不同巴氏杀菌处理对绵羊乳热加工特性的影响

Effect of different pasteurization treatments on hot working characteristic of sheep milk

目的探究绵羊液态乳的热加工特性。方法以牛乳为对照,分别通过低温长时杀菌((65±2)℃/30 min)、高温短时杀菌(85±2)℃/15 s)和超巴氏杀菌((121±2)℃/5 s)对绵羊乳进行杀菌处理,分析3种巴氏杀菌方式对绵羊乳pH值、黏度、蛋白沉淀量、酪蛋白粒径、zeta电位的影响,评价其热稳定性。结果相比于未处理组,3种巴氏杀菌处理均会显著增加绵羊乳pH值,超巴氏杀菌处理会引起绵羊乳黏度及蛋白沉淀量显著增大(P<0.05);在高温短时和超巴氏杀菌处理下,绵羊乳酪蛋白粒径显著增加(P<0.05),分别达到185.33 nm和242.70 nm。不同巴氏杀菌绵羊乳间Zeta电位无显著性差异;在同样处理条件下,牛乳黏度、蛋白沉淀量及酪蛋白粒径变化程度均小于绵羊乳。结论绵羊乳热加工特性较牛乳脆弱,加工温度易引起品质劣变,低温长时杀菌方式对绵羊乳的理化特性影响最小。

Objective To explore the thermal processing characteristics of sheep milk.Methods Taking cow milk as a control,the sheep milk was sterilized at low temperature for a long time((65±2)℃/30 min),short-term sterilization at high temperature(85±2)℃/15 s)and super pasteurization((121±2)℃/5 s),the effects of the 3 pasteurization methods on the pH,viscosity,protein precipitation,casein particle size and zeta potential of the sheep milk were analyzed,and its thermal stability after the thermal treatments was evaluated.Results Compared with the untreated group,the pH value of sheep milk was significantly increased by the 3 types of pasteurization,and the viscosity and protein precipitation of sheep milk were significantly increased by the super-pasteurization treatment(P<0.05).In the short time of high temperature and ultra-pasteurization treatment,the particle size of sheep milk casein increased significantly(P<0.05)to 185.33 nm and 242.70 nm respectively.There was no significant difference in Zeta potential between different pasteurized sheep milk.Under the same treatment conditions,the cow milk viscosity,protein precipitation and casein particle size changed less than sheep milk.Conclusion The thermal processing characteristics of sheep milk are weaker than cow milk,and the processing temperature is easy to cause quality deterioration.Low temperature and long sterilization have the least effect on the physicochemical properties of sheep milk.