optimal conditions of vacuum pre-cooling treatment, orthogonal tests were adopted. The effects of different processing technology on product quality were evaluated along with the effects of two major factors (end-temperature and pre-wetting) on the storage quality of sweet broad pea. Using non-vacuum pre-cooling as the control, the change in physiological and biochemical parameters of samples in both groups was compared. Similarly, the change of surface and internal temperatures as well as vacuum pressure was recorded. Weight loss rate, chlorophyll content, ascorbic acid content and sensory index were used as the major parameters. Results showed that vacuum pre-cooling treatment could slow down the decrease of vitamin C and chlorophyll contents effectively. Therefore, when end-temperature was set at 5 ℃, the storage quality of the pre-wetted samples was the best. Vacuum precooling can significantly extend the shelf life of sweet broad pea.
Preparation of Effervescent Tablets with Perilla Extract
2013, 34(6):  280-284.  doi:10.7506/spkx1002-6630-201306062
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Objective: To explore the preparation process and optimal formula of effervescent tablets with perilla extract. Methods: By mixing raw materials, preparing granules, drying, and compression, perilla solid beverage (effervescent tablets) was prepared. The formula was optimized by orthogonal tests by acid-base separated aqueous granulation. Results: The optimal formula of perilla effervescent tablet was composed of 10% penilla extract, 3% stevioside, 10% HPMC, 3% PEG 8000, and NaHCO3-citric acid ratio of 1:2. In order to improve the taste, the proportion of xylitol, lactose, erythritol, and 0.6% perilla flavouring essence were also added. Conclusion: The method for the preparation of effervescent tablets with perilla extract is simple and easy to operate. After dissolution in water, the effervescent tablets reveal a violet color, a special aroma of perilla and a pleasant sweet taste. The perilla solid beverage (effervescent tablets) is nutritious and popular.