蛋白含量对牦牛乳清蛋白浓缩物功能特性的影响

Effect of Protein Content on Functional Properties of Yak Whey Protein Concentrate

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 protein concentrate,WPC)主要成分(乳糖含量、pH值和总蛋白质含量)和功能特性(溶解性、持水性、持油性、起泡性、乳化性及热稳定性)的特征。结果表明:10 000 Da再生纤维素膜透析得到的牦牛WPC中总蛋白含量达到80%以上,不含乳糖,功能特性(溶解性、持水性、持油性、起泡性、乳化性及热稳定性)均显著高于经3 500 Da卷式膜、5 000 Da再生纤维素膜透析得牦牛WPC,WPC蛋白含量越高,其功能特性越好;不同蛋白含量的牦牛SWPC起泡能力、泡沫稳定性、乳化活性和乳化稳定性均显著(P<0.05)高于牦牛NWPC。牦牛乳WPC最不稳定温度为85℃,高于荷斯坦牛乳WPC的80℃,热处理会适当改善牦牛WPC的起泡性能、乳化性能和热稳定性。通过膜牦牛处理获取的高蛋白含量的WPC,功能特性较好,应用广泛,对解决牦牛乳清资源的利用问题、保护环境、提高企业的经济效益起到关键性作用。

Native whey protein concentrate(NWPC)and sweet whey protein concentrate(SWPC)were prepared by spiral-wound membrane ultrafiltration of native yak whey and sweet yak whey followed by sequential dialysis through regenerated cellulose membranes with different molecular mass cutoffs(MMCOs),respectively,and their major components(lactose,pH and total protein)and functional properties(solubility,water-holding capacity,oil-holding capacity,foaming properties,emulsifying properties and thermal stability)were evaluated.The results showed that the total protein content of the whey protein concentrates(WPCs)obtained after dialysis through 10000 Da MMCO cellulose membrane,which were found to contain no lactose,was over 80%.The solubility,water-holding capacity(WHC),oil-holding capacity(OHC),foaming properties,emulsifying properties and thermal stability were all significantly higher than those of the WPCs obtained after ultrafiltration through 3500 Da MMCO rolled membrane and after dialysis through 5000 Da MMCO cellulose membrane.The higher the protein content in WPC,the better the functional properties.After the same concentration treatment,the foaming capacity,foam stability,emulsifying capacity and emulsion stability of SWPCs were significantly(P<0.05)higher than those of NWPCs.Yak WPC was the most unstable at 85℃,which was higher than 80℃observed for Holstein cow milk WPC.The appropriate thermal treatment could improve the foaming properties,emulsifying properties and thermal stability of yak WPC.The yak WPC with high protein content obtained by membrane processing had good functional characteristics,making it having wide applications.It will play a key role in solving the problem of yak whey resource utilization,protecting the environment,and improving the economic benefits of enterprises.