膜技术在乳品工业中的应用

针对新兴边缘学科－－膜技术在乳品工业中的应用，从膜技术的基本理论方面同传统工艺相比较，突出表现膜分离技术可简化生产工艺，减少废水污染，提高乳品综合利用率，能耗低和效率高，因而具有显著的经济效益和环保作用，故其发展相当迅速，应用也越来越广泛。同时从理论上阐述了膜技术在乳品除菌，乳的标准化，牛乳的浓缩，乳蛋白浓缩，回收产品，乳蛋白质分级分离，乳清脱盐等方面的应用。     

钙与乳蛋白的相互作用机制及对其功能特性的影响研究进展

钙作为人体骨骼生长和调节生理功能的重要物质,广泛存在于乳品中。钙与乳中蛋白质如αs-酪蛋白、β-酪蛋白、κ-酪蛋白、α-乳白蛋白和β-乳球蛋白等发生相互作用,影响乳蛋白的结构稳定性,进而使其热稳定性、乳化性、溶解性、起泡性和凝胶性发生改变。本文综述了钙与各种乳蛋白之间的相互作用机制以及对其功能特性的影响,对系统理解钙与乳蛋白的结合具有重要意义,为钙类功能性乳品的深入研究以及工业化生产提供理论依据。     

乳蛋白共沉物的制备以及在食品工业中的应用

乳蛋白质共沉物（Co-precipitates），近年来由于其制造成本低，回收营养价值高，而且具有多种功能性质，日益受到世界乳品工业生产的重视，已成为乳品业又一重要产品和相关产业的一种重要原料物质．乳蛋白质并祝物是经过加热、加酸（或加钙）沉淀乳中酪蛋白和乳清蛋白，分离后加碱溶解后干燥得到的产品，此产品可以回收乳中90～95％的蛋白质，酪蛋白的产量比普通干酪产品提高7～21％，最可贵的是，该产品可回收60～75％以上的干酪素等产品不能利用，而营养价值很高的乳清蛋白．另外巾于产品是先经过沉淀脱水，其干燥成本远远低于脱胎乳粉…     

毛细管电泳法测定不同体细胞数的原料乳的蛋白组成及含量

为明确不同体细胞数(Somatic Cell Count,SCC)数量的原料乳蛋白质组成的变化规律。本研究首先建立了乳蛋白的毛细管电泳分析方法,并采集了不同SCC数量原料乳,分析其乳蛋白成分及含量的差异。结果表明,随着SCC数量的增加,原料乳中酪蛋白的占比显著降低(p<0.05),乳清蛋白比率相对增加;酪蛋白中β-酪蛋白B和β A1-酪蛋白的含量显著下降(p<0.05),水解为新的小片段。毛细管电泳技术能够更准确的分析原料乳蛋白质的组成及变化规律,有利于乳品企业在原料乳收购时进行更深一层的品质分析。     

膜技术在乳品工业中应用的最新进展

综述了膜技术的特点、分离机理、分类和在乳品工业中的应用,以及膜技术在乳品除菌、回收产品、乳清脱盐、牛乳的浓缩、乳蛋白浓缩、乳蛋白质分级分离、乳的标准化以及在酸乳和干酪制造等方面的应用。阐述了膜分离技术可简化生产工艺、提高效率、提高乳成分综合利用率,而且可以降低能耗、减少废水污染,因而具有显著的经济效益和环保作用,具有很好的发展和应用前景。同时也对存在的问题进行了分析。     

以乳品作为机能性素材载体之发展策略

乳品在西方日常饮食中扮演着重要的角色，但近三十年来，人均消费量持续减少，西方乳品业者亟待突破困境。乳品含有优质蛋白质及矿物质等营养成分，近年来亦陆续发现了多项机能性成分，如共轭亚麻油酸（conjugated IinoIeic aicd）、乳铁蛋白（lactoferrin）、鞘磷脂（sphingolipids）、硬脂酸（stearic acid）、乳清蛋白（whey proteins）及各式各样的胜肽（peptides）等。因此，如何充分利用乳品兼具营养和机能的特性，开发乳品成为符合流行之液态食品，并将乳品与其它机能性素材搭配以发挥加乘效果，已成为乳品业者开发新产品的重要策略方向。     

乳与乳制品中蛋白质测定标准发布

近日,由中国农业大学食品学院牵头,农业部乳品质量监督检验测试中心、农业部奶及奶制品质量监督检验测试中心（北京）、农业部食品质量监督检验测试中心（上海）共同完成的《乳与乳制品中蛋白质的测定双缩脲比色法》（NY／T 1678—2008）标准发布并实施。该标准的发布,标志着在利用其进行乳与乳制品中蛋白质测定的前提下,三聚氰胺等非蛋白含氮物将不会再被误判为蛋白质,也不会再出现蛋白质测定值虚高的问题。     

育儿奶粉的研制

育儿奶粉的研制孙云，韩兴杰，张国仁，滕大荣（齐齐哈尔乳品厂）前言近年来，随着乳品工业技术的发展，研制适合于婴幼儿生长发育的乳粉已成为系列，如婴儿配方乳粉Ⅰ、婴儿面己方乳粉Ⅱ、儿童乳粉、孕妇乳粉、强化乳粉等。育儿奶粉从调整乳中蛋白质、，脂肪、碳水化合物...     

乳蛋白基因多态性对加工与营养的影响

综述了乳蛋白基因多态性和检测方法以及其对乳品加工及人类营养影响的研究进展。酪蛋白的基因型较多,除了基因差异外,还有磷酸化水平与糖基化程度等其他影响因素。乳清蛋白部分,β-乳球蛋白(-βLG)的基因型较多,而α-乳白蛋白(-αLA)的基因型较少。乳蛋白基因多态性可从蛋白水平和基因水平两方面进行检测。乳蛋白基因型会显著影响乳的加工特性,包括热稳定性、凝乳性能及干酪的产率和品质。乳蛋白基因与人类营养息息相关,随着分子技术的发展,基因多态性的应用会更广,需进一步的研究来更好地描述多态性与乳品加工及营养之间的关系。     

乳蛋白作为食品配料的价值与应用

通过对乳蛋白质体系的组成、结构、营养和物理化学性质的分析，阐述乳蛋白的价值以及富含优质蛋白的乳制品作为蛋白性配料的应用。同时介绍一些特殊乳蛋白如乳铁蛋白、免疫球蛋白等的市场前景。     

Utilization of milk proteins as starting materials for other foodstuffs

The modern food-processing industry is placing more and more emphasis upon the utilization of protein ingredients to provide specific functional properties to a wide range of formulated foods. Isolated milk protein products represent an important and valuable source of protein ingredients due to their recognized superior nutritional, organoleptic and functional properties. This paper provides up-to-date information on the quantities, production processes, composition, general properties, and specific functional properties of the major milk protein products, e.g. caseinates, co-precipitates, lactalbumin, whey protein concentrates and milk blends. The subject of chemical and enzymic modification to improve certain functional properties of milk proteins is considered briefly.     

Rheological and textural properties of goat and cow milk set type yoghurts

Yoghurts were made from pasteurised and homogenised goat milk (2.5% protein), goat milk fortified with a milk protein isolate (5% protein) and cow milk (3% protein), by acidification with a starter culture at 43 °C until a pH of 4.6 was reached. The rheological and textural properties of gels and yoghurts were analysed using dynamic low amplitude oscillatory rheology and back extrusion texture analysis. Gelation and fermentation times of goat milk were longer, while gelation pH, storage moduli (G′) and yield stress values were lower, compared with those of cow milk. Textural properties of goat milk yoghurts such as firmness, consistency, cohesiveness and viscosity index were very poor. Consequently, the products could not be classified as set type yoghurts. Fortification of goat milk with a milk protein isolate contributed to a significant improvement of the rheological and textural properties of yoghurt.     

Milk Coagulation Properties and Milk Protein Genetic Variants of Three Cattle Breeds/Types in Sri Lanka

Milk coagulation is the primary step in the development of most dairy products. Raw milk from individual cows and different breeds exhibit distinct coagulation capacities. This variation is largely influenced by milk protein genetic variants. The aim of the present study was to evaluate differences in coagulation properties between milk obtained from three cattle breeds/types found in Sri Lanka. A total of 90 milk samples (400 mL from each individual) were collected from two Sri Lankan cattle breeds/types (Thamankaduwa White/TW and Local/“Batu” cattle) and one European cattle breed (Friesian). Collected samples were subjected to enzymatic coagulation using commercial rennet source (Chymax®, Christian Hansen Standard, Denmark) and lactic acid bacteria (LAB) coagulation using a commercial starter culture(YFL 8 12,Christian Hansen Standard, Denmark) to determine milk coagulation properties. Different properties of milk coagulum such as yield, curd firmness, syneresis and rheological properties were evaluated. The biochemical composition (lactose, protein, fat, solid-non-fat) of milk samples were determined. Capillary Zone Electrophoresis (CZE) method was used to determine milk protein genetic variants. Experimental design was Nested Completely Randomized Design with three treatments. Milk coagulation time and curd firmness after enzymatic-coagulation were not significantly different (p>0.05) among the breeds. Coagulum yield was significantly higher (p<0.05) for the TW type than that of other breeds. Coagulum yield was negatively correlated with β-caseinA1 and α-lactalbumin in both enzymatic (-0.58) and LAB coagulation (-0.69). Coagulum yield was positively correlated (p<0.05) with β-casein B variant (0.70), protein (0.34) and lactose (0.36) contents. Meltability value was weakly and positively (p<0.05) correlated (0.34) with fat content of milk. Overall results indicate that there is a significant correlation between milk coagulation properties and milk protein genetic variants in three cattle breeds/types considered in the current study. TW type is the unique among studied breeds in terms of coagulation properties and milk protein genetic variants.     

牛乳蛋白纳米乳液中蛋白改性技术及体系性质、应用研究进展

牛乳蛋白纳米乳液体系不稳定,易发生絮凝和相分离等现象。为了改善纳米乳液的稳定性,需要对牛乳蛋白进行改性处理。以牛乳蛋白中的酪蛋白和乳清蛋白为研究对象,介绍了化学改性方法及效果,以及目前牛乳蛋白纳米乳液在食品中的应用情况。牛乳蛋白的化学改性方法主要有酸碱化、酰化、脱酰胺、磷酸化、糖基化等,其中糖基化是操作简便、效果显著的常用的牛乳蛋白改性方法。以改性的牛乳蛋白制备得到的纳米乳液,其冻融稳定性、乳化性以及抗氧化性得到改善。牛乳蛋白纳米乳液可以包封活性物质,实现靶向递送,在食品工业中应用广泛,也可以作为药物的稳定剂在制药行业应用。     

Equine milk proteins: Chemistry,structure and nutritional significance

Equine milk has important nutritional and therapeutic properties that can benefit the diet of the elderly, convalescent or newborn. The protein content of equine milk is lower than that of bovine milk but similar to that of human milk. In this review qualitative and quantitative differences between the caseins and whey proteins of equine, bovine and human milk are discussed. Important biological and functional properties of specific proteins are reviewed and their significance in human nutrition considered. As well as characterizing equine milk proteins in the context of human nutrition and allergology, the potential industrial exploitation of equine milk is explored. Cross-reactivity of proteins from different species is discussed in relation to the treatment of cows’ milk protein allergy. While there is some scientific basis for the special nutritional and health-beneficial properties of equine milk based on its protein composition and similarity to human milk, further research is required to fully exploit its potential in human nutrition.     

Effect of milk protein genetic polymorphisms on rennet and acid coagulation properties after standardisation of protein content

The effects of milk protein genetic polymorphisms on the rennet and acid coagulation properties of milk after protein standardisation were investigated. Skim milk samples were adjusted to a protein concentration of 6.07 ± 0.06% by ultrafiltration (UF) before evaluating rennet coagulation and acid coagulation properties. Only the β-lactoglobulin (β-LG) genotypes influenced the rennet-clotting time before standardisation for the total protein concentration by UF; however, this effect was confounded with the β-LG concentration. After UF-concentration, a similar protein concentration between the samples was achieved in the retentate, then the rennet clotting time and rennet curd firmness at 30 min were significantly influenced by both the κ-casein (κ-CN) and β-LG genotypes. κ-CN genotypes significantly influenced the acid coagulation properties of both skim milk and retentate. Variations in the concentration of milk proteins (mostly α_S2-CN-12P) explained most of the differences in the rennet and acid coagulation properties of milk after protein standardisation by UF.     

EFFECT OF MILK PROTEINS AND STABILIZER ON ICE MILK QUALITY

Ice milk mixes were made with and without stabilizer/emulsifier as well as with and without milk protein isolate (sodium caseinate or whey protein isolate). The mixes were evaluated for rheological, freezing, melting, and sensory properties. Adding a stabilizer/emulsifier blend to ice milk changed its physical properties more than adding milk protein isolates. The mixes with stabilizer/emulsifier exhibited increased viscosity and chewiness and decreased drainage rate, iciness, and vanilla flavor intensity. The mixes with added caseinate exhibited increased viscosity compared with those with added whey protein isolate. Overall, the quality of ice milk mix was more dependent on stabilizer/emulsifier addition than on milk protein isolate addition.     

Different protein sources in concentrate feed for dairy cows affect cheese-making properties and yield

Soybean meal (SBM) is a commonly used protein source in feed. Yeast microbial protein could be used as a substitute for SBM, but its effect on cheese-making properties and yield is not known. Norwegian Red dairy cows (n = 48) in early or mid lactation were divided in 3 groups and fed a ration consisting of grass silage and concentrate, where the concentrates were barley based but with different additional protein sources. These were: completely barley based with no additional protein source (BAR), additional protein from SBM, or additional protein from yeast (Cyberlindnera jadinii; YEA). The SBM and YEA concentrates had a higher protein content than the barley concentrate. Four batches of cheese were made from pooled milk from each of the 3 groups of dairy cows. Milk samples were collected 5 times during the experiment. Milk from cows fed BAR concentrate showed inferior cheese-making properties (lower casein content, longer renneting time, lower content of phosphorus, and lower cheese yield) compared with SBM and YEA concentrates. Overall, SBM or YEA bulk milk had similar cheese-making properties, but when investigating individual milk samples, YEA milk showed better coagulation properties.     

Relationships between milk protein composition, milk protein variants, and cow fertility traits in Dutch Holstein-Friesian cattle

Selective breeding can change milk protein composition to improve the manufacturing properties of milk. However, the effects of such breeding strategies on other economically important traits should be investigated before implementation. The objectives of this study were to examine the association between cow fertility traits and (1) milk protein composition and (2) milk protein variants (β-lactoglobulin, β-casein, κ-casein, and β-κ-casein) in commercial Dutch Holstein-Friesian cattle. Data on 1,644 first-lactation cows were analyzed by fitting linear mixed models. Greater relative concentration of α_S1-casein within total milk protein had a positive phenotypic relationship with nonreturn rates and calving rate after first insemination. Furthermore, results showed virtually no significant relationship between cow fertility and concentration of other milk proteins or milk protein variants. Results of this study can be used to assess the correlated effects of breeding for improved milk protein composition on reproduction, thereby allowing for better evaluation of breeding programs before implementation. Our findings suggest that selecting cows based on milk protein composition or milk protein variants for improved manufacturing properties would have no negative influence on reproductive performance.     

Effect of composition on coagulation,curd firming,and syneresis of goat milk

The present study investigated the effect of different levels of fat, protein, and casein on (1) traditional milk coagulation properties, and (2) curd firming over time parameters of 1,272 goat milk samples. Relationships between fat, protein, and casein and some indicators of udder health status (lactose, pH, somatic cells, bacterial count, and NaCl) were also investigated. Traditional milk coagulation properties and modeled curd-firming parameters were analyzed using a mixed model that considered the effect of days in milk, parity, farm, breed, the pendulum of the instrument, and different levels of fat, protein, and casein. Fat, protein, and casein were also tested with the same model but one at a time. Information provided by this model demonstrated the effect of one component alone, without contemporarily considering that of the others. The results allowed us to clarify the effect of the major milk nutrients on coagulation, curd firming, and syneresis ability of goat milk. In particular, milk rich in fat was associated with better coagulation properties, whereas milk rich in protein was associated with delayed coagulation. The high correlation of fat with protein and casein contents suggests that the effect of fat on the cheese-making process is also attributable to the effects of protein and casein. When only protein or only casein was included in the statistical model, the pattern of coagulation, curd firming, and syneresis was almost indistinguishable. The contemporary inclusion of protein and casein in the statistical model did not generate computing problems and allowed us to better characterize the role of protein and casein. Consequently, given their strong association, we also tested the effect of casein-to-protein ratio (i.e., casein number). Higher values of casein number led to a general improvement in the coagulation ability of milk, suggesting that casein-to-protein ratio, not just protein or casein, should be considered when milk is destined for cheese making. These results are especially useful for dairy farmers who want to increase their profits by improving the technological quality of the milk produced.