Flavourzyme酶解大豆分离蛋白对酸奶发酵酸度及流变特性的影响研究

采用3个水解度(DH分别为3.12%、5.77%和8.83%)的大豆分离蛋白Flavourzyme酶解液取代不同量的牛奶(取代度分别为5%、7.5%和10%)用于酸奶发酵,探讨酸奶在发酵过程中的酸度变化和表观粘度变化,研究发酵酸奶在不同剪切速率下的切应力、流变指数和粘度系数。研究结果表明:当DH8.83%的大豆分离蛋白酶解产物替代7.5%～10%的牛奶时,其达到发酵终点所需时间最短。在牛奶中添加10%的DH3.12%大豆分离蛋白的水解产物能显著增加发酵酸奶的表观粘度。采用大豆分离蛋白酶解液替代部分牛奶生产酸奶能有效降低酸奶的柔性,其质构特性属于非牛顿流体。用DH3.12%大豆分离蛋白酶解液代替10%牛奶生产的酸奶在高剪切速率下其切应力远大于对照组。     

大豆分离蛋白发酵酸奶的制备研究

大豆酸奶是以大豆分离蛋白酶解液、牛奶为主要原料,经 乳酸菌发酵而成的一种营养保健酸奶。本文介绍了大豆 分离蛋白预处理条件,并通过正交实验确定了大豆分离 蛋白的酶解条件和大豆分离蛋白酶解液与牛奶共同发酵 的最佳条件。     

牛奶、大豆蛋白复合酸奶的研制

为了实现动物蛋白和植物蛋白的营养优势互补,将大豆分离蛋白溶解液替代部分牛奶制备发酵酸奶,并对质量的影响因素进行了研究。结果表明,大豆分离蛋白液的适宜浓度为14%,大豆蛋白液替代度为30%,稳定剂的用量为瓜尔豆胶0.15%。黄原胶0.05%,蔗糖添加量为7%。接种量为3%。     

酸溶性酶解大豆蛋白的研究

本论文通过酶法改性大豆蛋白，获得了在pH4．0条件下溶解良好的大豆蛋白。实验结果表明在1—3h的反应时间内，蛋白质经酶解达到了最大的的酸溶解性。最佳酶解工艺条件为：大豆分离蛋白浓度5％，酶用量5％(以反应物为100％计)，pH8．0，55℃，反应时间3．5h。在此条件下，大豆蛋白的水解值达到了10．35％。在实验中进一步通过采用SDS-PAGE电泳方法测定大豆蛋白酶解情况及产物分子量范围。     

糖基化与胰蛋白酶酶解对大豆蛋白构象和功能性质的影响

利用转谷氨酰胺酶催化壳寡糖与大豆蛋白分子发生交联反应制备糖基化大豆蛋白,随后用胰蛋白酶酶解制备水解度分别为1%、5%、10%和15%的大豆蛋白酶解产物,分析糖基化及酶解对大豆蛋白的三级结构和功能性质的影响。结果表明:糖基化大豆蛋白及其酶解产物具有更加疏松的三级结构;pH 4.0、7.0的酶解产物(DH15%)经过热处理(85℃)后,其热稳定性分别为50.74%和67.66%,热稳定性较好;糖基化提高了大豆蛋白的泡沫稳定性,水解度为10%的酶解产物具有最高的起泡性;糖基化也能够提高大豆蛋白的乳化稳定性,水解度为5%的酶解产物具有较好的乳化稳定性;大豆蛋白修饰产物的体外消化性不同,糖基化大豆蛋白对胃蛋白酶的敏感性差,而其酶解产物对胰蛋白酶的敏感性差。     

小麦面筋蛋白肽促酸奶发酵特性的研究

分别将经碱性蛋白酶、胃蛋白酶和风味蛋白酶酶解得到的小麦蛋白肽应用到酸奶发酵中替代部分牛奶蛋白,以酸奶p H、滴定酸度及蛋白质含量为指标,进行综合感官评价和质构分析,筛选出促酸奶发酵能力最好的酶解物。将小麦蛋白酶解物按分子质量进行膜分离,评价和比较了不同分子质量段的小麦面筋蛋白肽促酸奶发酵能力。结果表明,小麦蛋白肽具有促酸奶发酵能力。用碱性蛋白酶水解小麦蛋白36 h,可得到促酸奶发酵能力较好的酶解物,其中分子质量范围3~5 ku的小麦蛋白肽具有比其它分子质量段更好的促发酵能力,可缩短酸奶发酵周期1 h,同时明显改善酸奶的感官及质构特性。     

改善大豆分离蛋白溶解性的试验

采用木瓜蛋白酶对大豆分离蛋白进行了酶法改性试验。试验表明,酶法水解能显著提高大豆分离蛋白的溶解性。酶解的最佳条件是,pH7.0、温度55℃、底物浓度3％、酶的浓度12000u/g大豆分离蛋白。在此条件下酶解3h,大豆分离蛋白的水解度(DH)超过25％。即使在大豆蛋白的等电点,大豆分离蛋白酶解液仍然有较好的溶解性。     

酶解大豆分离蛋白的特性研究

木瓜蛋白酶水解大豆分离蛋白得到不同特性的水解物．当DH=33．1％时，溶解度为93％；当PH=8.2％时，乳化性则是最好；当DH=10．3％时，起泡性最好，水解物的粘度可达2.4CP．酶解后，大豆分高蛋白的促进酵母发酵特性和营养特性大大提高，在合DH=33.1％酶解物的培养基中生长的酵母是含未酸解大豆分高蛋白培养基中酵母数目的3．7倍，而DH=15％时，其消化性指数和酪蛋白相当．酶解液的氨基酸分布中，色氨酸和蛋氨酸为第一限制氨基酸，缬氨酸为第二限制氨基酸。对于感官特性，酶解大豆分高蛋白苦味增加而豆腥味减弱．     

抗坏血酸对大豆分离蛋白酶解产物功能特性影响研究

采用木瓜蛋白酶水解不同浓度的大豆分离蛋白,研究了抗坏血酸对较低水解度（DH为3.7%）和较高水解度（DH为8.9%）酶解产物黏度、发泡性、发泡稳定性、乳化性和乳化稳定性的影响.结果表明：在水解度为3.7%的、浓度为7%的大豆分离蛋白酶解液中添加0.3%抗坏血酸,体系的黏度最大、乳化性最强、乳化稳定性最高;在水解度为8.9%的、浓度为3%的大豆分离蛋白酶解液中添加0.3%抗坏血酸,体系的发泡性最大;在水解度为3.7%的、浓度为7%的大豆分离蛋白酶解液中添加0.5%抗坏血酸,体系的泡沫体积比最大.     

大豆酶解产物复合含氮糖浆用于啤酒发酵的研究

本文主要对大豆蛋白水解产物用于部分替代麦汁进行啤酒发酵的可行性进行了实验研究,并对发酵液的理化指标进行了检测分析.实验证明酵母在添加了大豆蛋白酶解液中的发酵液里可以正常发酵,所得啤酒各项指标均符合国家标准.     

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