新疆双峰驼乳杀菌条件的选择及其热稳定性

Selection of Sterilization Conditions for Xinjiang Bactrian Camel Milk and Its Thermal Stability

研究加热温度和时间与驼乳相对密度、滴定酸度、pH值、黏度、酒精稳定性、乳糖含量和总蛋白质含量的关系，用残活率对数值（1g（N/N0））评价杀菌效果，采用SDS-PAGE检测每个热处理水平驼乳蛋白质的变性程度。结果表明：在75℃热处理时间分别为5、10、15min时，菌落总数减少了60.2%、61.9%、81.9%。热处理对驼乳理化指标无显著影响（P＞0.05），对酒精稳定性影响显著（P＜0.05）。在60～75℃条件下，热处理时间对蛋白质含量的影响不显著（P＞0.05）；在65～100℃时，热处理温度对乳糖含量的影响显著（P＜0.05）。蛋白质的热稳定性：乳酸脱氢酶＞α-乳白蛋白＞白蛋白＞乳铁蛋白。60℃热处理对驼乳中蛋白质的影响不显著（P＞0.05）。65～100℃热处理对驼乳中蛋白质的影响显著（P＜0.05）。结论：在75℃热处理5～15min，可以杀灭81.9%的微生物，蛋白质的变性程度较低。

The relative density, titratable acidity, pH, viscosity, alcohol stability, lactose content and total protein contentof mixed milk samples from 10 bactrian camels in ürümqi suburb, Xinjiang autonomous region were determined as afunction of sterilization temperature and time. The sterilization efficiency was evaluated based on decimal logarithm ofsurvival fraction （lg （N/N0））. Protein denaturation in milk samples at each thermal treatment was assayed by SDS-PAGE.The results showed that after 5, 10 min and 15 min at 75 ℃, the total number of colonies was reduced by 60.2%, 61.9% and81.9%, respectively, without a significant effect on physiochemical parameters （P ＞ 0.05）; however, the alcohol stabilitywas significantly influenced （P ＜ 0.05）. Heating time at 60—75 ℃ did not significantly protein content （P ＞ 0.05）. Heatingtemperatures of 65—100 ℃ exhibited a significant effect on lactose content （P ＜ 0.05）. The thermal stability of variousprotein components followed the order： lactate dehydrogenase ＞ α-lactalbumin ＞ albumin ＞ lactoferrin. No significanteffect on milk proteins was observed after heat treatment at 60 ℃ （P ＞ 0.05）. The effect of heat treatment at 65—100 ℃ onmilk proteins was significant （P ＜ 0.05）. From these results, it can be concluded that heat treatment at 75 ℃ for 5—15 mincan kill 81.9% of the microbes in bactrian camel milk, resulting in lower degree of protein denaturation