液态乳制品中乳清蛋白和酪蛋白含量分析

随着居民对乳制品消费能力的提升,消费者对乳制品的品质提出了更高的要求,乳中功能蛋白因其重要的生物学功能成为研究热点。该实验采集13种风味发酵乳和风味酸乳以及15种其他液态乳制品,共计28个样品,采用高效液相色谱-串联质谱法测定28种液态乳制品中乳清蛋白和酪蛋白的含量。结果显示,不同来源、不同加工方式液态乳制品中乳清蛋白和酪蛋白的含量存在一定差异,鲜牛奶和纯牛奶中乳清蛋白和酪蛋白的含量普遍高于风味发酵乳和风味酸乳。该文评价了28种液态乳制品中乳清蛋白和酪蛋白的差异性,以期分析不同加工方式对乳品中功能蛋白含量的影响,为消费者购买高品质液态乳制品提供数据支撑。     

乳清蛋白及其新组分的性质,功能和新用途

在过去的十年，随着膜技术和离子交换技术的完善，以及对乳清本身认识的提高，乳清技术有了很大的进步。乳清产品是一种可应用在酸奶及许多产品中的多功能配料。对乳清蛋白功能的最新研究证明了在酸奶和发酵乳制品中使用乳清产品有许多好处。乳清浓缩蛋白有益于风味，改善...     

牛初乳与牛乳中乳清蛋白质组成及功能的对比分析

乳清富含多种功能特性和生物活性的蛋白质,本研究利用SDS-PAGE电泳将牛初乳与牛乳中乳清蛋白质的组成部分进行分离鉴定,发现牛初乳与牛乳中乳清蛋白质的组成存在较大的差异,且在牛初乳乳清中鉴定出290种蛋白,牛乳乳清中鉴定出325种蛋白。由GO功能注释分析发现,在生物过程中,牛初乳乳清蛋白在细胞定位建立和细胞定位中的作用略高于牛乳乳清蛋白。在分子功能上酶抑制活性作用是牛初乳乳清蛋白和牛乳中乳清蛋白的主要分子功能。在细胞组成上牛初乳乳清蛋白参与较多的是细胞外部分和细胞外空隙,与牛乳乳清蛋白相比参与的细胞组成大体相同。通过KEGG代谢通路分析可知,牛初乳和牛乳乳清蛋白均参与过补体及凝血级联反应通路。对牛初乳乳清蛋白组成进行研究,不仅能够增加牛初乳的利用率,并且为日后以乳清蛋白作为原料生产乳制品提供理论依据。     

蒙古族传统乳制品生产中乳清蛋白工业化生产

乳清蛋白具有重要的营养价值,应用范围很广,主要阐述了从蒙古族传统乳制品生产中得到的副产物乳清中开发利用乳清蛋白,并进行工业化生产的思考。     

乳制品摄入与糖尿病风险防控

综述了近年来国内外有关乳制品摄入与糖尿病防控相关的流行病学研究证据和可能机制。研究表明,乳制品摄入量与II型糖尿病风险之间有负相关性,摄入量在200 g/d以内时这种负相关性最为显著。在各乳制品种类中,发酵乳制品的作用更为肯定。乳制品中所含的钙、乳清蛋白以及共轭亚油酸等成分可能是改善糖尿病危险因子的有益成分。     

乳清蛋白变性的测定方法

本文综述了影响乳清蛋白变性的多种因素（ｐＨ、离子浓度等）和测定乳清蛋白变性的方法，比较了多种测定方法的优缺点和适用范围，为在某特定情况下选择适宜的测定乳清蛋白变性方法提供帮助。脱脂乳在烘烤食品、乳制品和加工食品中有着广泛地应用，在这些加工过程中热处理不可避免地引起乳清蛋白的变性，乳清蛋白的变性程度依赖于热处理常作为改善乳粉水吸收和功能性质的方法，更为重要的是乳清蛋白的变性影响着乳清蛋白的营养吸收和     

乳清蛋白的特性及应用

乳清蛋白具有一定的功能特性和生物学活性,在食品行业中应用越来越广泛。通过改性,可以显著改善乳清蛋白的功能特性,如热稳定性、热凝胶特性、乳化特性等。蛋白变性影响乳清蛋白的特性,本文论述了乳中成分和环境条件对变性的影响。乳清蛋白在食用膜、乳品检测、蛋白提纯等方面的综合利用充分体现了其在食品行业中良好的市场前景。     

不同乳酸菌在脱蛋白乳清中发酵的研究

为避免在发酵过程中乳清蛋白发生变性沉淀,本实验在发酵前采用热变性法将乳清蛋白提取出来,研究不同乳酸菌直投发酵剂(Lactobacillus DVI)在脱蛋白乳清中的发酵特性。结果表明,实验中所研究的四种直投乳酸菌发酵剂均能利用脱蛋白乳清中乳糖产酸或产香,干酪乳杆菌分别与其他三种乳酸菌进行复配发酵能获得较快的产酸速度和良好的风味。嗜热链球菌与干酪乳杆菌以1∶2比例,总接种量0.02%接种,发酵4h能够使酸度值上升12.97°T。     

产蛋白酶乳酸菌发酵乳清蛋白产支链氨基酸的研究

研究了一株产蛋白酶的德氏乳杆菌乳亚种(Lactobacillus delbrueckii subsp. lactis)815的高密度发酵条件,确定果糖为最佳碳源、牛肉浸粉和大豆蛋白胨为最佳氮源、发酵温度37℃、pH值恒定为5.5、通氮气。在该条件下,菌悬液活菌数为2.63×109cfu/mL,冷冻干燥后菌粉活菌数为2.93×109cfu/mL。以LB815菌株发酵乳清蛋白,并研究支链氨基酸(branched amino acid,BCAA)随发酵时间的变化情况。结果显示,BCAA在发酵5 h后开始积累,并在26 h含量达到最大值312.55 mg/kg,随后缓慢减少。以高产蛋白酶的乳酸菌菌株发酵乳清蛋白制备富含BCAA的乳清蛋白发酵液,可应用于运动型的发酵乳制品中,提高产品附加值。     

乳清蛋白及与其它乳成分的热聚合作用机制研究进展

乳蛋白决定奶类品质,而热加工会影响乳清蛋白尤其是β-乳球蛋白的稳定性。热处理时,乳清蛋白不仅自身发生不同程度的聚合,而且通过巯基-二硫键分别与酪蛋白胶束和乳脂球膜蛋白发生结合。乳清蛋白亦可与其它乳成分如乳糖、钙盐、乳脂发生热聚合作用。本文根据乳品受热温度的不同,针对乳清蛋白间及其与其它乳成分的相互作用途径进行分析,阐明热聚合作用过程及机理,对改善乳制品的热稳定性、凝胶性等功能性质具有重要的理论意义,拓宽乳清蛋白作为配料在相关食品体系中的应用。     

Effect of protein supplementation on the rheological characteristics of milk permeates fermented with exopolysaccharide-producing Lactococcus lactis subsp. cremoris

This research studied the effect of addition of whey proteins on the rheological properties of ultrafiltration permeate fermented with the exopolysaccharide (EPS)-producing strain Lactococcus lactis subsp. cremoris JFR1. Milk permeates containing 8% solids and various levels of added whey proteins (0, 2, 4, 6 and 8%) were fermented for 12 h at 30 °C. The rheological properties of the fermented samples were then evaluated and compared to controls fermented with a non-EPS producing strain. Scanning electron microscopy was also employed to confirm the existence of interactions between whey protein aggregates and EPS. The presence of EPS considerably increased the viscosity and viscoelastic properties of the media, especially in samples containing >2% whey protein added. The results obtained demonstrate the importance of EPS–protein interactions in structure formation and may help explain the viscosifying mechanism of EPS in fermented dairy products. Production of highly viscous material could potentially be employed in the future as a novel fiber-rich functional ingredient in dairy products.     

乳源ACE抑制剂(降血压肽)的研究现状

利用酶或微生物水解牛乳蛋白质可获得ACE抑制剂 (降血压肽 ) ,近来从乳酸菌发酵的酸奶中也找到了ACE抑制肽 ;经动物实验证明 ,口服一定量的ACE抑制肽或含有ACE抑制肽的酸奶可降低血压 ,而且对血压正常者没有影响。文章中综述了来源于乳蛋白质和发酵乳制品的ACE降血压肽的最新研究进展 ,对乳源ACE抑制剂的应用前景进行了展望     

Microparticulated whey proteins for improving dairy product texture

Use of microparticulated whey protein (MWP) was patented in 1988; since then much research has been conducted on use of MWP. This review provides an overview of the use and functionality of MWP in dairy applications and discusses how MWP interacts with other components in dairy matrices. For fermented dairy products, fine-tuning of the interaction potential of MWP is of major importance. For products where MWP serves as an inert filler (e.g., cheese, ice cream), initial processing should ensure that MWP will not interact with the product matrix ensuring creaminess and desired structural weakening. Future research should focus on how raw material composition and processing affect the properties of MWP, on the role of particle characteristics on interactions with other dairy product components, and on how to develop particulated ingredients suitable for high protein products and further clarifying the role of MWP in ensuring creaminess in complex dairy matrices.     

EFFECT OF FERMENTED WHEY PROTEIN CONCENTRATE ON TEXTURE OF IRANIAN WHITE CHEESE

The influence of fermented whey protein concentrate (FWPC) added before and after formation of cheese curd on the textural characteristics of Iranian white cheese was studied. The FWPC, prepared from whey obtained during cheese making, was added at different levels 5, 10, 15 and 20% (v/v) after (A) or before (B) cheese curdling. The changes in rheological parameters of cheeses were determined before and after 1 month of ripening. It was found that both incorporation level and stage of addition of FWPC (A and B) caused significant effects on texture profile analysis of cheeses. Increasing the level of FWPC in B group, except samples containing 10% FWPC, in contrast with A cheeses led to considerable increase in moisture and decrease in hardness and chewiness. Samples containing more than 15% FWPC had undesirable texture and were too soft. All experimental cheeses exhibited a decline in values for each rheological parameter after 1 month of ripening.

PRACTICAL APPLICATIONS

Perhaps the biggest story in the dairy industry in the past couple of decades has been the rise of new applications for whey and whey proteins. Once considered a waste product in the cheese manufacturing process, whey and whey protein products today are used for a wide range of functional and nutritional properties. In the cheese industry, particularly in soft cheese varieties, whey proteins have shown good applications to replace caseins as they act as fat replacer and bind more water than caseins, which results in softer cheeses. Therefore, this study was attempted to investigate the impact of fermented whey protein concentrate on textural attributes of Iranian white cheese.     

乳酸菌发酵蓝莓乳清混合体系体外抗氧化特性分析

本文利用嗜热链球菌,保加利亚乳杆菌及混合菌发酵乳清蛋白蓝莓汁混合物,比较研究了乳清蛋白,蓝莓汁单独发酵和混合发酵初始,24、36、48 h时对发酵产品体外抗氧化特性的影响。结果表明:通过嗜热链球菌发酵乳清蛋白蓝莓混合体系还原能力高于乳清蛋白和蓝莓单独发酵,在发酵24 h时,DPPH自由基清除能力最高达到63.01%。同时,超氧阴离子自由基清除能力与发酵前相比提高54.94%,发酵36 h时的还原能力和羟自由基清除能力最强。采用保加利亚乳杆菌发酵乳清蓝莓体系36 h时ABTS+自由基清除能力最强。采用嗜热链球菌和保加利亚乳杆菌混合菌种发酵蓝莓乳清体系24 h时,抗脂质过氧化能力与发酵前相比提高24.33%。因此,乳酸菌发酵对乳清蛋白和蓝莓汁混合体系的抗氧化能力具有提高和稳定的作用。该研究旨在为开发功能性乳酸菌发酵蓝莓乳清混合产品供理论基础,为蓝莓乳清混合发酵产物在食品及医药领域的应用提供研究依据。     

乳清产品在冰淇淋和冷冻乳制品甜食中的应用

<正> 乳清和乳清蛋白产品在过去的60多年中已经被成功应用于冰淇淋和其他冷冻乳制品甜食中。甜乳清、乳清浓缩蛋白(蛋白质含量34～89%)和乳清分离蛋白(蛋白质含量≥90%)是最常用的乳清产品。其他的乳清配料,如脱乳糖乳清和脱盐乳清也是常用的配料。成本优势和提升产品质量是使用乳清产品的主要出发点,     

N-Glycosidase F improves gel firmness in fermented milk products

Healthier dairy products can be obtained by reducing fat content, but removal of fat from fermented milk products causes a reduction in gel firmness. To compensate, costly protein enrichment with either skim milk powder or whey protein concentrate is typically necessary. An attractive solution could be substitution of protein enrichment with a texturising enzyme. We aimed to identify such enzymes and found that after treatment with N-glycosidase-F (PNGase-F), yoghurt gel firmness increased. Highly pure PNGase-F was produced in Escherichia coli and our studies revealed that PNGase-F could substitute addition of 2% SMP used for protein enrichment in yoghurt. The effect on gel firmness of PNGase-F was stable over a period of 28 days and a sensory panel described the yoghurts as having improved thickness. Our study shows that it is indeed possible to find satisfying enzyme solutions that can replace the need for protein enrichment.     

Encapsulation of Probiotic Bacteria in Biopolymeric System

Encapsulation of probiotic bacteria is generally used to enhance the viability during processing, and also for the target delivery in gastrointestinal tract. Probiotics are used with the fermented dairy products, pharmaceutical products, and health supplements. They play a great role in maintaining human health. The survival of these bacteria in the human gastrointestinal system is questionable. In order to protect the viability of the probiotic bacteria, several types of biopolymers such as alginate, chitosan, gelatin, whey protein isolate, cellulose derivatives are used for encapsulation and several methods of encapsulation such as spray drying, extrusion, emulsion have been reported. This review focuses on the method of encapsulation and the use of different biopolymeric system for encapsulation of probiotics.     

Interactions between milk proteins and exopolysaccharides produced by Lactococcus lactis observed by scanning electron microscopy

The interactions between exopolysaccharides produced by Lactococcus lactis ssp. cremoris JFR1 and dairy proteins (caseins and whey proteins) in fermented media (milk permeate and buttermilk) were observed using scanning electron microscopy. An immobilization technique by crosslinking was employed to bind the protein to the observation surface, so that a washing step could be performed to remove noninteracting material. The use of this novel technique allowed us, for the first time, to confirm that the exopolysaccharide molecules interact with dairy proteins. Exopolysaccharides appear as filament strands attached to the protein aggregates and to the bacterial cells. This new sample preparation technique proved to be very valuable for observing molecular interactions in fermented media.     

饲用乳制品及其副产品的加工技术与营养价值

介绍了饲用乳制品及其加工副产品的加工技术,以及乳粉、酪蛋白、乳清粉、乳清蛋白、代乳粉等产品的营养成分和营养价值。