两种脱毛蛋白酶活力的研究

本文对两种常用的脱毛蛋白酶(2709碱性蛋白酶与A.S1398蛋白酶)在不同pH值、温度等条件下的活力变化情况进行了研究.结果表明:2709蛋白酶的活力最适pH值为9.5～10,A.S1398蛋白酶为7.5～8.0且2709酶的pH值适应范围更广,对pH值的敏感度更低;两种酶活力的温度变化曲线具有相似性,温度越高,它们的活力衰减得也越快;两种蛋白酶受Mn2+强激活,Cu2+、Cr3+、Fe2+、Zn2+等离子则对其有抑制作用;表面活性剂如洗衣粉、平平加和JFC等对两种酶具有一定的激活作用.     

H2O2和NaHS对几种脱毛酶活力的影响

采用福林法和紫外分光光度法分析了几种蛋白酶活力的pH值曲线,并探讨了H2O2及NaHS对它们酶活力变化的影响.结果表明H2O2对NOWOLASE PE酶的活力影响较小,且具有一定的激活作用,而对2709酶、A.S1398酶和Basozym L10酶的影响极大;NaHS对2709酶和A.S1398酶的活力影响较小,且对2709酶的活力具有稳定作用,而对NOWOLASE XL酶、NOWOLASE PE酶和Basozyme L10酶的影响大.此结果为研究H2O2和NaHS辅助蛋白酶脱毛,以解决酶脱毛中小毛不易脱净的缺陷打下基础.     

双酶协同作用对大豆分离蛋白酶解的影响

从双酶配比、酶解pH值、酶解温度、酶解时间研究了中性蛋白酶（1398）和碱性蛋白酶（2709）对大豆分离蛋白酶解的影响，并运用正交试验设计和方差分析得到复合酶解最佳条件。单因素结果表明以双酶配比为1：3（1398：2709）、pH9．5、60℃和酶解3．5h时对水解较为有利。正交试验和方差分析表明，双酶配比（1398：2709）和pH值对酶解影响最为显著（P〈0．05），酶解时间和温度对酶解影响最不显著（P〉0．05）。     

天然有机物对中性蛋白酶活力的影响

本文探讨了两种不同天然有机物对1398中性蛋白酶活力的影响，测试了该蛋白酶的最适作用条件，即最适温度为50℃，最适pH值为7．6。较系统地分别考察了不同浓度的天然有机物H、天然有机物K及H与K同时对1398中性蛋白酶活力的影响，结果表明对酶活均有不同程度的激活，其中天然有机物H和K同时作用于蛋白酶，提高酶活最为显著。     

天然有机物对中性蛋白酶活力的影响

探讨了两种不同天然有机物对1398中性蛋白酶活力的影响,测试了该蛋白酶的最适作用条件,即最适温度为50℃,最适pH值为7.6.较系统地分别考察了不同浓度的天然有机物H、天然有机物K及H与K同时对1398中性蛋白酶活力的影响,结果表明对酶活均有不同程度的激活,其中天然有机物H和K同时作用于蛋白酶,提高酶活最为显著.     

中性蛋白酶芽孢杆菌BX-4产酶条件及部分酶学性质

采用稀释平板分离法从土壤中分离到一株产中性蛋白酶芽孢杆菌BX-4．通过单因素碳、氮源以及正交试验确定了最佳产酶培养基配方，同时还研究了起始pH值、金属离子、接种量对产酶的影响以及温度、pH值、金属离子以及表面活性剂对酶稳定性的影响；以最佳培养基为发酵培养基，于37℃、160r／min振荡培养48h，酶活达2519．35U／mL；该酶最适作用温度为55℃，最适作用PH值为7．5，在pH7．5缓冲体系中，55℃反应60min后仍有50％的酶活力，Ca^2＋和表面活性剂对酶有一定的激活作用，但激活作用不明显。     

酶法制取鲮鱼皮胶原蛋白寡肽工艺的研究

本文以水解度为指标,在2709碱性蛋白酶、537酸性蛋白酶、A.S.1.398中性蛋白酶三种蛋白酶中确定2709碱性蛋白酶为最佳水解用酶.在单因素试验的基础上利用通过响应面法优化2709碱性蛋白酶水解鲮鱼皮制取胶原蛋白寡肽的最佳工艺条件为:底物浓度120g/L,pH值10.0,酶与底物比2200U/g,温度50℃,水解时间2h,最大水解度为28.23%.     

海参体壁粗蛋白酶的提取及酶学性质研究

研究了海参体壁粗蛋白酶的提取方法和酶学性质，最佳提取条件为紫外线下照射30min，硫酸铵饱和度梯度为40％～60％。粗蛋白酶的最适pH值为5．0，最适反应温度为50℃，酶在50℃以下稳定性良好。在pH1．0-7．0范围内，Ca^2＋对酶有激活作用，Mn^2＋、Cu^2＋对酶有抑制作用。提取的海参体壁蛋白酶是一种含有巯基的，类似胰蛋白酶的酶类。     

米曲霉M3中性蛋白酶的提取及酶学特性研究

采用硫酸铵沉降法分离纯化米曲霉M3所产中性蛋白酶，并对其酶学性质进行了研究。结果表明：用硫酸铵沉降法所得粗酶粉的酶活力高达159781．1μ／g；该酶的最适反应温度为50℃，最适作用pH值为7．5；该酶在30～40℃时具有良好的热稳定性，在pH值6．5—7．5的条件下酶是稳定的；NH4^1 ，K^1 对该蛋白酶有明显的激活作用，Fe^3 则对其表现出强烈的抑制作用。     

黑曲霉胞外果胶酶特性的研究

对筛选出的A.niger A-03菌种产果胶酶的一些酶学性质进行了研究。结果表明：最适温度为50℃～55℃，随着温度的升高，酶的热稳定性下降；最适pH为4．0，果胶酶活力稳定的pH范围为3．5～4．5；最适盐浓度为0．2mol/L；Km值为147.1mg/mL；最大反应速度Vmax为19.2mg／min／mL；Ca^2 、AI^3 对果胶酶有激活作用，Hg 、Cu^2 对果胶酶有抑制作用。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press