牦牛原料乳冻藏条件对酸乳发酵性能的影响研究  

Effect of Frozen Storage Conditions of Raw Yak Milk on Fermentation Performance of Yoghurt

作　　者：王晶[1] 刘鹏莉 肖海滨 WANG Jing;LIU Pengli;XIAO Haibin(Department of Food and Biochemical Engineering,Yantai Vocational College,Yantai 264670,China;School of Chemistry and Chemical Engineering,Shandong University of Technology,Zibo 255049,China)

机构地区：[1]烟台职业学院食品与生化工程系,山东烟台264670 [2]山东理工大学化学化工学院,山东淄博255049

出　　处：《食品科技》2023年第2期44-49,共6页Food Science and Technology

基　　金：烟台职业学院2022年校本科研项目(2022XBZC028);国家自然科学基金项目(青年科学基金项目21907058)。

摘　　要：该研究考察了牦牛原料乳在不同冻藏方式(–20℃和–40℃)下分别贮存30、90、180 d时对酸乳加工品质的影响。结果发现,在–20℃冻藏30 d的牦牛乳制成酸乳与鲜牦牛酸乳相比品质无显著变化(P>0.05);冻藏30 d时,pH值下降至4.5需要(5.25±0.25)h,在–20℃和–40℃条件下冻藏180 d时,分别需要(6.50±0.17)h和(6.00±0.25)h;酸乳的最大酸化速率Vm随原料乳冻藏时间的延长呈下降趋势;在发酵完成时,–40℃组的嗜热链球菌和保加利亚乳杆菌的菌数分别为(8.57±0.10)、(7.64±0.10)lgcfu/mL,略高于–20℃组的(8.50±0.08)lgcfu/mL和(7.51±0.06)lgcfu/mL,–40℃冻藏后制备的酸乳感官品质更好,可进一步提高酸乳的发酵性能。因此,在–20℃短期冻藏的牦牛乳可以作为酸乳生产的备用奶源,但–40℃冻藏将更有益于牦牛酸乳今后的提质升级。This study investigated the effect of storage of raw yak milk at-20℃and-40℃for 30,90,180 d on the quality of yoghurt processing.The results showed that there was no significant change(P>0.05)in the quality of yak milk made from yak frozen at-20℃for 30 d compared with fresh yak milk.It takes(5.25±0.25)h for pH value to drop to 4.5 when frozen for 30 days,(6.50±0.17)h and(6.00±0.25)h when frozen for 180 days at-20℃and-40℃,respectively.The maximum acidification rate Vm of yogurt decreases with the extension of frozen storage time of raw milk.At the completion of fermentation,the numbers of Streptococcus thermophilus and Lactobacillus bulgaricus in the-4o℃group were(8.57±0.10)lg cfu/mL and(7.64±0.10)lg cfu/mL,respectively,slightly higher than those of(8.50±0.08)lg cfu/mL and(7.51±0.06)Ig cfu/mL in the-20 group.and the organoleptic quality of the yoghurt prepared after freezing at-4o C was better,which could further improve the fermentation performance of yoghurt.Therefore,short-term frozen yak milk at-2o℃can be used as a backup source for yoghurt production,but-40℃freezing will be more beneficial for future quality improvement of yak yoghurt.

关 键 词：牦牛原料乳 冻藏 牦牛酸乳 发酵性能 感官品质 

分 类 号：TS252.54[轻工技术与工程—农产品加工及贮藏工程]