20种蚕豆样品蛋白质含量与其蛋白组分的分子质量

采用微量凯氏定氮、蛋白质分级提取、变性凝胶电泳（SDS-PAGE）等技术研究了我国蚕豆主产区20种代表性蚕豆样品的蛋白质含量,蚕豆蛋白质中水溶性、盐溶性以及醇溶蛋白质的质量分数,以及蚕豆水溶性与盐溶性蛋白质亚基的分子量分布。结果表明：中国蚕豆主产区20种蚕豆样品的蛋白含量范围26.48～32.51g/100g,20种蚕豆蛋白含量差异显著（p<0.05）。20种蚕豆样品中的水溶性蛋白、盐溶性蛋白、醇溶蛋白的含量分别为88.6%～92.4%、4.3%～7.5%、 0.3%～2.5%、其他非蛋白氮为0.3%～2.5%。不同品种间的蚕豆水溶性、盐溶性蛋白亚基组成具有一定的差异;SDS-PAGE电泳分析,蚕豆水溶性蛋白共分离出10～19条迁移率不同的条带, 亚基分子量集中在43.0～95.0ku之间, 盐溶性蛋白共分离出7～16条不同迁移率的条带,因品种不同而不同。分子质量为65、55、48、43、32ku的谱带在20种蚕豆盐溶蛋白中均检测出来,为共有带。     

聚乙二醇/硫酸铵双水相萃取猪胃蛋白酶工艺研究

采用聚乙二醇/硫酸铵[PEG/（NH4）2SO4]建立稳定的双水相体系以分离猪胃蛋白酶。通过上下相体积比（VR）、比活力（SA）、纯化因子（PF）、酶活回收率（η）和SDS-聚丙烯酰胺凝胶电泳（SDS-PAGE）分析测定萃取效果。结果表明,萃取猪胃蛋白酶的最佳配比体系为25%PEG1000:18%（NH4）2SO4,所萃取的猪胃蛋白酶酶活回收率为91.5%,SDS-PAGE结果显示,萃取的蛋白质和猪胃蛋白酶对照品分子量大小一致。      

不同电解质溶液对反胶束萃取花生蛋白的影响研究

研究了KCl、NaCl、LiCl、MgCl2、NaNO3、KNO3、Na2SO4、MgSO4 8种不同的电解质对AOT/正己烷反胶束溶液萃取低温花生粕中花生蛋白的影响,对反胶束的含水量、蛋白质的提取率及通过SDS-PAGE电泳试验对蛋白质的亚基条带进行了比较。试验结果表明,电解质的种类会影响反胶束的含水量;阴离子与阳离子对反胶束溶液萃取大豆蛋白的前萃与后萃都有影响,电解质KCl和NaCl溶液所提取的蛋白质得率较高,分别为54.22%和50.19%;不同的电解质可以影响所得蛋白的亚基组成,可以用来分离不同的蛋白。     

乳饮料蛋白质种类及相对含量分析

利用SDS-PAGE电泳结合凝胶成像分析测定了乳饮料中的乳蛋白种类、相对含量及α-乳白蛋白(α-LA)和β-乳球蛋白(β-LG)的含量.     

不同多糖对冻藏过程中草鱼肌原纤维蛋白流变性的影响

以草鱼肌原纤维蛋白作为研究对象,添加魔芋葡甘聚糖降解产物及葡聚糖（7 000 D,T7）,测定草鱼肌原纤维蛋白质量浓度、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gelelectrophoresis,SDS-PAGE）和流变性质的变化,比较不同多糖对冻藏过程中肌原纤维蛋白的冷冻保护效果,探讨不同多糖对草鱼肌原纤维蛋白结构的冷冻保护机制。研究发现,随冻藏时间的延长,空白、酶解魔芋葡甘聚糖、辐解魔芋葡甘聚糖、T7及商业抗冻剂各组对应草鱼肌原纤维蛋白质量浓度和流变储能模量（G’）均下降,与冻藏过程草鱼肌原纤维蛋白SDS-PAGE的变化基本吻合。同时,添加上述不同多糖各组草鱼肌原纤维蛋白质量浓度和G’均高于空白组。研究结果表明：T7、酶解魔芋葡甘聚糖及辐解魔芋葡甘聚糖通过保护副肌球蛋白和肌球蛋白轻链,延缓草鱼肌原纤维蛋白的变性,其中,辐解魔芋葡甘聚糖效果最强,T7次之,酶解魔芋葡甘聚糖最弱,但都具有明显的冷冻保护作用。     

Methods for allergen analysis in food: a review

Food allergies represent an important health problem in industrialized countries. Undeclared allergens as contaminants in food products pose a major risk for sensitized persons. A proposal to amend the European Food Labelling Directive requires that all ingredients intentionally added to food products will have to be included on the label. Reliable detection and quantification methods for food allergens are necessary to ensure compliance with food labelling and to improve consumer protection. Methods available so far are based on protein or DNA detection. This review presents an up-to-date picture of the characteristics of the major food allergens and collects published methods for the determination of food allergens or the presence of potentially allergenic constituents in food products. A summary of the current availability of commercial allergen detection kits is given. One part of the paper describes various methods that have been generally employed in the detection of allergens in food; their advantages and drawbacks are discussed in brief. The main part of this review, however, focuses on specific food allergens and appropriate methods for their detection in food products. Special emphasis is given to allergenic foods explicitly mentioned in the Amendment to the European Food Labelling Directive that pose a potential risk for allergic individuals, namely celery, cereals containing gluten (including wheat, rye and barley) crustaceans, eggs, fish, peanuts, soybeans, milk and dairy products, mustard, tree-nuts, sesame seeds, and sulphite at concentrations of at least 10 mg kg^-1. Sulphites, however, are not discussed.     

Physicochemical Changes in Alaska Pollock Surimi and Surimi Gel as Affected by Electron Beam

ABSTRACT: Alaska pollock surimi and surimi gels (cooked) were subjected to various doses of electron beam (e-beam). Shear stress of surimi gels increased as the dose increased up to 6 to 8 kGy and then decreased. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed gradual degradation of myosin heavy chain as the dose increased. The degradation was slower for frozen samples. The integrity of actin was slightly affected by high doses (25 kGy). The amount of sulfhydryl groups and the level of surface hydrophobicity of Alaska pollock surimi decreased as the dose increased, suggesting formation of disulfide bonds and hydrophobic interactions. The sulfhydryl groups and hydrophobicity of surimi gels increased as the dose increased up to 6 kGy and then decreased.     

The effects of wheat sourdough on glutenin patterns, dough rheology and bread properties

Sourdough was prepared with cellular suspension containing 10⁹ cfu of each strain mL⁻¹ and incubated at 28 °C for 24 h and at 37 °C for 4 h. Two different sourdough levels (20 and 40%) were used in bread dough preparation. The bread doughs were proofed at 30 °C and 85% relative humidity for 60/120/180 min. When glutenin changes that occurred in samples 17, 18, 19, and 20 (40% SD 28) are compared with those that appeared in controls, it is obvious that, the relative intensities of some of the protein bands slightly decreased and a few fainter protein bands appeared (which did not exist in controls). A few fainter protein bands corresponding to the MM ≈ 25 kDa (high-mobility region) and the MM ≈ 66 kDa (low-mobility region) were appeared in the same samples. In the samples prepared with 20% sourdoughs incubated at 28 or 37 °C, the bands were still evident after 180 min of proof. This can be explained that glutenin fractions were not hydrolysed in these applications due to the delay in pH drop. The use of 40% sourdough incubated at 28 °C for 24 h resulted in sticky doughs and breads with lower volume, harder texture, unsatisfactory crumb grain and unpleasant flavour than the rest of the samples. The use of sourdoughs incubated at 37 °C for 4 h caused positive effect on loaf volumes, specific loaf volumes and crumb structure.     

Electrophoretic and HPLC methods for comparative study of the protein fractions of malts,worts and beers produced from Scarlett and Prestige barley (Hordeum vulgare L.) varieties

Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and reversed-phase high performance liquid chromatography (RP-HPLC) methods were used for studying the protein fractions (hordeins; albumins and other soluble proteins) of Scarlett and Prestige barley malts and to follow changes of the protein profile of worts and beers from these two malt varieties. Similar industrial brewing conditions were applied for both varieties.     

Application of two-dimensional electrophoresis to industrial process analysis of proteins in lupin-based pasta

Two-dimensional (2-D) IEF/SDS-PAGE is a powerful tool to get molecular “pictures” of food proteomes and monitor the processing effect(s) of a given food item on its protein profile. Still the use of 2-D approaches to this aim is rather uncommon.In this work, 2-D electrophoresis has been used to monitor the main steps of lupin-based gluten-free pasta production. Three different production lots, spanning over 1 year of pasta production, were analysed. Various samples at each critical production step, including seeds, raw materials, half-processed products and dry pasta, were used to generate the corresponding 2-D electrophoretic maps.Some differences in the protein profiles between the raw materials, i.e. lupin flour and lupin protein concentrate, were attributed to the different varieties which they arose from. On the other hand, the electrophoretic analyses showed only minor differences among the samples during the industrial processing. In particular, there was no alteration of the covalent continuity of the main polypeptide backbones. The disulphide pattern did not change during the process, either, and the constancy of the glycosylation pattern, as measured by the lectin Concanavalin A on the blotted maps, indicated that this molecular feature was not affected by the process too.The work shows how helpful the use of 2-D electrophoresis to trace proteins and evaluate the effects of the production processes in protein food manufacturing can be.