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Table of Content

01 January 2010, Volume 31 Issue 1
Basic Research
Effect of Different Somatic Cell Counts in Raw Milk on Characteristics of Mozzarella Cheese
DONG Jing-ying,MA Ying,CHEN Li-jun,LI Ling-juan
2010, 31(1):  1-5.  doi:10.7506/spkx1002-6300-201001001
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The aim of the present study was to investigate the characteristics of Mozzarella cheese made from milk containing different somatic cell count (SCC) at zero (0 cells/mL, after microfiltration), low (300000 cells/mL) and high (600000 cells/mL) levels. Analyses for cheeses included composition recovery and proteolysis, free fatty acid, free oiling off, meltability, texture and sensory after 1, 15, 30, 45, 60 days of storage. SCC did not significantly affect (P > 0.05) composition recovery. There were no significant differences in physicochemical characteristics between LSCC and HSCC cheeses, However, microfltration treatment significantly affected physicochemical characteristics of Mozzarella cheese. SCC below 600000 cells/mL was not among the important factors affecting Mozzarella cheese during 60 days of storage.

Effects of Heating Conditions on Gel Properties of Horse Mackerel Surimi
CHEN Hai-hua1,2,XUE Chang-hu2
2010, 31(1):  6-13.  doi:10.7506/spkx1002-6300-201001002
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Effects of heating conditions, including setting temperature, setting time and heating method on the gel properties were investigated by texture analysis and determinations of whiteness, water-holding capacity, microstructure, TCA-soluble peptides content, protein solubility. Results showed that heating temperature, time and method all had a significant effect on the gel properties of horse mackerel surimi. The optimum condition for processing horse-mackerel surimi was a two-step heating method with setting at 30 ℃ for 5 h (or at 40 ℃ for 4 h) and then heating at 90 ℃ for 20 min, which resulted in the formation of high compacted and uniformed three dimensional network structure observed under scanning electronic microscopy (SEM). Horsen mackerel surimi gel showed a structure with aggregates of sparse packed spherical proteins, arranged in clusters when setting at 50-70 ℃, which indicated the modori phenomena occurred.

Antioxidant Activity and DNA Damage Preventing Effect of Procyanidins from Litchi chinensis Pericarp
LI Shu-yi,ZHOU Wei-jing,SUN Zhi-da*,XIE Bi-jun
2010, 31(1):  14-18.  doi:10.7506/spkx1002-6300-201001003
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In order to evaluate antioxidant activity in vitro of procyanidins from pericarp of four cultivars (Baila, Feizixiao, Nuomizi, Huaizhi) of litchi (LPPC), superoxide anion radical, hydroxyl radical and hydrogen peroxide scavenging assays were carried out using pyrogallo-luminol, ferrous sulfate-Luminol-hydrogen peroxide and Luminol-hydrogen peroxide systems, respectively. In addition, copper sulfate-phen-VC-hydrogen peroxide-DNA system was used to determine the preventing effect of LPPC against DNA damage. Results showed that among the litchi cultivars, Baila LPPC possessed the best scavenging potency against superoxide anion and hydrogen peroxide and Feizixiao LPPC indicated the most efficient hydroxide radical scavenging ability and DNA damage preventing effect. In conclusion, procyanidins from pericarp of different litchi cultivars acted different antioxidant effects in different chemiluminescence systems.

Compositions and Formation Mechanisms of Turbid Materials in Hydrolysates of Pearl Oyster Protein
WU Sheng-xu1,CUI Chun1,ZHAO Mou-ming1,*,ZHANG Chao-hua2,QIN Xiao-ming2
2010, 31(1):  19-23.  doi:10.7506/spkx1002-6300-201001004
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Basic compositions contributing to turbidity of pearl oyster protein hydrolysates were investigated. Results showed that turbid materials were mainly composed of 54.3% crude protein and 26.1% ester. SDS-PAGE pattern confirmed that peptides with small molecular size were the major components of turbid materials; amino acid analysis revealed that hydrophobic amino acids in turbid materials were 42% and higher than the content in hydrolysates. SDS analysis exhibited more effective to dissolve turbid materials than guanidine hydrochloride, urea and sodium chloride. Moreover, particle size distribution analysis showed that SDS treatment could significantly reduce the particle size of turbid materials. Average particle size of turbid materials was reduced to 97.9 nm from 1954.3 nm in turbid materials at the concentration of 8% during SDS treatment. All of these investigations suggested that turbid system was formed by large molecular peptides through hydrophobic interaction. In contrast, lipids had little effect on the turbidity of hydrolysates.

Insight into Interaction of Caffeic Acid with Bovine Serum Albumin
LIU Quan-wen1,XU Hui1,LI Gui-hua1,*,ZHANG Ting2,QIAO Qing-an1
2010, 31(1):  24-28.  doi:10.7506/spkx1002-6630-201001005
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The binding reaction of caffeic acid with bovine serum albumin (BSA) was studied using fluorescence spectroscopy. Caffeic acid quenched the fluorescence of BSA through a static process. The primary binding pattern between caffeic acid and BSA included electrostatic and hydrophobic interaction, and the latter was identified to be the main force under physiological condition. It was found that caffeic acid was located near the Tyr residue region of site I in BSA by competing binding experiment using warfarin and ibuprofen as site markers by fluorescence spectra. The distance between the donor (BSA) and receptor (caffeic acid), r0, was obtained to be 3.64 nm according to Forster's non-radiative energy transfer theory. In addition, the effect of caffeic acid on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.

Comparison Studies of Main Active Compounds in Young Leaves of L.bararum and L.chinense
YAN Xiu-mei1,2,DONG Jing-zhou1,2,WANG Ying1,*
2010, 31(1):  29-32.  doi:10.7506/spkx1002-6630-201001006
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Young leaves of L.bararum and L.chinense with different geographical origins were compared for differences in main active compounds, such as polysaccharides and total flavonoids. Among geographical populations of each species and between the two species, no significant differences in contents of polysaccharides and total flavonoids were seen, respectively. While the content of polysaccharides in young leaves of L.chinense were significantly higher than that of L.bararum. Hence, L.chinense leaves were a potential source for medicinal food. Science there were significant differences in contents of polysaccharides and total flavonoids within the same geographical population of each species, it is of great interest to develop good varieties by interstrain breeding.

Comparative Studies of Processing Characteristics of Different Litchi Varieties
XU Yu-juan1,2,WEN Jing2,XIAO Geng-sheng2,ZHANG Ming-wei2,LI Sheng-feng2,WU Ji-jun2
2010, 31(1):  33-37.  doi:10.7506/spkx1002-6630-201001007
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Fruits of 25 litchi varieties were used as materials to study fruit quality, major components, physical-chemical parameters, soluble protein, total phenols and total antioxidant capacity. Results indicated that significant differences of juice rate, contents of total soluble solids and total acids, edible pulp rate, and sugar/acid ratio in fruits of different litchi varieties were observed. Huidonghongyan exhibited the highest juice rate and Tianyan the lowest, which were 70.76 % and 32.77 %, respectively. The highest content of total soluble solids was observed in Shuijingqiu to be 19.57 %; in contrast, the lowest content of total soluble solids in Jianjianghongnuo was 12.00 %. In addition, obvious differences in polyphenol oxidase (PPO) and peroxidase (POD) activities, and color stability were also observed in different litchi varieties. PPO activity was ranged from 0 to 35.00 U and POD activity from 15.3 to 6013 U. The color difference (ΔE) was ranged from 0.39 to 17.20 at 30 ℃ and from 1.64 to 38. 42 at 100 ℃. Preliminary evaluation indicated that Huidonghongyan, Nuomici, Yuanzhi, Heiye, Zhongshanzhuangyuanhong and Baitangyin were excellent litchi varieties for litchi juice and litchi wine making.

Effect of Phosphates on Sol and Gel Properties of PSE Porcine Myofibrillar Protein
SHANG Yong-biao1,2,XIA Yang-yi1,2,ZHANG Cai-xia1,LI Hong-jun1,2
2010, 31(1 ):  38-42.  doi:10.7506/spkx1002-6630-201001008
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PSE (pale, soft, exudative) meat myofibrillar protein reveals much lower solubility and poorer gel properties when compared with that of normal meat (red, firm and non-exudative, RFN). Our objective was to evaluate effects of phosphates on gel properties of porcine myofibrillar protein. PSE and RFN porcine longissimus muscles were used as experimental materials and effects of sodium hexametaphosphate (SHMP), sodium pyrophosphate (SPP) and sodium tripolyphosphate (TPP) on myofibrillar protein solubility, sol turbidity and gel properties were evaluated. Results showed that all the three kinds of phosphates evidently affected myofibrillar protein solubility and aggregation and gel strength. PSE gel formed with the addition of 0.25% TPP and RFN gel formed without the addition of TPP had approximate gel strength. In conclusion, phosphates could improve sol system environment so as to enhance sol and gel properties.

Rheological Properties of Soybean Beta-conglycinin Gels with Different Molecular Weight Dextrans
MIN Wei,YANG Xiao-Quan*
2010, 31(1):  43-47.  doi:10.7506/spkx1002-6630-201001009
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A HAAKE rheometer was employed for the rheological characterization of soybean β-conglycinin-dextran mixed gels in this study. Results showed that β-conglycinin-dextran mixture had a higher elastic modulus than single β-conglycinin. With the same molecular weight dextran, the elastic modulus of mixed gel increased with increasing dextran concentration; similarly, with the same concentration dextran, the elastic modulus of mixed gel increased with increasing molecular weight of dextran. The elastic modulus of β-conglycinin-dextran mixture in 0.25 mmol/L phosphate buffer (pH 7.6) was higher than that in 0.5 mmol/L phosphate buffer (pH 7.6); while, the initial gel formation temperature of β-conglycinin-dextran (the same molecular weight dextran, the same dextran concentration) mixture in the first buffer was less than that in the second buffer, namely, Tp0.25 < Tp0.5.

Antibacterial Activity of Bioactive Components in Ethanol Extract from Rape Bee Pollen
SUN Li-ping1, XU Xiang1,DING Xiao-yu2,LI Chun-yan2,AN Zhong-yao2,DONG Jie1,ZHANG Hong-cheng1
2010, 31(1 ):  48-50.  doi:10.7506/spkx1002-6630-201001010
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Antibacterial activity of rape bee pollen extract was investigated using Oxford cup method. Results indicated that 0.5% formic acid extraction fraction from ethanol extract of rape bee pollen exhibited strong antibacterial activity. Minimum inhibitory concentrations (MIC) of formic acid extraction fraction against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis were 25, 50, 50 mg/mL and 100 mg/mL, respectively. HPLC analysis showed that bioactive components with antibacterial activity in formic acid elution fraction were weakly polar substances.

Change of Isoflavone Contents in Sufu during Pre-fermentation and Salting
ZHOU Ying,LU Qi, LU Si-yi,PAN Si-yi*
2010, 31(1):  51-53.  doi:10.7506/spkx1002-6630-201001011
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In this study, change of isoflavone contents and compositions in sufu (fermented tofu) during pre-fermentation and salting was investigated. Results indicated that total content of isoflavones exhibited a gradual decrease during pre-fermentation and salting. The loss of isoflavones was mainly attributed to tofu preparation and salting process. The compositions of isoflavone were altered during pre-fermentation and salting, which revealed an increase of aglycones such as daidzein and genistein, and a corresponding decrease of glucosides such as daidzin and genistin. Total content of isoflavones in sufu treated with less than 10% salt was higher than that of sufu treated with 15% salt.

Antioxidant Activities and Contents of Total Phenolic Acid and Total Flavonoids in Vicia villosa Roth Honey
WANG Hai-min,YU Hai-xia,DONG Rui,LI Wei,CONG Hai-di,ZHENG Yi-nan*
2010, 31(1):  54-57.  doi:10.7506/spkx1002-6630-201001012
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Five commercially available Vicia villosa Roth honeys were evaluated for contents of total phenolic acid and total flavonoids, reducing power and DPPH radical scavenging activity. Results indicated that the content of total phenolic acid in the samples theoretically equivalent to that of catechin varied from 9.323 to 21.982 mg/100 g honey, and the content of total flavonoids theoretically equivalent to that of rutin from 0.842 to 2.295 mg/100 g honey. All the honey samples exhibited some antioxidant activity in a dose-dependent manner. A positive correlation was observed between total phenolic acid content and DPPH radical scavenging activity or reducing power. This demonstrated that the antioxidant activity of these honeys may be inked to the total phenolic acid content. In addition, total flavonoids content had no obvious correlation with total phenolic acid content, reducing power or DPPH radical scavenging activity.

Characterization of Collagens from Swim Bladders of Grass Carp
ZHANG Bao,CHEN Yun-zhong*,XU Ying,WEI Xue-fei,WANG Meng-jin
2010, 31(1):  58-62.  doi:10.7506/spkx1002-6630-201001013
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In order to make more effective use of fish waste materials, acid-soluble and pepsin-soluble collagens (ASC and PSC) were extracted from swim bladders of grass carp and properties of ASC and PSC were investigated. The yields of ASC and PSC were 4.7% and 11.1%, respectively, on the basis of dry weight. UV spectra of ASC and PSC from grass carp exhibited the maximum absorption peak at 230 nm. Amino acid profiles of ASC and PSC revealed that contents of hydroxyproline and proline were 16.87% and 17.55%, respectively. SDS-PAGE patterns indicated that both ASC and PSC were composed of at least two different α-chains (α1 and α2), which was similar to porcine type I collagen. The denaturation temperatures (Td) of ASC and PSC were 33.0 ℃ and 34.8 ℃, respectively, about 3 - 4 ℃ lower than that of porcine skin collagen (37 ℃). These results suggested that collagens from swim bladders of grass carp had potential as an alternative or a supplementary source of collagen from land vertebrates being used in different fields for industrial purposes.

Dynamic Changes of Main Milk Components during Early Lactation of Henan Dairy Goat and Its Hybrid
WANG Yu-qin,WANG Zhan-bin,WU Qiu-jue,ZHAO Shu-juan,WANG Hu,LI Dong-ming,PANG You-zhi
2010, 31(1):  63-65.  doi:10.7506/spkx1002-6630-201001014
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This study was conducted to test main nutritional components of milk from Henan dairy goat (DG) and its hybrid goat (HG) during early lactation. Results showed that dry substance content reached the maximum, 24.14 g/100 g and 26.17 g/100 g at 1 and 2 days post-lactation in DG and HG, respectively, and then decreased with prolonged lactation time; likewise, fat content reached the climax, 6.32 g/100 g and 5.38 g/100 g at 5 days and 4 days post-lactation, respectively, and then exhibited a descending trend. For both DG and HG, milk lactose content displayed a general ascending trend during early lactation. Protein content in DG milk was elevated gradually during 5-day colostrum-producing period, and then basically trended to be stable later; in contrast, protein in DG milk exhibited a trend to first decrease and then basically keep stable. Ash content in both milk was first decreased in early lactation stage and then fluctuated around a fixed value. Calcium content was basically kept stable over the whole tested lactation period. There was a slight increase in phosphorus content in early lactation stage followed by a fluctuated decrease. It was concluded that the main nutritional components of both milk changed with lactation time and the changes were closely related to feeding management and nutritional condition control for dairy goats.

Effect of Ultra-high Hydrostatic Pressure Treatment on Limonene in Navel Orange Juice
WANG Hai-xiang,PAN Jian*,XIE Hui-ming,YANG Yi,ZENG Qing-mei
2010, 31(1):  66-70.  doi:10.7506/spkx1002-6630-201001015
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With the aim of achieving an in-depth understanding of effect of ultra-high hydrostatic pressure treatment on limonene in navel orange juice, a mathematical model describing the relationship between limonene content and three treatment parameters, such as pressure(100-500 MPa), temperature (20-40 ℃) and treatment time (10-20 min) was created using Box-Behnken central composite design combined with regression analysis, and interactive effects of the three variables on the dependent variable were then evaluated using response surface methodology (RSM). This model was found to be significant (P< 0.0001) with a regression coefficient of 0.9938 and an adjusted regression coefficient of 0.9858. The predicted values of limonene content were in good agreement with the experimental values. This demonstrated the reliability of the created model in predicting limonene content in navel orange juice subjected to ultra-high hydrostatic pressure treatment under different conditions.

Comparative Studies on Processing Characteristics of Different Longan Cultivars
WEN Jing1,XU Yu-juan1,XIAO Geng-sheng1,LI Jian-guang2,LIAO Sen-tai1,WU Ji-jun1,
2010, 31(1):  71-75.  doi:10.7506/spkx1002-6630-201001016
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Fruits of 18 longan cultivars were analyzed for physical and chemical parameters, total antioxidant capacity, soluble protein and total phenolics. Results showed that there were remarkable differences in fruit juice rate, contents of total soluble solids and total acids, edible pulp rate and ratio of sugars to acids of tested longan cultivars. Fruit juice rate ranged from 36.02% to 55.74%, and the highest was exhibited in Shuiyan cultivar (55.74%) and the lowest in Hualuguangyan (36.02%).Total soluble solids content ranged from 11.3% to 21.77%, and the highest was exhibited in Baihuamu (21.77%) and the lowest in Qingkebaoyuan (11.3%). Besides, notable differences were also observed in PPO and POD activities and color stability of these longan cultivars. PPO ranged from 0 to 6.6 U, and POD from 72.7 to 1816.7 U. Longan fruits exposed to 30 ℃ and 100 ℃ revealed a total color difference (ΔE) value ranging from 0.24 to 3.68 and from 7.62 to 63.53, respectively. It was preliminarily evaluated that Shixia, Chuliang, Baihuamu, Hualuguangyan and Shuangzimu were excellent cultivars for longan juice and longan wine making. Among these longan cultivars, Shuangzimu and Qingkebaoyuan exhibited the highest and lowest total antioxidant capacity of 20.39 mmol/L and 3.73 mmol/L, respectively. Soluble protein content was fluctuated in the range of 45.82 (Jiluanyan) to 88.8 mg/L (Shixia). The highest total phenolics content valued at 749.95 mg/L was observed in Hualuguangyan, and the highest at 13.02 mg/L in Jiluanyan.

Adsorption of Lipoprotein onto Macroporous Resin
DING Yong
2010, 31(1):  76-78.  doi:10.7506/spkx1002-6630-201001017
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In this study, in vitro adsorption process of low density lipoprotein (LDL) onto macroporous resin was investigated. Lipoprotein from calf serum was used as the material to conduct adsorption experiments by 3 kinds of macroporous resins. The optimal resin was screened in terms of adsorption capacity towards LDL. Results indicated that macroporous resin D113 exhibited the highest adsorption capacity. Meanwhile, dynamic adsorption process was also described using a mathematical mode, which could well fit experimental data. Therefore, this model will provide practical reference for further research of LDL adsorption.

Variations in Major Components of Pu-erh Tea Infusion during Fermentation by Kombucha Culture
ZHAO Zhen-jun1,ZHOU Li2,LIU Qin-jin2,*
2010, 31(1):  79-83.  doi:10.7506/spkx1002-6630-201001018
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Different storage-age Pu-erh tea (1, 5, 10 years) infusion (8 g/L) sweetened with sucrose 50 g/L was filtrated and inoculated with kombucha culture for 8-day fermentation at 28 ℃. The fermentation broth was dynamically analyzed for microbial population, pH, tea polyphenols, total acidity, protein and biomass as well as high-boiling-point substances. Results showed that there were no obvious differences in microbial population, pH values, etc. between Pu-erh and green or black tea infusion fermented by kombucha culture. Therefore, Pu-erh tea infusion was an excellent matrix for kombucha fermentation. Added together, 35 non-volatile components (mainly including 14 alcohols and 13 acids) were identified by GC-MS in different storage-age Pu-erh tea infusion fermented by kombucha for 3, 4, 6, 7 days and 8 days. Alcohols were detected with the most frequencies at the initial fermentation stage (0-4 days), and acids were dominant later. Citric acid, nonahexacontanoic acid, l-(+)-ascorbic acid, 2, 6-dihexadecanoate, etc. were detected in the maturation period (the 7th day), which may be the crucial constituents in favor of health in fermented Pu-erh tea infusion by kombucha.

Effects of Storage Conditions on Total Number of Bacteria and Coliform Group in Shellfish
LIU Li-juan1,2,MENG Xiang-li3,JIANG Xiang-yang1,REN Li-hua1,SONG Xiu-kai1,
2010, 31(1):  84-86.  doi:10.7506/spkx1002-6630-201001019
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In order to investigate the changing trend of microorganisms in shellfish, total number of bacteria and coliform in 3 species of shellfish such as Ruditapes philippinarum, Chlamys farreri and Solen gouldii Conrada stored at -18, 4, 15 ℃ and 22 ℃ for different periods were determined. Results indicated that an obvious decrease in total number of bacteria in shellfish stored at -18℃ for more than 24 h was observed; in contrast, no obvious change in shellfish stored at other temperature conditions for 12 h or at 4 ℃ for 24 h was observed. Moreover, a positive correlation between total number of bacteria and coliform group in shellfish stored at 22 ℃ was also observed. Taken together, the original status of microorganisms present in shellfish can be remained for a longer period of time at the environmental condition of 0 ℃.

Thermodynamic Study of Adsorption of Chaenomeles sinensis Polyphenols onto NKA-9 Resin
ZHANG Jian-xin,LIU Li-li,DUAN Xu-chang
2010, 31(1):  87-90.  doi:10.7506/spkx1002-6630-201001020
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Thermodynamic adsorption characteristics of Chaenomeles sinensis polyphenols onto NKA-9 resin were studied. Results showed that adsorption equilibrium data obtained within the temperature range of 298-308 K and concentration range of 20-40 mg/mL could be well fitted by the Langmuir-type and Freundlich-type isotherm equations and the adsorption was favorable type. Meanwhile, the changes of enthalpy, free energy and entropy were measured. It was indicated that the adsorption was an endothermic process.

Isolation and Antioxidant Activity of Water-soluble Acidic Polysaccharide from Prunella vulgaris Linn
WEI Ming,XIONG Shuang-li*,JIN Hong,XU Guo-bo,XIA Cui
2010, 31(1):  91-94.  doi:10.7506/spkx1002-6630-201001021
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An acidic polysaccharide with antioxidant activity was obtained from Prunella vulgaris Linn through sequential steps of water extraction and alcohol precipitation, then decolorization and deproteinization by HZ-820-type unpolar resin adsorption, and finally purification. 3-Hydroxydiphenyl-sulfuric acid and barium chloride-gelatin turbidimetric methods were used to determine contents of galacturonic acid and sulfate in the polysaccharide, and the results were (58.85 ± 0.46)% and (7 ± 0.52)%, respectively. Ultraviolet and infrared (IR) spectral analyses indicated that the monosaccharide composition of the polysaccharide consisted of galacturonic acid, xylose, glucose, rhamnose, and galactose and it belonged to the nonglycoprotein family. Moreover, this polysaccharide revealed strong scavenging activities against hydroxyl free radicals and DPPH free radicals.

Cassava Modified Starches: Rheological Properties and Applications in Surimi-based Products
LIU Hai-mei
2010, 31(1):  95-97.  doi:10.7506/spkx1002-6630-201001022
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The rheological properties and their mathematical models of four kinds of cassava modified starches by esterification and cross-linking, acetylation, oxidation and pregelatinization, respectively, were investigated to understand the regular flow. Along with this, the correlation of rheological properties of cassava modified starches and gel properties of silver carp surimi was also analysed. Results showed that the four kinds of starches were all pseudoplastic fluid in aqueous solution. The Arrhensius equation could accurately describe the influence of temperature on flow behavior of cassava modified starches. The more the flow properties of aqueous solution of cassava modified starches were far away from Newton fluid and the bigger the viscosity coefficient became, the better the surimi gel properties became.

Assessment of Sensory and Textural Properties and Water-Holding Capacity of Pork Sausages Containing Oat Flour
XIA Jian-xin,WANG Hai-bin*
2010, 31(1):  98-101.  doi:10.7506/spkx1002-6630-201001023
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In order to explore the effect of addition of oat flour on quality properties of pork sausages, the textural attributes of pork sausages containing oat flour were assessed by sensory evaluation and instrumental determination (texture profile analysis, TPA), and correlation analysis was conducted among the assessment results by the two approaches. Meanwhile, the water-holding capacity (WHC) of compound sausages was also determined. Results indicate that the compound sausages had an excellent texture and overall acceptability when oat flour was at 14% addition level. Hardness obtained from TPA was significantly (P < 0.05) correlated with sensory hardness (r = 0.898) and cohesiveness obtained from TPA significantly (P < 0.05) correlated with sensory hardness or springiness (r = -0.863, -0.825). WHC of compound sausages was slowly increasing with increasing level of added oat flour, ranged from 94.33% to 94.83%. However, WHC did not increase obviously when the addition level was beyond 17%. It was nferred that oat flour added to sausages may help improve WHC of compound sausages. Therefore, compound oat flour sausages with good acceptability, texture and WHC could be made from meat added with oat flour in an appropriate proportion.

Effect of Thermal Treatment on Mechanical and Barrier Properties and Structure of Soy Protein-isolate Edible Films
MA Dan1,2,ZHANG Chao1,MA Yue1,ZHAO Xiao-yan1,*,YUE Xi-qing2,LEI An-liang2
2010, 31(1):  102-104.  doi:10.7506/spkx1002-6630-201001024
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With the aim of revealing the differences in mechanical and barrier properties and protein structure of soy proteinisolate edible films produced at different thermal treatment temperatures and correlation between them, this study was conducted. Films produced at 90 ℃ showed the best mechanical and barrier properties. The difference in protein structure was evaluated in terms of disulfide bond content, hydrophobic value and main secondary structures including alpha-helix and beta-sheet. It was demonstrated that disulfide bond content and alpha-helix presented a positive correlation with mechanical and barrier properties of the films, which were negatively correlated with hydrophobic value.

Effect and Mechanism of Plasticizers on Properties of Modified Cellulose Films
ZHAO Li-chao,PENG Zhi-ni,YOU Man-jie,LIU Xin,CHEN Yong-quan
2010, 31(1):  105-109.  doi:10.7506/spkx1002-6630-201001025
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Effect of plasticizers on properties of carboxymethyl cellulose (CMC) and methyl cellulose (MC) films was studied, and the mechanism was discussed through scanning electron microscopic (SME), infrared spectrometric and X-ray diffractometric observations. Results showed that 0.2% glycerol added exhibited a good plasticizing effect on CMC films, while, for MC films, the optimal plasticizer was polyethylene glycol at a concentration of 0.4%. The effect of plasticizers on film properties depended on the material-plasticizer compatibility.

Extraction Kinetics of Grape Seed Procyanidins
ZHAO Ping,SONG Xue-juan,ZHANG Yue-ping,ZHANG Zhi-jun
2010, 31(1):  110-112.  doi:10.7506/spkx1002-6630-201001026
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According to the mass transfer mechanism, the extraction process of grape seed procyanidins could be described with the concentration of procyanidins. In the present study, a kinetic equation was established on the basis of mass equilibrium. In order to evaluate the equation, experiments for extracting procyanidins from grape seed with ethanol under different temperatures were carried out. The relationship between balance concentration of procyanidins and extraction temperature was obtained by fitting experimental data. Additionally, the important kinetic parameters were calculated using Arrhenius equation and the apparent activation energy for extraction process was calculated to be 2.08×104 J/mol. The results of verification experiment showed that the presented kinetic equation could describe the extraction process of grape seed procyanidins and the extraction process accorded with diffusion theories. This kinetic equation can provide a good theoretical base for further study on extraction of grape seed procyanidins.

Change and Safety Assessment of Nitrite in Meat Products during Processing and Storage
LIU Wan-chen,LIU Ai-ping,ZHAO Rong,CHEN Shu-min,RONG Hui
2010, 31(1):  113-116.  doi:10.7506/spkx1002-6630-201001027
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A certain amount of nitrite residue was kept in meat products during preparation processing. In order to investigate the change of nitrite in different meat products during preparation and storage, three kinds of meat products such as manor ham, Australia beef and lilac burned chicken were used as the materials to track the change of nitrite content and optimize critical preparation processing and storage. Meanwhile, nitrite content of poultry products in market was also investigated. Results indicated that nitrite content of meat products exhibited an obvious descending trend during thermal treatment. In addition, nitrite content in refrigerated meat products exhibited faster decrease than that of frozen meat products with the same package condition. However, currently available poultry products in market were generally low in nitrite content so that a negative impact to the inhibition of Clostridium botulinum was observed. Therefore, these investigations can provide a good academic base for studying the change of nitrite content in meat products during preparation processing and storage as well as a great guidance to design optimal addition amount of nitrite in meat products during preparation.

Separation and Antioxidant Activity of Corn Gluten Meal Hydrolysate
LI Hong-mei1,YANG Rui1,YU Lei1,ZHANG Xue-zhong2
2010, 31(1):  117-122.  doi:10.7506/spkx1002-6630-201001028
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Corn gluten meal was hydrolyzed by proteolysis with alkaline protease and the refined hydrolysate was then separated and purified by Sephadex G-15 and G-10 column chromatographic and preparative HPLC methods. With α-tocopherol as a positive control, the hydrolysate and its fractions were evaluated for antioxidant activity by DPPH radical scavenging assay, linoleic acid auto-oxidation inhibition assay, ferric reducing/antioxidant power (FRAP) assay and superoxide anion scavenging assay based on pyrogallol auto-oxidation method. Results revealed that fraction II eluted from Sephadex G-10 column exhibited the highest antioxidant activity, a relative molecular mass distributed in range of 400 to 700 D detected by MS and an amino acid composition mainly consisting of glutamic acid, alanine, leucine, histidine, proline and phenylalanine.

Effects of Ionic Strength and Temperature on Whey Protein Gelation
WANG Yan1,2,WANG Cun-tang1,2,JIANG Ji-feng1,2,QU Lei3
2010, 31(1):  123-126.  doi:10.7506/spkx1002-6630-201001029
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This study was designed to examine effects of gelation temperature and CaCl2 level on Ca2+-induced cold gelation of whey protein. Results showed that low gelation temperature and increased CaCl2 concentration were in favor of the formation of clear gel. Gels formed at 0, 10 or 20 ℃ exhibited an increase in hardness with increasing CaCl2 concentration. In addition, a sharp increase was observed in the water-holding capacity of gels formed at 0 or 10 ℃ when the CaCl2 concentration was increased from 20 to 40 mmol/L. With the exception of gels formed at 0 ℃ with 20 mmol/L CaCl2, lower temperature resulted in higher gel strength and water-holding capacity. Therefore, temperature and CaCl2 concentration are both key factors affecting cold gelation of whey protein.

Effect of Ultrafine Comminution on Physico-chemical and Functional Properties of Vital Wheat Gluten
ZHANG Hui,BIAN Ke,WAN Xiao-le
2010, 31(1):  127-131.  doi:10.7506/spkx1002-6630-201001030
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In the present study, vital wheat gluten (WG) was comminuted into 8 different meshes using a jet mill, and effect of comminution degree on physico-chemical and functional properties of WG was examined. Results showed that with decreasing particle size, there was an obvious decrease in moisture content in WG and the water absorbing capacity exhibited an ascending trend below 500 mesh and a descending trend between 900 mesh and 500 mesh and held the line approximately above 900 mesh. Whiteness, foaming properties, emulsifying properties, water holding capacity and oil holding capacity had different increases as particle size decreased. Therefore, ultrafine comminution can improve some properties of VWG and the improvement in physico-chemical and functional properties varies with comminution degree.

Construction of Saccharomyces cerevisiae Strain with Barley Lipid Transfer Protein 1 Secretory Capability
ZHANG Hong-bo,RUAN Hui,MA Li-kai,GUO Qin,ZHANG Wei,CHEN Qi-he,
2010, 31(1):  132-136.  doi:10.7506/spkx1002-6630-201001031
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In order to enhance the foam stability of green draft beer, barley lipid transfer protein 1 (LTP1) encoding DNA sequence from Hordeum vulgare was modified to construct yeast Saccharomyces cerevisiae expression plasmid YEp181-KAMLC of barley LPT1 using the plasmid YEplac181. The expression of barley LTP1 was regulated by alcohol dehydrogenase promoter (ADH1 promoter) and terminator cytochrome C terminator (CYC1) of Saccharomyces cerevisiae, and the matured form of barley LTP1 was secreted under the lead of α-mating factor 1 signal peptide. Fermentation for 132 h at 30 ℃ gave a yield of barley LTP1 as high as 29.45 mg/L.

Analysis of SSR Information in EST Resource of Lentinus edodes
WANG Yan-fang,ZHAO Yan-hong*,WANG Ai-yun,WANG Qin-qin,LIU Lin-de,ZHOU Rui-lian,YU Xiao-fei
2010, 31(1):  137-140.  doi:10.7506/spkx1002-6630-201001032
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Simple sequence repeats (SSRs) were investigated in 12144 qualified ESTs downloaded from Nucleotide ESTs database of Lentinula edodes in NCBI. There were 359 SSRs in all the ESTs sequences of Lentinus edode, which were composed of 243 di- (67.69%), 114 tri- (31.76%), 1 penta- (0.28%) and 1 hexa- (0.28%) nucleotide SSRs. The estimated frequency of SSRs was approximately 1 SSR per 33.8 ESTs. Total length of SSRs was 7727 kb, accounting for about 2.94% of total ESTs sequences. In addition, we selected 100 ESTs sequences in Lentinus edodes and designed 100 primer pairs for EST-SSR markers, of which 20 were arbitrarily selected and synthesized. Selection and investigation of these primers were performed with 4 wild-type strains of Lentinula edodes. There were 16 primer pairs characterized by clear and stable target bands, of which 11 presented genetic diversity. Our findings indicated that these Lentinula edodes EST-SSRs markers developed in this study were useful and effective.

Isolation and Screening of Exopolysaccharides-producing Lactic Acid Bacteria from Inner Mongolia Dairy Tofu
ZHANG Xue,LI Da,ZHAO Yu-juan,NIU Chun-hua,YANG Zhen-nai*
2010, 31(1):  141-144.  doi:10.7506/spkx1002-6630-201001033
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Four Lactobacilli stains were isolated and screened from traditional fermented dairy products dairy tofu popular in Inner Mongolia. According to phenotypic, physiological-biochemical and API tests, the strains were all identified as Lactobacillus plantarum and named C2, C8, C15, and C21, respectively. The negative staining method was used to observe their capsules, and the results indicated that except strain C2, all the others produced capsular polysaccharides and the capsules could be seen by using optical microscopy. The 48 h growth and exopolysaccharide-producing ability of the four strains were analyzed. It was found that all these strains exhibited a gradually increasing exopolysaccharides production during 48 h culture, and strain C21 produced the highest amount of exopolysaccharides.

Double Enzyme Hydrolysis for Preparation of Corn Peptides
LI Yan-li1,CONG Jian-min2,CHEN Guang1,*
2010, 31(1):  145-148.  doi:10.7506/spkx1002-6630-201001034
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Double enzyme hydrolysis was used to prepare peptides from corn gluten meal. In order to maximize degree of hydrolysis (DH), crucial hydrolysis parameters were optimized. Results showed that a maximum DH of 80.97% was obtained by optimized sequential hydrolysis for 1.5 h using protease alkaline at 55 ℃ and pH 8.5 with 5 g/100mL substrate concentration and 4% enzyme dose followed by 1.5 h using papain at pH 7.5 with 3.5% enzyme dose, which was significantly higher that obtained by single enzyme hydrolysis.

Effects of Different Carbon and Nitrogen Sources on Content of Polysaccharide in Liquid Submerged-fermented Mycelia and Broth of Hericium erinaceus
WANG Jing-jian,WEN Lu*,WENG Liang,JI Hong-hui,SUN Juan
2010, 31(1):  149-151.  doi:10.7506/spkx1002-6630-201001035
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In order to exploit new carbon and nitrogen sources for Hericium erinaceus, effects of kind and amount of carbon and nitrogen sources on the content of polysaccharide in harvested mycelia and broth of Hericium erinaceus after 35-day liquid submerged fermentation. The phenol-sulfuric acid method was used to determine polysaccharide content. Results showed that the optimal carbon and nitrogen sources were starch and soybean dregs for polysaccharide production in Hericium erinaceus mycelia, respectively, and the content of polysaccharide was as high as 162.17 mg/g when the amounts of starch and soybean dregs were 4.0% and 1.5%. In conclusion, starch and soybean dregs are the optimal choices of carbon and nitrogen sources for polysaccharide production in Hericium erinaceus due to low cost and broad source, which will have a promising popularilization prospect in practical production.

Fermentation Characteristics and Phylogeny of Several Lactobacilli Strains Isolated from Spontaneously Fermented Yak Yoghurt from Western Sichuan Plateau
TIAN Hong,ZHANG Xiao-ping*,YAN Yi-lan
2010, 31(1):  152-156.  doi:10.7506/spkx1002-6630-201001036
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According to sensory evaluation and acidity determination, 6 Lactobacilli strains (4-1, 4-7, B-2, E-1, E-5, J-2) were selected from 109 isolated from spontaneously fermented yak yoghurt samples from western Sichuan plateau. The fermentation characteristics of these strains, including growth curve, acid production, fermented yoghurt viscosity, acetaldehyde synthesis were compared. Along with this, the phylogenic analysis based on 16S rDNA sequence was performed. Results showed that maximum growth was observed in the strains cultured for 14 h in MRS medium or 8 h in 10% skim milk at 42 ℃, and the acidity of yoghurt fermented with each of them reached the Chinese national standard of GB2746—1999 for yoghurt, and the viscosity and acetaldehyde amount were in the ranges of 1050-4900 mPa·s and 15.11-26.64μg/mL, respectively. Strains E-1 and E-5 revealed weaker acid-producing ability during cold storage when compared with other four strains. The highest values of viscosity and acetaldehyde amount of yoghurt fermented with each strain appeared on the 5th and 2nd day of cold storage. Furthermore, only slight change was observed in the viscosity of yoghurt fermented with strains E-1 or E-5. The highest acetaldehyde content in yoghurt fermented with strains J-2 or E-5 was observed on the 3rd day of cold storage, while that in yoghurt fermented with other four strains alone on the 2nd day. Homology analysis of 16S rDNA gene sequence indicated that there was a homology above 99% among strains 4-7, E-1 and E-5 and these strains and L.plantarum strains were included in the same branch of phylogenetic tree based on 16S rDNA gene sequence. Strain J-2 belonged to the L.paracasei family, and exhibited a homology of 97.6% to the representative stain of this family, L. paracasei SM63 (AJ441107 ). There was a homology of 99% between strains 4-1 and B-2, which were included in the L. fermentum branch. All these results showed that strains E-1 and E-5 had a good potential as starters for yoghurt production..

Enzymolysis for Preparation of ACE Inhibitory Peptides from Konjac Fly Powder
XU Huai-de,WANG Li,WANG Xing
2010, 31(1):  157-160.  doi:10.7506/spkx1002-6630-201001037
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In order to achieve an in-depth development of konjac fly powder, the technology for preparation of angiotensin- I-converting enzyme (ACE) inhibitory peptides by hydrolyzing this resource was studied. The optimum protease and the optimum hydrolysis conditions were determined for maximizing ACE inhibitory activity in vitro of konjac fly powder hydrolysate. Results showed that alkaline protease was the optimum protease to hydrolyze konjac fly powder protein. The optimum conditions for alkaline protease-catalyzed enzymolysis were as follows: substrate concentration 2.25%, temperature 50 ℃, enzyme concentration 3500 U/(g substrate), and pH 8.0 for a hydrolysis duration of 270 min. Under the optimum conditions, the ACE inhibitory ratio of konjac peptides with a yield of 12.70% was 95.69%. After freeze drying, konjac peptides powder with yellowy color and an IC50 of 0.80 mg/mL was obtained, which comprised 52.67% peptides and 62.30% protein. In conclusion, the developed enzymolysis technology is feasible for the preparation of ACE inhibitory peptides with high biological activity from konjac fly powder.

Enzymological Characterization of Polyphenol Oxidase from Chayote Fruits
ZHANG Fu-ping,ZHANG Xi-chun
2010, 31(1):  161-164.  doi:10.7506/spkx1002-6630-201001038
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Freshly-prepared crude polyphenol oxidase (PPO) from chayote was enzymologically characterized in the present study. Results showed that the optimal reaction pH and temperature for this enzyme were 7.5 and 30 ℃, respectively, and substrate concentration was positively correlated with enzyme activity. This enzyme could quickly catalyze the oxidation of pyrogallic acid as a substrate, but exhibited relatively low catalysis activity towards catechol, hydroquinone and resorcinol. The activity of this enzyme was inhibited by vitamin C, citric acid, sodium tetraborate, magnesium chloride and EDTA-2Na in decreasing order. With increasing concentration, there was an increase in inhibitory effects of vitamin C and citric acid against enzyme activity.

Protoplast Fusion between Cordyceps sinensis and Cordyceps militaris
GUO Cheng-jin1,ZHAO Run2,ZHU Wen-bi3
2010, 31(1):  165-171.  doi:10.7506/spkx1002-6630-201001039
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Fusion between protoplasts from Cordyceps sinensis and Cordyceps militaris subjected to heat and ultraviolet inactivations, respectively, was studied. In order to maximize fusion rate, five crucial fusion conditions were optimized using orthogonal array design. A maximum fusion rate of 2.74 × 10-5 was achieved through 20 min fusion at 35 ℃ under the promotion of 40% PEG and 0.08 mmol/L CaCl2 (pH 7). Besides, the genetic relationships among the parent and fusant strains were quested by morphologic observation, rivalry experiments and RAPD-PCR identification.

Biochemical Characteristics of Phenoloxidase from Portunus trituberculatus
ZHENG Dan1,DUAN Qing-yuan2,*,ZHU Li-hua1,ZHONG Hui-ying1,YANG Jia-feng1,WANG Jie1
2010, 31(1):  172-176.  doi:10.7506/spkx1002-6630-201001040
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Crude phenoloxidase (PO) was extracted from Portunus trituberculatus and characterized biochemically. This enzyme exhibited an optimal pH of 8.2 and temperature of 55 ℃ for catalyzing the oxidation of pyrocatechol as a substrate. Optimal enzyme stability was observed in the ranges of pH 7.8-8.4 and 25-40 ℃. Browning reaction catalyzed by this enzyme obeyed the Michaelis-Menten equation. The values of Km and Vmax at 30 ℃ and pH 7.2 were calculated to be 0.531 mol/L and 0.049 A530nm/min, respectively. Twelve inhibitors tested all had a certain inhibitory effect against this enzyme, among which phytic acid was the strongest inhibitor, followed in turn by sodium metabisulfite, L-cysteine, oxalic acid and ascorbic acid.

Fed-batch Fermentation of Glutathione
PAN Ya-lei,HE Xiao-xian,CHEN Shan
2010, 31(1):  177-180.  doi:10.7506/spkx1002-6630-201001041
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In order to obtain high glutathione (GSH) yield and dry cell weight, fed-batch fermentation in a 5 L fermentor was adopted for glutathione production by a DL-ethionine, zinc chloride-resistant mutant of Saccharomyces cerevisiae. Strategy for fed-batch feeding of glucose at an initial concentration of 20 g/L was investigated. Results showed that the fed-batch feeding strategy of adding 22, 24, 24, 24, 24 g/L and 22 g/L glucose at intervals of 3 h from 12 to 27 h of fermentation resulted in 72.49 mg/L GSH concentration and 28.52 g/L dry cell weight, which was 2.86 times and 4.93 times as high as those obtained by single batch fermentation. This meant that fed-batch fermentation could remarkably promote strain growth and enhance GSH production.

Separation, Purification and Characterization of Trypsin from Anchovy
LU Ying-tao1,KANG Cong-min1,*,WANG Lin1,XUE Chang-hu2
2010, 31(1):  181-184.  doi:10.7506/spkx1002-6630-201001042
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Anchovy endogenous crude protease is mainly composed of four proteases. Trypsin plays the most important role in reactions with casein. Trypsin-like protease was purified using a combined separation method of ion exchange chromatography and gel filtration chromatography. Preliminary characterization of purified trypsin was also conducted. Results suggested that the purified trypsin from anchovy exhibited excellent thermal and pH stability. The optimal pH and temperature of this enzyme was 9.0 and 55 ℃, respectively. It also exhibited high substrate specificity. According to inhibition profile of specific protease inhibitors and metal ions, trypsin was a kind of metal-activated enzyme rather than a kind of metalloenzyme.

Screening and 16S rDNA Sequence-based Identification of Proteolytic Strains from Harbin Dried Sausage
ZHANG Gen-sheng,LI Da-long,LI Zhi,YUE Xiao-xia
2010, 31(1):  185-188.  doi:10.7506/spkx1002-6630-201001043
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A total of 41 cocci strains were isolated from Harbin dried sausage to evaluate their potential proteolytic activity by qualitative and quantitative methods. Total genomic DNA was extracted from these strains with proteolytic activity and then was subjected to PCR amplification and 16S rDNA sequencing for the identification of their systematic classification. Results indicated that 10 of these strains had proteolytic activity. CHMS34.1, CHMS34.3, CHMS34.9 and CHMS34.15 exhibited strong proteolytic activity, which were 282, 312, 310 U and 305 U, respectively. Meanwhile, their 16SrDNA sequences exhibited a high similarity with those of some strains of Staphylococcus presented in GenBank. Therefore, systematic classification revealed that CHMS34.1 and CHMS34.15 belonged to the Staphylococcus pasteuri family, CHMS34.3 the Staphylococcus simiae family, and CHMS34.9 the Staphylococcus xylosus family.

Breeding of SGA-producing Strains for Liquor Brewing and Preliminary Enzymological Characterization of Produced SGA
XIA Yan-qiu1,ZHU Qiang1,DING Xiu-qin2,WANG Zhi-jun3
2010, 31(1):  189-193.  doi:10.7506/spkx1002-6630-201001044
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A new strain SP7 with strong gelatinized starch-digesting glucoamylase (RSGA) activity and a synergistic effect on compound enzyme system was isolated from rotten sweet potatoes, which was preliminarily identified as Aspergillus niger by morphologic taxonomy test. A mutant stain, SP7-2 was obtained from SP7 subjected to combined UV and LiCl mutagenesis, which resulted in 3446 U/g RSGA activity under solid-state fermentation and 12.5% (V/V) alcohol degree of liquor brewing with uncooked materials. A broad activity towards raw starch with both small and large granule sizes was observed and glucose was the only hydrolysis product. Substrate specificity of this enzyme exhibited an order from high to low as corn starch, sweet potato starch, potato starch, rice starch, cassava starch and wheat starch. The optimal temperature and pH for enzyme activity towards raw sweet potato starch as a substrate were 40 ℃ and 4.0, respectively. After incubation at 60 ℃ for 1 h, the activity of this enzyme remained less 5%. However, more than 90% of maximum activity was remained after incubation at pH 3.5 for 1 h at room temperature. Therefore, SP7-2 SGA was a temperature-sensitive and acid-tolerant enzyme, which exhibited great prospect in the application of liquor brewing.

Effect of Cyclophosphamide on Micronucleus Rate in Vicia faba Root Tips
DING Xiao-wen,LI Hong,WANG Hai-yan
2010, 31(1):  194-197.  doi:10.7506/spkx1002-6630-201001045
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Objective: To study the optimal concentration of cyclophosphamide and evaluation standard of micronucleus tests in Vicia faba root tips. Methods: Micronucleus tests were conducted in Vicia faba root tips treated with different concentrations of cyclophosphamide. Results: Micronucleus rate in Vicia faba root tips exhibited a good reproducibility and dose-effect relationship at the concentration of cyclophosphamide below 40.0 mg/L. Mutagenesis of tested samples was observed when micronucleus index was over 1.5. Conclusion: Concentrations of cyclophosphamide between 0.8 mg/L and10.0 mg/L could be used as the positive control and micronucleus index could be used to assay mutagenicity due to its accuracy, rapidness and practical value.

Selection of Cryoprotectants for Lactobacillus acidophilus and Pre-freezing in Liquid Nitrogen during Lypholization
ZHU Dong-sheng,MA Liu-liu,LI Qing-qing,CHEN Qi-he,ZHENG Xiao-dong,HE Guo-qing*
2010, 31(1):  198-200.  doi:10.7506/spkx1002-6630-201001046
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Lypholized yogurt starter culture is becoming more and more important in our life. In this study, the optimal cryoprotectant formula for Lactobacillus acidophilus was determined using orthogonal array design to be composed of 15% nonfat milk powder, 4% trehalose, 1% vitamin C and 1.5% glutamate. During lypholization process of Lactobacillus acidophilus, higher survival rate was achieved using pre-freezing in liquid nitrogen than unusing. In addition, an obvious effect of liquid nitrogen droplet size on survival rate of Lactobacillus acidophilus was also observed during pre-freezing process. The smaller droplet size of liquid nitrogen resulted in a higher survival rate of Lactobacillus acidophilus.

Screening and Application of Excellent Lactic Acid Bacterial Strains from Pickled Vegetables from Western Hunan Province
CHEN Jian-hua,ZHU Wang-yin,DU Ya-tian*
2010, 31(1):  201-205.  doi:10.7506/spkx1002-6630-201001047
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To develop and investigate the production process and technique of folk pickled vegetable food popular in ethnic minority areas of western Hunan province, China, 8 acid-producing bacterial strains were isolated from 4 kinds of pickled vegetables sampled from these areas with BCP and TYA culture media by streak plate and spread-plate techniques, respectively. Further, strain A5 with the strongest acid producing ability, followed by strains A6 and B2, was screened together with them. According to morphological features and biochemical properties, all the screened stains were preliminarily identified as Lactobacillus. Milk and white radish fermentation experiments indicated that strain A5 had the best ability to produce aroma and mucoid substances and acids. The growth of this strain tended to be stable after 22 h of culture and the highest acid productivity was observed at 40 h.

Effect of Fermentation Conditions on Growth of Tea Fungus and Acidity in Tea Broth
WAN Chun-mei,CAI Ying-qi,WANG Xiao-ting,WANG Fang*
2010, 31(1):  206-210.  doi:10.7506/spkx1002-6630-201001048
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Tea infusion with sugar was used as the medium to conduct fermentation experiments with tea fungus. Acetic acid bacteria and yeast counts were determined during fermentation process to establish growth curves. Meanwhile, acidity in tea infusion was also determined. Results indicated that acetic acid bacteria and yeast counts were different and acidity in tea infusion also exhibited a difference at different fermentation conditions.

Isolation and Identification of An Excellent Strain of Acetobacter spp. for the Fermentation of Changshanhuyou Tangelo Vinegar
LIU Qian-qian1,YANG Ying2,LU Sheng-min2,*,TAO Ning-ping1,XIA Qi-le2,XING Jian-rong2
2010, 31(1):  211-214.  doi:10.7506/spkx1002-6630-201001049
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Objective: To screen an acetic acid-producing strain for the fermentation of Changshanhuyu Tangelo vinegar. Methods: Acetic acid-producing strains were screened from spontaneously fermented Changshanhuyou Tangelo vinegar ans tested for alcohol tolerance, acetic acid-producing rate and alcohol-consuming rate. Meanwhile, the sensory evaluation of vinegar fermented by these strains was carried out and the optimal strain screened was identified using VITEK-32 automatic microorganism analysis system. Results: Three strains were screened and named HY05, HY19 and HY36, respectively. Among these strains, HY05 exhibited the best properties and could resist 14% alcohol. Alcohol was consumed quickly at 10% initial concentration of alcohol and the fastest rate of acetic acid production was also observed. Changshanhuyou Tangelo vinegar fermented by HY05 exhibited a high quality with yellow color, fragrant odor and transparent texture. Through colonial characteristic analysis and cell morphology observation, HY05 was identified to be Acetobacter pasteurianus, designated as A. pasteurianus HY05. Conclusion: A. pasteurianus HY05 was suitable for the production of Changshanhuyu Tangelo vinegar.

Characteristics of Glycogen Phosphorylase from A Thermophilic Bacterial Strain (Ⅱ)
CHEN Shi-qiong1,TANG Qing-yan2
2010, 31(1):  215-218.  doi:10.7506/spkx1002-6630-201001050
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In order to provide valuable evidences for the in-depth understanding and application of glycogen phosphorylase from Thermoanaerobacter tengcongensis MB4T (Tte-GlgP), the substrate spectrum of Tte-GlgP was determined by ESI-MS method. When soluble starch and maltoheptaose were respectively used as the substrates, the production of alpha-D-glucose- 1-phosphate (G-1-P) was clearly revealed in the ESI-MS chromatogram. When glycogen, maltodextrin and maltotriose were subjected to the same reaction, the production of G-1-P was also clearly detected. These results suggested Tte-GlgP had a relative wide substrate spectrum. To evaluate the relative activity of Tte-GlgP towards these substrates, a modified coupledenzyme method was used to measure the production of G-1-P in these reactions. When 0.25% soluble starch, glycogen, maltodextrin, maltoheptaose, maltopentaose, and maltotriose were used as substrate, respectively, it was established that the transformation efficiency represented by the production of G-1-P (μmol/L), was relatively higher for maltooligosaccharides (maltoheptaose and maltopentaose, with production of 86.83 μmol/L and 85.79 μmol/L G-1-P, respectively), maltodextrin (82.9 μmol/L G-1-P) and soluble starch (69.68 μmol/L G-1-P), but lower for glycogen and maltotriose (45.81μmol/L and 43.60 μmol/L G-1-P, respectively) at the same reaction condition. These results were consistent with those of ESI-MS analysis. Both suggested that Tte-GlgP could transform a wide variety of glucans into G-1-P, with maltooligosaccharides, maltodextrin and starch as the optimum substrates. For the determination of optimum conditions for reaction of Tte-GlgP with soluble starch as the substrate, 50 mmol/L potassium phosphate buffers with pH ranging from 5.0 to 9.0 were used to prepare the reaction mixtures. The reactions were performed respectively at 50, 60 ℃ and 80 ℃ for 30 min, and the highest activity of Tte-GlgP was achieved at pH 8.0 in all these assays, suggesting that the optimum pH for Tte-GlgP was pH 8.0. Then with this optimum pH (8.0), the reactions were performed at different temperature from 37 ℃ to 80 ℃ for 30 min to detect the optimum temperature, which was revealed to be 60 ℃. To determine the thermostability, Tte-GlgP was incubated at different temperatures from 50℃ to 80℃ for 0-21 h, and the residual activity was measured by the modified coupled-enzyme method (0.25% soluble starch was used as substrate). Results suggested that there were still 90% and 64% residual activity after treatment for 6 h at 60 ℃ and 70 ℃, respectively. Thus the Tte-GlgP is indeed a thermostable enzyme as expected.

Antioxidant Properties of Ferulic Acid in vitro
ZHAO Wen-hong,DENG Ze-yuan*,FAN Ya-wei,LI Jing,RUAN Zheng
2010, 31(1):  219-223.  doi:10.7506/spkx1002-6630-201001051
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This study aimed to investigate antioxidant activities of ferulic acid (FA) in vitro by evaluation of protective effect against red blood cell (RBC) hemolysis and swelling of liver mitochondrion in rat detected by spectrophotometric method and inhibitory effect against serum autooxidation and spontaneous and H2O2-Fe2+-induced lipid peroxidation in liver homogenate and hydroxyl radical, superoxide anion radical, DPPH radical scavenging and ferric reducing antioxidant power assays. Results showed that FA had stronger reducing power with above 2-fold enhancement when compared with VC, effectively scavenged hydroxyl radicals generated by Fenton reaction, superoxide anion radicals generated in hypoxanthin-xanthine oxidase system and DPPH radicals, with IC50s of 1.09 mmol/L, 0.62 mmol/L and 23.56 μmol/L, respectively, and could provide good protection against RBC hemolysis and serum autooxidation and inhibit significantly spontaneous and H2O2-Fe2+-induced lipid peroxidation in liver homogenate. Thus, it was concluded that FA possessed outstanding anti-oxidant properties.

Anti-fatigue Function of Compound Pu’er Tea with American Ginseng in Mice
MA Wei-guang1,HUANG Zhi-pu1,YOU Wen-long2,YOU Wen-xin2,ZENG Guang-yuan3,LIU Yu-qing4
2010, 31(1):  224-226.  doi:10.7506/spkx1002-6630-201001052
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This study was carried out to provide useful experimental evidences for the development of Pu’er tea-related products. Rotarod performance test, weight-loaded swimming test and liver glycogen determination were adopted for comparing anti-fatigue function of common Pu’er tea and compound Pu’er tea with American ginseng in mice. Totally 96 SPF ICR mice (18-22 g, half male and half female) were randomly divided into 8 groups of 12 mice each, namely blank control group, positive control group, three common Pu’er tea groups and three compound Pu’er tea with American ginseng groups. Positive control group was administrated by gavage with 200 mg/kg bw Panax notoginsenosides. High-, medium- and low-dose Pu’er tea and compound Pu’er tea with American ginseng were administered at 5.0, 2.5 g/kg bw and 1.25 g/kg bw, respectively. Mice administer with the same volume of water (20 mL/kg bw) were served as blank control group. All mice were administered once a day for continuously 14 days. Results showed that both medium and high doses of common Pu’er tea and compound Pu’er tea with American ginseng could significantly prolong the rotarod performance time in mice. In addition, different increases in weightloaded swimming time were observed in mice administered with both kinds of tea for continuously 14, and a big increase in mice administered with compound Pu’er tea with American ginseng. Furthermore, the two kinds of tea enhanced the static storage of liver glycogen to different extents.

Effect of Whey Protein Peptides on Growth and Development of Young Rats
XU Lin-lin,MA Yi,XU Ya-jun,LI Yong
2010, 31(1):  227-231.  doi:10.7506/spkx1002-6630-201001053
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Objective: To investigate the effect of low-molecular-weight whey protein peptides (WPP) on physical development, bone growth and blood parameters in young rats. Methods: Forty male SD rats were randomly divided into 4 groups of 10 rats each, designated as control group, groups with WPP intervention at low, middle and high doses, which were 0.225%, 0.45 % and 1.35 % WPP, respectively. All rats were subjected to feeding for 42 consecutive days. Body weight and length of each rat were measured once a week. Blood parameters, femur length and diameter, bone mineral content and bone density of each rat were analyzed at the end of experimental period. Results: WPP intervention at the dose of 0.45 % and 1.35 % resulted in an obvious increase in body weight, femur length, and food utilization rate of rats. Compared to the control group, the bone mineral density and mineral content of proximal femur in rats treated with 1.35 % WPP exhibited a significant increase although no significant impact on femur dry weight, length and diameter. Moreover, the levels of serum creatinine and uric acid in rats treated with 0.45 % and 1.35 % WPP were significantly decreased. Conclusion: WPP could promote growth and development of young rats, and enhance their bone mineral density.

Experimental Study on Hypolipidemic Effect of Water Decoction of Chickpea Seeds in Rats
TIAN Chun-yuan1,ZHOU Xiu-jia2
2010, 31(1):  232-234.  doi:10.7506/spkx1002-6630-201001054
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SD male rats were used as experimental animals to investigate whether water decoction of chickpea seeds (WDCS) has hypolipidemic effect. Seventy-two rats were randomly divided into 6 groups of 12 rats each. Rats fed normal diet were served as normal control group and all other groups were fed high fat diet over the whole experimental period. Blood lipid level in rats was assayed after 10 d of high fat diet feeding and 4 weeks and 6 weeks of continuous WDCS administration by gavage. Results showed that WDCS resulted in a decrease in rat serum TC, LDL-C and TG and an increase in HDL-C and APO AI and more significant changes in these blood lipid parameters were observed in high dose administered rats. Therefore, WDCS has a good regulatory effect on blood lipid level in hyperlipidemic rats.

Anti-inflammatory Effect of Fritillaria ussuriensis Maxim. Combined with Snow Pear Juice
LI Xia1,GAO Wen-yuan1,*,HUANG Li-jing1,2,ZHANG Yan-jun2
2010, 31(1):  235-239.  doi:10.7506/spkx1002-6630-201001055
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Objective: To investigate anti-inflammatory effects and action mechanisms of aqueous extract of Fritillaria ussuriensis Maxim., snow pear juice and Pingbei Xueli Yin (BLY). Methods: Animal models of auricular edema induced by xylene in mice, capillary permeability induced by acetic acid in mice and paw edema induced by albumen in rats were established to observe anti-inflammatory effects of aqueous extract of Fritillaria ussuriensis Maxim., snow pear juice and BLY. The contents of PGE2 and MDA in inflammatory exudates were measured to explore anti-inflammatory mechanisms of three samples. Results: Aqueous extract of Fritillaria ussuriensis Maxim., snow pear juice and BLY exhibited good attenuation effects on auricular edema induced by xylene, paw edema induced by albumen and permeability increase of capillary induced by acetic acid. Meanwhile, the three experimental samples revealed an obvious inhibition effect on the increase of PGE2 and MDA. Moreover, snow pear juice and BLY exhibited an obvious dose-dependent inhibition effect on the increase of PGE2 and MDA. Conclusion: All of them have a good anti-inflammatory effect. A synergistic effect of Fritillaria ussuriensis Maxim. and snow pear juice on anti-inflammation is achieved. The three administration samples all had a negative regulation function on the level of PGE2 and MDA, which suggests that the anti-inflammatory effect might be related to the reduction of PGE2 and MDA levels.

Isolation, Purification and Hemorrheological Effect of Glycoprotein from Gastrodia elata (GGE2b) in Blood Stasis Rats
DING Cheng-shi
2010, 31(1):  240-242.  doi:10.7506/spkx1002-6630-201001056
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Objective: To isolate and purify glycoprotein from Gastrodia elata (GGE2b) and investigate its hemorrheological effect in acute blood stasis rats. Methods: Soluble extracts of Gastrodia elata were purified by DEAE-Sepharose column chromatography and fast protein liquid chromatography (FPLC) to obtain GGE2b. Acute blood stasis rat model was developed by hypodermic adrenaline injection combined with cold-shock treatment. Totally 60 male rats were randomly divided into 6 groups of 10 rats each, namely saline group, acute blood stasis model group, PGE2b administration groups at doses of 30, 60 and 120 mg/kg, and positive control group administered with Danshen injection. Effect of GGE2b on whole-blood viscosity, plasma viscosity, red blood cell (RBC) accumulation, RBC aggregation index and RBC deformability index in acute blood stasis rats was examined. Results: GGE2b was successfully purified from Gastrodia elata through combined technology of DEAE-Sepharose column chromatography and FPLC. Moreover, GGE2b administration at the doses of 60 mg/kg and 120 mg/kg in rats resulted in a dramatic decrease of plasma viscosity (P < 0.05), whole-blood viscosity (P <0.01) and RBC aggregation index (P< 0.05), and increase of RBC deformability index (P <0.05). Conclusion: It is feasible to purify glycoproteins from Gastrodia elata using chromatography technology. GGE2b can result in a significant improvement of abnormal hemorrheology in rats with acute blood stasis.

Nutrients and Antioxidant Activity of Longan Seeds
WEN Liang-juan,LI Ying-jun,MAO Hui-jun,ZHANG Yuan-chun,
2010, 31(1):  243-246.  doi:10.7506/spkx1002-6630-201001057
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Longan seeds were used as materials to analyze nutritional compositions and antioxidant activity. Results indicated that contents of starch, reducing sugar, total sugar and protein in Shixia longan seeds were higher than those in Dawuyuan and Chuliang longan seeds. Ethanol extract of each of the cultivars exhibited good antioxidant activity due to powerful scavenging capacity against DPPH and hydroxyl free radicals. Moreover, scavenging capacities of extract from Shixia longan seeds against DPPH and hydroxyl free radicals were higher than those of Dawuyuan and Chuliang. However, ethanol extract of each of the longan cultivars exhibited weak scavenging capacity against NO2.

Toxicological Mechanisms of Microcystin-LR in Mice
LI Zhe,BIAN Ai,SHEN Li-zhen,XU Chuan-lai*
2010, 31(1):  247-250.  doi:10.7506/spkx1002-6630-201001058
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Objective: To explore the possible toxicological mechanisms of microcystin-LR (MC-LR) in mice. Methods: Organ index and blood biochemical parameters were examined in mice intraperioneally administered with microcystin-LR at the dose of 30 μg/kg bw at 1, 4 and 8 h postadministration. Results: A significant increase in liver index of mice treated with MC-LR at 4 h postadministration was observed; but no obvious change in kidney index was observed at this time point. A significant increase in blood catalase (CAT) content and activity was determined. An initial increase and final decrease in blood urea nitrogen (BUN) was also monitored; however, superoxide dismutase (SOD) only exhibited little change. Conclusions: MC-LR attracts hepatocytes first, produces a large amount of free radicals, destroys cell membranes and heptocytes, interrupts metabolism of amino acids, and results in hyperemia and swelling of liver. Followed by liver damage, kidney insufficiency is also initiated; permeability of kidney tubules is increased as a result of MC-LR treatment. As the time goes on, MC-LR causes a permanent damage to organism. This damage, however, is not seen apparently due to repair function in the organism, that is, the MC-LRcaused damage to organism is reversible to a certain extent.

Sterilization Mechanisms and Synergistic Strategy of Dense-phase Carbon Dioxide (DPCD) Treatment to Heat-sensitive Juice
ZENG Qing-mei,ZHOU Xian-han,YANG Yi,SI Wen-gong,LI Zhi-qiang,LIU Kun,GAO Yuan
2010, 31(1):  251-257.  doi:10.7506/spkx1002-6630-201001059
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Dense-phase carbon dioxide processing (DPCDP) is proposed as an alternative technique to conventional heat sterilization in food industry, which is carried out at pressure less than 100 MPa and moderate temperature. Microorganisms are inactivated due to cell burst in liquid culture with a sudden release of pressurized CO2, inactivation of enzymes or other sterilization mechanisms. Meanwhile, this technique exhibits no side effects on flavor, taste and nutrients; moreover, it is characterized by lower energy consumption, less cost for processing and industrial equipments, and no toxin production. Although DPCDP can be used for sterilization of vegetable bacteria, it is difficult to sterilize bacillus by DPCDP at the moderate temperature condition. Moreover, previous reports related to DPCDP for vegetable bacteria mainly focused on sterilization experiments on designated medium such as buffer or broth. However, the sterilization effect of DPCDP on vegetable bacteria is affected by medium so that it is still far away from practical applications. The inactivation mechanism of DPCDP for vegetable bacteria is still not clear as yet. Similarly, its sterilization mechanisms for bacillus have rarely been investigated. In order to further develop DPCDP for the sterilization of vegetable bacteria and bacillus, and provide theoretical evidences for industrial applications of DPCDP, mechanisms and synergistic strategies for the enhanced effect of DPCDP on the treatment to heatsensitive apple juice are reviewed in this paper, which also suggests that urgent problems such as sterilization mechanisms of acidification and extraction, sterilization mechanisms for bacillus, and synergistic strategies for DPCDP need resolving as soon as possible.

Current Research and Development Trend for Shelf Life of Frozen Food
SONG Chen,LIU Bao-lin*,DONG Qing-li
2010, 31(1):  258-261.  doi:10.7506/spkx1002-6630-201001060
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Shelf life of food is an important index for food quality and safety so that it is of practical significance to study food shelf life. In this paper, the concepts of shelf life and frozen food are introduced and the effect of temperature on shelf life and quality of frozen food is discussed. Due to the special properties of frozen food and problems in cold chain logistics, the prediction of shelf life for frozen food at fluctuating temperature conditions is becoming the focus of current studies. Therefore, three important stages for shelf life are demonstrated here in detail. In addition, the future creative points and development trend for shelf life of frozen food are also proposed.

Application of Whey Protein in Food Industry: A Review
LU Xiao-ming,WANG Jing-bo,REN Fa-zheng,CHEN Shang-wu*
2010, 31(1):  262-267.  doi:10.7506/spkx1002-6630-201001061
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Application of whey protein in food industry is briefly reviewed in this paper. Major components including α - lactalbumin, β-lactoglobulin and lactoferrin, functional properties including gel-forming property, coating property and filmforming property, production technology including membrane separation technology, absorption separation technology and affinity chromatography, modification methods including physical modification and enzymatic modification of whey protein are included. Meanwhile, the future application prospect of whey protein in the Chinese food industry is proposed.

Research Progress of Lutein Biosynthesis by Microalga
WU Zheng-yun1,SHI Xian-ming2,*,ZENG Juan1
2010, 31(1):  268-273.  doi:10.7506/spkx1002-6630-201001062
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Lutein is a natural pigment with multiple physiological functions for health protection. Nowadays, commercially available lutein products are mostly extracted from marigold, which suffers from some problems such as limited material resource and low productivity. Due to its promising, lutein biosynthesis by microalga has been attracted increasingly extensive attentions in recent years. Here, research progress of lutein biosynthesis by microalga including strain selection, biosynthetic pathway elucidation, culture parameter optimization, kinetic model establishment and extraction technique development are reviewed.

Application of Supercritical Fluid Extraction for Detection of Pesticide Residues in Cereal Grains: A Review
ZHANG Yan1,WANG Song-xue*,SUN Chang-po
2010, 31(1):  274-277.  doi:10.7506/spkx1002-6630-201001063
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Supercritical fluid extraction (SFE) technique is a method to extract bioactive components from liquid or solid materials by supercritical fluid. As one of the methods in green analytical chemistry, it has been widely applied to analyze hazardous substances in food, feedstuff and environmental samples. Since cereal grains are the most important raw materials of food, pesticide contamination in cereal grains becomes one of the main concerns in food safety. In this paper, current applications of unmodified and modified supercritical fluid in analyzing the pesticide residues of cereal grains are reviewed. Besides, future development trends of SFE are also discussed.

A Review of Application of Irradiation Technology in Sterilization and Preservation of Meat Products
DUAN Xin,OU Jie*,LI Bai-lin
2010, 31(1 ):  278-282.  doi:10.7506/spkx1002-6630-201001064
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Irradiation is a physical method that uses exposure energy of atomic energy beam to sterilize and preserve food. Due to its characteristics of environmental protection, safety and high efficiency, this method that can efficiently restrain or eliminate pathological or spoiled organisms has been widely applied in sterilization and preservation of meat products. In this paper, mechanisms of radiation sterilization, current research progress of food irradiation at home and abroad, safety evaluation of food irradiation and irradiation standards for meat products are reviewed. Meanwhile, the research progress of 60Co γ-ray irradiation, electron beam irradiation and X-ray irradiation in sterilization and preservation of meat products are discussed. Moreover, effects of irradiation on sterilization are also summarized. Furthermore, the feasibility and advantages of applying X-ray irradiation in sterilization and preservation of meat products are also explored. Therefore, a future possibility for applying X-ray irradiation as a pilot technology in the field of food is proposed.

Melamine Contamination and Control Countermeasures in Food
DUAN Wen-zhong1,MA Yu-song1,CHEN Rui-chun1,GUO Chun-hai1,PANG Jin-xia2
2010, 31(1):  283-286.  doi:10.7506/spkx1002-6630-201001065
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To explore pathways of melamine contamination in food, food chains contaminated by melamine without artificial addition tracked and detected. Our investigations indicated that melamine with different concentration levels was detected in the agricultural products and food resources that were related to contaminated food chains. In conclusion, the major pathways for melamine contamination in environment and food are due to the use of chemical products related to "cogeneration" technology of melamine, the application and metabolism of cyromazine and the migration of melamine from polymeric resin generated by melamine as raw materials. These investigations can provide a useful base for the development of scientific and rational control countermeasures for melamine contamination.

A Review of Application of Chromatographic Techniques to Determination of Antibiotic Residues in Milk and Related Food Products
ZHAI Zong-de,CAO Cheng-ming,GE Yu,ZHOU Yao-bin,ZHANG Hui,NING Xiao-jun
2010, 31(1):  287-291.  doi:10.7506/spkx1002-6630-201001066
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Nowadays, the safety of milk and related food products has become one of the health concerns of the country and even the world due to the melamine milk powder incident that broke out in China in 2008. As a consequence, the development of analytical techniques for hazardous and toxic substances in milk and related food products is becoming one of the hot research interests. In order to provide a useful guidance for effectively solving the antibiotic residue problems in milk and related food products, this paper reviews the applications of chromatographic (gas, liquid) and chromatographic-mass spectrometric techniques to the determination of antibiotic residues in milk and related food products according to antibiotic kind.

Research Advances of Novel Microecologic Probiotics Bacillus coagulans
DONG Hui-jun,JIANG Jun-yun,ZHENG Li-jun,PANG Jun-xing
2010, 31(1):  292-294.  doi:10.7506/spkx1002-6630-201001067
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Bacillus coagulans, which belongs to Bacillus and exerts similar function to Bacillus acidi lactici and Bacillus bifidus in healthcare, is characterized by strong resistance to heat, acid and bile salt. In addition, it has capabilities of inhibiting pathogenic bacteria in intestine. Bacillus coagulans has been applied in many aspects of healthcare, medicine, food and prologue abroad. Although the research and development on Bacillus coagulans have carried out for about ten years at home, the level falls behind in the world. In this paper, the characteristics, probiotic mechanisms, fermentation performance and clinical research of Bacillus coagulans are summarized in detail.

Research Progress of Ganoderma lucidum Polysaccharides
MAO Jian1,2,MA Hai-le1,*
2010, 31(1):  295-299.  doi:10.7506/spkx1002-6630-201001068
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Ganoderma lucidum polysaccharides as the major bioactive components have been attracted tremendous attentions due to their unique health functions. Biological activities and health functions of polysaccharides from Ganoderma lucidum have close relationships with their chemical structures such as molecular weight, glycosidic bond type and polysaccharide composition. Extensive investigations reported that polysaccharides from Ganoderma lucidum played important roles in reducing blood glucose and blood lipid, anti-tumor, immunoregulation and antioxidation functions. Due to many restriction factors of solid cultivation, liquid fermentation has become a major method for producing Ganoderma lucidum polysaccharides. However, the optimization of fermentation conditions is one of the critical factors for mass production of Ganoderma lucidum polysaccharides. Traditional extraction methods for Ganoderma lucidum polysaccharides such as hot-water extraction and alkaline extraction have the drawbacks of time-consuming and low extraction efficiency. However, ultrasonic-assisted extraction can remedy those defects, and therefore has attracted more and more attentions.