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01 March 2010, Volume 31 Issue 5
Basic Research
Change of Endogenous Formaldehyde in Portunus trituberculatus during Storage and Processing
MIAO Lin-lin,ZHU Jun-li,LI Jian-rong*
2010, 31(5):  1-4.  doi:10.7506/spkx1002-6300-201005001
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In an effort to understand content and origin of formaldehyde in Portunus trituberculatus, different parts of Portunus trituberculatus stored at different temperatures or processed using different recipes were analyzed for the content of formaldehyde by high-performance liquid chromatography (HPLC). Results indicated that the contents of formaldehyde in various parts of the fresh material such as cream, body muscle and leg muscle were all lower than 10 mg/kg and exhibited an obvious difference. The highest formaldehyde content was determined in leg muscle. Meanwhile, a significant decrease in the content of formaldehyde in the fresh material was observed during both refrigerated and frozen storage, whereas an obvious increase in the content of formaldehyde was determined in crab paste and liquor-soaked crabs. Similarly, cooking and steaming also resulted in an obvious increase in the content of formaldehyde. Therefore, it was possible that no trimethylamine oxidase pathway was present in Portunus trituberculatus, However, formaldehyde generation could result from decomposition reaction at high temperature, which was similar with squid and other fishery products. Moreover, Fe2+ in pickled Portunus trituberculatus products also could promote the formation of formaldehyde.

Uncertainty of Growth Model Parameters for E. coli in Low-temperature Cooked Sausages
DONG Qing-li
2010, 31(5):  5-8.  doi:10.7506/spkx1002-6300-201005002
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In order to verify the uncertainty and variability of E. coli growth in low-temperature cooked sausages, the variation of E. coli growth in cooked sausages was investigated based on Monte Carlo analysis of stochastic model. Results indicated that the maximum specific growth rate of E. coli obtained by Monte Carlo analysis was lower than that of experimental data fitted by Baranyi model, whereas lag time exhibited an opposite trend to this parameter. Therefore, Monte Carlo analysis provided a theoretical basis for further risk assessment of spoilage bacteria, and also offered useful references for quality control of meat industry.

Preparation Using Porcine Pepsin and Characteristic Analysis of Fresh Cheese
PANG Zhi-hua,BAI Ge-man,YUN Zhan-you,REN Fa-zheng*
2010, 31(5):  9-13.  doi:10.7506/spkx1002-6300-201005003
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Due to the serious shortage of calf rennet (CR) in cheese industry, the research and development of its substitutes has become a hot topic. In order to obtain a better alternative to CR, fresh porcine gastric mucosa was used as the material to extract pepsin, and crude pepsin obtained was further purified to obtain pure porcine pepsin (PPe). The cheese prepared using PPe was evaluated through the analysis of chemical compositions, yield and texture properties. Results indicated that PPe was superior to microbial rennet for better chemical composition of prepared cheese, especially at the middle dosage. In terms of textural characteristics, prepared cheese using PPe was more similar to that using CR than using microbial rennet or commercial porcine pepsin, and no obvious differences in hardness, elasticity, adhesion, gumness and chewness were observed between prepared cheeses using high dosage of PPe and CR (P>0.05). Therefore, PPe is an attractive alternative to CR for the manufacture of cheese.

Change Trend of Formaldehyde in Squid Muscle and Products during Processing and Storage
ZHU Jun-li,LI Jian-rong*
2010, 31(5):  14-17.  doi:10.7506/spkx1002-6300-201005004
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In order to explore the origin of endogenous formaldehyde in squid, the changes of formaldehyde content in squid muscle and products during processing and storage were monitored. Results indicated that the formaldehyde content in squid muscle was significantly lower than that in squid products. Squid muscle exhibited a gradual decline of formaldehyde content due to its corruption during storage at 25 ℃ or 4 ℃. In contrast, the formation of formaldehyde in squid muscle exhibited a significant increase with increasing cooking temperature. Moreover, cooking and baking processes significantly promoted the formation of formaldehyde during the preparation of squid shreds, while the formaldehyde content did not reveal obvious change during the preparation of squid circles. In addition, the formaldehyde content in Peru and north pacific squid shreds exhibited a trend to first decrease and then increase regardless of storage temperature (25, 4, -20 ℃). Therefore, heating treatments during processing make a major contribution to formaldehyde formation in squid products, which can be inhibited during low-temperature storage.

Maillard Reaction between Bovine Serum Albumin and Dextran
LIN Hua, YU Shu-juan*
2010, 31(5):  18-22.  doi:10.7506/spkx1002-6300-201005005
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Bovine serum albumin was conjugated with dextran under dry-heating or wet-heating conditions to obtain two kinds of Maillard reaction products. Meanwhile, the products obtained were investigated by SDS-PAGE electrophoresis and molecular exclusion chromatography. Results indicated that weaker Maillard reaction under dry-heating condition was observed at higher polymerization stage, and the resulting products exhibited a broad molecular distribution. Compared with dry-heating condition, the Maillard reaction under wet-heating was prone to higher polymerization stage so that the products had a narrow molecular distribution. Moreover, PAS staining confirmed glycosylation products with different conjugation degrees under the above two thermal conditions. The molecular structure properties of Maillard reaction products under dry-heating or wetheating conditions were also analyzed by molecular exclusion chromatography.

Antioxidant Activity of Extract from Balanophora spicata Hayata in vitro
DENG Jing1,2,MO Zheng-chang1,2,JI Guang-quan1,2,YANG Juan2,*
2010, 31(5):  23-25.  doi:10.7506/spkx1002-6300-201005006
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DPPH· free radical scavenging assay and ferric reducing power assay in vitro were used to evaluate the antioxidant activities of ethanol extract, petroleum ether extract, chloroform extract, ethyl acetate extract, n-butanol extract, water extraction fraction, water-soluble crude polysaccharides and alkaline-soluble crude polysaccharides from Balanophora spicata Hayata. Results indicated that the extracts from Balanophora spicata Hayata all exhibited strong scavenging capacity against DPPH free radicals, especially ethyl acetate extract, n-butanol extract, ethanol extract and water-soluble crude polysaccharides, which were nearly equivalent to vitamin C for DPPH free radical scavenging activity. The fact that ethyl acetate extract exhibited an IC50 value of 6.0 μg/mL suggested that a little stronger antioxidant activity of ethyl acetate extract than vitamin C. Meanwhile, the above extracts all revealed stronger ferric reducing power.

Basic Research
Effect of Transglutaminase on Properties of Soy Protein Isolate Film
JIANG Yan1,TANG Chuan-he2,WEN Qi-biao2,ZHANG Hong-mei1
2010, 31(5):  26-29.  doi:10.7506/spkx1002-6300-201005007
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Effect of transglutaminase (TGase) reaction time on the properties of TGase-modified soy protein isolate (SPI) films before casting was studied. Moderate TGase reaction of film-forming solution (≤ 60 min) before casting facilitated the improvement of mechanical properties of SPI films, especially the tension strength (TS) value. However, TGase reaction time should not be excessively extended, because precasting TGase reaction could result in the aggregation of SPI components and decrease of soluble protein content. When TGase was used to modify SPI films, on the one hand, TGase reaction could induce the cross-linking of protein; on the other hand, excessive cross-linking could lead to the precipitation of protein. Therefore, appropriate reaction time for inhibiting aggregation induced by TGase during the cross-linking of protein is very important for TGase-modified SPI film.

Preparation and Functional Properties of Maillard Reaction Products between Limitedly Hydrolyzed Rice Proteins and Different Molecular Weight Dextrans
JI Wei,MA Jian-guo,LI Yue,ZHONG Fang*
2010, 31(5):  30-34.  doi:10.7506/spkx1002-6300-201005008
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In this study, the changes in functional properties of Maillard reaction products between limited hydrolyzed rice proteins and different molecular weight dextrans were investigated. The functional properties of glycosylated rice protein products were determined. Results indicated that dextran was the most suitable polysaccharide for Maillard reaction with rice proteins. The optimal process for the maintenance of nutritional value of rice and alleviation of browning was achieved by using hydrolyzed rice proteins with 5% hydrolysis degree for the 20 min Maillard reaction at pH 11 and 100 ℃.

Effect of Solution Conditions on Solubility and Heat-induced Gel Strength of PSE Porcine Myofibrillar Proteins
SHANG Yong-biao1,2,LI Hong-jun1,2,XIA Yang-yi1,2,CHEN Zong-dao1,2,*
2010, 31(5):  35-39.  doi:10.7506/spkx1002-6300-201005009
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Pork longissimus dorsi muscles of normal and PSE quality were sampled to investigate the effects of solution conditions such as pH as well as NaCl and sodium tripolyphosphate (TPP) concentration on the solubility and heat-induced gel strength of porcine myofibrillar proteins by the analyses of absorbance, textural properties and SDS-PAGE profile. Results showed that pH, NaCl and polyphosphate concentration all had a significant effect on the above parameters of porcine myofibrillar proteins (P < 0.05), and high protein solubility achieved by the adjustment of solution conditions favored the improvement of functional properties of PSE porcine myofibrillar protein.

Effect of Superfine Grinding on Functional Components and Properties of Lentinus edodes Stems
GAO Hong1,2,SHI De-fang1,2,HE Jian-jun1,2,WANG Shao-hua1,2,ZHOU Ming1,2,ZHANG Qi3
2010, 31(5):  40-43.  doi:10.7506/spkx1002-6300-201005010
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The effect of superfine grinding on dissolution rate of polysaccharides, content of dietary fibers and physical properties of Lentinus edodes stems was investigated. Results indicated that Lentinus edodes stems exhibited a doubled increase in dissolution rate of polysaccharides, an increase from 43.23% to 48.91% in total dietary fiber, an increase from 5.66% to 15.64% in soluble dietary fiber, and an enhancement of 37%, 46% and 109% in water-holding capacity, oil-holding capacity and swelling capacity, respectively, when ground to the powder of 8.05 μm in particle size. Therefore, superfine grinding technology will be a feasible approach to the in-depth exploitation of Lentinus edodes stems due to its promotion on utilization rate of polysaccharides and significant improvement on functional properties of dietary fibers.

Oxidation Stability of Soybean Lecithin Powder
ZHOU Feng-ying1,WANG Jin2,WANG Shi-rang2,QU Yan-feng2,YU Dian-yu2
2010, 31(5):  44-47.  doi:10.7506/spkx1002-6300-201005011
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The content change of soybean lecithin was investigated during storage under various illuminations. Results indicated that illumination had a significant effect on the peroxide value of soybean lecithin. Fluorescent lamp, ultraviolet lamp and incandescent lamp exhibited an effect on acid the value of soybean lecithin from strong to weak. After the dark storage for 60 h, the peroxide value and acid value of soybean lecithin were 21.10 mmol/kg and 38.83 mgKOH/g, respectively. Meanwhile, the effect of different packaging materials on soybean lecithin was also investigated under the identical illumination condition. The packaging materials with better photopathy could result in the smaller peroxide value of soybean lecithin. The preservative effect on soybean lecithin exhibited an order as follows: aluminum foil membrane > composite film > polyester film > olypropylene film. The peroxide value of soybean lecithin packaged by aluminum foil membrane under illumination for 60 h with fluorescent lamp was still as low as 21.18 mmol/kg.

Oxidative Stability and Color Properties of Beef from Yanbian Yellow Cattle of Different Ages during Frozen Storage
TANG Dan,MA Yun,LIANG Cheng-yun*
2010, 31(5):  48-51.  doi:10.7506/spkx1002-6300-201005012
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In order to investigate the effect of age on beef quality, Yanbian yellow cattle of below 1, 1.5-3, 5-6 and 9- 10 years old were chosen as the experiment subjects to determine the change of color, pH, metmyoglobin and TBARS in beef during frozen storage. Results indicated that the lowest metmyoglobin content and TBARS value were both observed in beef from cattle of 1.5-3 years old, and there was a significant difference between beef from cattle of 1.5-3 years old and that of5-6 or 9-10 years old (P<0.05). In addition, beef from cattle of 1.5-3 years old exhibited the highest values of CIE a* and CIE c* (P<0.05) and the lowest value of CIE h (P<0.05). This suggests that the best Yanbian beef should be gained from cattle of 1.5 - 3 years old.

Correlation between Water-holding Capacity and Textural Properties of Chicken Sausage Products Added with Sodium Caseinase under the Treatment of High Hydrostatic Pressure
CHEN Jian-liang,RUI Han-ming,QIU Zhi-min
2010, 31(5):  52-57.  doi:10.7506/spkx1002-6300-201005013
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In this study, correlation between water-holding capacity (WHC) and textural properties of chicken sausage products with 1.5% sodium caseinate subjected to 50 - 600 MPa high hydrostatic pressure (HHP) treatment for 5 - 40 min were investigated in single factor experiments. The mechanism of cross-interaction was also analyzed by scanning electron microscopic (SEM) observation. Results indicated that the WHC of samples treated at 200-500 MPa for 10-30 min exhibited a significant enhancement compared with samples without pressure treatment (P<0.01). Meanwhile, too low pressure such as 50 MPa and too high pressure such as 600 MPa could result in a significant reduction of WHC (P<0.01). Moreover, there was a first prompt and then slow increase in the textural properties including hardness and chewiness as pressure increased; whereas, no obvious effect of pressure-holding time on WHC and textural properties was observed. Furthermore, a significant correlation between WHC and textural properties of samples was observed under different pressure levels (P<0.01), which revealed the simultaneous improvement of both WHC and textural properties.

Basic Research
Color Enhancing Effect Caffeic Acid on Purple Corn Anthocyanins
MU Ni,WU Hai-hao,GU Ying-juan,FAN Gong-jian,YANG Zhen-dong,GU Zhen-xin*
2010, 31(5):  58-62.  doi:10.7506/spkx1002-6300-201005014
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The effect of caffeic acid on absorption spectrum, color and composition of anthocyanins extracted from purple corn cobs were investigated. Results showed that caffeic acid resulted in the increase of color intensity and the blue-shift of maximum absorption peak of anthocyanin solution. This suggests the color enhancing effect of caffeic acid on anthocyanins. Thermal stability experiments also exhibited that caffeic acid could inhibit the fading rate of anthocyanins, and increase their half-life and activation energy. High performance liquid chromatography-electrospray ionization mass spectrometry (HPLC/ESI-MS) analysis results demonstrate that the color enhancing effect of anthocyanins is achieved via the production of cyanidin-3-glucosedevinylcatechol, pelargonidin-3-glucosede-vinylcatechol and peonidin-3-glucosede-vinylcatechol as a result of addition reaction between cafeic acid and anthocyanins.

Effect of Reaction Time on DPPH and ABTS+ Radical Scavenging Assays for Antioxidant Capacity Evaluation
LIN Lian-zhu,ZHAO Mou-ming*
2010, 31(5):  63-67.  doi:10.7506/spkx1002-6300-201005015
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Due to the operation simplicity of DPPH and ABTS+ radical scavenging arrays for evaluating antioxidant capacity and without a need for specific equipments, both assays have been widely chosen to evaluate antioxidant capacity. EC50 is generally used as a representative parameter for antioxidant capacity of antioxidants determined using DPPH· assay at 30 min of fixed reaction time or using ABTS+· assay at 6 min of fixed reaction time. The results of this investigation indicated that a big difference was made by the compositions and structures of antioxidants to reaction rates with DPPH·and ABTS+·free radicals. The reaction equilibrium time was also different so that wrong estimations might be achieved at the condition of fixed reaction time.

Changes in Chemical Composition and Edible Quality of Venison from Different Anatomical Locations during Postmortem Aging
XU Bo1,ZHOU Guang-hong2,XU Xing-lian2,LI Chun-bao2,HU Ping2
2010, 31(5):  68-72.  doi:10.7506/spkx1002-6300-201005016
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The changes in chemical composition and edible quality of venison from different anatomical locations including M longissimus dorsi (LD), M semitendinosus (ST), M supraspinatus (SP) and M poasos major (PM) of a hybrid F1 deer from crossed Xifeng female sika deer with Tianshan male wapiti deer during postmortem aging. Results indicated that anatomical location had a significant effect on chemical composition and edible quality of venison during postmortem aging. Aging time had a significant effect on water and crude fat contents, Warner-Bratzler shear force (WBSF), and thaw drip and cooking losses of venison from different locations, whereas no significant effect on collagen content was observed. Among the above four locations, LD exhibited the highest crude fat and collagen contents and lowest water content, WBSF and cooking loss (P<0.05). Aging time also had a significant effect on WBSF of LD and ST (P<0.05), while had no significant effect on WBSF of PM aged for 3 days and SP (P >0.05).

Effect of Food Additives on Protein Autolysis of Tilapia
HUANG Dong-xiang1,2,YU Xin2,*,LI Lin1
2010, 31(5):  73-77.  doi:10.7506/spkx1002-6300-201005017
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This study aimed to examine the effects of 13 kinds of food additives on protein autolysis of tilapia through the content determination of amino nitrogen, soluble protein and soluble solids in hydrolyzed tilapia muscle. Results indicated that the promotion of protein autolysis in tilapia was observed when food additives were added within a certain range, such as glucose less than 2.00% (m/m), sodium benzoate less than 0.02% (m/m), sodium sulfite less than 0.03% (m/m), chlorine sodium less than 10% (m/m) and citric acid less than 0.10% (m/m). Calcium chloride and ascorbic acid obviously propelled tilapia protein autolysis, whereas lactic acid, tartaric acid and EDTA-2Na had some inhibitory effects against tilapia protein autolysis at the concentration of larger than 1.00% (m/m), 0.10% (m/m) and 0.02% (m/m), respectively, and potassium chloride, magnesium sulfate and magnesium chloride had no obvious effect on tilapia protein autolysis. Moreover, sodium benzoate, citric acid, lactic acid and tartaric acid could reduce the odor and attenuate the spoilage of tilapia.

Quality Properties of Commercial Rice
DU Shuang-kui,YANG Hong-dan,YU Xiu-zhu,ZHANG Ya-li,LI Zhi-xi*
2010, 31(5):  78-81.  doi:10.7506/spkx1002-6300-201005018
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Quality properties of commercial japonica rice, indica rice, and glutinous rice were investigated using general cooking and tasting evaluation methods. Meanwhile, viscosity properties of flour pastes from three kinds of commercial rice were determined using a Brabender Micro Visco-Amylograph analyzer. Results indicated that japonica rice had the best quality properties and taste attribute, glutinous rice took second place, and the quality properties and taste attribute of indica rice were the worst. Japonica rice also exhibited the lowest peak viscosity and breakdown rate. However, its gelatinization temperature, final viscosity and retrogradation value were between indica rice and glutinous rice. For glutinous rice, peak viscosity and breakdown rate were both the highest, while the lowest gelatinization temperature, final viscosity and retrogradation value were observed. In contrast, although indica rice exhibited middle levels of peak viscosity and breakdown rate, it had the highest gelatinization temperature, final viscosity and retrogradation value. The above results demonstrate that indica rice has the largest gel strength and is prone to aging, whereas, glutinous rice exhibits an opposite character. Thus, glutinous rice is sensitive to shear force and heating.

Amino Acid Composition Analysis and Food Value Investigation of Wild Ophipogon japonicus Resources in Sichuan Basin
LIU Jiang,CHEN Xing-fu*,LIU Wei-guo,WANG Feng,WAN Yan,ZHANG Jing
2010, 31(5):  82-85.  doi:10.7506/spkx1002-6300-201005019
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Objective: To analyze amino acid compositions and characterization of Ophipogon japonicus in Sichuan basin for exploring its food value. Method: Amino acid composition was determined using a HITICHI L-8800 automatic amino acid analyzer. Results: Amino acids in Ophipogon japonicus were identified and the contents of total amino acids and essential amino acids in Ophipogon japonicus were higher than common vegetables and fruits. The level of essential amino acids in most samples was lower than FAO/WHO recommended pattern. A special effect of Pro, Glu, Phe and Met on flavor in a dose-dependent manner was observed. High-flavor amino acids showed a high content. Conclusion: Although Ophipogon japonicus is not suitable for a common food, it can be used as a natural raw material of nutritional supplements, fresh-keeping agents, food additives, and flavoring agents. Plentiful resource of Ophipogon japonicus in Sichuan Basin can be exploited.

Risk Matrix-based Risk Monitoring Model of Food Safety
LIU Qing-jun,CHEN Ting*,ZHANG Jing-hua,WANG Tan
2010, 31(5):  86-90.  doi:10.7506/spkx1002-6300-201005020
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Based on substantial analysis of testing data from food safety supervision and inspection system, a risk monitoring system of food safety was established to conduct the comprehensive evaluation for risk possibility and risk loss of food safety. This risk-monitoring model was a 2-dimensional matrix between risk possibility and risk loss of food safety. In the monitoring and analysis of food safety situation in urban wholesale market for agricultural and sideline products, this model exhibited an effective control to the situation of food safety during circulation in market, and provided the security of food supply in market.

Structure and Properties of Sodium Alginate-Sodium Carboxymethylcellulose-Gelatin Compound Film
LI Hui1,LU Li-xin1,2,*,WANG Li-qiang1,2
2010, 31(5):  91-95.  doi:10.7506/spkx1002-6300-201005021
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A compound film was successfully prepared by coagulation of sodium alginate (NaAlg), sodium carboxymethylcellulose (CMC) and gelatin (GLE) in aqueous solution. FT-IR, XRD, SEM and UV-Visible spectroscopy were used for the structural characterization of this compound film, and along with this, its mechanical properties, water solubility and UV absorption were also measured. Results indicated strong interaction and good compatibility among sodium alginate, sodium carboxymethylcellulose and gelatin were observed. This compound film showed obviously improved physical and chemical properties, when compared with single NaAlg and CMC films and their compound film.

Textural Properties of κ-Carrageenan-Konjac Gum Compound Gel
WEI Yu,WANG Yuan-lan*,HU Yun-chu
2010, 31(5):  96-100.  doi:10.7506/spkx1002-6300-201005022
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Konjac andκ-carrageenan were used to form a compound gel. The effects of konjac/κ-carrageenan ratio, compound gel concentration, pH Value, ionic strength, KCl and CaCl2 on textural properties of this compound gel were investigated. Results indicated that an excellent synergistic effect on hardness, elasticity and cohesiveness of compound gel was exhibited due to the molecular interaction betweenκ-carrageenan and konjac gum. An optimal gelation was achieved under the following conditions: compound gel concentration 2.0 g/100mL, pH 3.0-6.0, ionic strength 0.3-0.4 mol/L, 0.1-0.4 g/100mL KCl and 0.1 g/100mL CaCl2. These results can provide theoretical references for the application of this compound gel in food industry.

Isolation and Identification of Norartocarpetin in Mulberry
XU Li1,JI Chang-jiu2,TAN Ning-hua2,YANG Li-rong 2,YU Mao-de1
2010, 31(5):  101-103.  doi:10.7506/spkx1002-6300-201005023
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Norartocarpetin, one of the flavonoids groups, has anti-inflammatory, antibacterial, antivirus and tyrosinase inhibitory activities and other important biological activities. In the present study, norartocarpetin was obtained from leaves of artificial triploid mulberry variant, Jialing 20, by 95% alcohol extraction and silica column chromatographic purification. Based on physicochemical characteristics and NMR spectral data, the structure of norartocarpetin was identified with relative molecular weight of 286 and its molecular formula was C15H10O6. These results will provide the basis for the further research on bioactive compounds and flavones from mulberry.

in vitro Nitrite Scavenging Capacity of Litchi Pericarp Pigment
SONG Ru1,WEI Rong-bian2,HU Jin-shen1,ZHOU Gui-xiao1
2010, 31(5):  104-107.  doi:10.7506/spkx1002-6300-201005024
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The nitrite scavenging capacity of litchi pericarp pigment was evaluated in vitro by spectrophotometric method and compared with those of tea extract and vitamin C. Results indicated that the reaction between litchi pericarp pigment and nitrite for 10 min resulted in perfect scavenging of nitrite. The scavenging rate against nitrite first increased and then tended to keep stable with increasing dose of litchi pericarp pigment. Heating treatment and low pH of reaction system could improve the scavenging effect against nitrite. As a result of heating treatment at 100 ℃ for 10 min, the nitrite scavenging rates of vitamin C at the concentration levels of 1 and 10 mg/mL were both the highest. Moreover, the nitrite scavenging rate of litchi pericarp pigment at the low concentration level of 1 mg/mL was (42.76 ± 0.98)%, which was higher than that of tea extract ((37.92 ± 0.79)%) (P<0.05) at the identical concentration level; while the nitrite scavenging rate of tea extract was higher than that of litchi pericarp pigment at the high concentration level of 10 mg/mL (P<0.05). Furthermore, high nitrite scavenging rate of litchi pericarp pigment was also observed under simulated gastric and body temperature conditions in vitro, with the values of (23.55± 0.45)% and (51.62± 0.91)% at the concentration levels of 1 and 10 mg/mL, respectively.

Fatty Acid Composition Analysis and Inhibitory Effect against Superoxide Anion Free Radicals of Essential Oils from Panjin Crab Eggs and Muscle
ZHANG Lan-jie1,WANG Hong-kuan2,LI Tie-chun1,HOU Fang-fang2
2010, 31(5):  108-110.  doi:10.7506/spkx1002-6300-201005025
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Crab eggs and muscle sampled from Panjin crabs were used as the materials to extract essential oil by Soxhlet extraction method. The resulting essential oils were analyzed for fatty acid composition by gas chromatography-mass spectrometry (GCMS) and G1701BA chemical workstation data processing system based on peak area normalization was used for the quantitation of fatty acids. Experimental results demonstrate the excellent inhibitory effect of essential oils from Panjin crab eggs and muscle against superoxide anion free radicals.

Antioxidant Activities and Mechanism of Extracts from Spice Materials
ZHANG Hui-yun1,2,KONG Bao-hua2,*,SUN Xu1
2010, 31(5):  111-115.  doi:10.7506/spkx1002-6300-201005026
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Antioxidant activities and mechanism of extracts from six spice materials including clove, rosemary, cassia bark, liquorice, nutmeg and round cardamom were investigated by different assays. Spice materials were extracted using 95% ethanol and the antioxidant activities of these extracts were evaluated by the determinations of inhibitory rate against thiobarbituric acidreactive substances (TBARS) in a liposome model system, scavenging rate against 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, ferric reducing-antioxidant power (FRAP), chelating capacity to Cu2+ or Fe2+, and total phenol content by Folin-Ciocalteau method when commercial butylated hydroxyanisole (BHA) was served as the positive control. Results indicated that the extracts from clove, rosemary, cassia bark, liquorice, nutmeg and round cardamom all exhibited a stronger inhibitory effect against TBARS and higher total phenol content. Meanwhile, total phenol content was significantly negatively correlated with TBARS (r =-0.69, P<0.05) and scavenging capacity against DPPH free radicals (r = 0.84, P<0.05). Moreover, scavenging capacity against DPPH free radicals was also significantly correlated with FRAP value (r = 0.84, P < 0.05). However, there was no correlation found between TBARS and FRAP value or scavenging capacity against DPPH free radicals (P>0.05). Furthermore, Fe2+ chelating capacity also did not exhibit correlation with TBARS, scavenging capacity against DPPH free radicals or FRAP value (P>0.05). Therefore, it can be concluded that the antioxidant activities of extracts from these spice materials mainly result from polyphenolic components through scavenging free radicals, chelating metal ions and donating hydrogen.

Shelf Life Prediction Kinetic Model of Pickled Tuber Mustard
XIONG Fa-xiang,DAN Xiao-rong,DENG Mian,LIU Kun,LU Xiao-li*
2010, 31(5 ):  116-120.  doi:10.7506/spkx1002-6300-201005027
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In this study, pickled tuber mustard was used as the experimental subject to deal with the changes of its sensory quality, crispness and total number of colonies during storage at different temperatures (5, 25 or 37 ℃) and constant illumination intensity of 4000 lx and constant relative humidity of 80%. Kinetic models were developed for crispness or total number of colonies as a function of storage time and temperature based on Arrhennius equation, and a shelf life prediction kinetic model was determined as follows: y = 238.57e-0.0162x (R2 = 0.9853). This model was shown to have a high fitting accuracy and exhibit a good reliability in predicting the shelf life of pickled tuber mustard products.

Selenium Content and Speciation of Selenium-enriched Bifidobacterium
LIANG Jia1,2,LI Yu-feng1,*,ZHAO Jin-xuan1,2,WANG Xiao-yan1,3,LI Bai1,HU Wei2,
2010, 31(5):  121-124.  doi:10.7506/spkx1002-6300-201005028
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Selenium contents and speciations in powder and capsules containing selenium-enriched Bifidobacterium subjected to cell wall disruption by combinatorial ultrasonic and enzymatic hydrolysis method were determined by high performance liquid chromatography connected with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Results indicated that the selenium contents in powder and capsules containing selenium-enriched Bifidobacterium were (168.11 ± 2.26) μg/g and (15.68 ± 0.07) μg/g, respectively. The selenium content in capsules containing selenium-enriched Bifidobacterium was nearly 100 times as high as that of commercially available selenium-enriched rice, but was less than one tenth of that of commercially available selenium-enriched yeast. A complicated selenium speciation was found in selenium-enriched Bifidobacterium products, and the major amino acid containing selenium was selenomethionine (SeMet), which was up to 59% of total selenium amount.

Plastein Reaction-based Modification of ACE Inhibitory Peptides Derived from Casein in the Presence of Proline
LI Ya-yun,ZHAO Xin-huai*
2010, 31(5):  125-130.  doi:10.7506/spkx1002-6300-201005029
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ACE inhibitory peptides with IC50 value of 47.1 μg/mL were prepared by hydrolyzing casein with alkaline protease from Bacillus subtilis and further modified by plastein reaction under the catalysis of the same protease in the presence of proline. The optimal conditions for plastein reaction were determined using response surface methodology at the fixed concentration of 35% (m/m) peptides and the reaction time of 6 h as follows: reaction temperature 47.8 ℃, molar ratio of proline to total free amino groups in ACE inhibitory peptides derived from casein 0.54, and addition level of alkaline protease 9.5 kU/g proteins. Under these optimal reaction conditions, a maximal decrease of free amino groups in reaction mixture of 195.7 μmol/g proteins was obtained. Six modified products with different modification degrees were prepared by adjusting reaction time. ACE inhibitory activities and IC50 values of these modified peptides were also analyzed. Results indicated that ACE inhibitory activity of modified products revealed irregular change with increasing modification degree. When the reaction mixture had a decrease of free amino groups of 195.7 μmol/g proteins, there was a decline of IC50 value of modified products to 0.2 μg/mL.

Effect of Rare Earth Element Cerium on Cell Growth and Polysaccharide Production in Protocorm-like Bodies of Dendrobium huoshanense during Suspension Culture
WANG Kai,PAN Li-hua,ZHA Xue-qiang,LUO Jian-ping*
2010, 31(5):  131-136.  doi:10.7506/spkx1002-6300-201005030
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In this study, the effects of cerium, one kind of rare earth elements, on cell growth, polysaccharide biosynthesis, and utilization of carbon, nitrogen and phosphorus sources in protocorm-like bodies of Dendrobium huoshanense during suspension culture were investigated. Results indicated that cerium could improve the utilization of carbon and nitrogen sources in protocorm-like bodies of Dendrobium huoshanense, significantly increase the contents of intracellular polysaccharides, nitrate and phosphate, and enhance cell growth and polysaccharide biosynthesis. The concentration of cerium was optimized to be 10 μmol/L, which could result in the improvement of cell growth rate from 0.501 to 0.649 g/(L·d). At this optimal concentration, the maximum dry weight of protocorm-like bodies was up to 25.45 g/L after 24 days of cell culture, which was increased by 20.2% compared with the control. Similarly, the highest production of polysaccharides was reached to 3.35 g/L after 18 days of cell culture, which was 1.53-fold amount of the control.

Preliminary Study on Mechanism of GSE-induced Apoptosis in Saccharomyces cerevisiae
ZHANG Nan1,CAO Si-shuo2,HUANG Kun-lun1,2,LUO Yun-bo1,GUO Xing2,YUAN Yan-fang2,XU Wen-tao1,2,*
2010, 31(5):  137-140.  doi:10.7506/spkx1002-6300-201005031
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In this study, grape seed extract (GSE) was used to induce apoptosis of Saccharomyces cerevisia and explore the mechanism of GSE-induced apoptosis. Results indicated that the minimum inhibition concentration of GSE on the growth of Saccharomyces cerevisiae was 0.13 mg/mL. Meanwhile, GSE resulted in nuclear condensation and DNA strand break of Saccharomyces cerevisiae cells according to TUNEL and DAPI staining. Detection of reactive oxygen species (ROS) also revealed that GSE could lead to a larger increase of ROS in Saccharomyces cerevisiae cells.

Development of A Novel Refolding Method Using Inclusion Bodies from Green Fluorescent Protein
ZHANG Ting1,FENG Yan-ye1,SHEN Ya-ling1,JIN Wei-rong2,YANG Zhong1,WANG Ju-fang3,WANG Xiao-ning1,3,*
2010, 31(5):  141-146.  doi:10.7506/spkx1002-6300-201005032
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Target proteins overexpressed in Escherichia coli often result in the formation of inclusion bodies, which need further refolding in vitro to gain their native structures and biological functions. In order to improve the refolding rate by dilution refolding method, recombinant green fluorescent protein (GFP) inclusion bodies were used as the model to develop a novel dual denaturation- dilution refolding method in this study. This novel method used the alkaline solution containing arginine as the first denaturant to dissolve GFP inclusion bodies, and then exhibited a gradient reduction in pH of the solution to mildly form the arget protein aggregates. The denatured aggregates were refolded by dilution in urea solution. Results indicated that the recovery rate of refolded GFP by this novel method was over 80%, which was 1.5 to 2.3 times higher than that of traditional methods. Moreover, the stability of refolded GFP by this novel method was highly consistent with the natural protein. Therefore, this developed method for protein refolding could be used to refold proteins, especially GFP-related proteins from inclusion bodies with high efficiency. This investigation will also provide optimal methods for protein refolding from inclusion bodies through combinatorial design and extended applications of different denaturants.

Isolation and Screening of Yeast for Cashew Apple Wine
CHEN Wen-xue1,2,HU Yue-ying2,LIU Si-xin2,XIN Xiao-chen2,LIN Jun-fang1,*,LI Cong-fa2,*
2010, 31(5):  147-149.  doi:10.7506/spkx1002-6300-201005033
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Sixty-five yeast strains were isolated from orchard soil and cashew apples. A yeast strain with excellent performance for the fermentation of cashew apple wine was selected and designated as D1B2 strain. This strain exhibited powerful gasproducing and fermentation capabilities under the conditions of 300 mg/L SO2 and pH 1.16. The flavor of cashew apple wine fermented by this yeast was similar with that of fresh fruits.

Effects of Temperature and pH on Kinetic Parameters of Enzymatic Hydrolysis of Bovine Bone Protein
CAI Li-hua,MA Mei-hu*
2010, 31(5):  150-154.  doi:10.7506/spkx1002-6300-201005034
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In this study, kinetic properties of bovine bone protein hydrolysis by alcalase, neutrase, pepsin and trypsin were investigated. The initial rate of enzymatic hydrolysis was used to evaluate the optimal reaction conditions for these proteases. Results indicated that the optimal temperature and pH were 55 ℃ and pH 11.7 for alcalase, 45 ℃ and pH 7.3 for neutrase, 30 ℃ and pH 1.5 for pepsin, 55 ℃ and pH 9.3 for trypsin. The decreasing order of these proteases for Km and Vmax was neutrase, alcalase, trypsin and pepsin; and pepsin, alcalase, trypsin and neutrase, respectively.

Effect of Tibetan Mushroom Inoculum on Quality and Anti-bacterial Activity of Fermented Milk
JIAO Hui,SHI Jun-ling*
2010, 31(5):  155-159.  doi:10.7506/spkx1002-6300-201005035
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Our previous investigations demonstrated that granular inoculum of Tibetan mushroom exhibits much higher fermentation rate to milk than liquid inoculum. However, long time is required for the formation of granular inoculum. In order to explore the necessity of granular inoculum of Tibetan mushroom for milk fermentation, the effects of granular inoculum and liquid inoculum on curding time, sensory evaluation, textural properiesy, fermentation characteristics and antibacterial activity of fermented milk were investigated and compared. Results indicated that granular inoculum of Tibetan mushroom exhibited higher fermentation rate, shorter curding time, better product quality and stronger anti-bacterial activity of fermented milk than liquid inoculum.

Purification and Properties of Pyrophosphatase from Beef Semitendinosus
SUN Zhen-zhen,PENG Zeng-qi*,JIN Hong-guo,SHI Jie
2010, 31(5):  160-164.  doi:10.7506/spkx1002-6300-201005036
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Pyrophosphatase (PPase) was isolated and purified from beef semitendinosus through homogenization with 0.25 mol/L sucrose, extraction with 0.6 mol/L NaCl solution, precipitation with 50%-70% ammonium sulfate, and ion-exchange chromatography on DEAE-52 cellulose column. SDS-PAGE showed a single band with the relative molecular mass of 72 kD. This enzyme exhibited high substrate specificity to sodium pyrophosphate. Mg2+ as an activator could promote the activity of pyrophosphatase; whereas, Ca2+, EDTA-Na2 and EDTA-Na4 all exhibited an inhibitory effect on its activity. The optimal pH and temperature for reaction were 6.8 and 47 ℃, respectively.

High-density Fermentation and Functional Characterization of Recombinant Xylanase PTX2
YIN Jia,WANG Li,HE Jun,YU Bing,CHEN Dai-wen*
2010, 31(5):  165-168.  doi:10.7506/spkx1002-6300-201005037
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Recombinant xylanase PTX2 was prepared in a 15 L fermentor through high-density fermentation. After methanol induction at 28 ℃ for 96 h, the highest cell density and the maximal xylanase activity were achieved to 78 g/L and 560 U/mL, respectively. Diet supplemented with 500 U/kg of unprocessed PTX2 could result in an increase of average body weight gain of weaned piglets by 16.9%, an obvious decrease in intake/body weight gain ratio, and an increasing trend of apparent digestibility of crude protein (CP), ash, calcium and crude fiber (CF). Therefore, the potential benefit of PTX2 in feeding weaned piglets demonstrates an attractive application value and industrial development of this enzyme.  

Liquid Cultivation of Edible Mushroom in Oat Emulsion and Development of Beverage from the Culture
ZHANG Zhe,SHI Jun-ling*
2010, 31(5):  169-174.  doi:10.7506/spkx1002-6300-201005038
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Characteristics of liquid cultivation of four strains of Ganoderma lucidum and one strain of Hypsizygus marmorens were investigated by using oat emulsion as the medium. During the cultivation, pH, intracellular polysaccharide (IPS), extracellular polysaccharide (EPS), cell dry weight, and β-glucan content were measured every day. Characteristics of the fermentation process were analyzed according to the change of these parameters. A beverage was developed on the basis of cell-free liquid culture of the Ganoderma lucidum strain, LINGZHI3. All of four Ganoderma lucidum strains grew well in oat emulsion and produced a large amount of IPS and EPS. The profiles of IPS exhibited a good match with dried cell weight (DCW) and IPS reached a maximum level on the 6th day, while EPS on the 5th, 6th and 7th day for four strains of Ganoderma lucidum. EPS production of Hypsizygus marmorens exhibited a decreasing trend during the whole cultivation. The highest IPS did not match with the highest DCW and exhibited a negative relationship. These results indicate that oat is a good medium for the production of Ganoderma lucidum polysaccharides by submerged liquid cultivation, but not good for Hypsizygus marmorens polysaccharides. A high quality beverage was developed through adding 1.5 g/L CMC-Na to clarify fermented broth of Ganoderma lucidum. This beverage exhibited a good balance between sweet and sour taste, stable texture, clear appearance and plentiful nutrients, and also contained 103 g/L polysaccharides, 1 g/L total acid, 11.6 g/L amino acids and 40 g/L soluble solids.

Bioengineering
Enhanced Production of Cordycepin by Submerged Culture Using Additives in Cordyceps militaris
WEN Ting-chi1,2,KANG Ji-chuan1,2,*,LEI Bang-xing1,2,LI Guang-rong1,HE Jin1
2010, 31(5):  175-179.  doi:10.7506/spkx1002-6300-201005039
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The effects of different additives on cordycepin production by submerged culture of Cordyceps militaris were investigated. Results indicated that the addition of adenine, glycine, adenosine or L-glutamine could result in a large improvement in cordycepin production by submerged fermentation of C. militaris. In addition, a synergistic effect on cordycepin production was also observed in combinatorial applications of two additives. Moreover, in the combinatorial application, adenine was much better than adenosine, especially the combinatorial formula of 1 g/L adenine and 8 g/L glycine, which resulted in a cordycepin production of 1644.21 mg/L, exhibiting a 4.66-fold increase than that obtained in the basal medium culture. The analysis of nucleic acid-related compounds obtained by various cultures indicated that 80% cordycepin synthesized by C. militaris was secreted in the culture broth. The whole metabolism system for nucleic acids were linked to each other so that most nucleic acidrelated compounds could directly or indirectly participate in the production of cordycepin.

Extraction and Antimicrobial Effect of Active Components from Chaetoceros curvisetus
WANG Qin1,LIU Chao2,ZHANG Shao-jun2,SUN Li-qin2,WANG Chang-hai1,2,*
2010, 31(5):  180-183.  doi:10.7506/spkx1002-6300-201005040
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Antimicrobial activities of crude lipid, polyphenol, terpenoid and water extracts obtained from Chaetoceros curvisetus were evaluated by cylinder plate method. In order to identify the contribution of active components to antimicrobial activity, gas chromatography was used for the characterization of different polar lipid extracts. The minimum inhibitory concentration of petroleum ether extract was also determined. Results indicated that crude lipid, polyphenol and terpenoid extracts exhibited different antimicrobial activities. Petroleum ether extract revealed the strongest antimicrobial activity, and water extract exhibited no antimicrobial activity. All extracts also exhibited stronger inhibitory effect against bacteria than against fungi, especially against gram-negative bacteria. Eight kinds of polyunsatured fatty acids including trans-linoleic acid, γ-linolenic acid, and cis-11,14-eicosadienoic acid were determined in petroleum ether extract, which suggested that the antibacterial components were weakly polar polyunsaturated fatty acids.

Isolation and Screening of Lactic Acid Bacteria from Yak Yogurt in Tianzhu Pasture Region of Gansu
LI Xiao-peng,ZHANG Wei-bing,SUN Guo-zheng,LI Jing,GAN Bo-zhong*
2010, 31(5):  184-189.  doi:10.7506/spkx1002-6300-201005041
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In this study, 96 strains of lactic acid bacteria (LAB) were isolated from 22 home-made yak yogurt samples collected from Tianzhu pasture region of Gansu. Totally 12 strains of genetically stable lactic acid bacteria were obtained through preliminary selection based on genetic stability, coagulation time, titratable acidity, water-retention rate and sensory evaluation. Finally, 4 lactobacilli and 2 lactococci with excellent performance were selected through the evaluation of acidification ability acetaldehyde-producing ability, diacetyle-producing ability, protein degradation ability, number of living bacteria during cold storage and resistance to adverse environment.

Enzymological Properties of Oxalate Oxidase from Rice Bran
ZHOU Hai,LUO Wei,LIU E-e*,PENG Xin-xiang
2010, 31(5):  190-193.  doi:10.7506/spkx1002-6300-201005042
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The activity of oxalate oxidase (OxO, EC1.2.3.4) was detected in rice bran and this enzyme was found to be mainly rich in cell wall. The optimal reaction pH and Km values of this enzyme towards oxalate as a substrate were 2.5 and 0.63 mmol/L, respectively. An inhibitory effect against OxO was observed when oxalate concentration was over 2.0 mmol/L. Meanwhile, the enzyme exhibited high thermo-stability and resistance to SDS, pepsin and NaCl. Although EDTA, NH4+, Cl-, Mn2+, CO32-, Na+, K+, H2PO4 -, SO42 -, Fe2+ and PO43 - at the concentration of 1 mmol/L had no effect on OxO activity, NO3 -, Co2+, Zn2+, Cu2+, Mg2+, Ca2+and Al3+ at the identical concentration exhibited strong an inhibitory effect against OxO activity. Therefore, OxO from rice bran may be widely used to detect oxalate level, which will provide theoretical evidence for the ingredient analysis of functional foods.

Optimization of Nutrient Factors in Medium for Lactobacillus fermentum Growth
YE Xue-fei,RUAN Hui,FENG Shi-kai,ZHU Cheng-liang,HE Guo-qing*
2010, 31(5):  194-196.  doi:10.7506/spkx1002-6300-201005043
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In this study, the optimal basal medium and the optimal carbon source, nitrogen source and growth factor in it were chosen for Lactobacilus fermentum growth, and the optimal addition amounts of the three nutrient factors were investigated using orthogonal array design. Results indicated that MRS medium was the most suitable for Lactobacilus fermentum growth, and its optimal formula consisted of 2.0% glucose, 0.5% beef extract, 0.5% casein peptone, 2% corn syrup, and other unchanged basic ingredients. The number of living Lactobacilus fermentum cells was over 1010 CFU/mL after 16 h to 18 h of cultivation in optimized MRS medium at 37 ℃, which exhibited a 10-fold increase compared with that in original MRS medium.

Cloning and Plasmid Construction of Soybean Peroxidase Gene for Prokaryotic Expression System
ZENG Jia-yu1,YUAN Hong-xia1,LIAO Shi-qi2,*,ZHOU Si-tong1,LIANG Qiong1
2010, 31(5):  197-200.  doi:10.7506/spkx1002-6300-201005044
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The cloning and plasmid construction of soybean peroxidase (sbp) for prokaryotic expression system will provide more information to study the structure and function of soybean peroxidase by means of molecular biology. Total RNA was extracted from soybean root. Soybean peroxidase gene was obtained by RT-PCR technique and transferred into pPICZα-A vector through restriction endonuclease digestion. The resulting recombinant pPICZα-A-sbp expression vector was transformed into E. coli and the amplified recombinant pPICZα-A-sbp expression vector was selected and sequenced. Results indicated that cloned DNA sequence from soybean root exhibited 92% homology to the reported sbp (U51191 (GmEpa1) DNA sequence. Therefore, pPICZα-A-sbp was successfully constructed, which will provide base for its expression in Pichia pastoris (Gs115).

Bioengineering
Purification and Characterization of Laccase from Ganoderma weberianum
CHEN Qiong-hua1,ZHOU Yu-ping2,CHEN Xiao1,KE De-sen1,CHENG Hui-zhen2,TIAN Chang-en1,2,*
2010, 31(5):  201-205.  doi:10.7506/spkx1002-6300-201005045
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The laccase from Ganoderma weberianum TZC-1 was purified using fractional ammonium sulfate precipitation, dialysis, polyethylene glycol condensation and high performance liquid column chromatography. Compared to the crude extract, its purity exhibited a 37.1-fold improvement and the recovery rate of enzyme activity was 21.3%. Meanwhile, SDS-PAGE analysis revealed a single band with molecular weight of 40 kD. Moreover, the optimal reaction conditions of this laccase towards ABTS as substrate included 50-60 ℃ of reaction temperature and pH 4.6. The Km value was 13.8 μmol/L under these optimal reaction conditions. Furthermore, the activity of the enzyme exhibited excellent stability below 60 ℃ and pH 3.0- 5.5, but could be inhibited by Fe2+, Al3+ and Mn2+ and enhanced by Hg+, Cu2+ and Mg2+. No obvious effect on laccase activity was observed due to Zn2+, Ba2+ and K+.

Isolation, Purification and Enzymological Characterization of Catalase from Aloe
ZHU Hong,LI Xiang-yun,DENG Yu,WANG Song,FU Wei-li,TANG Liang-ting,GAO Zhao-wei,TANG Yun-ming*
2010, 31(5):  206-210.  doi:10.7506/spkx1002-6300-201005046
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Objective: To obtain catalase from aloe and explore its enzymaological properties. Methods: Catalase was isolated and purified through fractional ammonium sulfate precipitation, ion-exchange chromatography on DEAE-Sepharose, ionexchange chromatography on CM-Sepharose and gel filtration on Sephacryl S-200. SDS-PAGE was used to identify the purity and relative molecular mass of the catalase. Results: Aloe catalase revealed a 228.05-fold purification and a recovery rate of activity of 14.10%. The specific activity of the purified aloe catalase was measured to be 17427.30 U/mg. Aloe catalase was characteristic of 239.90 kD relative molecular mass and 60.60 kD molecular mass of subunit. This demonstrates that the enzyme consists of four identical subunits. Moreover, the optimal reaction temperature and pH of the enzyme were 45 ℃ and 7.5, and its apparent Km towards hydrogen peroxide as the substrate was 34 mmol/L. Conclusion: Aloe catalase has been successfully isolated and purified, which exhibits excellent thermostability and acid-alkali tolerance.

Screening and Identification of Cellulose-producing Strains
CAO Hai-peng,YUAN Shuai,ZHAO Kun,ZHANG Xia,HU Cheng*
2010, 31(5):  211-214.  doi:10.7506/spkx1002-6300-201005047
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Wounded fruits were used as raw materials to isolate and obtain a cellulose-producing strain, G-29, with high productivity and genetic stability through static enriching culture and repeated screening. The morphology, physiological and biochemical characteristics and 16S rDNA sequence of G-29 were analyzed. This strain was identified to be a new subspecies of Gluconacetobacter intermedius in the species of Gluconacetobacter. This strain has been preserved in China Center for Typical Culture Collection (CCTCC) with the collection number of CCTCC NO: M208234.

Effect of Exogenous Enzymes on the Hydrolysis of Phytic Acid in Brown Rice
LIU Zhi-wei,CHEN Hua-xing,ZHANG Chen
2010, 31(5):  215-218.  doi:10.7506/spkx1002-6300-201005048
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In order to improve the nutritional value of brown rice, phytic acid, an anti-nutrition factor in brown rice, was degraded through hydrolysis with exogenous enzymes. Degradation amount of phytic acid was employed as an evaluation parameter to examine the effects of pH, temperature, hydrolysis time and enzyme dose on enzymatic hydrolysis of phytic acid. The synergistic effect between cellulase or pectinase and phytase was also investigated. Results indicated that the optimal process of phytase hydrolysis was achieved by using an enzyme dose of 0.4 U/mL for 4 h reaction at pH 5.2 and 50 ℃. Meanwhile, the individual and combined additions of cellulase and pectinase could both significantly improve phytase activity, promote the hydrolysis efficiency of phytase, and enhance the degradation rate of phytic acid.

Bioengineering
Response Surface Methodological Approach for Optimization of Compound Protectant Formulation for Lyophilized Lactobacillus plantarum
HAN De-quan1,YANG Li-juan1,SUN Qing-shen1,WU Tong1,SUN Hong-shu2
2010, 31(5):  219-224.  doi:10.7506/spkx1002-6300-201005049
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The formulation of protectant for lyophilized Lactobacillus plantarum was optimized by means of response surface methodology. First, based on the single factor experiments, Plackett-Burman design was used to evaluate the importance of ingredients of compound protectant formula affecting cell viability of Lactobacillus plantarum. Second, steepest ascend method was used to obtain the maximum response regions of the most important ingredients. Finally, central composite design combined with response surface methodology was employed to investigate the optimal compound protectant formula. Results indicated that the most important ingredients included skimmed milk, glycerol and vitamin C, and their optimal amounts in 100 mL of protectant formula were skimmed milk 13.68 g, glycerol 1.97 g and vitamin C 0.20 g. The optimal cell survival rate was observed to be 85.01% using the optimal compound protectant, which was very close to the expected value (84.85%) and also exhibited an increase of 63.48% compared with using a single protectant, and the number of living Lactobacillus plantarum was 4.98 × 1010 CFU/g.

Alginate-Agar Immobilization of Recombinant Dextransucrase
ZHANG Hong-bin,YI Xiao-nan,WU Ding-tao,HU Xue-qin
2010, 31(5):  225-228.  doi:10.7506/spkx1002-6300-201005050
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Recombinant dextransucrase was immobilized with sodium alginate and agar. The immobilization conditions and enzymological properties of the enzyme were also investigated. Results indicated that immobilized dextransucrase could retain high activity via the immobilization using 4% sodium polymannuronate mixed with 1% gelatin at the ratio of 1:1 mixing. The transformation efficiency of the immobilized dextransucrase still retained 40% after repeated transformation for 6 times. The optimal volume ratio between mixed carrier and enzyme solution was 2:1, which achieved the highest enzyme activity. The optimal reaction temperature, pH and sucrose concentration as the substrate for the immobilized recombinant dextransucrase were 40 ℃, 5.4 and 5 g/100mL, respectively. The enzyme activity remained 44% after storage at 35 ℃ for 1 h. The thermal stability of the immobilized enzyme was better than that of the free enzyme. The Km value of this immobilized dextransucrase was 28.35 mmol/L.

Effect of Organic Solvent Extract from Ferula ferulaeoides on Activities of Enzymes in Fermenation Supernatant and Mycelia of Pleurotus ferulae
BAI Yu-jia1,LI Guo-qiang2,HUANG Wen-shu1,FENG Zuo-shan1, *
2010, 31(5 ):  229-232.  doi:10.7506/spkx1002-6300-201005051
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In this study, Pleurotus ferulae NB-1 was used for liquid fermentation. The chloroform soluble fraction of 95% ethanol extract from Ferula ferulaeoides root was added to fermentation culture medium of the strain. After 7 days of fermentation at 27.5 ℃, the resulting fermentation broth was harvested and separated into supernatant and mycelia by centrifugation, and the activities of laccase, polyphenol oxidase (PPO) and protease in the supernatant and mycelial PPO were determined. Results indicated that the addition of the chloroform soluble fraction of 95% ethanol extract from Ferula ferulaeoides root at the levels of 10, 50 and 100 mg to 100 mL of fermentation culture medium resulted in 40-, 50- and 50-fold increases of laccase activity, 4.43-, 30.14- and 43.14-fold increases of PPO activity and 0.99-, 0.85- and 0.67-fold increase of protease in the supernatant, and 1.6-, 0.93- and 1.06-fold increases of mycelial PPO activity, respectively when compared with no addition. These results demonstrate that the chloroform soluble fraction of 95% ethanol extract from Ferula ferulaeoides root exhibits a promotion effect at low concentration and an inhibition effect on PPO activity at high concentration. Moreover, protease activity exhibits a decreasing trend in a dosedependent manner.

Preliminary Identification and Analysis of Cellulase-producing Strains from Carrot
HOU Jin-hui,LIU Quan-de,GAO Ming-xia,GUO Xiang,YE Jun
2010, 31(5):  233-236.  doi:10.7506/spkx1002-6300-201005052
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In this study, a strain, HP1, with high cellulase activity was isolated from the surface of carrots. The 16S rDNA fragment of HP1 was identified to be 1435bp by PCR. The sequence was analyzed by bioinformatics method and aligned with sequences published in NCBI Genbank. This strain exhibited 99% similarity with Bacillus cereus. According to colony observation combined with physiological-biochemical analysis, HP1 was preliminarily identified to belong to Bacillus sp., which was a new strain of Bacillus based on sequence and biochemical analyses. The accession number of this strain in NCBI was FJ908092.

Bioengineering
Effect of AMP-activated Protein Kinase on Glycolysis in Mutton
MA Xia,LI Ze,JIN Ye*
2010, 31(5):  237-239.  doi:10.7506/spkx1002-6300-201005053
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In order to investigate the effect of AMP-activated protein kinase (AMPK) on glycolysis in biceps femoris muscle from postmortem Mongolia sheep carcases, lactic acid concentration, hexokinase activity and pH change were determined after the inhibition of AMPK activity in mutton muscle samples by araA. Results indicated that the inhibition of AMPK activity resulted in a significant decrease in lactic acid accumulation (P<0.01), an obvious inhibition of hexokinase activity (P<0.01), and a great reduction in the rate of pH decrease (P<0.01). Moreover, a regular change in three indices was also observed due to the change of AMPK activity.

Effect of Vitamin on Nitrite-induced Micronucleus of Vicia faba Root Tip Cells
ZHAO Xin,HU Ying-kao,CAI Min-hua,HU Xiao-ju,LI Ya-xuan*
2010, 31(5):  240-243.  doi:10.7506/spkx1002-6300-201005054
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Nitrite has been widely used as the preservative at the low dosage in foods. However, it also exhibits obvious teratogenic and carcinogenic effects. In this study, the micronucleus technique of Vicia faba root tips was used to investigate the effects of three kinds of vitamin on cell division and nitrite-induced micronucleus appearing. Results indicated that vitamin C, riboflavin and niacin at the appropriate amount could all obviously reduce the micronucleus rate and exhibited an excellent antagonistic effect on nitrite-induced carcinogenesis. Meanwhile, excessive vitamin concentration could also result in the improvement of micronucleus frequency and destroy root tip cells. Therefore, vitamin at appropriate amount can inhibit the damage of cells due to nitrite, which suggests that it is necessary for us paying attention to the dosage during the intake of vitamin supplements.

Effect of Trypsin Hydrolysis on Functional Properties of Buckwheat Protein Isolate
GONG Qian,TANG Chuan-he,YANG Xiao-quan*
2010, 31(5):  244-247.  doi:10.7506/spkx1002-6300-201005055
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In this study, the effects of limited trypsin hydrolysis and heating treatment on physicochemical and functional properties of buchwheat protein isolate (BPI) were investigated. Results indicated that higher hydrolysis degree could result in the improvement of protein solubility and emulsification stability, and the reduction of surface hydrophobicity, emulsifying ability and stability, and foaming ability and foam stability. However, heating treatment could lead to the increase of protein solubility, surface hydrophobicity and foaming ability, and the decrease of emulsifying activity and emulsifying stability. Moreover, heating treatment could inhibit the reduction trend of foam stability due to decreasing hydrolysis degree.

Application of Phytase in Non-cooked Fermentation of Sorghum for Ethanol Production
XU Hong-xian,RUAN Zhen-hua,DUAN Gang*
2010, 31(5):  248-251.  doi:10.7506/spkx1002-6300-201005056
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To the best of our knowledge, the application of phytase in non-cooked processing was first reported for the fermentation of sorghum to produce ethanol in this study. Results indicated that the addition of phytase in the non-cooked sorghum during fermentation could drive the fermentation rate, increase the ethanol production, reduce the formation of impurities, significantly decrease phytic acid content in distilled supernatant and lees, improve the nutritional protein value and decline the release of organic phosphorus.

Survival of Escherichia coli O157:H7 in Home-made Yogurt during Storage at 4 ℃
LAI Wei-hua1,2,Daniel Y. C. Fung2,*,Beth Ann Crozier-Dodson2
2010, 31(5):  252-255.  doi:10.7506/spkx1002-6300-201005057
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In this study, preheated milk was inoculated with 3% (V/V) of plain yogurt and 2.15 (lg(CFU/mL)) of Escherichia coli O157:H7 to carry out the fermentation at 45 ℃ for 5 h. The resulting fermented yogurt was stored at 4 ℃. Samples were processed using Pathatrix, a large volume recirculating immunomagnetic capture system that utilized paramagnetic beads coated with antibody to facilitate the specific capture of E. coli O157: H7 from yogurt. Then the beads were resuspended in 1% peptone solution, spread onto sorbitol-MacConkey agar and incubated at 37 ℃ for 24 h. E. coli O157:H7 exhibited a gradual decrease and could not be detected after 12 days. Therefore, it is necessary for detecting E. coli O157:H7 during the process of manufacture and storage of dairy products.

Ultraviolet-induced Protoplast Mutagenesis for Breeding High-performance Strains of Cordyceps sinensis
ZHU Yun-lan,CHEN An-hui,WANG Tao,CHEN Hong-wei*
2010, 31(5):  256-260.  doi:10.7506/spkx1002-6300-201005058
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Cordyceps sinensis was used as original strain to conduct protoplast mutagenesis with ultraviolet (UV) illumination for obtaining high-performance mutants. Results showed that 30-second UV illumination gave protoplast-regenerated strains of Cordyceps sinensis No.3 with the highest intercellular polysaccharide production and No.8 with the highest biomass and ability to enrich selenium. The intercellular polysaccharide content (calculated on the basis of dry weight of Cordyceps sinensis mycelia) in strain No. 3 reached up to 54.570 mg/g, which was increased by 52.9 % when compared with that in original strain. Strain No. 8 exhibited 1.3445 g/100mL biomass and 125.8 μg/g selenium content (also calculated on the basis of dry weight of Cordyceps sinensis mycelia), which were increased by 55.16% and 50.11%, respectively, when compared with original strain.

Toxicity Analysis of Common Carp Transferred Salmon Growth Hormone Gene
LIANG Li-qun1,WANG Jing2,CAO Ding-chen1,WANG Xiao-jun2,YAN Xue-chun1,CHANG Yu-mei1,SUN Xiao-wen1
2010, 31(5):  261-265.  doi:10.7506/spkx1002-6300-201005059
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In order to investigate the toxicity of transgenic carp with salmon growth hormone gene, mice were fed diet containing flesh of transgenic carp with salmon growth hormone gene or non-transgenic carp. The diets containing flesh of transgenic carp with different proportions of 10%, 5% and 2.5% were given to mice for 90 consecutive days. Acute oral toxicity experimental results revealed that mice fed transgenic carp were normal as the control group fed non-transgenic carp during the period of 90 days. The mice exhibited free movements and shining coats without any abnormal symptoms and abnormal secretions in their noses, eyes and mouths. Meanwhile, no obvious difference in toxic indices between experimental group and control group was observed. Moreover, no abnormal change in hematological and biochemical indices, routine urine test, viscera coefficients and histopathological examinations was observed in mice fed transgenic carp with salmon growth hormone gene. Therefore, salmon growth hormone gene has no toxicity and transgenic carps are safe to mice as edible foods.

in vivo Digestion Promoting Function of Extracts from Plum Fruits
WEN Jing,XU Yu-juan,XIAO Geng-sheng,WU Ji-jun,ZHANG Rui-fen,TANG Dao-bang
2010, 31(5):  266-269.  doi:10.7506/spkx1002-6300-201005060
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Objective: To probe into the digestion promoting capacity of extracts from plum fruits. Methods: Plum fruits were sequentially extracted with 85% ethanol for 3 times and concentrated by rotary evaporator to obtain brown-colored syrup-like digestion promoting extract. The extract was then fractionated into chloroform, ethyl acetate and water soluble fractions. The digestion promoting function of these fractions was evaluated by the determinations of body weight gain, average daily dietary intake, food utilization rate, digestive enzyme activity in rats and the observation of small intestinal movement in mice. Results: Ethyl acetate soluble fraction of plum fruit extract could obviously improve average intake amount of diet in rats, promote the secretion of gastric juice and pepsin in rats, and exhibit an obvious promotion effect on ink propulsive rate in mice. Conclusion: Ethyl acetate soluble fraction of 85% ethanol extract from plum fruits has obvious promoting digestion function.

Protective Effect of Burdock Inulin and Jerusalem Artichoke Inulin against Chronic Alcohol-induced Oxidative Injury in Mice
LU Zheng1,ZHANG Jing1,GAO Zhao-lan1,ZHANG Bo1,*,XU Yong-jie2
2010, 31(5):  270-273.  doi:10.7506/spkx1002-6300-201005061
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Objective: To investigate and compare the protective effects of burdock inulin and Jerusalem artichoke inulin against oxidative damage of organs in mice based on the examinations of body weight, viscera coefficients, and GSH and MDA contents of kidney, brain, heart and testis. Methods: Male mice were randomly divided into 6 groups, which were designated as Burdock inulin groups at low, middle and high dosages, Jerusalem artichoke inulin group, alcohol model group and blank control group to perform the corresponding treatments for 20 consecutive days. At the end of administration, all mice were sacrificed and anatomized to harvest kidney, brain, heart and testis for measuring the contents of GSH and MDA. Results: Compared with the blank control group, no obvious differences of GSH content in kidney, heart and testis and a significant difference of GSH content in brain of the alcohol model group were observed. Meanwhile, the alcohol model group exhibited an obvious increase of MDA content in kidney and brain and no obvious difference of MDA content in heart and testis. However, compared with the alcohol model group, the GSH content exhibited a significant decrease in kidney of the mice treated with burdock inulin at different dosages and in brain of the mice treated with burdock inulin at middle and high dosages; whereas, the GSH content exhibited an obvious difference in heart and testis of the mice treated with burdock inulin. Moreover, the MDA content exhibited a significant decrease in kidney of the mice treated with burdock inulin at middle and high dosages, in brain of the mice treated with burdock inulin at high dosage and in testis of the mice treated with Burdock inulin at high dosage; whereas, the MDA content exhibited an obvious difference in heart of the mice treated with burdock inulin. Conclusion: alcohol can result in significantly oxidative damage of kidney and brain tissue in mice, but exhibit less damage to heart and testis. Burdock inulin and Jerusalem artichoke inulin both exhibit a protective effect against oxidative damage of these organs.

Microbial Survey during Preparation Processing of Chicken Products
LIANG Rong-rong1,ZHANG Yi-min1,LI Fei-yan1,PA Li2,LI Jun-yong3,LUO Xin1,*
2010, 31(5):  274-278.  doi:10.7506/spkx1002-6300-201005062
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Microbiological contaminant during preparation processing of chicken products was investigated due to the short shelf-life in this study. Results indicated that slaughterhouses exhibited the more contaminant than the segmentation-houses. However, the microbiological counts of chicken carcass and its segmented parts were ranged in 2.12-3.95 (lg (CFU/cm2)), which was still lower than the maximum limit issued by the guideline for food standards in China. On the other hand, the microbiological counts of chicken by-products were ranged in 3.87-4.31 (lg(CFU/cm2)), which was higher than that of chicken parts. Serious contamination of manufacture environment during whole preparation processing of chicken products was also detected to be unacceptable level. The microbiological counts of chicken balls and chicken fillets were 4.27 (lg(CFU/g)) and 5.78 (lg(CFU/g)), respectively, which could not meet the requirements for food safety in China.

Effect of Sudan I on Blood and Organ Coefficients of Mice
WANG Ai-hua1,LI Ji-lian1,ZHANG Bin2
2010, 31(5):  279-282.  doi:10.7506/spkx1002-6300-201005063
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In this study, the blood and organ coefficients of mice with long-term intake of Sudan I were investigated. Totally 40 male Kunming mice were randomly divided into 4 groups, which were designated as control group fed normal diet and three groups fed diets containing Sudan I at doses of 250, 500, 1000 mg/kg. Body weight (bw) determination and blood routine examination were conducted every 10 days. After 60 days, all mice were sacrificed and organ coefficients were calculated. Results indicated that slow body weight gain of the mice fed dietcontaining Sudan I was observed during the period of 60 days. The coefficients of liver/bw, spleen/bw and kidney/bw in the mice fed diet containing Sudan I were all obviously higher than those of the control mice. In addition, with increasing intake time of Sudan I, the number of red blood cells and the content of hemoglobin of mice exhibited a gradual decrease trend; In contrast, the number of white blood cells and clotting time exhibited an increase trend, especially for the mice in the group fed diet containing Sudan I at the dose of 1000 mg/kg. These investigations confirm that Sudan I can resulted in the damage of blood cells and organs.

Ninety-day Rat Feeding Study of 5'-Nucleotide
LIANG Rui,WANG Nan,ZHANG Jia-li,ZHAO Ming,LIANG Jiang,WANG Jun-bo*
2010, 31(5):  283-287.  doi:10.7506/spkx1002-6300-201005064
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Objective: To explore the safety of 5’-nucleotide in rats. Methods: Totally 96 rats were randomly divided into 6 groups and fed diet containing 5’-nucleotide at doses of 0, 0.01, 0.04, 0.16, 0.64 g/kg bw and 1.28 g/kg bw for 90 consecutive days. The changes of body weight, dietary intake amount, food utilization rate, blood pressure, blood routine, biochemical parameters, and pathological results of the rats were recorded at intervals of one week during the administration of 5’- nucleotide. Results: No obvious difference in total body weight gain, total dietary intake amount, food utilization rate and systolic blood pressure was observed between 5’-nucleotide treatment groups and control group. However, compared with the rats in control group, body weights of male rats in nucleotide treatment group exhibited a significant increase in the first 4 weeks (P < 0.05). Similarly, total food utilization rates of the rats treated with 5’-nucleotide at doses of 0.01, 0.04 g/kg bw and 0.16 g/kg bw exhibited significantly higher than that of control group in the first 2 weeks (P <0.05). In addition, compared with the control group, white blood cells, red blood cells, hemoglobin, platelets, total protein, albumin, alanine transaminasse, triglyceride of male rats also revealed a significant difference. However, all of these values were still in the normal range. No histopathological change was observed in kidney and other organs or tissues. Conclusion: It is safety to rats fed 5’-nucleotide at the dose of 0.01-1.28 g/kg bw.

Immunoregulatory Effect of Laboratory Prepared Yogurt containing c9, t11- Conjugated Linoleic Acid in Mice
WANG Xuan-lin1,TAN Ying-xia1,YU Cheng-yu1,LI Su-bo1,HE Min1,LI Wei-jing1,CHEN Bing-qing2,YU Qun1,*
2010, 31(5):  288-292.  doi:10.7506/spkx1002-6300-201005065
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A yogurt with c9, t11-conjugated linoleic acid (CLA) was prepared by adding suitable substrate and nutrients to milk for Lactobacillus fermentation. Milk fat was extracted and CLA was quantitatively determined by gas chromatography to design the administration dosage and study the immunoregulatory function of CLA in mice. Results indicated that the administration of CLA at a dose of 0.05 g/kg bw·d for 30 consecutive days could significantly enhance immunoregulatory function in mice. This fact demonstrates an excellent immunoregulatory effect of CLA in mice.

Digestion Properties of Buckwheat Starch
HONG Yan,GU Juan,GU Zheng-biao
2010, 31(5):  293-297.  doi:10.7506/spkx1002-6300-201005066
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The digestion properties of buckwheat starch were investigated through the determination and comparison of digestion rates in vitro and in vivo among buckwheat starch, corn starch, wheat starch and buckwheat flour. The glycemic index of four samples was determined by human clinical trial. Meanwhile, the blood glucose level in mice orally administered these samples was investigated at 15, 30, 45, 60, 90 min and 120 min postadministration. A digestion model in vitro was established according to Englyst method and the digestion curves of these sample in vitro were also achieved. Results indicated that buckwheat starch exhibited a slower absorption than corn starch and wheat starch, whereas a faster absorption than buckwheat flour.

Effect of Bean Porridge on Glycemic Response and Satiety in Human Body
ZHOU Wei,FAN Zhi-hong*,WANG Lu,ZHAO Jian-jing
2010, 31(5):  298-301.  doi:10.7506/spkx1002-6300-201005067
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In order to explore the effect of mixed cooking for common grains and beans on response of blood glucose and satiety, glycemic index and satiety index of adzuki bean porridge (A), adzuki bean-rice mixed porridge (AR), black bean porridge (B), black bean-rice mixed porridge (BR) and rice porridge (R) were determined. Ten healthy human subjects were given iso-energy (300 kcal) food to determine and record blood glucose and satiety levels of these food samples during 240 min with glucose as the control sample. Glycemic index of black bean porridge, red bean porridge, bean-rice mixed porridge and rice porridge were 16, 24, 70 and 102, respectively. Glycemic index exhibited a negative correlation with satiety index (r =-0.924, P < 0.01). Moreover, the satiety index was positively correlated with the meal time (r = 0.908, P <0.05). Therefore, the grain-bean mixed porridge with moderate glycemic index can provide higher satiety feeling, which are good diets for people who need to control blood glucose and body weight.

Transgenic Animals and Corresponding Food Safety Assessment Methods: A Review
XU Jun-feng,CHEN Xiao-yun,SUN Cai-xia
2010, 31(5):  302-306.  doi:10.7506/spkx1002-6300-201005068
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Transgenic food safety has an important impact to trade barrier and human health. In this paper, safety assessment methods for transgenic animals and genetic modifications is reviewed based on the connotation and extension of food safety and substantial equivalent principle. These investigations will be applied in the safety assessment of foods and food processing containing transgenic animals as well as unexpected effects in genetic modification processing. Moreover, a framework of food safety assessment for transgenic animals and food products containing transgenic animals is systematically described, which will provide a theoretical reference for food safety assessment and government supervision.

Research Progress in Structure and Hypolipidmic Mechanisms of Pectic Polysaccharides
CAI Wei-rong1,SUN Yuan-lin2,TANG Jian3
2010, 31(5):  307-311.  doi:10.7506/spkx1002-6300-201005069
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Pectin is complex polysaccharides in cell walls of all plants. It is one of the most important food additives due to its abundant source and safety. Increasing attention has been paid to using pectic polysaccharides for the hypolipidemic function because of increasing number of hyperlipidemic patients. In this paper, the structure of pectic polysaccharides, and the effects of pectic polysaccharides on cholesterol absorption, bile acid chelation and secretion, plasma lipoprotein cholesterol metabolism and colon glycolysis are reviewed. All of these investigations will provide a reference to further explore structure-activity relationship of pectic polysaccharides on hypolipidemic function.

Research Progress of Bioactive Components in Garlic
YAN Miao-miao1,XU Zhen2,XU Chan1,GUO De-ping1
2010, 31(5):  312-318.  doi:10.7506/spkx1002-6300-201005070
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Current research progress of bioactive components in garlic is reviewed in this paper. The bioactive components in garlic are classified as volatile compounds including lipid-soluble sulphur compounds, and non-volatile compounds including water-soluble sulphur compounds, sapogenins, saponins, flavonoids and phenols. In addition, biosynthesis pathways of sulphur compounds, roles of alliinase, pharmacological actions as well as side-effects of garlic are also described.

Problems of Food Safety and Establishment of Control Model in China
LU Jian1,SUN Yong2,GENG Ning1,XU Chun-xiang1,ZHANG Xiao-qiang1
2010, 31(5 ):  319-324.  doi:10.7506/spkx1002-6300-201005071
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The current problems of food safety are analyzed in this paper. A regulation system as a control model is proposed to supervise and control the problems of food safety related to agricultural inputs, primary agricultural products, food additives, food-related products, food processing, food distribution, food safety laws, food regulations and standards, food safety information collection and analysis, food safety risk evaluation and analysis, early expectation, food safety traceability system, documentation regulation of food additives and food ingredients. This new regulatory regime of food safety can effectively ensure food safety.

Risk Assessment of Phthalate Plasticizers in Food Contact Products
CAO Guo-zhou,XIAO Dao-qing,ZHU Xiao-yan
2010, 31(5):  325-327.  doi:10.7506/spkx1002-6300-201005072
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Phthalates, or phthalate esters are widely used as plasticizers (substances added to plastics to increase their flexibility) in food contact materials and products. The safety of these food contact materials and products is one of the major concerns for consumers. In this paper, the risk assessment is conducted through the investigations of harmfulness, dosage and exposure of phthalates in food contact materials and products. Exposure to phthalates in a certain extent results in health damage of consumers. Therefore, restriction of phthalates should be accomplished during the manufacture of food contact materials and products and corresponding alternative materials should be developed.

Fundamental Issues of Non-thermal Processing in Food
ZHOU Lin-yan,LIAO Hong-mei,HU Xiao-song,LIAO Xiao-jun*
2010, 31(5):  328-333.  doi:10.7506/spkx1002-6300-201005073
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Thermal processing (pasteurization and/or sterilization) has been used as an effective and economical technique for ensuring microbiological food safety in food industry. However, it also results in the deterioration of quality such as color alteration, taste modification, aroma loss, nutrient degradation and textural change. Currently, non-thermal processing (NTP) has attracted extensive attention and gained more acceptances from government, food industry and academic institutes since it can inactivate microorganisms and enzymes at lower temperature. The researches and applications related to NTP have been rapidly developed, and high hydrostatic pressure (HHP) has successfully been commercialized. Based on the comprehensive analysis, five fundamental issues dealing with microorganisms, enzymes, food quality, food safety and others are reviewed and discussed in this paper.