米渣蛋白碱性蛋白酶酶解条件优化

米渣是优质的蛋白质资源。以淀粉糖企业副产品米渣为原料,以水解度和起泡性为评价指标,利用碱性蛋白酶对米渣蛋白进行酶解,首先研究酶添加量、pH、底物浓度等因素对米渣蛋白质水解度的影响,然后通过响应面试验得出最佳酶解条件。结果表明,酶解最适条件是底物浓度6%、酶解时间90min、加酶量2%、pH为8.5、酶解温度55℃,在此条件下得到的酶解液起泡性高。     

蛋白酶水解米渣蛋白的研究

以味精厂下脚料米渣为主料 ,利用木瓜蛋白酶、中性蛋白酶、碱性蛋白酶和复合蛋白酶为单酶及其双酶组合对米渣蛋白进行水解。通过正交试验和验证试验确定酶解米渣蛋白最适条件及最佳方案     

蛋白酶水解米渣蛋白的研究

以味精厂下脚料米渣为主料，利用木瓜蛋白酶，中性蛋白酶，碱性蛋白酶和复合蛋白酶为单酶及其双酶组合对米渣蛋白进行水解。通过正交试验和验证试验确定酶解米渣蛋白最适条件及最佳方案。     

双酶法水解米渣蛋白工艺研究

运用碱性蛋白酶和中性蛋白酶双酶水解米渣蛋白质,以大米蛋白水解度为考核指标,通过研究确定双酶法水解米渣蛋白最佳工艺及工艺参数.米渣原料经90℃高温水洗两次后,首先按碱性蛋白酶最佳酶解条件:温度为55℃、pH值为10.0、酶量为6,000μ/g、时间为4h,进行第一次酶解,达到酶解时间后,高温灭酶10min,冷却后调pH为...     

鲢肉酶解工艺及其产物对大鼠ACE抑制活性的研究

研究了四种蛋白酶水解白鲢鱼肉的工艺条件,并采用离体培养的方法研究其水解产物对大鼠血管紧张素转化酶(AntiotensinI-ConcertingEnzyme,ACE)的抑制活性。研究结果表明1398中性蛋白酶、复合风味酶、碱性蛋白酶和复合蛋白酶的最适水解温度分别为40、55、55和50℃,最适起始pH分别为7.5、7.0、7.5和6.5。复合风味酶的水解产物具有较高的ACE抑制活性,其12h的水解产物水解度为28.05%,ACE活性抑制率为64.75%。在优化酶解条件下,采用复合风味酶水解白鲢不同部位的蛋白质,蛋白质提取率可达90%,水解度22%～40%,在酶解液浓度相同时(1mg/ml),白肉酶解产物对ACE的抑制率最高。     

菜籽蛋白酶解预处理条件研究

以脱脂菜籽粕制备的菜籽蛋白为主要原料,水解度为考察指标,探讨了蛋白酶的选择及湿热处理条件对蛋白质水解的影响。结果表明,碱性蛋白酶、酸性蛋白酶、中性蛋白酶和木瓜蛋白酶4种酶在其最适条件下水解菜籽蛋白能力顺序为碱性蛋白酶中性蛋白酶酸性蛋白酶木瓜蛋白酶。选择碱性蛋白酶进行菜籽蛋白水解,通过完全试验得出菜籽蛋白的湿热处理最佳工艺条件为:温度100℃,时间30min,此条件下,水解度可达到18.51%。     

环文蛤肉复合酶的水解工艺初探

以环文蛤为原料,采用酶水解的方法制备环文蛤肉水解液。先选用中性蛋白酶、碱性蛋白酶、木瓜蛋白酶和菠萝蛋白酶,分别对环文蛤肉进行单酶水解实验;并用复合酶解新技术对环文蛤肉进行水解研究。实验结果表明:3种酶复合水解的最佳工艺为:在料水比1:8(m/v)、pH7.0、50℃条件下,用中性蛋白酶6000U/g原料先水解4h,再依次使用碱性蛋白酶4000U/g、菠萝蛋白酶12500U/g连续水解4h后水解度达到43.27%。复合酶解液中游离氨基酸含量丰富,约为117.89μg/mL,其中必需氨基酸占51.39%。环文蛤肉经复合蛋白酶水解,适当调配可制作营养丰富、海鲜风味浓郁、具有一定保健功能的口服液。     

两种蛋白酶对米渣蛋白的酶促降解作用

碱性蛋白酶和木瓜蛋白酶均可水解从米渣中提取的蛋白质,前者酶解米渣蛋白的效率明显优于后者。通过分析底物浓度、酶用量、溶液酸碱度、酶解温度和时间对酶促降解米渣蛋白效率的影响,得出碱性蛋白酶和木瓜蛋白酶各自水解米渣蛋白的最适条件,即碱性蛋白酶作用底物的浓度、酶的用量、溶液pH、酶解温度和时间分别为0.6%、50U/ml、8.5、45℃和4h;木瓜蛋白酶则依次为0.9%、300U/ml、6.0、70℃和4h。     

酶法水解滑菇蛋白制备抗氧化肽的工艺优化

本文研究了酶法水解滑菇蛋白制备抗氧化肽的工艺条件,通过水解度与羟自由基(·OH)清除率来综合评价水解产物的抗氧化能力。以·OH清除率为指标,从碱性蛋白酶、中性蛋白酶、风味蛋白酶、木瓜蛋白酶和胰蛋白酶5种蛋白酶中筛选最适酶。在单因素实验研究酶浓度、底物浓度与水解时间对酶解产物·OH清除率和水解度影响的基础上,通过L_9(4~3)正交实验对水解工艺进行优化。结果得出,碱性蛋白酶活力高于其他4种蛋白酶,能使蛋白质充分水解,正交实验各因素对水解产物·OH清除率的影响程度依次为底物浓度酶浓度水解时间。其中,碱性蛋白酶的最佳水解工艺条件为:底物浓度3.0%、酶浓度3500 U/g、p H9.0、温度55℃、水解时间3.5 h。在此条件下,水解产物的·OH清除率可达82.7%,水解度为23.1%。碱性蛋白酶水解滑菇蛋白制备抗氧化肽的工艺可行,为滑菇蛋白高附加值产品的开发提供技术参考。     

复合酶法水解蟹肉的研究

研究碱性蛋白酶和复合风味蛋白酶水解螃蟹肉的工艺条件。探讨了时间、酶用量、初始pH值、固液比浓度和温度对螃蟹肉水解效果的影响。在单因素试验的基础上,通过多因素响应面设计实验,获得最适水解工艺条件为时间4h、碱性蛋白酶先水解1h后再加入复合风味蛋白酶共同作用、初始pH值为8.3,固液比浓度为1∶2.5,温度60℃,碱性蛋白酶用量为1.2×10-3AU/g(蛋白质)、复合风味蛋白酶用量1.5LAPU/g,此时蛋白质的水解率为22.8%,TCA可溶性氮增长率含量为40.47%。     

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