乳清蛋白制备可食用膜的研究进展

乳清蛋白作为奶酪制造工业的副产品,通常用于婴儿配方奶粉和运动食品中。目前,人们正在努力寻找乳清蛋白新的应用,例如制成可食用膜。可食用膜是延长食品保质期、提高食品质量而不造成环境污染的一种“绿色”产品。乳清蛋白除了作为选择性水分和气体迁移屏障外,还可以作为许多功能成分的载体,包括抗氧化剂、抗菌剂、香料和着色剂等。因此,本文对乳清蛋白作为基质生产可食用膜的功能特性、成膜机理及其在食品工业中的应用等方面进行了概述。     

乳清浓缩蛋白可食用包装膜的研制

以乳清浓缩蛋白为基质,通过加入成膜剂、增塑剂制得可食用包装膜。研究了不同成膜剂添加量、不同增塑剂添加量、不同转谷氨酰胺酶添加量对成膜的影响。通过响应面分析表明,制备乳清浓缩蛋白可食用膜的最佳条件是：乳清浓缩蛋白浓度10%、添加山梨醇5%、无水氯化钙1.2166%、转谷氨酰胺酶0.018%,在60~65℃的温度范围成膜。     

乳清蛋白可食用膜抑菌性、溶解性的研究

主要研究了Nisin、纳塔霉素和溶菌酶不同组合添加下乳清蛋白可食用膜的抑菌性和溶解性,结果表明:随着抑菌剂浓度的增加,膜的抑菌效果增强,不同抑菌剂组合下膜的抑菌效果不同,0.35%Nisin和0.08%溶菌酶组合下抑菌效果更好。在酸性环境中,当添加0.03%溶菌酶和0.25%纳塔霉素时,可有效降低膜的溶解性;在中性环境中,各组膜的溶解性几乎相当,在碱性环境中,大部分膜的溶解性要低于其在酸性环境中。     

乳清浓缩蛋白可食用膜成膜工艺的研究

研究了乳清浓缩蛋白可食用膜的成膜工艺,分析了蛋白质浓度、甘油浓度和加热温度对可食用膜透水性和透氧性的影响,并确定了可食用膜阻隔性能的优化工艺参数。研究结果表明,可食用膜的阻水性随蛋白质浓度和甘油浓度的增大而下降,阻氧性随甘油浓度增大而下降。加热温度为70℃时,膜的阻水性和阻氧性达到最佳。响应面分析表明,当蛋白质浓度为100 g/L,甘油浓度为27 g/L,加热温度为69℃时,乳清浓缩蛋白可食用膜的综合通透性能为最佳,其透湿系数为0.004 35 g·mm/(m~2·h·kPa),透氧系数为0.134 cm~3·mm/(m~2·min·kPa)。     

转谷氨酰胺酶改性可食用膜的研究进展

转谷氨酰胺酶可催化蛋白发生交联反应,从而改性可食用蛋白膜和复合膜的组织结构和特性,如抗拉强度、断裂伸长率、阻水性、阻油性、透氧系数等,在食品工业中具有广阔的应用前景.本文介绍转谷氨酰胺酶改性对大豆蛋白可食用膜、乳清蛋白可食用膜、明胶可食用膜和复合膜的特性影响以及应用前景.     

乳清蛋白的酶法改性研究

采用碱性蛋白酶、风味蛋白酶、木瓜蛋白酶、中性蛋白酶、复合蛋白酶、胰蛋白酶、胃蛋白酶在各自的最适条件下对乳清蛋白粉进行水解,通过HPLC方法测定酶解产物中α-乳白蛋白（α—La）和β-乳球蛋白（β—Lg）的含量。结果表明,碱性蛋白酶对其水解最快,其次为木瓜蛋白酶,而在胃蛋白酶和胰蛋白酶作用下则不易酶解,而且发现α-La比β—Lg更容易水解。     

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.     

乳清蛋白酶改性综述

乳清蛋白通过改性 ,可以加强其功能性质 ,从而合理利用资源 ,开发新产品 ,扩大在食品中的应用。乳清蛋白的改性方法有化学改性、物理改性和酶改性。酶改性主要包括水解和交联。其中 ,用转谷氨酰胺酶改性具有比较大的发展潜力。     

乳清蛋白酶改性综述

乳清蛋白通过改性,可以加强其功能性质,从而合理利用资源,开发新产品,扩大在食品中的应用。乳清蛋白的改性方法有化学改性、物理改性和酶改性。酶改性主要包括水解和交联。其中,用转谷氨酰胺酶改性具有比较大的发展潜力。     

乳清蛋白酶改性综述

乳清蛋白的酶法改性主要包括水解和交联。其中，用转谷氨酰胺酶改性具有比较大的发展潜力。     

乳清蛋白可食膜的研究进展

论述了乳清蛋白组成及其功能特性,乳清蛋白可食膜的成膜机理、主要性能及其影响因素和应用。综述了国内外乳清蛋白可食膜的研究进展,提出了乳清蛋白可食膜研究中存在的问题和未来发展趋势。     

Calcium binding of peptides derived from enzymatic hydrolysates of whey protein concentrate

This study was carried out to investigate the peptides derived from enzymatic hydrolysates of whey protein concentrate. The physiological activity of peptides in whey protein may be used in food additives to promote the absorption of calcium and prevent bone disorders. The whey protein was hydrolysed by trypsin, and the separation of peptides, the properties of hydrolysates and the analysis of the ability to inhibit the formation of calcium phosphates were then investigated. Calcium-binding peptides were produced by tryptic hydrolysis of whey protein concentrate and further purified by precipitation and chromatography on DEAE-cellulose. The hydrolysates were loaded onto an ion-exchange column, followed by stepwise elution with 0, 0.25, 0.5, and 0.75 m NaCl in equilibration buffer to separate the peptides. Trypsin hydrolysates were shown to peak with 0.25 m NaCl and 0.5 m NaCl. The results of SDS-PAGE analysis showed that the peptides with a small molecular weight of about 1.4 to 3.4 kDa were present in the fraction resulting from 0.25 m and 0.5 m NaCl stepwise elution by ion-exchange chromatography of tryptic hydrolysates. The results of this study show that the whey protein hydrolysates produced by the action of trypsin have the ability to inhibit the formation of calcium phosphates.     

TG酶和羟丙基甲基纤维素改善乳清蛋白可食膜性能

以乳清浓缩蛋白(WPC)为基料,通过添加羟丙基甲基纤维素(HPMC,添加量为蛋白质量的5%~25%)和转谷氨酰胺酶(TG酶)对膜的性能进行改良,研究HPMC的添加量和转谷氨酰胺酶的交联作用对复合膜性能的影响。结果表明:HPMC能显著提高蛋白膜的抗拉强度,降低复合膜的断裂伸长率(p<0.05),TG酶能有效改善乳清蛋白-羟丙基甲基纤维素复合膜的柔韧性。当HPMC的添加量为乳清蛋白的20%时,复合膜的抗拉强度较好,表观光滑平整。制备WPC-HPMC复合膜进行奶茶粉、方便面调料包、油包,苏打饼干的初步包装实验,研究了包装产品在储藏12 d期间质量变化情况。结论:乳清蛋白-羟丙基甲基纤维素复合膜具有一定包装应用潜能。     

热处理和调节pH改性乳清蛋白浓缩物对搅打稀奶油加工性质的影响

通过热处理和调节p H对乳清蛋白浓缩物80(Whey protein concentrate,WPC80)进行改性处理,并将改性后的WPC80添加至低脂稀奶油中,以改善其搅打性质。结果表明调节WPC80溶液的p H为3,在80℃下加热15min时具有最佳的溶解性和起泡性,相同p H条件下,不同的热处理时间会对溶解性和起泡性产生不同的影响;将热处理和p H改性后WPC80加入搅打稀奶油中,研究发现不同热处理时间,p H为5改性的WPC80可以显著提高搅打稀奶油的打发率(p<0.05),但是p H为7处理的WPC80使稀奶油的泡沫稳定性增加了154.67%~193.42%。因此可通过热处理和调节p H改性的WPC80来提高低脂稀奶油的搅打特性,且此操作方法简单易行。      

热处理和调节pH改性乳清蛋白浓缩物对搅打稀奶油加工性质的影响

通过热处理和调节p H对乳清蛋白浓缩物80(Whey protein concentrate,WPC80)进行改性处理,并将改性后的WPC80添加至低脂稀奶油中,以改善其搅打性质。结果表明调节WPC80溶液的p H为3,在80℃下加热15min时具有最佳的溶解性和起泡性,相同p H条件下,不同的热处理时间会对溶解性和起泡性产生不同的影响;将热处理和p H改性后WPC80加入搅打稀奶油中,研究发现不同热处理时间,p H为5改性的WPC80可以显著提高搅打稀奶油的打发率(p0.05),但是p H为7处理的WPC80使稀奶油的泡沫稳定性增加了154.67%~193.42%。因此可通过热处理和调节p H改性的WPC80来提高低脂稀奶油的搅打特性,且此操作方法简单易行。     

Transglutaminase and hydroxypropyl methyl cellulose enhance mechanical properties of whey protein concentrate film

Whey protein and cellulose derivatives are abundant and renewable raw materials that provide an environmentally friendly alternative to fossil fuel sources used for food packaging. A novel biodegradable composite film comprising whey protein concentrates (WPC) aqueous solutions (10%, w/v) with different concentrations of Hydroxypropyl methylcellulose (HPMC) (0, 1, 2, 3, 4 and 5 wt% of WPC) was prepared in the present study. The effect of transglutaminase (TG) on the functional properties of the film was investigated. SDS-PAGE profiles indicated that TG modulated the formation of intermolecular cross-linking of WPC. FT-IR results showed that HPMC modified the mechanical properties of WPC. Incorporation of HPMC decreased the transparency and improved the tensile strength and extensibility of the film. TG addition led to a significant enhancement of the mechanical properties of the film. These findings indicated that TG promoted the formation of WPC-HPMC composite film with improved mechanical properties.     

乳清浓缩蛋白WPC80凝胶工艺确定及其凝胶特性分析

以乳清浓缩蛋白(WPC80)为研究对象,分析了温度、时间、料液浓度、钙离子强度、乳糖浓度及pH值对其凝胶的影响,并通过测试样品凝胶特性。确定了WPC80凝胶的最佳工艺条件:配置质量分数为9%的WPC80溶液,室温400 r/min搅拌30 min至样品全部溶解;4℃储存10 h以上,便于蛋白溶解及水合;添加质量分数为0.12%的氯化钙;65℃,转速为80 r/min恒温水浴30 min;调节样品pH值为5.5;85℃水浴静置20 min形成凝胶。     

Effect of denatured whey protein concentrate and its fractions on rennet-induced milk gels

Denatured whey protein concentrate was fractionated by centrifugation to study the effect of its different components (sedimentable aggregates, non-sedimentable component, and diffusible component) on rennet-induced coagulation of milk and gel contraction capacity. Milk coagulation properties were characterized by optical density measurement and dynamic rheometry. The contraction kinetics of the gel during cooking was also characterized. The diffusible component of denatured whey protein concentrate showed no significant effect on coagulation or contraction parameters. Sedimentable aggregates negatively influenced the kinetics of rennet gel formation, as measured by rheology; these aggregates also reduced the contraction capacity of the gel. The non-sedimentable component negatively influenced milk coagulation properties, as measured with both optical and rheological methods, and decreased the contraction capacity of the gel. The results suggest that, beyond the effect of sedimentable whey protein aggregates, soluble proteinaceous complexes (non-sedimentable and non-diffusible) could interact with renneted casein micelles and limit gel formation and contraction.