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Table of Content

15 June 2011, Volume 32 Issue 11
Basic Research
Clearance Effect of Apple Polyphenols on Nitrite in Mimic Gastric Juice
LI Gui-xing,HU Xiao-dan,SUN Hong-nan,TAO Xiao-yun,SUN Ai-dong
2011, 32(11):  1-4.  doi:10.7506/spkx1002-6630-201111001
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In mimic gastric juice, the clearance rates of apple polyphenols, tea polypheonls and vitamin C on nitrite were compared to explore the effect of apple polyphenols on the clearance of nitrite. The results showed that apple polyphenols, tea polyphenols and vitamin C could scavenge nitrite to different extents. The clearance rate of nitrite by apple polyphenols exhibited a logarithmic increase with increasing concentration over the low concentration range. Despite tea polyphenols having a slightly higher scavenging effect at low concentration (0.01%-0.02%), the scavenging effect of apple polyphenols against nitrite was stronger when the concentration was greater than or equal to 0.03%. The maximum nitrite scavenging rates of apple polyphenols, tea polyphenols and vitamin C were (98.2± 1.3)%, (97 ± 0.2)% and (88.6 ± 1.0)%, respectively. The nitrite scavenging effect of mixed apple polyphenols and tea polyphenols, resulting in a scavenging rate of (92.6±0.3)% was better than that of either of them alone; similarly, apple polyphenols plus vitamin C also exhibited a higher scavenging rate, which was up to (65.7±0.3)%. The scavenging rate of apple polyphenols plus tea polyphenols plus vitamin C was (90.7± 0.3)%, which was slightly lower than that of mixed apple polyphenols and tea polyphenols but higher than that of apple polyphenols plus vitamin C. The scavenging effect of apple polyphenols reached its maximum level (98.7± 0.2)% after 2 h of incubation. Therefore, apple polyphenols as a natural extract has excellent clearance effect on nitrite in mimic gastric juice.
Effect of Hot Boiling on Muscle Characteristics and Textural Property of Young Anchovy (Engraulis japonicus)
SHENG Li-yi,LIU Shu-lai,LU Fei,ZHANG Jian-you,DING Yu-ting
2011, 32(11):  5-8.  doi:10.7506/spkx1002-6630-201111002
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The effect of hot boiling under varying conditions of temperatures and time on muscle characteristics and textural property of young anchovy were investigated. The results showed that water loss rate, weight loss rate, endogenous protease activity, protein solubility, free amino nitrogen content and texture properties of young anchovy were significantly affected by hot boiling. Higher hot-boiling temperature and longer hot-boiling time were more suitable for the inactivation of endogenous proteases and dehydration of the fish, but resulted in more serious protein denaturation and the loss of free amino acids, which caused fish muscle texture to become denser. Therefore, we concluded that the optimal hot-boiling temperature and time are 80-90 ℃ and 4 min, respectively.
Affecting Factors of Heat Capacity of Fruits and Vegetables
ZHANG Min,ZHONG Zhi-you,YANG Le,CHEN Jian-hua,CHE Zhen-hua
2011, 32(11):  9-13.  doi:10.7506/spkx1002-6630-201111003
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The heat capacity of food plays an important role in manufacturing, circulation and fresh-keeping processes. The heat capacities, soluble solid contents, water contents and densities of 35 fruits and vegetables were determined by a simultaneous determination method. The results showed that the 35 fruits and vegetables revealed a slow increase in heat capacity with increasing temperature, and the growth rate of heat capacity decreased gradually until no change over the temperature range investigated. The heat capacities of these fruits and vegetables were significantly correlated with the water contents or soluble solid contents, and had no significant correlation with the densities. Moreover, the heat capacity-water content correlation was positive, while the heat capacity-soluble solid content correlation in a negative manner.
Effect of Storage Time on Phenolic Components and Antioxidant Activity of Red Wine
FANG Yu-lin,MENG Jiang-fei,ZHANG Ang,ZHANG Zhen-wen,LIU Jin-chuan,HAN Guo-min, LIU Shu-wen
2011, 32(11):  14-20.  doi:10.7506/spkx1002-6630-201111004
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In order to explore the effect of storage time on phenolic components of red wine, red wine from Cabernet Sauvignon was sealed in stainless steel tanks for 3 years, and variations in phenolic components and total antioxidant capability during aging period were detected. The results indicated that total phenols did not exhibit an obvious change after storage for 1 year; in addition, total flavonoids and total flavanols in red wine reached up to their respective maximum values, and then exhibited a gradual decrease with extended aging time. However, total anthocyanins revealed a gradual decrease. During the storage period, gallic acid gradually replaced salicylic acid as the major hydroxybenzoic acid, and the total content exhibited a gradual downward trend but remained higher than hydroxycinnamic acid, another phenolic acid. Among all the identified phenols, the content of catechin was the highest. Most of the identified phenols reached their peaks after 1 year of aging, followed by a progressive decline. During the whole aging period, the relative content of flavonoids was increased, while the relative content of non-flavonoids exhibited an opposite change. DPPH scavenging capability and cupric ion reducing anti- oxidant capacity (CUPRAC) reached their maximum values after aging for 1 year, and then declined gradually; in contrast, hydroxyl radical scavenging capability exhibited a gradual decrease throughout the aging period. In terms of DPPH scavenging capability and CUPRAC, hydroxycinnamic acid had stronger antioxidant activity than hydroxybenzoic acid; on the other hand, salicylic acid, quercetin and ferulic acid had strong hydroxyl radical scavenging capability.
Effect of Irradiation on Degradation of Ochratoxin A in Maize
CHI Lei,HA Yi-ming,WANG Feng,XUE Xiao-feng
2011, 32(11):  21-24.  doi:10.7506/spkx1002-6630-201111005
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Objective: To explore the effect of γ-irradiation on the degradation of Ochratoxin A in maize. Methods: Maize samples contaminated with ochratoxin A were irradiated by 60Co-γ ray initially at different doses, then ochratoxin A in samples was analyzed by HPLC and nutritional components were also determined. Results: The content of ochratoxin A in maize exhibited a significant decrease, and the degradation rate of ochratoxin A could reach up to 50% at the dose of 10 kGy. The nutritional components were not destroyed by γ-irradiation. Conclusion: γ-Irradiation can degrade ochratoxin A in maize without decreasing the quality of maize.
in vitro Antioxidant Activity of Polysaccharides from Viscum articulatum
ZHONG Wen-wu,PENG Wen-shu,YU Zheng-yun,CHEN Yi-jian
2011, 32(11):  25-28.  doi:10.7506/spkx1002-6630-201111006
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Crude polysaccharide samples respectively obtained from Viscum articulatum from two different hosts by microwave-assisted aqueous extraction and subsequent ethanol precipitation were determined for their polysaccharide contents. The abilities of the two polysaccharide samples to scavenge hydroxyl free radicals generated by Fenton reaction, superoixde anion free radicals generated by autoxidation of 1,2,3-benzenetriol and DPPH radicals were spectrometrically evaluated. Meanwhile, their suppressing effects on hydroxyl radical-induced lipid peroxidation of lecithin were spectrometrically examined by thiobarbituric acid method. The results showed that both crude polysaccharides had obvious scavenging effect on active radicals and inhibitory effect on lecithin peroxidation to some extent. However, these antioxidant effects differed between the two polysaccharide samples.
Changes of Endogenous Enzyme Activities and Major Components in Brown Rice during Germination
DING Jun-zhou,LIU Zhen,ZHAO Si-ming,XIONG Shan-bai
2011, 32(11):  29-32.  doi:10.7506/spkx1002-6630-201111007
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Objective: To investigate the changes of endogenous enzyme activities and major components as well as their correlation in brown rice during germination. Methods: Z944 rice was used as the material to prepare germinated brown rice by incubating at 30 ℃ for 72 h. Analysis of endogenous enzyme activities and major components in germinated brown rice was conducted every other 12 h during germination. Results: The activities of α-amylase, β-amylase, protease, glutamic acid decarboxylase and phytase in germinated brown rice exhibited an upward trend and reached up to 5.45 U/g, 3.78 U/g, 14.08 U/g, 9.72 U/100g and 3.44 U/g, respectively at the end of the generation period. However, the contents of γ-aminobutyric acid, reducing sugars and free amino acids showed a tendency to decline and the corresponding final values were 44.16, 9.59 mg/g and 1.99 mg/g, respectively Conclusion: The activities of 5 endogenous enzymes investigated had a significant correlation with the contents of their metabolic substrates or metabolites, and some of them were also significantly correlated with non-enzyme metabolic substrates or corresponding metabolites. The nutritional value of 72 h germinated brown rice is higher than that of ungerminated brown rice and therefore 72 h germinated brown rice is suitable for the development of novel brown rice food products.
Bitterness Removal in Guanxi Pomelo Juice by Naringinase from Aspergillus niger DB056
WENG Cong-ze,CAI Hui-nong,NI Hui,XIAO An-feng,LI Li-jun
2011, 32(11):  33-38.  doi:10.7506/spkx1002-6630-201111008
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High performance liquid chromatography (HPLC) was used to determine naringin and hydrolysates in Guanxi pomelo juice to explore the optimal conditions of bitterness removal for Guanxi pomelo juice by the naringinase from Aspergillus niger DB056. Under optimized conditions, the naringinase was used to debitter Guanxi pomelo fresh fruit juice, cloudy concentrated juice and clarified concentrated juice. The results showed that the optimal debittering conditions were natural pH, 40-55 ℃treatment temperature, 90 U/mL naringinase amount and 80 min treatment time. Under the optimal debittering conditions, the naringin in pomelo juice could be effectively degraded into prunin and naringenin by the enzyme and the removal rate of naringin was up to 89%; meanwhile, the debittering efficiency of cloudy concentrated juice was up to 80%. Therefore, naringinase has an excellent debittering capability for Guanxi pomelo juice.
Acetylcholinesterase and Esterase Activities in Kidney Bean Seedlings and Their Sensitivity to Pesticides
JI Shu-juan,QIN Feng-da,BAI Bing
2011, 32(11):  39-42.  doi:10.7506/spkx1002-6630-201111009
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In this paper, the activities of acetylcholinesterase (AChE) and esterase in kidney bean seedlings and their sensitivity to pesticides were analyzed. Results indicated that the activities of AChE and esterase were varied during different germination and growth periods of kidney bean seedlings. The specific activity of AChE was the highest after 6 days of germination, which was up to 0.969 U/mL, and the esterase activity reached up to 1.9433 U/mL after 2 days of germination. The AChE from 6-day-old kidney bean seedlings was more sensitive to pesticides than the esterase from 2-day-old kidney bean seedlings, and the detection limits for dichlorvos, oxidized dimethoate and methomyl were 0.025, 0.07 mg/kg and 0.07 mg/kg, respectively, which were all below the maximum allowable residue limits. Therefore, AChE derived from kidney bean seedlings can meet the requirements for rapid detection of organophosphorus and carbamate pesticide residues.
Total Flavonoid Contents, Antibacterial Activities and Antioxidant Activities of Four Extracts from Dimocarpus longan Seeds
HUANG Xiao-dong
2011, 32(11):  43-47.  doi:10.7506/spkx1002-6630-201111010
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Four extracts including water extract, 95% ethanol extract, acetone extract and ethyl acetate extract from Dimocarpus longan seeds were determined for their total flavonoid contents by polyamide adsorption-aluminum nitrate color reaction method. Meanwhile, their antibacterial activities were evaluated by cylinder-plate method and minimal inhibitory concentration (MIC) method. In addition, the abilities of these extracts were tested to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, hydroxyl radicals and superoxide anion radicals and inhibit lipid peroxidation. The results showed that the 95% ethanol extract had the highest content of total flavonoids, which was (3.90 ± 0.12)% among the four extracts. Its antibacterial activities against Escherichia coli, Proteus vulgaris, Bacillus subtilis, Sarcina lutea, Staphylococcus aureus, Erwinia carotorora and Xanthomonas campestris were stronger than the other extracts. Its inhibition zones were more than 15 mm at the concentration of 100 mg/mL. The MICs of the four extracts against all tested bacteria were not higher than 100 mg/mL. The four extracts superoxide anion radicals had a relatively weak scavenging effect on superoxide anion radicals but could strongly scavenge DPPH and hydroxyl free radicals and resist lipid peroxidation. In terms of IC50 (the concentration required for 50% inhibition), the scavenging effects of the four extracts against DPPH, hydroxyl and superoxide anion radicals ranked in the following sequence: the water extract, the 95% ethanol extract, the acetone extract and the ethyl acetate extract. The IC50 values of the water extract were 0.20, 0.15 mg/mL and 2.69 mg/mL, respectively. Therefore, it can be clearly seen that the 95% ethanol extract is a suitable source of botanical antibacterial agent, and the water extract is more suitable to be deeply developed and utilized as a source of botanical natural antioxidant.
Application of Bacterial Cellulose in Tofu Preparation
ZHANG Yan-yan,LU Zhi-gang,LIU Li,MAO Wen-ying,ZHAO Yan-ming,SUN Bo
2011, 32(11):  48-51.  doi:10.7506/spkx1002-6630-201111011
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Objective: To figure out whether or not addition of bacterial cellulose can improve the cellulose content and quality of tofu. Methods: Bacterial cellulose as a dietary fiber was added into tofu to explore the effect on gel strength, water-holding capacity and sensory quality of tofu. Results: The best quality property of tofu was achieved when bacterial cellulose was added at a level of 3.0 g/100 mL. Meanwhile, the gel strength and water loss rate of tofu supplemented with bacterial cellulose was up to 181 g and 17.2%, respectively. In addition, the gel strength showed no obvious difference compared to that of tofu without added bacterial cellulose, but there was a 9.5% reduction in the water loss rate. Conclusions: Tofu supplemented with the appropriate amount of bacterial cellulose has delicate and slick texture, good elasticity, non-rough feeling and improved dietary fiber content.
Comparison on Browning Degrees and Antioxidant Activities of Maillard Reaction Products from Different Systems
XIAO Jun-xia,HUANG Guo-qing,PEI Xiao-hui,SUN Ping,WANG Cheng-rong
2011, 32(11):  52-55.  doi:10.7506/spkx1002-6630-201111012
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Glucose, fructose, methionine, glycine and arginine were used to conduct Maillard reaction to explore the effect of heating time and mixing ratio on browning degrees of Maillard reaction products (MRPs). The antioxidant activity of the MRP with the highest browning degree was also determined. The results showed that the MRPs of glucose-glycine and fructose-glycine systems under the conditions of 2:1sugar-to-glycine ratio, pH 9.0 and incubation at 100 ℃ for 180 min had the highest browning degree. The MRPs of both glucose-glycine and fructose-glycine systems revealed strong antioxidant activities and the MRP of the fructose-glycine had higher reducing capacity and antioxidant value than that of the glucose-glycine system. The highest inhibition rate for hydroxyl and superoxide anion free radicals of the MRP from the glucose-glycine system reached up to 50.65% and 45.42%, respectively; however, the highest inhibition rate for hydroxyl and superoxide anion free radicals of the MRP from the fructose-glycine system reached up to 57.55 % and 28.54%, respectively.
Morphology Change of Coacervated Orange Oil Microcapsules during Preparation with Different Stirring Speeds
DONG Zhi-jian,ZHANG Xin-yu,LI Ji-zhen,MA Yong,LU Chang-xin,MENG Liang-yu,ZHANG Li-hua
2011, 32(11):  56-59.  doi:10.7506/spkx1002-6630-201111013
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In this paper, the effect of stirring speed on morphology change of coacervated orange oil microcapsules during preparation process was investigated. Meanwhile, the effect of loading amount of microcapsules on release rate was also explored. The results showed that the coacervated microcapsules possessed spherical multinuclear structure and the particle size exhibited a gradual decrease with increasing stirring speed from 200 to 600 r/min. The coacervated microcapsules remained spherical and multinuclear structure at a stirring speed ≤ 400 r/min during gelation and hardening phases. Otherwise, the irregular coacervated microcapsules were observed at higher stirring speed. As the stirring speed rose, the loading amount of microcapsules also exhibited an obvious increase and the particle size revealed an obvious reduction, thus resulting in the decrease in release rate of the coacervated microcapsules. Therefore, the optimal stirring speed was 400 r/min for coacervated spherical multinuclear orange oil microcapsules during the preparation process, which could provide excellent slow-released characteristics.
Purification and Structural Identification of Polyphenols in Kudingcha
SUN Yi,ZHANG Xin,ZHANG Wen-qin,ZENG Xiao-xiong,HU Qiu-hui
2011, 32(11):  60-63.  doi:10.7506/spkx1002-6630-201111014
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The polyphenolic substances in Kudingcha made from Ilex kudingcha C.J. Tseng and green tea made from Camellia sinensis L. were analyzed by high-performance liquid chromatography with diode-array detector (HPLC-DAD). The chromatographic patterns of the two types of tea were distinctively different. The results indicated that the polyphenolic substances in kudingcha might be quite different from those in green tea. In addition, 5 compounds were isolated from kudingcha extract by semi-preparative HPLC and identified as hydroxytyrosol glucoside, 5- caffeoylquinic acid (5-CQA), 3,4-dicaeoylquinic acid (3,4-di-CQA), 3,5-dicaeoylquinic acid (3,5-di-CQA) and 4,5-dicaeoylquinic acid (4,5-diCQA) by mass spectroscopy (MS) and nuclear magnetic resonance (NMR) spectroscopy, respectively. Therefore, the major phenolic compounds in kudingcha made from Ilex kudingcha C.J. Tseng were CQA and its derivatives.
Effect of High-pressure Carbon Dioxide Treatment on the Inactivation of Bacillus subtilis Spores
GAO Yuan,ZHOU Xian-han,ZENG Qing-mei,FAN Wei,SUN Xiao-ya
2011, 32(11):  64-68.  doi:10.7506/spkx1002-6630-201111015
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Bacillus subtilis spores were suspended in phosphate buffer and treated by high-pressure carbon dioxide (HPCD) at the range of 5-25 MPa combined with mild heating. The results showed that Bacillus subtilis spores were inactivated by 3.84 magnitude orders after heating treatment for 30 min at 45 ℃ followed by treatment at 20 MPa for another 30 min. HPCD treatment alone resulted in an inactivation by 2.44 magnitude orders. Continuous HPCD treatment at 10 MPa for 30 min could result in a decrease in the viable spore count of Bacillus subtilis by 0.67 magnitude orders. After the first cycle of intermittent HPCD treatment (held at 10 MPa for 10 min and then at 30 min for another 10 min), Bacillus subtilis spores were inactivated by 2.55 magnitude orders. Meanwhile, the combined effects of each of three combinations of germination inducers and different combinations of heating and subsequent HPCD treatment (30 ℃ plus 10 MPa or 30 MPa and 50 ℃ plus 10 MPa or 30 MPa) were investigated. The inducing effect of germination inducers at 10 MPa was not so obvious as at 30 MPa.
Texture Properties of Freshwater Fish and Their Correlation with Nutritional Components
HU Fen,LI Xiao-ding,XIONG Shan-bai,FU Na,WANG Hong-mei,YANG Xiao-bo,DU Wei-guang,NI Ping
2011, 32(11):  69-73.  doi:10.7506/spkx1002-6630-201111016
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Five common kinds of freshwater fish such as Ctenopharyngodon idellus Cuv. et val. (grass carp), Carassius auratus cuvieri (crucian carp), Hypophthalmichthys molitrix Cuv (silver carp), Cyprinus carpio Linn (carp) and Megalobrama amblycephala (blunt-snout) from Hubei province were selected to conduct the analysis of texture properties and nutritional components. The results indicated that five kinds of freshwater fish ranked in the order of grasp carp, carp, crucian carp, blunt-snout and silver carp according to muscle hardness. The hardness, springiness, adhesiveness and chewness of the muscle from the five kinds of freshwater fish exhibited an increase trend due to the growth of fish and the increase of body weight. The muscle springiness was positively correlated with the water content and negatively correlated with fat content. Principal component analysis was performed based on 7 parameters of textural profile analysis (TPA). Top 3 factors were selected and the cumulative contribution to variance was up to 94.62%. Muscle hardness and springiness were the dominant factors.
Investigation and Application of Quantitative Structure Property Relationship for the Migration of Esters Additives in PE Film
WANG Tian-rui,LI Mei-ping,ZHANG Sheng-wan
2011, 32(11):  74-78.  doi:10.7506/spkx1002-6630-201111017
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The migration of esters additives in PE film under the conditions of four different food stimulants (distilled water, 4% acetic acid, 20% ethanol and hexane) was explored by gas chromatography-flame ionization detector (GC-FID). The correlations between migration and initial content (c0) of esters additives, alcohol-water partition coefficient (lgP) of esters additives, topological index (Q0), polarity of food stimulants (Ps), temperature (T) and time (t) of migration were investigated, and a QSPR model was established. The correlation coefficient (R) for the established model and leave-one-out (LOO) cross validation coefficient (RLOO) were 0.9300 and 0.8950, respectively. Simultaneously, the stability of the established model were strictly analyzed by external validation and the Qext was 0.9282. Moreover, the actual application of the model was discussed. The results showed that the correlations between migration behavior and C0, lgP, Q0, Ps, T and t were significant and the established model revealed excellent stability and predictability. The proposed model can provide an important support to explore the migration of esters into packed foods.
Oxidative Stability of Purified DHA Oil from Schizochytrium sp.
GONG Dong-ping, CHEN Yuan-li, ZHANG Hong-man, HU Yao-chi, HUANG He
2011, 32(11):  79-82.  doi:10.7506/spkx1002-6630-201111018
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The oxidative stability of purified DHA oil from Schizochytrium sp. was studied. The change of fatty acid composition and minor components in DHA oil was determined by the multilayer chromatography. Methanol extract of DHA oil was also investigated for its 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenge activity. The oxidative stability of purified and non-purified DHA oil under light and Schaal oven conditions was monitored by measuring peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Results showed that DPPH radical scavenging ability of methanol extract and the oxidative stability of DHA oil decreased significantly after removal of minor compounds by methanol extraction.
Effect of High Pressure Carbon Dioxide and Ultra-high Pressure on Structure of Polyphenol Oxidase and Pectin Methylesterase
LIU Ye,ZHANG Chao,ZHAO Xiao-yan,HU Xiao-song
2011, 32(11):  83-87.  doi:10.7506/spkx1002-6630-201111019
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In order to investigate the mechanism of high pressure carbon dioxide (HPCD) and ultra-high pressure inactivating polyphenol oxidase (PPO) and pectin methylesterase (PE), SDS-PAGE, infrared spectroscopy, and fluorescence spectroscopy were applied to study the structural change of PPO and PE after the treatments. After HPCD and ultra-high pressure treatments for 60 min, the activity of PPO and PE decreased as the pressure ascent in the investigated range. SDS-PAGE analysis showed that no peptide chains were cut off, but according to the infrared and fluorescence spectral profiles the protein secondary and tertiary structures of the two enzymes were changed after the treatments. Hence, HPCD and ultra-high pressure inactivate PPO and PE through changing their advanced structures.
Changes in Meat Quality Characteristics of Goose Breast Muscle after Tumbling
SHI Pei-lei,MIN Hui-hui,LI Chun-bao,XU Xing-lian,ZHOU Guang-hong
2011, 32(11):  88-92.  doi:10.7506/spkx1002-6630-201111020
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The changes of meat quality characteristics of goose breast muscle after vacuum tumbling were investigated. Results showed that the pH value was increased significantly, while the L* value, a* value, cooking loss, pressing loss and muscle fiber diameter was decreased significantly; the sarcomere length showed an extremely significant increase, and the share force and the denatured temperature of three proteins measured by DSC were decreased extremely significantly. An extremely significant decrease in the muscle fiber diameter and a highly significant increase in the sarcomere length were observed. The values of b* was changed insignificantly. Fitting of the NMR data resulted in 3 water fractions, namely bound water, immobilized water and free water with respective transverse relaxation times of T2b, T21 and T22. After the tumbling, T23 disappeared, while T21 and T22 were increased significantly. The correlations among all the investigated indexes were significant or extremely significant. Hence, tumbling process can improve the quality of goose meat.
Enzyme Activities and Protein Composition of Henan Dairy Goat Milk
WANG Yu-qin,REN Guo-yan,YU Hong-ye,WANG Chao-li,QI Yan-xia,WU Qiu-jue,WANG Zhan-bin
2011, 32(11):  93-96.  doi:10.7506/spkx1002-6630-201111021
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The activities of four enzyme (γ-glutamyl transpeptidase, γ-GT; alkaline phosphatase, AKP; peroxidase, LP; amylase, AMY) in Henan dairy goat milk (a local variety of dairy goat in the west part of Henan province) was measured and the milk protein composition was determined by SDS-PAGE in this study. The results showed that the activities of r-GT, AKP, LP and AMY in colostrum and common milk of Henan dairy goat were 322.46 U/100 mL and 247.71 U/100 mL, 248.62 U/100 mL and 200.14 U/100 mL, 281.76 U/mL and 205.07 U/mL, and 71.20 U/100 mL and 22.15 U/100 mL, respectively. The activity of AKP was significantly higher in colostrums milk compared to common milk (0.01

Preliminary Study on Carbohydrate Metabolism during Maize Germination
LIU Juan,SHI Xiao-yuan,WANG Qing-nan,CHEN Qin-bin,CAI Lu,HAN Yong-bin
2011, 32(11):  97-102.  doi:10.7506/spkx1002-6630-201111022
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In this study, the maize variety Suyu 24 was used as the material for the investigation of the changes of main physio-biochemical reaction and carbohydrate components during germination. The results showed that as the germination proceeded, the content of dry matter decreased, and shoot length and germination rate increased at different degrees, respiratory intensity showed an increasing tendency, while soluble protein content reached the lowest level at the end of the 60th h and decreased by 39.47% compared to that of non-germinated control. The activities of α-amylase, β-amylase and total amylases gradually rose throughout the 108-h germination period and were 4.74, 16.82 and 14.41 times higher than those in non-germinated control at the end of the 60th h and 18.33, 69.77 and 59.58 times at the end of the 108th h. Under the function of amylases, the total starch content declined gradually and reached its minimum level at the end of the 60th h, which was 12.62% lower than that of non-germinated control; similarly, the amylose content displayed a general tendency to descend, and its values at the end of the 60th h was decreased by 3.19% compared to that of non-germinated control. The change trend of the DE value followed a decrease-increase-decrease pattern and a remarkable change was observed after the 36h h until the end of the germination, resulting in the maximum value 84 h after the beginning of the germination, which was increased by 13.71 times compared to that of non-germinated control. Correlation analysis of various parameters under investigation demonstrated that major physiological changes had a considerable effect on the composition of carbohydrates during the germination of maize.
Bioengineering
Mixed Fermentation of Meitauza by Actinomucor elegans and Zymomonas mobilis
XU Xi-lin,LI Ying-qiong
2011, 32(11):  103-106.  doi:10.7506/spkx1002-6630-201111023
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The mixed fermentation conditions of meitauza by Actinomucor elegans and Zymomonas mobilis were optimized by orthogonal array design based on the sensory evaluation of meitauza. The optimal fermentation process to achieve the highest sensory evaluation was steaming soybean residues for 15 min followed by inoculating 1.0 mL of 105 CFU/mL Actinomucor elegans suspension and 0.2 mL of 107 CFU/mL Zymomonas mobilis suspension into 100 g of steamed soybean residues for incubation at 28 ℃ for 3 days. During the fermentation process, the pH exhibited an initial increase from 5.12 to 8.40 and then a slow drop to 8.09, the content of amino nitrogen revealed a quick increase and then a slow drop and the total crude protein declined gradually. An obvious increase in hardness and chewiness of meitauza was observed during the whole fermentation process.
Comparison on Antioxidant Enzyme Activities in Six Strains of Nostoc commune
FENG Jia,WU Qin,LI Zhen,XIE Shu-lian
2011, 32(11):  107-109.  doi:10.7506/spkx1002-6630-201111024
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Objective: To compare antioxidant enzyme activities in 6 strains of Nostoc commune and screen the strain with higher stress resistance. Methods: Catalase (CAT) and ascorbate peroxidase (APX) were determined by spectrophotometry. Glutathione peroxidase (GSH-PX) was determined by DTNB staining method. Results: the highest activity of CAT was determined in Heyeping strain, which revealed a significant difference from the other five. In addition, Qiuqiangou stain revealed significantly higher activities of GSH-PX and APX than the other strains. Conclusion: Qiuqiangou strain has higher stress resistance than the other strains investigated on the basis of antioxidant analysis.
Preparation and Identification of Anti-idiotypic Antibody against Anti-okadaic Acid Monoclonal Antibody
LIN Chao,WANG Dong-xu,REN Hong-lin,LIU Zeng-shan,ZHOU Yu,LI Yan-song,YAN Dong-ming,WANG Li-qi,LU Shi-ying
2011, 32(11):  110-113.  doi:10.7506/spkx1002-6630-201111025
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Objective: In order to develop a toxin-free detection method for okadaic acid (OA) from the shellfish, an anti-idiotypic antibody against anti-OA toxin monoclonal antibody (McAb) was prepared and identified. Methods: F(ab’)2 fragment from anti-OA McAb that was massively produced by the mouse ascites method and purified by caprylic acid and saturated ammonium sulfate was prepared by pepsin cleavage. Japanese big-ear white rabbits were immunized with the F(ab’)2 fragment and then their sera were taken for determination of reactivity between serum antibodies and anti-OA McA by agar gel diffusion test, indirect ELISA and indirect competitive ELISA. Results: The anti-idiotypic antibody had positive reaction with anti-OA McAb and competitively inhibited the binding of anti-OA McAb with detection antigen (OA-OVA). Conclusion: The prepared anti-idiotypic antibody against anti-OA monoclonal antibody has inner image of OA antigen and can be used to replace OA toxin standard in ELISA.
Tolerance of Lactobacillus plantarum NCU116 in Stimulated Digestive Environments
XIONG Tao,SONG Su-hua,HUANG Jin-qing,HUANG Yin,XIE Ming-yong
2011, 32(11):  114-117.  doi:10.7506/spkx1002-6630-201111026
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The tolerance of Lactobacillus plantarum NCU116 in several stimulated human digestive environments such as artificial gastric fluid, artificial intestinal fluid, bile salt environment and high salt environment was investigated. The results showed that survival rates of Lactobacillus plantarum NCU116 were 32.62% and 45.76% after 3 h of incubation in artificial gastric fluid with pH 1.5 and pH 2.5, respectively, and a higher survival rate was achieved when the pH of artificial gastric fluid equaled or exceeded 3.5. After 4 h incubation in artificial intestinal fluid, the strain revealed a survival rate of 49.63%. The number of viable NCU116 cells after 24 hours of incubation in bile salt environment exhibited a downward trend as the concentration of bile salt increased from 0.03 to 1.00 g/100 mL, and remained higher than 107 CFU/mL at the highest bile salt concentration. The number of viable NCU116 cells after 24 hours of incubation in high-concentration NaCl environment slightly declined with increasing NaCl concentration from 1 to 8 g/100 mL, and was higher than 108 CFU/mL when the NaCl concentration was 8 g/100 mL. In summary, Lactobacillus plantarum NCU116 has excellent tolerance in artificial gastric fluid, artificial intestinal fluid, bile salt environment and high salt environment and will thus have promising application prospects in the food and healthcare food industries.
Establishment of Gompertz Model for the Growth and Inactivation of Aeromonas spp. in Pork
DONG Qing-li,ZENG Jing,DING Tian,ZHONG Yan-qian,LIU Rui
2011, 32(11):  118-122.  doi:10.7506/spkx1002-6630-201111027
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In order to predict microbial growth and inactivation of Aeromonas spp. based on Gompertz model, pork leg was disinfected by 80 ℃ sterile water, inoculated with Aeromonas spp., and then transferred into aseptic package for storage at the growth temperatures of 0, 4, 15, 25, 30 ℃ and 35 ℃ and inactivation temperatures of 40, 45, 50 ℃ and 55 ℃, respectively. The Gompertz model was applied to fit the growth curve and mirror image curve of thermal inactivation for Aeromonas spp., respectively. The judgment coefficient (R2), bias value (Bf) and accuracy (Af) were used to evaluate the established models. The results showed that the Gompertz model could describe microbial inactivation with a high R2.
Optimization of Process Conditions for Immobilizing Tannase by Corncob
FAN Chao,LI Ji-lie,WANG Hui,HAO Ju-xi,DING Li-xia,LI Zhong-hai
2011, 32(11):  123-128.  doi:10.7506/spkx1002-6630-201111028
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The process conditions for immobilizing tannase by modified corncob were explored. The Box-Behnken design and response surface methodology were used to optimize immobilization conditions of tannase by modified corncob. The results showed the optimal process conditions were enzyme-to-carrier ratio of 26:1, pH 6.8, immobilization time of 8.0 h and immobilization temperature of 36 ℃. Under the optimal conditions, the activity of immobilized enzyme was (16085 ± 5) U/g, the recovery rate of tannase activity was 44.68%. The optimal reaction pH and temperature of immobilized tannase were 4.5-5 and 60 ℃, respectively.
Effect of Natural Fermentation on Physico-chemical Characteristics of Yinmi Starch
YANG Chao,NAN Nan,FU Xiao-yan,CHEN Peng,XIE Bi-jun,SUN Zhi-da
2011, 32(11):  129-136.  doi:10.7506/spkx1002-6630-201111029
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In this paper, content changes of the major chemical components in Yinmi powder (prepared by fermentation, steaming, drying and grinding using glutinous rice as raw material) and fermentation supernatant during 15-day natural fermentation of rice were investigated, and the effect of traditional natural fermentation on characteristics of Yinmi starch granules, digestibility and intrinsic viscosity was explored. The results showed that during the natural fermentation period, the contents of crude fat and crude protein declined with the maximum amplitude of 22.95% and 63.10%, respectively with increasing fermentation time; similarly, the content of total free amino acids in Yinmi powders with different fermentation times was decreased to different extents compared to unfermented rice, and 5-day fermentation resulted in the highest decrease amplitude of 54.31%. During the early part of the fermentation period, the pH of fermentation supernatant was decreased from 6.44 on the first day to 4.44 on the fourth day as the fermentation time was prolonged, and then tended to stable after reaching 3.90 or so on the fifth day. Throughout the fermentation period, titratable acidity and total free amino acids in fermentation supernatant were increased while the content of soluble sugar was decreased. Yinmi powder contained more digestive starch than raw rice, and their solubility and swelling power had similar temperature dependent changes and ascended with increasing temperature. Under the observation of scanning electronic microscope (SEM), Yinmi starch granules revealed an adhesive form. Compared with original rice, the crystallinity and intrinsic viscosity of Yinmi starch declined.
Effect of Thermo-tolerant Xylanase from Thermophilic Geobacillus sp. PZH1 on the Quality and Shelf-life of Steamed Bread
WANG Shi-feng, LIN Kong-liang,QIN Xiao-pei,CHEN Xue-min,LIU Pei-pei,GUO Xiao-hu, ZHANG Bo
2011, 32(11):  137-140.  doi:10.7506/spkx1002-6630-201111030
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In this paper, the effect of thermo-tolerant xylanase from thermophilic bacterium Geobacillus sp. PZH1 on the quality and shelf-life of steamed bread was investigated. The results showed the thermo-tolerant xylanase significantly elevated the volume of steamed bread and improved its textural properties. Meanwhile, the xylanase restrained the bacterial growth and prolonged the shelf-life of steamed bread.
Construction and Transformation of Plasmid Containing Swollenin Gene for Lentinus edodes
LIU Yan,YAO Qiang,GONG Zhi-yuan,GAO Xing-xi,HAN Jian-dong,REN Peng-fei,ZHANG Xue-mei,REN Hai-xia,LI Jin,QU Ling
2011, 32(11):  141-145.  doi:10.7506/spkx1002-6630-201111031
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Swollenin can loosen cellulose and enhance its enzymatic hydrolysis. An expression plasmid containing swollenin(swo) gene was constructed and successfully transformed to Lentinus edodes by PEG-mediated transformation method with an efficiency of 1 transformant/μg plasmid DNA. PCR and Southern blot indicated that swollenin was successfully integrated to the genome of L. edodes. Both tested transformants of L. edodes can form fruit bodies and transformant II still revealed good cultivation characteristics. Transformation of swo gene into L. edodes can provide an exploration into breeding of new varieties of L. edodes.
Changes in Microbial Community Composition of Chilled Chicken during Storage
SUN Yan-yu,ZHOU Guang-hong,XU Xing-lian
2011, 32(11):  146-151.  doi:10.7506/spkx1002-6630-201111032
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The microbial community structure of chilled chicken during storage was studied by PCR amplification and denaturing gradient gel electrophorsis based on 16S rDNA. Activated sludge samples were collected from both chicken breast and drumstick. The total DNA was extracted and 16S rDNA was amplified by using a universal primer. The microbial community structure was analyzed by denaturing gradient gel electrophoresis and compared with the traditional culture. The traditional culture showed that no obvious difference in dominant microorganisms between chicken breast and drumstick was observed and the change trend of two curves was consistent. The DGGE pattern revealed that initial microorganisms with a large number of contaminants were not necessarily dominant spoilage bacteria; however, the microorganisnms that could adapt to the low-temperature and hypoxia environments developed to dominant spoilage bacteria. Moreover, an obvious difference between chicken breast and drumstick was detected. The dominant bacteria of traditional culture and DGGE were not exactly the same. Based on the determination by different methods, the bacteria of chilled chicken were lactic acid bacteria, Coliform, Brochothrix thermosphacta, Shewanella putrefaciens, Granulicatella adiacens and Carnobacterium sp.
Identification of Two Lactic Acid Bacterial Strains Isolated from Sichuan Pickles and Effect of Fermentation Conditions on the Quality of Pickles Co-fermented by them
AO Xiao-lin,ZHANG Xiao-ping,SHI Ling,ZHANG Xian-qin
2011, 32(11):  152-156.  doi:10.7506/spkx1002-6630-201111033
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Two lactic acid bacterial strains (Pickle-1 and Pickle-2) isolated from homemade pickles with good acid-producing capacity and special flavor were identified by 16S rRNA sequence analysis. Pickle-1 and Pickle-2 were identified as Lactobacillus fermentum and Lactobacillus plantarum, respectively. Both strains were combinedly used to make pickled radish by the method of artificial inoculation, and the effects of four culture factors including the ratio between them, total inoculation concentration, fermentation temperature and salinity on the quality of pickles were explored. The results indicated that fermentation temperature exhibited the strongest effect on the sensory quality of pickled radish, viable lactic acid bacteria and acid-producing rate, and the total inoculation concentration of Pickle-1 and Pickle-2 made the strongest contribution to nitrite.
Anti-microbial Activity of Fermentation Supernatants of Eurotium cristatum
LI Jia-lian,HU Bo-han,ZHAO Yong-biao,LIU Su-chun,JIANG Yue-jun,LIU Zhong-hua
2011, 32(11):  157-160.  doi:10.7506/spkx1002-6630-201111034
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The anti-microbial activities of hot water extract from Poria brick tea, PDA liquid medium and their fermentation supernatants by Eurotium cristatum against bacteria, fungi, mold and actinomycetes were determined by filter paper disc method. Meanwhile, the effects of factors including pH, temperature, UV on the anti-microbial activities of PDA fermentation supernatant were explored. The results indicated that both fermentation supernatants had an obvious anti-bacterial activity but no obvious inhibition effect against yeast and mold. Preliminary studies on the anti-microbial stability of the PDA fermentation supernatant showed that it had better stability under each of the following conditions: 40-120 ℃, UV irradiation for 10 h and pH 2-10.
Comparison of Different Cell Wall Disruption Methods for Yeast Total RNA Extraction
YI Yi,RONG Yuan-ping,CHENG Qian-wei,LI Ya,WANG Xiao-lin
2011, 32(11):  161-164.  doi:10.7506/spkx1002-6630-201111035
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Five methods such as liquid nitrogen grinding, repeated freeze-thawing, ultrasonic treatment, vortex shaking with glass beads and snailase hydrolysis were used to break the cell wall of yeast for the extraction of total RNA by the Trizol method. Based on total RNA concentration and purity, these methods were compared for their effects on total RNA extraction from yeast. The results showed liquid nitrogen grinding and repeated freeze-thawing were the most effective and convenient methods for total RNA extraction from yeast by Trizol.
Characterization of Microbial Community Structure in Daqu Starter Based on Biomarkers
QIN Zhen,ZHENG Jia,PENG Yu-wen,JIN Yang,HUANG Jun,ZHOU Rong-qing
2011, 32(11):  165-170.  doi:10.7506/spkx1002-6630-201111036
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A biochemical technique for characterizing the microbial community structure in Daqu starter was established on the basis of different biomarkers. The microbial community structure was characterized by using the content of phospholipid fatty acids (PLFAs) determined by GC-MS and the biomass of predominant microbial community in Daqu starter was estimated by the content of ergosterol. A total of 18 species of PLFAs were determined quantitatively in Daqu starter. The predominant PLFAs were 16:0, 18:2ω6,9 and 18:1ω9, which reached up to 90% of total PLFAs. The results showed that predominant microbial community in Daqu starter was fungi. According to the relative ratio between ergosterol content and fungal biomass in Daqu starter, fungal biomass in five kinds of Daqu starters was in the range of (110.45±4.60)-(218.47±11.19)μg/mg dry weight.
Physiological, Biochemical and Molecular Biological Identification of a Xylitol-producing Strain
QU Jia-le,MIN Wei-hong,WANG Qiao-ling,FANG Li
2011, 32(11):  171-175.  doi:10.7506/spkx1002-6630-201111037
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In this paper, an unreported strain (CTD249) with the capability of transforming xylose to xylitol was identified by physiological, biochemical and molecular biological methods. Meanwhile, a phylogenetic tree was constructed to analyze the genus which the strain CTD249 belongs to. The results indicated that the strain CTD249 and Pichia guilliermondii were in the same branch with more than 99% sequence similarity. This strain was identified as Pichia guilliermondii. With the initial xylose concentration of 20 g/L, the output of xylitol was up to 12.0 g/L after 48 h cultivation.
Synergistic Antibacterial Effect of Lysozyme with Cell Permeabilizers on Escherichia coli
YIN Jin-feng,SHI Feng,WANG Xiao-yuan
2011, 32(11):  176-180.  doi:10.7506/spkx1002-6630-201111038
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In order to enhance the antibacterial activity of hen egg white lysozyme against gram-negative bacteria such as Escherichia coli ATCC25922 and DH5α, the antibacterial effect of lysozyme combined with each or both of the permeabilizers glycine and ethylenediaminetetraacetate (EDTA-Na2) was analyzed, and the outer membrane permeability and cell surface morphology of E. coli were also examined. The results showed that ATCC25922 was more sensitive to lysozyme than DH5α and its outer membrane permeability was higher than that of DH5α. Due to the combinatorial application with glycine or EDTA-Na2, the antimicrobial activity of lysoyme against both E. coli strains was obviously improved, which indicated the synergistic antibacterial effect of lysoyme and each of the permeabilizers. 1-N-phenylnaphthylamine (NPN) uptake assay showed that the outer membrane permeability of E. coli strains was increased when the cells were treated with lysozyme supplemented with cell permeabilizers. TEM image of ATCC 25922 cells also revealed the synergistic effect of lysozyme supplemented with cell permeabilizers on damaging cell surface structure. Therefore, improving the outer membrane permeability of E. coli is helpful for enhancing the antibacterial effect of lysozyme on the bacterium.
Effect of Sodium L-Glutamate on Protein Expression ofγ-Aminobutyric Acid-Producing Lactobacillus brevis NCL912 under Acid Stress
HUANG Gui-dong,LI Chao-bo,CAO Yu-sheng,LI Hai-xing
2011, 32(11):  181-186.  doi:10.7506/spkx1002-6630-201111039
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Lactobacillus brevis NCL912 is aγ-aminobutyric acid-producing strain isolated from fermented vegetables. In the present study, protein expression in Lb. brevis NCL912 was investigated at the proteomic level and the effect of sodium L-glutamate (L-MSG) on protein expression was also explored under acid stress by two-dimensional gel electrophoresis, mass spectroscopy and bioinformatics. Eleven spots of 26 differential expressed proteins from the culture with L-MSG and 8 spots of 25 proteins from the culture without L-MSG were identified. The results showed that Lb. brevis NCL912 might launch the common acid resistance systems such as protein synthesis, glycometabolism and stress proteins to protect the cells against acid stress, which was irrelevant to L-glutamate. Meanwhile, exogenous amino acids might change the expression of some of the proteins which were involved in cell membrane formation and signal transduction in media with L-glutamate, thus benefiting the survival and growth of the cells. Therefore, the acid resistance-responsive system is a very complex network system, which is related to not only exogenous amino acids, but also the expression of bacterial proteins.
Breeding of a High Pullulan-producing Non-pigmented Mutant of Aureobasidium pullulans by UV-induced Mutagenesis
JIN Jian-zhong,WANG Hui-juan,KONG Wei-jia,GE Hai-tao,ZHANG Ning,LI Bing-xue
2011, 32(11):  187-191.  doi:10.7506/spkx1002-6630-201111040
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A non-pigmented mutant having enhanced ability to produce pullulan was successfully obtained using Aureobasidium pullulan NG as the original strain by UV-induced mutagenesis and was named as UVMU3-1. Compared with the original strain, the mutant strain UVMU3-1 displayed similar capability of growth and differentiation. The polysaccharide produced by the mutant strain was identified as pullulan by infrared spectroscopy. Tank fermentation experiments showed that the pullulan-producing capability of the mutant strain was higher than that of the original strain and that the 72 h cultivation of 200 mL of seed culture of the mutant in 5 L of YDA culture medium provided a glucose conversion of 52.78%. In conclusion, UVMU3-1 is a potential strain for pullulan production in industrial fermentation.
Breeding of a Cellulase-producing Trichoderma koningii Mutant Strain and Optimization of Its Fermentation Conditions
JIANG Shao-tong,WU Jin-chang,YANG Pei-zhou,PAN Li-jun
2011, 32(11):  192-197.  doi:10.7506/spkx1002-6630-201111041
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The parent strain Trichoderma koningii was implanted with N+ beam for breeding a mutant strain with the ability to produce cellulase. It was found that the curve of survival rate of the parent strain revealed a saddle shape and a high positive mutation rate in the treatment dose range of 10× 1014 to 12.5 × 1014 ions/cm2. Under the implantation conditions of 15 keV and 12.5 × 1014 ions/cm2, a high cellulase-producing mutant with excellent genetic stability was obtained and named as HF-6. The activity of cellulase in the screened mutant was roughly 0.217 U/mL, which was 52.82 % higher than the parent strain. Three main factors (fermentation conditions) that affect cellulase production by HF-6 including pH, medium volume in 250-mL shake flask and ammonium sulphate concentration were screened out of 8 factors by Plackett-Burman design. Response surface methodology was employed to optimize the three factors based on a three-factor, three-level Box-Behnken experimental design, which resulted in a mathematical model of filter paper activity (FPA) against the three factors. The optimum fermentation conditions were determined as follows: pH 5.75, 4.23 g/L ammonium sulphate and 63 mL of culture medium in 250-mL shake flask, respectively. Under these conditions, the experimental FPA activity in fermentation broth was 0.233 U/mL (an average of 3 replicates).
Optimization of Expression Conditions for Milk-derived Immune Peptides in E. coli BL21
HU Di,ZHANG Shao-hui
2011, 32(11):  198-203.  doi:10.7506/spkx1002-6630-201111042
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The target genes of 4 previously reported milk-derived immuno-modulating peptides were designed, and the prokaryotic expression plasmid pTYB11 with the target genes was then constructed and transformed into E. coli BL21 by recombinant DNA technique. Expression conditions such as IPTG concentration, expression temperature and expression time of the plasmid encoded milk-derived immune peptides in E. coli BL21 cells were optimized by orthogonal array design. The quantitative analysis of the fusion protein by 15% SDA-PAGE showed that the optimal expression conditions were the induction of IPTG at the concentration of 0.1-0.2 mmol/L, and expression temperature of 12-15℃ for 20 h. A 59.2 kD fusion protein was identified in Western Blotting and its expression amount was found to account for 40% of total proteins.
Immobilization ofβ-Galactosidase onto Epoxidized Dialdehyde Oxycellulose
GUO Qing-qi,ZHANG Na,FANG Gui-zhen
2011, 32(11):  204-208.  doi:10.7506/spkx1002-6630-201111043
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Epichlorohydrin and sodium peridate were used to conduct the epoxidation and dialdehyde oxidation of cellulose for preparing epoxidized dialdehyde oxycellulose. The prepared epoxidized dialdehyde oxycellulose was used as the carrier to immobilizeβ-galactosidase. Immobilization conditions and the enzymatic properties and microstructure of immobilizedβ-galactosidase were investigated. The results showed that the maximum activity of immobilizedβ-galactosidase was 0.528 U/g under the optimal immobilization conditions: 4 h immobilization time, pH 6.5 and 1:15 enzyme/carrier ratio (m/m). Compared with the freeβ-galactosidase, the optimal reaction temperature, thermostability and pH stability of immobilizedβ-galactosidase were increased. After the immobilization ofβ-galactosidase, it binding affinity towards substrate was also increased. In addition, the immobilizedβ-galactosidase remained 64% of its original activity after its 5th repeated use. Infrared spectrum and scanning electron microscope analysis showed that the epoxy group and aldehyde group of epoxidized dialdehyde oxycellulose could covalently react with amino groups ofβ-galactosidase to form immobilizedβ-galactosidase.
Screening of Lipid-producing Rhodotorula and Optimization of Its Fermentation Conditions
XU Zhen-jie,HU Rong,LI Zhen,CHENG Zi-zhang,HUANG Qian-ming
2011, 32(11):  209-215.  doi:10.7506/spkx1002-6630-201111044
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Eighteen Rhodotorula strains (SCAU 1 through 18) that can produce carotenoids were isolated from natural environment and subjected to preliminary screening with Sudan Black dye and further screening by shake-flask culture. As a result, strain SCAU-13 was found to have the highest lipid content of 14.63% and identified as Rhodotorula graminis. The strain was mutagenized respectively with UV light, diethyl sulfate (DES) and their combination, resulting in 13 mutants, and strain M124 containing the largest amount of lipids among the 13 mutants was screened out, which was 42.42% and 2.90 times as high as that of the original strain SCAU-13. Orthogonal array optimization showed that the optimal fermentation conditions for lipid production by strain M124 were glucose as carbon source, (NH4)2SO4 as nitrogen source, carbon-to-nitrogen ratio of 60:1, initial pH 6.0, peptone concentration of 1.8 g/L, yeast extract concentration of 4 g/L and MgSO4 ·7H2O concentration of 0.5 g/L. Under the optimal culture conditions, the cellular biomass and the lipid content of dry bacterial cells were (53.67 ± 0.17) % and (13.55 ± 0.10) g/L, respectively, and the yield of lipid (7.27 ± 0.03) g/L fermentation broth.
Mutation Breeding of an Erythritol-producing Moniliella acetoabutans Strain
LIU Peng,WANG Ze-nan,LI Ying,ZHANG Qiu-zi,WU Hong-yin
2011, 32(11):  216-221.  doi:10.7506/spkx1002-6630-201111045
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A genetically stable strain, named EW29, was obtained using Moniliella acetoabutans E54 as the starting strain by microwave- DES mutagenesis followed by screening by high osmotic plate culture and shake flask culture. The stain was further mutagenized by nitrogen ion implantation and then a strain EN59 was screened out of the resulting mutants by shake flask culture. The strain EN59 could produce 55.13 g/L erythritol after 90 h of fermentation, which was increased by 20.3% compared with EW29 and 36.9% compared with E54. The fermentation medium composition for EN59 was optimized to be 250 g/L glucose, 5 g/L yeast extract, 0.3 g/L KH2PO4, 0.04 g/L MnSO4 ·4H2O, 0.03 g/L CuSO4 ·5H2O and pH 4. The concentration of erythritol was over 69.00 g/L after 90 h fermentation under the optimal condition. The final concentration of erythritol reached up to 71.14 g/L after 126 h fermentation in 5 L fermentor.
Screening of Composite Fermentation Strains for Pickled Vegetable Commercialized in Northwest China
MENG Xian-gang,TANG Ying
2011, 32(11):  222-227.  doi:10.7506/spkx1002-6630-201111046
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Totally 53 strains were separated from fermented pickled vegetable commercialized in northwest China. Four excellent strains such as AC-5 with high acid-producing rate, Y7 with moderate mellow taste, L5 with 78.17% nitrite-degrading capacity and L8 with the highest acceptability for fermentation flavor were screened out by single strain fermentation, molecular identification, physiological and biochemical tests, acid production and nitrite degradation. These strains can provide highly effective fermentation for northwest pickled vegetable.
Optimization of Fermentation Conditions for Kombucha Tea
ZUO Yong,BIAN Ming-hong
2011, 32(11):  228-231.  doi:10.7506/spkx1002-6630-201111047
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The strains of lactobacillus, acetic acid bacteria and yeast isolated in laboratory were used together for the fermentation of Kombucha tea, and medium pH, dissolved oxygen concentration, temperature, and fermentation time were evaluated for their effects on Kombucha tea fermentation. The results showed that the optimal fermentation conditions were total inoculation amount of 5% (lactobacillus: acetic acid bacteria: yeast = 2:2:1, m/m), using traditional culture medium with 40% volume in the fermentation vessel, fermentation temperature of 30 ℃ and fermentation time of 5 d.
Cloning and Expression of Lipase Gene in S. cerevisiae and Its Characterization
ZHANG Wei-guo,WANG Xiao-ning,LIN Ying
2011, 32(11):  232-238.  doi:10.7506/spkx1002-6630-201111048
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Two lipase nucleotide sequences were cloned from DNA and total RNA of R. miehei 3.4960 by PCR and RT-PCR, respectively. The sequencing results showed that the nucleotide sequence from the DNA of R. miehei 3.4960 was composed of five introns and six extrons. The lengths of five introns were 75, 58, 64, 73 bp and 59 bp, which were located at the 600-674, 929-986, 1076-1139, 1227-1299 and 1382-1440 sites of nucleotide sequence, respectively. There were five-site mutations between the nucleotide sequence from total RNA of R. miehei 3.4960 and mRNA (EMBL Accession No. A02536) from R. miehei, which could result in one amino acid substitution. The RML gene was successfully expressed in S. cerevisiae MT8-1. The characteristics of RML showed that its optimal temperature and pH were 45 ℃ and 8.6, respectively. RML activity was inhibited by Cu2+ and Fe2+, and activated by Ca2+ and Mg2+. The RML activity was higher for substrates with long chains, especially a substrate with a chain length of C12, but it was very low for substrates with short chains.
Purification and Characterization of Cold-adapted Neutral Protease from Enterococcus faecalis RQ15
ZHU Wei-wei,LI Yang,ZHU Wan-qin,WANG Yan-hua,JI Bao-ying,SUN Cui-huan
2011, 32(11):  239-242.  doi:10.7506/spkx1002-6630-201111049
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The protease from Enterococcus faecalis RQ15 was characterized after purification with DEAE Sepharose Fast Flow and SuperdexTM 75. The molecular weight of the protease was determination by SDS-PAGE to be 32.4 kD. The optimal reaction temperature and pH of protease were 35-40 ℃ and 7.5, respectively. The protease was characterized to be a cold-adapted enzyme. It had more activity at 20-40 ℃ and a wide range of pH tolerance.The activity of the protease could be activated by Zn2+ but inhibited by Ag+, Hg2+ and EDTA-Na2 significantly. The Km and Vmax of the purified protease were 1.31 × 10-4 mol/L and 6.92×10-6 mol/(L ·s), respectively.
Enhancing Effect of Mutagenesis with He-Ne Laser Followed by NTG on Protease and Amylase Activities in Aspergillus oryzae
GE Jing-ping,CHEN Fang-bo,WANG Hai-man,CHAI Yang-yang,PING Wen-xiang
2011, 32(11):  243-247.  doi:10.7506/spkx1002-6630-201111050
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A protease- and amylase-producing strain named Aspergillus oryzae HDF-C14 was isolated from soybean paste and mutagenized with He-Ne laser combined with NTG. A mutant HDF-C14-HN5 was obtained and applied to the fermentation of soybean paste. The protease activity in the obtained sauce koji reached up to 1572.64 U/g and the amylase activity reached up to 2815.23 U/g. Thus, this strain can be used industrially.
Effects of Fengycin from Bacillus subtilis fmbJ on Respiratory Chain and Nutrients Utilization of Rhizopus stolonifer
TANG Qun-yong,ZHOU Xiao-hong,LU Zhao-xin,LU Feng-xia,WANG Yu-feng,BIE Xiao-mei
2011, 32(11):  248-254.  doi:10.7506/spkx1002-6630-201111051
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The effect of fengycin produced by Bacillus subtilis fmbJ on the respiration, mitochondrial NADH dehydrogenase activity, succinic dehydrogenase and nutrients utilization of Rhizopus stolonifer was studied in this paper. The results showed that fengycin mainly restrained the hexose monophosphate pathway. With the increase of fengycin concentration, the activity of NADH dehydrogenase was decreased in vivo, while kept stable in vitro. Both in vivo and in vitro, the activity of succinic dehydrogenase stepped down first and then went up with fengycin concentration. Furthermore, fengycin had an important impact on the utilization of carbohydrates and protein as well as protein synthesis in R. stolonifer. Therefore, fengycin could inhibit the respiratory metabolism and break the balance between anabolism and catabolism in R. stolonifer, subsequently inducing the pathological changes and growth inhibition.
Screening of Potential Symbiotic Lactic Acid Bacteria and Yeasts from Koumiss
LIU Min-min,HE Yin-feng
2011, 32(11):  255-259.  doi:10.7506/spkx1002-6630-201111052
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A total of 8 lactic acid bacteria (LAB) and 7 yeast strains that had previously been isolated from koumiss from Xilinguole region in Inner Mongolia of China were applied for potential symbiotic characteristic screening. Metabolites of LAB and yeasts were added interactively into their respective media in the treatment groups, while in the control groups the same volume of normal saline was used. The turbidity was monitored during the stationary phase. Three pairs of LAB (LC) and yeast (YE) with positive interaction were disclosed as follows: LC1 and YE3, LC4 and YE3, LC5 and YE4 , among which the positive interaction between LC5 and YE4 was highest (P <0.01). LC5 and YE4 co-cultured in skim milk medium showed an increased cell density compared to those obtained in separate culture. The further research showed that the growth of LC5 during fermentation was advanced by the addition of YE4 metabolites with increased titratable acidity and stable pH value. Likewise, the growth of YE4 was also enhanced by LC5 metabolites and the pH value was increased and almost reached the optimum value for yeasts.
Synthesis and Identification of Artificial Antigen for Melamine
SONG Gui-ping,ZHENG Hai-tao,HE Ji-guo
2011, 32(11):  260-264.  doi:10.7506/spkx1002-6630-201111053
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To develop an immunoassay for melamine residues, melamine hapten MEA and MEB were synthesized by the reaction between 2-Chloro-4,6-diamino-1,3,5-triazine and aminocaproic acid or p-aminobenzoic acid, respectively. Then two artificial antigens (MEA-BSA and MEB-OVA) were prepared by active ester method (AE) and mixed anhydride method (MA) respectively. Mass spectral analysis demonstrated the successful synthesis of MEA and MEB. Characterization of MEA-BSA and MEB-OVA was conducted by using UV spectrophotometric method. The numbers of hapten molecules per protein molecule estimated by ultraviolet spectrophotometry according to the absorbance at 253.5 nm for two conjugates were 25.28 and 13.11 respectively. The results suggested that the artificial antigens can be used for preparing specificity anti-melamine antibody.
Nutrition & Hygiene
Effect of Corn Peptides on Alcohol Dehydrogenase Activity in Live of Mice after Drinking and Its Anti-alcohol Mechanism
GUO Hui,HE Hui,HAN Ying,HUANG Wen-hao,ZHANG Xiao-bo
2011, 32(11):  265-269.  doi:10.7506/spkx1002-6630-201111054
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In order to explore the anti-alcohol mechanism of corn peptides (CP) on heavy-drinking mice, blood alcohol concentration (BAC) was determined by gas chromatography (GC), ADH activity in liver was detected by NAD+ method and the amino acid composition of CP was analyzed. The results showed that CP could activate ADH in liver in a dose-dependent way. CP at the dose of 600 mg/kg ·bw could significantly increase ADH activity in mice administered with alcohol (P < 0.01), result in an ADH activation rate of up to 30.1%, and remarkably reduce BAC in mice (P< 0.01). The scavenging rate of BAC was positively correlated with the dose of CP. The scavenging rate of BAC and the ADH activity in mice from CP group were remarkably higher than that in mice from alcohol model group after the administration of alcohol for 20-200 min. Compared with the model group, the scavenging rate of BAC in mice from the CP group was significantly different during alcohol administration for 20-120 min (P< 0.05 or P< 0.01). Amino acid analysis showed that CP had high hydrophobicity. The highest hydrophobic fraction was the most potent hydroxyl radical scavenger with scavenging rate of 83.05%. Therefore, CP can continuously activate ADH in liver, which likely to be related to hydrophobic short peptides in corn.
Anti-thrombosis Effect of Rose Essential Oil
SHE Wen-bo,GAN Lu,AN Xiao-jing,MA Jian-hui,CHEN Hong,ZHENG Qiu-sheng,WANG Zhen-hua
2011, 32(11):  270-272.  doi:10.7506/spkx1002-6630-201111055
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Objective: To investigate the effect of rose essential oil on whole blood platelet aggregation and arteriovenous shunt thrombosis in rats. Methods: The platelet aggregation in whole blood samples from rats was induced by adenosine diphosphate (ADP), calcium ionophore (A23187) and CaCl2, respectively. The inhibitory effect of rose essential oil at the doses of 25, 50 mg/L and 100 mg/L on platelet aggregation was measured by electric resistance method in vitro. Fifty male Wistar rats were randomly divided into 5 groups including the control group, aspirin positive control group and three groups respectively administered with rose essential oil at the doses of 25, 50 mg/kg and 100 mg/kg. After oral administration of aspirin or rose essential oil once daily for 3 consecutive days, the effect of rose essential oil on thrombosis were explored by arteriovenous shunt thrombosis method. Results: Rose essential oil could significantly inhibit platelet aggregation induced by ADP, A23187 or CaCl2 in vitro and the arteriovenous shunt thrombosis in vivo in a dose-dependent manner. These results demonstrated that rose essential oil had strong anti-platelet aggregation and anti-thrombosis activity in vitro and in vivo.
Effect of Lactosucrose on Chyme Metabolites in Rats with Colitis
ZHOU Yan,PENG Zhang-zhi,RUAN Zheng,YIN Yu-long,,LI Ling,HUANG Xiao-liu,ZHANG Cui
2011, 32(11):  273-276.  doi:10.7506/spkx1002-6630-201111056
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Objective: To explore the effect of lactosucrose on hime metabolites in established rat model with ulcerative colitis. Methods: TNBS was used to induce ulcerative colitis in rats, and the obtained ulcerative colitis rats were randomly divided into 4 groups including the normal group, model control (MC) group, lactosucrose (LS) group and sulfasalazine (SASP) group. The last two groups were orally administered 2 mL of normal saline containing 250 mg/kg LS and normal saline containing 250 mg/kg SASP for 21 consecutive days, respectively. The normal and model groups were given the same volume of normal saline. All the mice were killed after 24 hours of fasting after the last administration. The short chain fatty acid contents, pH and NH3-N in cecum and colon were determined. Results: Compared with the NC group, a significantly decreased acetic acid and butyric acid in cecum and colon, a significantly declined propionic acid in colon and a significantly increased pH and NH3-N were observed in MC group (P < 0.01); Compared with MC, when the rats treated with LS, acetic acid (P < 0.05) and butyric acid (P < 0.01) in cecum were significantly increased; pH (P<0.05) and NH3-N (P < 0.01) were significantly decreased; NH3-N in colon were significantly decreased (P < 0.05). Conclusion: LS can be used as a functional food with potential therapeutic effect on colitis. The mechanism for relieving the injury of colon tissues in colitis may be due to the increased content of butyric acid and decreased content of NH3-N in the intestinal tract.
ffect of Active Polysaccharide Fraction from Agaricus blazei Murill on Mouse Macrophages
JIA Wei, FAN Hua
2011, 32(11):  277-280.  doi:10.7506/spkx1002-6630-201111057
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Agaricus blazei Murill (ABM) is rich in polysaccharides, and has obvious treatment and prevention efficacy for cancers. A bioactive polysaccharide fraction (ABMB3) was isolated from hot water extract of A. blazei fruit bodies and purified by ethanol precipitation, anion-exchange and gel filtration chromatography. Phase-contrast microscopic observations revealed that the size of mouse macrophages was increased after exposure to ABMB3. ABMB3-activated macrophages could secret TNF-α and IL-1β, and produce a large amount of NO in vitro. Meanwhile, the capacity of the cells for phagocytizing latex beads was also significantly increased. Moreover, ABMB-3-induced activation of mouse macrophages in the presence of L929 tumor cells for 48 h could result in an increased percentage of phagocytes target cells when compared with untreated controls. Therefore, ABMB3 alone had no effect on the growth of L929 cells.
Effect of Different Doses of Apple Dietary Fiber on Blood Glucose in Diabetic Mice and Blood Lipid in Hyperlipidic Mice
LI Han-chen,WANG Jin-xia,MENG Jun,LIU Su-wen,LI Jun
2011, 32(11):  281-283.  doi:10.7506/spkx1002-6630-201111058
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In order to explore the effect of apple dietary fiber on blood glucose level in diabetic mice and blood lipid level in hyperlipidic mice, apple dietary fiber at 4%, 2% and 1% doses was added to a basal diet for ICR mice with diabetes and to a high-fat diet for normal ICR mice, respectively. In the hypoglycemic evaluation of apple dietary fiber, ICR mice with diabetes fed the basal diet without added apple dietary fiber served as a model control group. The normal control and model control groups used for the hypolipidemic evaluation were given the basal diet and high-fat diet, respectively. Blood glucose and blood lipid of all the mice were determined at the end of the hypoglycemic and hypolipidemic treatments. The results indicated that the blood glucose level of the diabetic mice administered with apple dietary fiber at low doses did not exhibit an obvious decrease; however, the blood glucose was obviously inhibited in the mice administered with apple dietary fiber at the dose of 4% compared to the model control group. Meanwhile, apple dietary fiber at the dose of 4% also could effectively decrease serum total cholesterol (TC) and atherosclerosis index (AI) although it is difficult to decrease to normal level. On the other hand, apple dietary fiber at the high dose could result in the reduction of serum triglyceride to the normal level. Conclusion: Apple dietary fiber at the high dose level of 4% can reduce the blood glucose and blood lipid, but it does not reveal an obvious effect at the low dose level.
Effect of Polysaccharide PGEB-3-H from Gastrodia elata Blume on Short Chain Fatty Acids in the Intestinal Tract of Rats
LING Bo,ZHAO Guo-hua, MING Jian
2011, 32(11):  284-287.  doi:10.7506/spkx1002-6630-201111059
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In this paper, the effect of polysaccharide PGEB-3-H on short chain fatty acids in the intestinal tract of rats was investigated. SD rats were used as experimental models and administered with PGEB-3-H at high, medium and low doses (400, 200 mg/(kg ·d) and 100 mg/(kg ·d) for 4 consecutive weeks. The stool samples of rats were collected at the designed time points. The short chain fatty acids in the intestinal tract of rats were analyzed by gas chromatography. Results indicated that polysaccharide PGEB-3-H had an obvious effect on the production of ethanoic acid, propionic acid, butyric acid, isobutyric acid, valeric acid and caproic acid; in contrast, it did not reveal an obvious effect on the production of isovaleric acid and heptanoic acid. Meanwhile, different administration doses of PGEB-3-H also revealed different effects on short chain fatty acids. An obvious effect on the production of short chain fatty acids was observed in the medium and low dose groups of PGEB-3-H. The highest level of short chain fatty acid production in the intestinal tract of rats was observed in the period of 7-14 d after the administration of PGEB-3-H.
Monosaccharide Composition Analysis of Two Polysaccharide Fractions from Ganoderma lucidum and Their Effects on inhibiting Tumor Growth in Mice by 5-Fluracil
LIU Yan-fang,TANG Qing-jiu,ZHANG Jin-song,YANG Yan,ZHOU Shuai,WU Di,JIA Wei,FENG Na
2011, 32(11):  288-291.  doi:10.7506/spkx1002-6630-201111060
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Objective: To analyze the monosaccharide composition of two polysaccharide fractions from Ganoderma lucidum, and then explore their effects on inhibition of tumor growth in mice by 5-fluracil (5-FU). Methods: Polysaccharide fractions named as BW and GLB were separated from the fruit bodies of Ganoderma lucidum by DEAE-Sepharose Fast Flow column, macroporous resin adsorption and ultrafiltration. The monosaccharide composition of both polysaccharide fractions was comparatively analyzed by high performance anion exchange chromatography. Tumor-bearing mice were treated with BW or GLB coupled with 5-FU. Tumor inhibition rate and immune index were determined. Results: The polysaccharide contents of BW and GLB were 54.28% and 51.64%, respectively. The major monosaccharide components in both extracts were fucose, galactose, glucose and mannose. The contents of glucose and mannose in GLB were much higher than those in BW. Meanwhile, the combinatorial treatment for tumor in mice using BW and 5-FU could obviously improve the inhibition rate for tumor growth compared with the single treatment of 5-FU. However, GLB could antagonize 5-FU-induced bone marrow cell reduction in mice. Conclusion: BW combined with 5-FU could improve the anti-tumor effect of 5-FU, and GLB combined with 5-FU could decrease the toxicity of 5-FU on bone marrow cells.
Bioavailability Study of Microbial Calcium Produced by Co-fermentation of Lactobacillus rhamnosus and Lactobacillus acidophilus
WAN Ting-ting,LUO Ai-ping,YIN Yan-yang,LIU Hai,TANG Ying-ying
2011, 32(11):  292-295.  doi:10.7506/spkx1002-6630-201111061
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Bioavailability of calcium preparations is an important indicator for evaluating calcium absorption efficiency. In order to evaluate bioavailability of a microbial calcium from co-cultured Lactobacillus rhamnosus and Lactobacillus acidophilus in bovine bone power medium, KM mice fed feed containing different calcium sources and contents were used as the model to determine feed consumption, fecal calcium, urinary calcium, bone calcium and blood calcium, and calculate the absorption rate and retention rate of calcium. Meanwhile, the bioavailability of the microbial calcium was compared with that of calcium carbonate at identical doses. The results indicated that the bone calcium content in the microbial calcium group at low or standard dose revealed a significant difference when compared with the calcium carbonate agent at the same dose (P < 0.05). An obviously higher apparent absorption rate of the microbial calcium was observed when compared with calcium carbonate group (P < 0.01). No obvious difference in blood calcium level between the microbial calcium group and calcium carbonate group was observed although the blood calcium level was higher in the microbial calcium group (P > 0.05). Therefore, the microbial calcium is an ideal calcium preparation with high biological activity and bioavailability.
Sedative and Hypnotic Effects of Water-soluble Alkaloids from Male Flowers of Eucommia
LI Xin,LIU Yan,ZHU Wen-xue,GUO Han,LIU Shao-yang
2011, 32(11):  296-299.  doi:10.7506/spkx1002-6630-201111062
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Objective: To explore the sedative and hypnotic effects of different doses of water-soluble alkaloids from male flowers of Eucommia. Methods: Water-soluble alkaloids were extracted from Eucommia male flowers by an acidic water extraction method, their effect on spontaneous activities of mice, hypnotic function with and without the presence of pentobarbital sodium and anticonvulsant effects were investigated at different doses. Results: Water-soluble alkaloids from Eucommia male flowers could decrease the frequency of spontaneous activities, significantly increase sleeping ratio below the threshold dose, prolong the sleeping time and shorten the sleeping latency. Meanwhile, these alkaloids also could effectively reduce the eclamptic ratio of the mice and significantly prolong the convulsion latency. Conclusion: Water-soluble alkaloids of Eucommia male flowers have obviously sedative and hypnotic effects in mice and there is a synergistic effect between them and pentobarbital sodium.
Fatigue-alleviating Effect of Peptides from Porcine Blood
HU Bin,CHEN Yi-zi
2011, 32(11):  300-305.  doi:10.7506/spkx1002-6630-201111063
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Objective: To investigate the fatigue-alleviating effect of peptides from porcine blood (PPB). Methods: Totally 200 male Kunming mice were randomly divided into one control group and three test groups. The mice from the control group were administered intragastrically with distilled water, and the mice from three test groups were administered intragastrically with PPB at doses of 0.83, 1.70 g/kg and 3.33 g/kg for 30 consecutive days. At 30 min after the last administration, loaded swimming time and anti-hypoxia survival time of the mice were recorded. The fatigue indices including red blood cell number, hemoglobin content, hepatic glycogen, muscle glycogen, blood urea nitrogen (BUN), blood lactate of the mice were assayed. Then, 32 more male Kunming mice were divided into one control group and one test group. The control group and the test group were administered intragastrically with distilled water and PPB at the dose of 1.70 g/kg for 30 consecutive days, respectively. At 30 min after the last administration, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), nitric oxide synthase (NOS), lactate dehydrogenase (LDH), creatine kinase (CK), and the contents of malondialdehyde (MDA) and nitric oxide (NO) were measured. The skeletal and cardiac muscles were subjected to histopathological examination. Results: PPB could significantly prolong the loaded swimming time and anti-hypoxia survival time of the mice, and obviously increase the number of red blood cells and the contents of hemoglobin, hepatic glycogen and muscle glycogen as well as the activities of SOD and GSH-Px, decrease the activities of NOS, LDH and CK, and the contents of BUN, MDA, NO and LA. PPB had obvious protective function against exercise-induced damage of skeletal and cardiac muscles. Conclusion: PPB has obvious fatigue-alleviating effect at the optimal dose of 1.70 g/kg. Its anti-fatigue effect is correlated to enhanced antioxidant enzyme activities (resulting in the alleviation of skeletal and cardiac muscle damages caused by excess free radicals generated after endurance exercise for a long time), reduced occurrence of central fatigue following the production of excess NO as a result of lower activity of NOS and enhanced aerobic metabolism capacity in the body.
Effect of Phytosterol on Blood Lipid in Hyperlipidemia Rats
ZHANG Ze-sheng,HOU Dong-mei,HE Wei,WANG Jing-yi
2011, 32(11):  306-309.  doi:10.7506/spkx1002-6630-201111064
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Objective: To explore the effect of phytosterol on lowering blood lipid in vivo. Methods: The experimental animals were divided into 5 groups including the control group fed with a basal diet, model group given with a high-fat diet and three intervention groups administered with phytosterol at does of 0.5%, 1.0% and 2.0%. Hyperlipidemic indicators were tested. Results: Total cholesterol (TC), triglyceride(TG) and non-high density lipoprotein cholesterol (non-HDL-C) exhibited a significant decrease and high density lipoprotein cholesterol (HDL-C) revealed an obvious increase in a dose-dependent manner in rats from the intervention groups. However, the model group exhibited opposite results. The activity of cholinesterase (CHE) was decreased in plasma and liver in the model group, but the CHE activity in the intervention groups was improved. Conclusion: Phytosterol has obvious effect on lowering blood lipid and inhibiting lipid peroxidation, thereby having hepatoprotective effect.
Anti-fatigue and Anti-hypoxia Functions of Degreased Peptides from Antarctic Krill in Mice
XU Kai,LIU Yun,WANG Ya-en,LI Li-de,JIANG Guo-liang
2011, 32(11):  310-313.  doi:10.7506/spkx1002-6630-201111065
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Objective: To explore the anti-fatigue and anti-hypoxia effect of degreased peptides from Antarctic krill in mice. Methods: The mice were randomly divided into four groups including the control group administered with water and three experimental groups administered with degreased peptides from Antarctic krill at doses of 0.2, 1.0, 5.0 g/(kg ·d) for 28 consecutive days, respectively. The swimming time and the contents of lactic acid (LA), blood urea nitrogen (BUN) and lactate dehydrogenase (LDH) in serum, liver glycogen, survival time and oxygen consumption in hypoxia tolerance test, survival time after sodium nitrite poisoning were determined. Results: The degreased peptides from Antarctic krill at high dose could improve the swimming time, serum LDH activity, lactate clearance rate and the content of liver glycogen and decrease BUN in serum. Meanwhile, these degreased peptides at high dose could also increase the survival time in both hypoxia tolerance test and sodium nitrite poisoning experiment. Conclusion: The degreased peptides from Antarctic krill can eliminate fatigue and increase anti-hypoxia capacity in vivo. These investigations will have a significant impact on human health care.
Chemical Evaluation of Nutritional Values for Proteins from Majiagou Celery Leftover Pieces
ZHAI Er-lin,LI Chun-yan,CHI Yi-xian,CHI Cui-cui,ZHUANG Gui-dong,CHI Yu-sen
2011, 32(11):  314-317.  doi:10.7506/spkx1002-6630-201111066
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Based on the analysis of protein content and amino acid composition in Majiagou celery leftover pieces (stems, leaves and other wastes left after the processing of Majiagou celery for fresh-cut vegetables), their nutritional values were comprehensively evaluated by amino acid score. The results indicated that proteins from Majiagou celery leftover pieces were rich in essential amino acids, and the first limiting essential amino acid was tryptophan. The IEAA was 95.88 by comparing with the ideal protein model recommended by FAO/WHO. According to the amino acid balance of proteins, proteins from Majiagou celery leftover pieces can be considered as fine vegetable proteins that deserve to be exploited.
Reviews
Recent Progress of Research on Gamma-Glutamyltranspeptidase in Saccharomyces cerevisiae
ZHANG Yuan-yuan,ZHENG Fei-yun,LI Yong-xian,LI Qi,GU Guo-xian
2011, 32(11):  318-323.  doi:10.7506/spkx1002-6630-201111067
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The current status of the research on γ-glutamyltranspeptidase (γ-GT) in Saccharomyces cerevisiae is presented in this paper, especially the structure and catalytic mechanisms of γ-GT. γ-GT highly affects the amount of intracellular glutathione in Saccharomyces cerevisiae cells, and plays an important role for the detoxication, resistance to environment stress, and amino acid transportation in S. cerevisiae. Now γ-GT also contains important significance in clinical medicine and the fields of agriculture and industry.
Exposure Assessment Methods for Hazardous Materials in Bee Products
WU Li-ming,LI Yun,YU Lin-sheng
2011, 32(11):  324-328.  doi:10.7506/spkx1002-6630-201111068
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Based on the honey bee industry in China and the characteristics of honey bee products, this article puts forward the dietary exposure assessment techniques for hazardous materials from the aspects of data (mainly relevant to the content and consumption data) and methods (tires exposure methods, including simple point estimation, complex point estimation, and probability estimation), in order to provide a reference for further studies on exposure assessment.
Research Progress on Structure-antitumor Activity Relationship of Polysaccharide and Its Mechanism
XIE Hao-gui,CHEN Mei-zhen,ZHANG Yu-qiang
2011, 32(11):  329-333.  doi:10.7506/spkx1002-6630-201111069
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Polysaccharides are a class of macromolecules widely found in plants, animals and microorganisms, with various bioactive activities, including immunomodulatory, antitumor, hypoglycemic, antiviral, and antioxidant etc. Among a number of biological activities, the antitumor effect is relatively clear. This article focuses on the research progress on the structure-antitumor activity relationship and its mechanism of polysaccharides at home and abroad in recent years.
A Review of Detection Methods for Microbial Toxins in Foods
LI Xiao-bei,OU Jie,WANG Jing
2011, 32(11):  334-339.  doi:10.7506/spkx1002-6630-201111070
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Microbial toxin in food products usually refers to the toxin produced by microbial metabolism. It includes peptide toxins, lipopolysaccharide (LPS), mycotoxins, biogenic amines and aldehyde compounds from fatty acid oxidation. This paper briefly introduces partial detection technologies at home and abroad, including polymerase chain reaction (PCR), enzyme linked immunosorbent assay (ELISA), high performance liquid chromatography (HPLC), solid-phase microextraction-gas chromatography-mass (SPME-GC-MS), solid-phase microextracton-gas chromatography-olfactometry (SPME-GC-O), etc. The detection technologies are comprehensively evaluated for their features and suitable conditions. Moreover, the recent progress of the research is summarized on their application for detecting several common microbial toxins.