双酶分步水解酱香型白酒丢糟中粗蛋白的工艺研究

以水解度(DH)和蛋白质得率为评价指标,研究了酸性蛋白酶、中性蛋白酶、碱性蛋白酶和木瓜蛋白酶分别对酱香型白酒丢糟中粗蛋白的水解效果。结果表明:碱性蛋白酶和木瓜蛋白酶的水解效果最好。在碱性蛋白酶和木瓜蛋白酶的水解条件单因素试验的基础上进行正交优化试验,得到两种酶的最佳水解条件。为进一步提高丢糟中粗蛋白的水解度和蛋白质得率,采用碱性蛋白酶和木瓜蛋白酶对酱香型白酒丢糟中粗蛋白进行分步酶法水解。结果表明,酱香型白酒丢糟中粗蛋白的最佳水解工艺条件为先用碱性蛋白酶酶解(酶解温度为55℃,料液质量比为1︰10,加酶量[E]/[S]为2.0%,p H 8.0,酶解时间为3 h),灭酶后,再用木瓜蛋白酶酶解(其他条件不变,加酶量[E]/[S]为0.2%,酶解时间为1 h)。在此条件下得到水解度和蛋白质得率,分别为32.91%,49.16%。     

六种商品蛋白酶对鲢鱼蛋白水解效果比较研究

选用中性蛋白酶、碱性蛋白酶、胰蛋白酶、木瓜蛋白酶、动物蛋白水解酶、风味蛋白酶对鲢鱼蛋白进行酶解,以水解度为评价指标筛选出各种蛋白酶的最佳水解工艺条件,通过水解度和水解液综合风味选出水解效果最佳的酶.结果表明:风味蛋白酶、动物蛋白水解酶和木瓜蛋白酶为水解效果较好的酶,其水解度和水解液综合风味评分分别为:风味蛋白酶16.97％和8.4,动物蛋白水解酶23.38％和7.0,木瓜蛋白酶26.34％和5.6;三种酶的最佳水解条件分别为:风味蛋白酶酶用量为0.7％(W ∶ W),温度55℃,pH值8.0,液固比5 ∶ 1(W∶ V),时间4 h;动物蛋白水解酶酶用量为0.7％(W∶ W),温度55℃,pH值8.0,液固比5∶ 1(W ∶ V),时间4 h;木瓜蛋白酶酶用量为0.7％(W ∶ W),温度55℃,pH值7.0,液固比5 ∶ 1(W ∶ V),时间4h.     

木瓜蛋白酶水解豌豆蛋白的工艺研究

研究木瓜蛋白酶对豌豆蛋白的水解作用,分析了酶量、底物浓度、温度、pH、水解时间因素对水解度的影响,确定木瓜蛋白酶水解豌豆蛋白制备豌豆多肽的最佳水解条件为:酶浓度8%(E/S质量比),底物浓度7%(固液比).反应温度65℃,反应时间3.5 h,pH6.5,并利用高效液相色谱法测定豌豆多肽分子量.试验结果表明,当水解度为30%时,豌豆多肽混合物分子量80%集中在500u左右.     

Plackett-Burman法和中心组合法优化罗非鱼下脚料酶解工艺

采用Plackett-Burman(PB)试验、最陡爬坡试验和中心组合设计法对木瓜蛋白酶和风味蛋白酶复合酶解罗非鱼鱼头鱼排酶解工艺进行优化。首先,采用Plackett-Burman设计从影响酶解效果的6因素中筛选出水解时间、固液比2个显著影响因素,在此基础上,通过最陡爬坡试验逼近最大水解度区域,然后通过中心组合设计试验对显著因素进行优化。得出最佳工艺条件为水解时间4h、固液比1:6.25(g/mL),温度45℃、自然pH值、酶用量0.3%、复合酶(风味蛋白酶:木瓜蛋白酶比例)1:3,酶解条件优化后实验测得罗非鱼鱼头鱼排的水解度为22.38%,与预测值21.50%接近。说明本优化工艺具有可行性。     

响应面法优化豆豉蛋白酶解工艺

以豆豉蛋白为原料,选用木瓜蛋白酶与复合风味酶分步水解制备豆豉蛋白水解物。通过单因素试验和响应面分析,确定了木瓜蛋白酶的水解条件为:反应温度62.93℃、pH7.49、酶/底物4.91%、底物浓度5.48%,在此条件下水解5h;木瓜蛋白酶水解液再加入复合风味酶酶解,优化的水解条件为:在pH6.0,酶/底物为3%,55℃条件下反应3h,豆豉蛋白最终水解度达到28.37%。     

风味蛋白酶水解菜籽蛋白中2S和12S条件的优化

通过单因素试验和正交试验,研究了风味蛋白酶对菜籽蛋白中2S(RP-2S)和12S(RP-12S)的水解条件。结果表明,水解RP-2S的最佳酶解条件为底物浓度1%,酶与底物浓度比(E/S)95LAPU/g,酶解温度50℃,pH 7.0,酶解时间3 h,此条件下RP-2S的水解度达33.64%;水解RP-12S的最佳酶解条件为底物浓度1%,酶与底物浓度比(E/S)85 LAPU/g,酶解温度50℃,pH 6.6,酶解时间3 h,此条件下RP-12S的水解度达19.97%。     

双酶法水解鲣鱼头的工艺条件探讨

确定中性蛋白酶、木瓜蛋白酶、风味酶两两组合双酶水解鲣鱼头的最佳组合,利用正交试验探讨了加水量、酶浓度、温度、水解时间对双酶水解效果的影响,确定了适宜的水解条件。结果表明:木瓜蛋白酶和风味酶双酶同时水解效果最好,最适水解条件为:温度60℃、加水比1∶4、酶浓度2600IU/g原料(木瓜蛋白酶∶风味酶为1∶1)、水解时间2h,蛋白质的水解率为23.4%,氮利用率为57%。氨基酸分析表明,水解液的氨基酸总量为2.46g/100mL。其中必需氨基酸占35.79%,游离氨基酸为0.37g/100mL,占氨基酸总量的15.01%。     

木瓜蛋白酶酶解7S大豆球蛋白的研究

采用实验室提取的7S大豆球蛋白为底物,以水解度为试验考察指标,选择底物浓度、温度、时间、pH值、木瓜蛋白酶酶添加量进行试验.结果表明,木瓜蛋白酶酶解7S大豆球蛋白的最佳工艺条件为:底物浓度4.5%,酶解时间3 h,体系pH值7.2,酶解温度50℃,酶用量为6 000 U/g.原7S大豆球蛋白氮溶解指数(NSI)为40.6%,经最佳酶解条件处理后其NSI值为78.5%.     

复合酶法制备植物小分子肽的研究

以大豆蛋白、花生蛋白为原料进行合理配比后,采用动态超高压均质预处理,再采用复配酶(木瓜蛋白酶与胰蛋白酶)和复合风味蛋白酶进行两步复合酶解.结果显示,超高压均质后,酶解度可提高2%-3%.最优条件为:超高压均质压力为60MPa;木瓜蛋白酶和胰蛋白酶按1:1复配,复配酶水解温度60℃,pH6.5,酶用量250U/g,底物浓度5%;复合风味酶水解温度55℃,pH6.0,酶用量200U/g.高效液相凝胶色谱法测定纯化后的小分子肽,分析表明分子量主要集中在3000Da以下.     

酶法水解对薏米粉溶解与吸湿特性的影响

通过酶法水解提高薏米粉的溶解性。应用木瓜蛋白酶、胰蛋白酶和风味蛋白酶对薏米蛋白进行水解,测定水解度,结果表明:按木瓜蛋白酶50%,风味蛋白酶50%的比例,最适加酶量为4.0%([E]/[S]),采用双酶水解薏米粉,其固形物溶解度指数(DSI)提高了32.5%,但当相对湿度大于43.16%时,水解薏米粉的吸湿性也增强。根据薏米粉在25℃,相对湿度范围32.78%~97.30%的吸湿量及等温吸湿曲线,Henderson方程能较好的拟合试验结果。     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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