乳清浓缩蛋白的应用

乳清是干酪或干酪素生产的副产品。随着新技术的不断推出,乳清产品已受到越来越多的关注,现已作为多种不同需求的食品配料使用。乳清是蛋白质的经济来源,它能给食品加工提供许多功能性成分。乳清产品（包括乳糖）能改善质构、增强风味和色泽,起乳化和稳定作用,改善流动性和在于混料中的分散性,有助于延长货架期和表现出许多能改善食品品质的特性。由于乳清加工和精制技术上的发展;在过去几年中,乳清产品在食品中的应用增长迅猛,其中婴儿食品使用乳清已有数年,因为它能提供许多营养成分,但许多有关乳清的最新应用于培烤食品、乳饮…     

乳清蛋白酶解制备ACE抑制肽的研究

采用碱性蛋白酶、中性蛋白酶、胃蛋白酶、胰蛋白酶和木瓜蛋白酶水解乳清蛋白制备ACE抑制肽，通过体外检测法测定其ACE抑制率。结果表明，碱性蛋白酶水解物的ACE抑制率最大。采用三因素二次通用旋转设计对碱性蛋白酶水解乳清蛋白的水解条件进行优化。研究了底物浓度、温度和酶与底物的质量比对ACE抑制率的影响，建立了回归方程，分析了各因素对ACE抑制率的影响．确定了最优的水解条件。     

乳清蛋白的酶解及其性质研究

研究了碱性蛋白酶对乳清蛋白的水解作用。通过正交试验，得出最优水解条件为：[E／S]=5％、T=60℃、pH=8．0，水解度=21．6％；离子交换法脱盐处理，脱盐率77．1％，蛋白回收率81．8％；多肽水解液在等电点附近溶解度为90％，经灭菌处理后溶解度高达94％以上。     

酶解乳清蛋白制备降胆固醇活性肽的工艺研究

利用生物酶技术酶解乳清蛋白,制备具有降胆固醇活性的多肽,通过响应面试验、二次旋转回归设计建立回归模型,以胆固醇胶束溶解度抑制率为评价指标,对乳清蛋白的酶解条件进行了优化。结果表明,乳清蛋白的最佳酶解条件为：酶解时间8.5 h、酶解温度55 ℃、酶解pH 8.0、加酶量4.7%、乳清蛋白含量5.8%,在此条件下,酶解乳清蛋白得到的活性肽的胆固醇胶束溶解度抑制率为18.21%。     

复合酶解乳清蛋白制备降血压肽的研究

采用碱性蛋白酶、胰蛋白酶水解乳清蛋白制备ACE抑制肽,通过体外检测法测定其ACE抑制率。通过正交试验,得出最优水解条件,即碱性蛋白酶和胰蛋白酶[E1/E2]之比为5:4,温度为45℃,pH值为8.0,时间为150min,水解度11.92%的条件下,乳清蛋白肽对ACE的抑制能力最强,达到60.19%。     

超滤浓缩大豆乳清蛋白

本文对超滤技术在浓缩大豆乳清蛋白中的应用进行初步的探索,探索压力、温度、运行时间和浓缩倍率对浓缩大豆乳清蛋白的影响,结果表明截留率在92%以上。     

超滤浓缩乳清蛋白并分离乳糖的研究

采用管式超滤装置,选用切割分子量为20000的聚丙烯腈膜,对乳清进行了超滤浓缩试验。结果表明,降低乳清pH值可提高透液通量,把乳清调整至pH7．0,再离心除去不溶性钙盐,可获得最大透液透量。中性乳清经离心沉降后,在进口压力0.24MPa,温度45℃条件下浓缩180min,平均透液通量达到29．1kg／m2·h,蛋白质含量提高到2.85％,透过液中乳糖浓度变化不大。     

分步酶解制备乳清蛋白源ACE抑制肽的工艺研究

以云南乳饼加工副产物—乳清水中获得的乳清蛋白粉为原料,采用分步酶解技术获得ACE抑制肽。通过酶的选择、单因素和响应面优化实验,选取了碱性蛋白酶和木瓜蛋白酶为适宜用酶,确定了最佳酶解工艺条件为酶解温度50℃,酶解时间3 h:2 h,料液比1:35(g/mL),此时酶解产物的ACE率达到88%。本研究可为后续相关功能性食品开发提供借鉴。     

碱性蛋白酶限制性酶解乳清浓缩蛋白成胶特性的研究

研究了利用碱性蛋白酶限制性酶解乳清蛋白对其凝胶特性、成胶温度、凝胶粒径和蛋白组分水解情况的影响,结果表明,酶解可以提高乳清蛋白的凝胶特性,在酶解70min时达到最大值,此时乳清蛋白的水解度为7．22％,当酶解时间超过70min后随着水解时间的延长凝胶特性略有下降;各水解时间点乳清蛋白成胶温度均为80℃;酶解后乳清蛋白凝胶的粒径值下降了90％以上,且酶解30min后形成的凝胶粒径值都在50um以内;在碱性蛋白酶的限制性酶解作用下,仅部分β-乳球蛋白和很少部分牛血清白蛋白被酶解,而大部分α-乳白蛋白被酶解。     

酶解对乳清蛋白抗原性影响的研究

研究了酶解对乳清蛋白抗原性的影响。选择了7种常见蛋白酶在同一水解模式下水解乳清蛋白，用竞争ELISA法测定水解物的残留抗原性，从而间接测定其过敏性变化。结果表明，酶解能有效降低乳蛋白抗原性，但水解物仍能与特异抗体反应，保留一部分抗原性。不同酶对乳清蛋白过敏原的影响不同，酶的特异性对乳清蛋白水解物的抗原性有较大的影响，碱性蛋白酶降低乳蛋白抗原性的效果最佳，对抗β-乳球蛋白（β-LG）和抗α-乳白蛋白（α-LA）抗体的抗原性分别降低了50．02％和99．72％。     

蛋白含量对牦牛乳清蛋白浓缩物功能特性的影响

通过不同截留分子质量的再生纤维素膜过滤纯化牦牛原乳清液和牦牛甜乳清液,分别制取牦牛原乳清蛋白浓缩物(native whey protein concentrate,NWPC)和牦牛甜乳清蛋白浓缩物(sweet whey protein concentrate,SWPC),研究蛋白含量不同的乳清蛋白浓缩物(whey pr...     

Microencapsulating Properties of Whey Protein Concentrate 75

ABSTRACT Emulsions containing various levels of soya oil dispersed in solutions of whey protein concentrate (WPC) 75 (5% w/v) were spray-dried to yield powders with oil contents ranging from 20% to 75% (w/w). The effect of homogenizing pressure and oil/protein ratio on oil globule size distributions and protein load of the emulsions and the microencapsulation efficiency (ME) and redispersion behavior of the powders were examined. Emulsion oil droplet size decreased with increasing homogenization pressure but was not affected by oil/protein ratio. Emulsion protein load and ME of the powders were negatively correlated with increasing oil/protein ratio. Powders with an oil/protein ratio < 0.75 were least susceptible to destabilization during spray-drying.     

酶法水解乳清蛋白工艺研究

以乳清蛋白为原料,选择碱性蛋白酶水解乳清蛋白.通过四因素三水平正交试验设计方法对碱性蛋白酶水解乳清蛋白的工艺条件[酶-底浓度比(E/S),pH,水解温度,水解时间]进行优化,确定了碱性蛋白酶酶解乳清蛋白的最佳水解条件为酶-底浓度比0.05,pH8.0,反应温度60℃,水解200min,此条件下水解度为21.92％.各因素对水解度的影响主次顺序为酶-底浓度比(E/S)＞水解温度＞水解时间＞pH.     

乳清浓缩蛋白(WPC-80和WPC-34)对酸奶品质特性影响的研究

酸奶的生产主要以鲜奶、奶粉、乳清浓缩蛋白(WPC)等乳成分为主要原料，原料的选择直接影响到酸奶的品质。本文对乳清浓缩蛋白(WPC-80和WPC-34)代替部分全脂奶粉和脱脂奶粉生产酸奶时，对产品的保水性、粘度、口感及组织状态进行了比较分析。结果表明WPC-80和WPC-34代替10％-20％全脂奶粉和脱脂奶粉生产酸奶时，可改善酸奶的品质，提高酸奶的保水性。     

乳清浓缩蛋白对松仁蛋白溶解度及其乳液稳定性的影响

为研究蛋白质-蛋白质相互作用对松仁蛋白(PKP)溶解度、结构和乳液性质的影响,以PKP和乳清浓缩蛋白(WPC)为研究对象,采用pH循环法制备PKP-WPC复合蛋白,利用SDS-PAGE、内源性荧光光谱、紫外-可见光谱、圆二色谱、荧光探针和ζ-电位等方法分析了复合蛋白结构特性和表面特性,再以PKP-WPC复合蛋白为原料,分别制备了油相体积分数为3%、10%和50%的乳液,并对制备的乳液性质进行了检测。结果表明:当WPC与PKP的质量比为1.0∶1.0,且体系pH值经历由7.0到12.0再回到7.0时的1次pH循环后,PKP的水溶性可从48.53%提高到92.43%。SDS-PAGE结果显示,PKP-WPC复合蛋白完整保留了PKP和WPC的亚基。内源性荧光光谱、紫外-可见光谱和圆二色谱结果表明,静电相互作用、疏水相互作用和氢键是驱动PKP和WPC相互作用的主要作用力,PKP与WPC相互作用使复合蛋白具有较高的结构韧性,抵抗酸诱导的构象折叠;WPC的加入改变了PKP的二级结构,α-螺旋、β-转角和无规卷曲结构的含量增加,而β-折叠结构相对含量降低。PKP-WPC复合蛋白具有较高的表面电荷(-34.74mV)来抵抗蛋白质的聚集。与由PKP制备的乳液相比,由PKP-WPC制备的乳液平均粒径和乳层析指数减小,ζ-电位绝对值增大,稳定性显著提高。乳液的性质因油相体积分数的不同而有较大的差异。油相体积分数为3%的复合乳液液滴小且分布均匀,稳定性好于油相体积分数为10%和50%的复合乳液。通过pH循环法,通过添加WPC,提高了PKP的溶解度,获得了稳定性较佳的PKP乳液,研究可为新型蛋白产品的研发提供理论基础,拓宽松仁蛋白在加工食品中的应用范围,推动PKP-WPC双蛋白乳液研究的发展。     

Chemical Pretreatment and Microfiltration for Making Delipidized Whey Protein Concentrate

Chemical pretreatment, microfiltration (MF) and ultrafiltration (UF) were applied to produce delipidized whey protein concentrates (WPC). Processes including both chemical pretreatment and MF resulted in WPC with <0.5% lipids. Low-pH UF and isoelectric point (PI) precipitation were more effective for lipid removal than chemical pretreatment by thermocalcic aggregation. Protein permeation ratios in MF processes were improved by UF preconcentration of whey. Protein permeation and flux were different between the two MF membranes used. Isoelectric point precipitation increased β-Lg contents, but not α-La, in the resulting WPC (B). Minor proteins exhibited lower concentrations in WPC B and MF WPC products.     

Whey Protein Concentrate as a Proteinase Inhibitor in Pacific Whiting Surimi

The most effective inhibition of autolytic proteinase activity was found at 3% whey protein concentrate (WPC) with residual proteinase activity at 14.2%. WPC reduced papain and trypsin activities linearly with lowest residual activities of 8.7% and 41.4%, respectively. An unidentified high-molecular-weight protein was inhibitory for papain and trypsin with no inhibitory components detected at the region r 100,000. The highest shear strain of surimi was obtained with WPC at 4%. The values were 1.89 when rapidly cooked at 90°C for 15 min and 1.62 when pre-heated at 60°C for 30 min prior to cooking at 90°C.     

Flow Properties, Firmness and Stability of Double Cream Cheese Containing Whey Protein Concentrate

As estimated on-line, the viscosity after cooling of double cream cheese curd containing heat-denatured WPC (DCC +) increased from 1.4 Pa.s to 1.7 Pa.s when cooled to the range of 45°C to 24°C, and then decreased from 1.7 Pa.s to 1.0 Pa.s when cooled from 24°C to 15°C. The viscosity of DCC^- (without heat-denatured WPC) increased from 1.5 Pa.s to 2.2 Pa.s at temperature shift from 40°C to 15.5°C. The firmness of stored DCC + and DCC^-, respectively, decreased from 15.1N to 6.5N when cooled to temperatures from 45°C to 15°C, and from 17.9N to 9.9N when cooled from 40°C to 15.5°C, as recorded by cone penetrometry. The structure of DCC+ cooled to 15°C collapsed after penetrometry, and DCC+ cooled to 20°C destabilized during shearing in coaxial cylinder rheometer. A new phase in DCC+ based on milk fat globules liberated by cluster disruption may be the cause of the structural and textural instability.     

The Potential Source of B. licheniformis Contamination During Whey Protein Concentrate 80 Manufacture

The objective of this study was to determine the possible source of predominant Bacillus licheniformis contamination in a whey protein concentrate (WPC) 80 manufacturing plant. Traditionally, microbial contaminants of WPC were believed to grow on the membrane surfaces of the ultrafiltration plant as this represents the largest surface area in the plant. Changes from hot to cold ultrafiltration have reduced the growth potential for bacteria on the membrane surfaces. Our recent studies of WPCs have shown the predominant microflora B. licheniformis would not grow in the membrane plant because of the low temperature (10 °C) and must be growing elsewhere. Contamination of dairy products is mostly due to bacteria being released from biofilm in the processing plant rather from the farm itself. Three different reconstituted WPC media at 1%, 5%, and 20% were used for biofilm growth and our results showed that B. licheniformis formed the best biofilm at 1% (low solids). Further investigations were done using 3 different media; tryptic soy broth, 1% reconstituted WPC80, and 1% reconstituted WPC80 enriched with lactose and minerals to examine biofilm growth of B. licheniformis on stainless steel. Thirty‐three B. licheniformis isolates varied in their ability to form biofilm on stainless steel with stronger biofilm in the presence of minerals. The source of biofilms of thermo‐resistant bacteria such as B. licheniformis is believed to be before the ultrafiltration zone represented by the 1% WPC with lactose and minerals where the whey protein concentration is about 0.6%.     

High Hydrostatic Pressure Affects Flavor-binding Properties of Whey Protein Concentrate

ABSTRACT: The effects of high hydrostatic pressure (HHP) on flavor-binding properties of whey protein concentrate (WPC) were determined with benzaldehyde, heptanone, octanone, and nonanone. After HHP treatment (600 MPa, 50 °C, for 0-, 10-, or 30-min holding time), flavor-binding properties of WPC were studied by intrinsic fluorescence titration and static headspace analysis. The HHP treatments increased the number of binding sites and the apparent dissociation constants of WPC for benzaldehyde. HHP treatment of WPC for 0 min increased the number of binding sites of WPC for heptanone and octanone. As observed by headspace analysis, HHP treatments did not result in significant changes in the flavor retention for benzaldehyde in WPC solutions. Flavor retention of 100 ppm and 200 ppm heptanone and octanone in HHP-treated (10 min) WPC was significantly lower than for untreated WPC and HHP-treated WPC for 0 min or 30 min. For flavor retention of nonanone, significant decreases were only observed at 100 ppm when WPC solutions were HHP-treated for 10 min. While use of HHP treatment of WPC has potential in real food systems, these findings demonstrate the importance of careful selection of HHP treatment times and flavor concentrations for desired outcomes in food applications.