• Volume 32,Issue 12,2013 Table of Contents
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    • Advances on Application of 1-Methylcyclopropene for Postharvest Storage of Mango Fruit

      2013, 32(12):1233-1243. DOI: 10.3969/j.issn.1673-1689.2013.12.001

      Abstract (543) HTML (0) PDF 734.24 K (2471) Comment (0) Favorites

      Abstract:Mango is a typical climacteric fruit that is very sensitive to ethylene. 1-MCP(1-methylcyclopene) is a new ethylene action inhibitor,which can occupy ethylene receptor irreversibly,and then blocks the normal combination of ethylene to combine on the receptor,inhibits a series of physiological and biochemical reactions associated with fruit ripening,thus delays fruit senescence and maintains fruit quality during postharvest storage. This review focuses on the mechanism and effect of 1-MCP on postharvest ripening of mango fruit,including biochemical and physiological indices such as respiration rate,ethylene production output,fruit quality and physiological disorders etc. At the same time,application of 1-MCP structural analogues and 1-MCP in combination with other preservation methods are also introduced. The foreground in application of 1-MCP is prospected to provide references for the application and research of 1-MCP on mango postharvest handling and storage.

    • Cloning and Bioinformatics Analysis of Epoxide Hydrolase Gene from Aspergillus usamii

      2013, 32(12):1244-1252. DOI: 10.3969/j.issn.1673-1689.2013.12.002

      Abstract (655) HTML (0) PDF 1.42 M (1688) Comment (0) Favorites

      Abstract:Epoxide hydrolase can be effectively used in the resolution of epoxides for producting optically active epoxides and vicinal diols. A gene encoding a novel epoxide hydrolase from Aspergillus usamii E001 was cloned by using reverse transcription PCR and newly constructed Thairpin structure-mediated PCR amplification(THSO-PCR) techniques. The cloned gene(named Aueh2) is 2,481 bp in length,harboring 5′ and 3′ flanking regulatory regions and the encoded cDNA sequence interrupted by six introns. The open reading frame of Aueh2 encodes a protein of 395-aa(designated AuEH2) with the calculated molecular weight of 44.6 kD. The primary structure analysis of AuEH2 demonstrated that it is a hydrophilic protein,and belongs to the α/β hydrolase fold family. The structure of AuEH2 displays that the catalytic center is situated between the α/β core domain and the lid domain with a catalytic triad consisting of Asp191,His369,and Glu343. The results will lay a foundation for further research of the AuEH2 and its application in depth.

    • Effect of Dissolved Oxygen Level on the Rheological Properties of Curdlan Fermented by Agrobacterium sp. ATCC 31749

      2013, 32(12):1253-1260. DOI: 10.3969/j.issn.1673-1689.2013.12.003

      Abstract (515) HTML (0) PDF 659.31 K (1554) Comment (0) Favorites

      Abstract:Curdlan is a water-insoluble extracellular polysaccharide produced by Agrobacterium sp. under nitrogen-limited condition. A strategy was established to maintain a constant dissolved oxygen(DO) level by real-time control of the air ventilation volume. The DO levels kept stable at 5%, 25%,50% and 75%,respectively,during curdlan-producing period. Afterwards,the effects of DO level on the fermentation of A. sp. ATCC 31749 and curdlan rheological properties were investigated. The results indicated that curdlan productivity decreased remarkably at DO 5%, whereas the curdlan specific production rate kept constant when DO level was more than 25%. Furthermore,the pseudoplastic fluid pattern was observed in curdlan-alkali solution. The viscosity of curdlan solution increased rapidly along with the fermentation time,and the non-Newtonian fluid behavior turned more obvious. At the same fermentation time,the curdlan solution reached the highest viscosity at DO 25%,while the viscosity decreased both at DO 5% and 75%. It was concluded that curdlan products with different rheological properties can be prepared by controlling of the dissolved oxygen level.

    • Analysis of Selenium Speciation in the Selenized Yeasts by RPLC-ICP-MS

      2013, 32(12):1261-1265. DOI: 10.3969/j.issn.1673-1689.2013.12.004

      Abstract (474) HTML (0) PDF 550.45 K (1606) Comment (0) Favorites

      Abstract:The aim of this study is to detect the selenium speciation in the selenized yeasts. For this,to hydrolyze the proteins in the selenized yeasts through enzymatic digestion and to extract various amino acids composed the proteins in the yeats,the selenized amino acids were mensurated by reverse phase ion pair liquid chromatography and inductively coupled plasma and mass spectrometer(RPLC-ICP-MS),then the species of the selenized amino acids were confirmed. It was found that Selenomethionine was confirmed primary speciation of selenized amino acids in thesolutions of proteins hydrolyzed by enzyme through comparing the retention time of the amino acids with standard selenized compounds in the chromatography column. Conclusion:The method to extract the amino acids from proteins hydrolyzed by the enzyme and determination technology of RPLC-ICP-MS were suitable for analysis of selenium speciation in the selenized yeasts.

    • Protective Effects of Soy Isoflavones and Saponins on Acute Liver Injury Induced by Acetaminophen in Mice

      2013, 32(12):1266-1269. DOI: 10.3969/j.issn.1673-1689.2013.12.005

      Abstract (390) HTML (0) PDF 378.91 K (1451) Comment (0) Favorites

      Abstract:The protective effect of soy isoflavones and saponins on acute liver injury induced by acetaminophen(APAP) in mice was investigated in this manuscript. The mice were randomly assigned to the normal control,model control,soy isoflavone,saponin and bifendate(positive control) groups. Animals were treated once daily for 7 days. APAP were given intraperitoneally to the mice of groups,then the alanine aminotransferase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP),albumin(ALB),inducible nitric oxide synthase(iNOS),nitric oxide(NO),lipid hydroperoxide(LOOH),malondialdehyde(MDA),glutathione(GSH),catalase(CAT),glutathione peroxidase(GSH-Px) and superoxide dismutase(SOD) were detected by the colorimetric method. The administration with soy isoflavones and saponins could(1) reduced the serum ALT,AST and ALP;(2) increased the serum ALB level;(3)decreased hepatic iNOS activity and NO level,(4) decreased the hepatic LOOH and MDA contents,and(5)increased the CAT,GPx,SOD activities and GSH level of liver in mice with acute liver injury. Those results demonstrated that soy isoflavones and saponins have protective effects on acute liver injury induced by APAP in mice, probably via anti-inflammatory and nti-oxidative activities.

    • CS/MnS Composite Film Synthesized by a Template-Mediated Route

      2013, 32(12):1270-1273. DOI: 10.3969/j.issn.1673-1689.2013.12.006

      Abstract (717) HTML (0) PDF 387.70 K (1180) Comment (0) Favorites

      Abstract:Chitosan(CS)/MnS composite film was prepared by a template- mediated route. Its structure was characterized by infrared spectra analysis(IR).The surface morphology of the CS/MnS composite film was examined using a scanning electron microscope. UV-Vis spectra were used to characterize the size of MnS was about 50 nm. This TGA/DSC result indicated that a strong and uniform interaction between chitosan and nanoparticles.

    • Study on Substrate Specificity of Aminopeptidase from Recombinant Bacillus subtilis and the Cooperative Hydrolysis of Corn Protein

      2013, 32(12):1274-1280. DOI: 10.3969/j.issn.1673-1689.2013.12.007

      Abstract (980) HTML (0) PDF 529.80 K (1734) Comment (0) Favorites

      Abstract:The substrate specificity of aminopeptidase from the recombinant Bacillus subtilis was investigated by employing nine types of p-nitroanilide derivatives of amino acids as substrates. The results indicated that the aminopeptidase shows the highest acitivity for Leu-pNA,whose amino acid moiety is hydrophobic leucine. The enzyme also shows high hydrolytic activity to Arg-pNA and Lys-pNA,whose amino acid moieties are basic amino acids. Followed are Ala-pNA,Ile-pNA,ValpNA,Phe-pNA and Pro-pNA,which contain hydrophobic amino acid moiety. However,Glu-pNA which contains acidic amino acid moiety can hardly be hydrolyzed. Then the hydrolysis of corn protein was carried out by the combination of aminopeptidase and endoprotease. With the hydrolysis degree as index by using the single factor experiment,aminopeptidase combined with alkaline protease obtained high efficiency:(1) The content of free amino acid was 4.89 times and 6.05 times than that of alkaline protease aminopeptidase was used alone,respectively.(2)The molecular weight of the peptides was mostly less than 1 000 Da,14.57% is within 500 ~1 000 Da,and 68.42% is within 180~500 Da.(3)The hydrolysis degree was 65%. These results suggested that aminopeptidase combined with alkaline protease hydrolyzes protein raw material.

    • Study on Ultrasonic-Assisted Desugar of Red Bayberry Juice Concentrated

      2013, 32(12):1281-1286. DOI: 10.3969/j.issn.1673-1689.2013.12.008

      Abstract (511) HTML (0) PDF 490.83 K (1611) Comment (0) Favorites

      Abstract:In this manuscript,the process of ultrasonic-assisted desugar of the concentrated red bayberry juice was studied.The single factor test and the orthogonal test were used to study the effect of 85% ethanol content,ultrasonic power,ultrasonic treatment time and alcohol precipitation time on the removal rate of the total sugar in the red bayberry juice.The results showed that the primary and secondary factors are as follows:85% ethanol content >ultrasonic power >alcohol precipitation time>ultrasonic treatment time.The optimum process parameters were as follows:85% ethanol content for 110 mL/30 mL bayberry juice dilution;ultrasonic power for 200 W;ultrasonic treatment time for 45 minutes;alcohol precipitation time for 5.2 hours.

    • Separation of Cypermethrin and Stereoselectivity of Antibodies to Cypermethrin Isomers

      2013, 32(12):1287-1292. DOI: 10.3969/j.issn.1673-1689.2013.12.009

      Abstract (507) HTML (0) PDF 448.25 K (1732) Comment (0) Favorites

      Abstract:With the developing of chromatographic separation,it is inevitable that cypermethrin isomers with high insecticidal activities would be prepared. In this work,HP-silica column and Sino-Chiral OD column were chosed as the stationary phase and examined using the ultraviolet detector to separation and isomer’s preparation of cypermethrin by the liquid performance spectrometer of Waters 484. Then,the configurations of cypermethrin isomers were identified according to the separation results by Sino-Chiral OD column and the reported studies. Finally,the inhibition effect of monoclonal antibodies to cypermethrin isomers was performed. The results demonstrated that only two of eight cypermethrin isomers,CP1(1R-cis-R) and CP2(1R-cis-S), were recognized by the antibodies,and CP1 was more sensitivity than CP2. Fifty percent inhibition concentration of CP2 with high insecticidal activities was 23.62 ng/mL. This results indicated that immunological technology for the determination of CP2 isomer could be established in the future.

    • Green and Nontoxic Enzyme-Linked Immunosorbent Assay for Aflatoxin B1 Detection

      2013, 32(12):1293-1297. DOI: 10.3969/j.issn.1673-1689.2013.12.010

      Abstract (405) HTML (0) PDF 475.44 K (1527) Comment (0) Favorites

      Abstract:A environmental-friendly and nontoxic enzyme-linked immunosorbent assay(ELISA) for the detection of aftoxin B1(AFB1) in wheat flour sample was developed. In this method,the standard substance was substituted by the anti-idiotype antibody(anti-id antibody). The anti-id antibodies were prepared by immunizing the rabbits with the F(ab’)2 fragments that were obtained by digesting the monoclonal antibodies(11A9 and 1G3) against AFB1. Two kinds of anti-id antibodies was prepared and both could mimic the three-dimensional structural of AFB1 and caused specific inhibition to the 11A9 mAb. The correlation of the AFB1 and anti-id antibodies were analyzed by regression. The green ELISA based on anti-id antibody was applied in the analysis of spiked wheat flour sample. The recovery intra-and inter-assay was between 111.89% and 126.98%,respectively,while the CV less than 10%. The results indicated that the environmentalfriendly and nontoxic ELISA could be used for actual samples.

    • Study on Formation of Bromate in Ozone Disinfection of Mineral Water

      2013, 32(12):1298-1302. DOI: 10.3969/j.issn.1673-1689.2013.12.011

      Abstract (447) HTML (0) PDF 464.02 K (2262) Comment (0) Favorites

      Abstract:In order to decrease the bromate content in the mineral water,the effect of ozone, bromide,and water quality on bromate formation were investigated by using the different concentration bromide with different ozone concentrations for 5 min to ozonatedthe mineral waters, ultrapure water and drinking water.Meanwhile,drinking water with certain bromide was applied for the CT(ozone concentration×contact time,CT) effect on the bromate formation. It was found that with the increase of ozone and bromideconcentrations,the generated bromate increased. When ozone concentration was ≥0.4 mg/L,with the same bromide addition,the bromates generated in mineral water were more than that in ultrapure water and drinking water. At the same time,the bromate produced in the 3 kinds of mineral waters were different,but above 10 μg/L. The increase of CT value(ozone concentration×contact time,CT)led to the steep increase of generated bromate. Therefore,decreasing in the concentration of ozone and bromide may minimize the formation of bromate in ozone disinfection of mineral water.

    • Magnetic Nanoparticles-Based Bioassay for the Detection of Salmonella Using Upconversion Nanoparticles as Labels

      2013, 32(12):1303-1310. DOI: 10.3969/j.issn.1673-1689.2013.12.012

      Abstract (524) HTML (0) PDF 767.73 K (1796) Comment (0) Favorites

      Abstract:In this work,a sensitive fluorescent bioassay was developed for the detection of gramnegative bacterium Salmonella specific target DNA sequences. The NaYF4 :Yb3 +Er3 +upconversion nanoparticles(UCNPs) was prepared with high green upconversion fluorescent intensity. The biotinylated Salmonella target DNA complementary sequence 2 was attached to the avidin-conjugated UCNPs and served as the fluorescent signal probe. Then,the as-prepared Fe3 O4 magnetic nanoparticles(MNPs) was first surface modified with avidin molecule,and then combined with the biotinylated Salmonella target DNA complementary sequence 1 which served as the magnetic capture probe. The target DNA could be detected based on the DNA hybridization reaction. The fluorescent intensity was proportional to the concentration of target DNA in the range of 0.01 pmol/L to 10 pmol/L with detection limit as low as 3 fmol/L. The presented upconversion fluorescent method is simple,fast,sensitive,specific,and furthermore,it offers another great promise for the application of nanomaterials in biosensor design.

    • Two Kinds of Different Drying Methods Affect on Different Desalination Pretreatment Duck Egg Quality

      2013, 32(12):1311-1318. DOI: 10.3969/j.issn.1673-1689.2013.12.013

      Abstract (496) HTML (0) PDF 748.10 K (2215) Comment (0) Favorites

      Abstract:In this manuscript,the apparent density,color,and functional characteritics(gelling, foaming and emulsifying) were used to evaluate the quality of fresh duck egg white(FDEW) dried with conventional freeze-drying(CFD) and a pulse-spouted bed microwave freeze-drying(PSMFD),and desalted duck egg white(DDEW) with and without ultrasound pretreatments dried by FDEW and PSMFD. With fresh duck eggs as a control group. The results demonstrated that PSMFD yields dried DEW with a better color of higher L* and lower b* values as well as lower apparent density compared to FD. Apart from that,dried DEW with PSMFD can form a more transparent gelatin,higher foaming stability(FS) and emulsifying activity index(EAI) in comparison with CFD. After PSMFD,except for lower color difference and apparent density values,ultrasound pretreatment can produce the dried DDEW with higher gel hardness(831.251 g),higher foaming capacity(FC(86.7%)) and FS(93.3%),and higher emulsifying stability(ES(26.48 min)) relative to those obtained without ultrasound pretreatment.

    • Preparation of Dextran Antibody and Establishment of It’s Elisa Immunoassay

      2013, 32(12):1319-1326. DOI: 10.3969/j.issn.1673-1689.2013.12.014

      Abstract (1096) HTML (0) PDF 817.64 K (1738) Comment (0) Favorites

      Abstract:In this study,dextran neoglycoprotein antigens were prepared evaluated and finally obtained dextran polyclonal antibodies,and an enzyme-linked immunosorbent assay(Elisa) detection method was developed according to Elisa theory. The method was put to use for quantitative analysis of dextran in practical samples. Dextran neoglycoprotein antigens were prepared by Reductive Amination method,and were confirmed by SDS-PAGE and free amino detection. The impact factors such as different oxidation degree of dextran,the conjugate reaction time to BSA were investigated. The antigens interacted with standard antibody and were evaluated through Elisa. The immunogen was immunized with white rabbits to obtained antibody respectively. A general and broad class-specific Elisa immunoassay was developed for dextran detection. The best preparation conditions were obtained(ndextran /noxidant of NaIO4 =1/120,the reaction time of 24 h),and the antigen with best combination with standard was selected. The optimized conditions of assay used coating antigen at 10 μg/mL,reaction time of antibody and rabbit-anti-bovine IgG in 45 min,blocking reagents with 5% calf serum. The developed indirect competitive Elisa method was put to use for quantitative analysis of dextran T40 in commercial sugar. The different preparation condition of dextran neoglycoprotein antigen has effect on its immunocompetence. The developed Elisa detection method with good linear and accuracy was practical for dextran determination.

    • Breeding of Torula sp. B84512 Haploid and Analysis of Erythritol Production Characteristics

      2013, 32(12):1327-1332. DOI: 10.3969/j.issn.1673-1689.2013.12.015

      Abstract (716) HTML (0) PDF 526.05 K (1773) Comment (0) Favorites

      Abstract:The Torula sp. B84512 was used for the industrial production of erythritol. To obtain a haploid genetics hybrid breeding of Torula sp. B84512,spore-producing cultivation of B84512 were done after cultured on Mcclary medium for 7 days at 30 ℃,and the sporulation rate could reach to 45%. Lysing the ascospore cell with snail enzyme for 150 min,10 haploid strains were screened. Furthermore,3 of them exhibit the highest ability to produce erythritol,and named as Torula sp. B84512-7,B84512-8 and B84512-9,respectively. With the PCR verification,Torula sp. B84512-7 and B84512-8 were verified as alpha type but Torula sp. B84512-9 was a type. The erythritol production of heterozygous Torula sp. B84512-79 reached at 97 g/L which was 56% of that of the parental strain. Therefore,Torula sp. B84512-7 and Torula sp. B84512-9 could be used for the further genetic manipulation.

    • Expression of Thermophilic Endo-1,4-β-xylanase in Bacillus subtilis

      2013, 32(12):1333-1337. DOI: 10.3969/j.issn.1673-1689.2013.12.016

      Abstract (732) HTML (0) PDF 546.62 K (1821) Comment (0) Favorites

      Abstract:The PCR primers were designed based on the endo-1,4-β-xylanase gene of the Thermopolyspora flexuosa was PCR amplified using designed primer. The amplified product was then digested and ligated into plasmid pHT43. After transformation of Escherichia coli DH5α,the positive clones were selected and the correct plasmids were largely extracted and transformed into Bacillus subtilis WB800N,the expression was induced by 1mM IPTG. SDS-PAGE electrophoresis of the extracellular supernatant showed that the targeted protein was successfully expressed. The apparent molecular weight of the endo-1,4-β-xylanase is 27 kD. The optimal reaction temperature is 80 ℃,whereas the optimal pH is 6. Hence,an engineered B. subtilis strain which could secrete endo-1,4-β-xylanase was successfully constructed.

2013年
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