高酮体乳的蛋白热稳定性研究

Heat stability of milk protein with high concentration of ketone

以正常乳和高酮体牛乳为原料,测定其在65°C、75°C、85°C和95°C下加热10 min的变性和聚集程度、乳清蛋白氮指数、表面巯基以及表面疏水性等,研究其在不同热处理条件下的理化性质变化及聚集行为。生乳的电泳图谱表明高酮体乳乳的β-酪蛋白(β-CN)、κ-酪蛋白(κ-CN)、α-乳白蛋白(α-LA)比例高于正常牛乳。热稳定性结果表明,热处理导致乳蛋白变性,并发生一定程度的聚集。随着处理强度的增加,乳蛋白变性程度增加。在75～95°C处理下,两种乳均发生一定程度的变性。在85°C和95°C处理下,高酮体乳蛋白表现出更差的热稳定性。

To explore the thermal stability of milk with different concentrations of ketone,we collect normal milk and milk of subclinical ketosis cows from the ranch.Then these samples are heated at 65℃,75℃,85℃ and 95℃ for 10 minutes to test the degree of protein degeneration and gathering.Electrophoregram of raw milk showed that β-CN,κ-CN and α-LA ratio of normal milk were higher than that of high-ketone milk.The results of the thermal stability show that the heat treatment causes the milk protein to denature and to some degree of aggregation.With the increase of treatment intensity,the degree of milk protein denaturation increased.During 75~95℃ treatment,both milk undergoes some degree of denaturation.With the increase of treatment intensity,the degree of milk protein denaturation increased.High-ketone milk proteins showed poorer thermal stability at 85℃ and 95℃.