热处理及成熟温度对低脂牦牛乳硬质干酪理化性质及品质影响

Effects of heat treatment and ripening temperature on the physicochemical properties and quality of low-fat yak milk hard cheese

干酪减脂符合消费者健康需求,生产工艺是改善低脂干酪品质经济而简便的方式之一。该实验以未热处理、65℃30 min、75℃1 min、85℃15 s和4、12℃分别作为原料乳热处理和成熟温度条件,制作低脂牦牛乳硬质干酪,测定不同成熟时间(0、1、3、6个月)干酪的理化、品质指标。结果表明,随着原料乳热处理温度增加,干酪出品率、水分和总游离氨基酸含量增加,NaCl含量呈现降低趋势;3组热处理组干酪的硬度显著高于未热处理组,但随热处理温度增加,硬度下降;不同热处理组干酪之间弹性差异较小;85℃处理组干酪的黏聚性在成熟后期,显著低于其他3组干酪;整个成熟期内,85℃处理组感官品质评分均较高。相同热处理原料乳制作的干酪,12℃成熟时的硬度始终显著低于4℃成熟干酪,但是其NaCl和总游离氨基酸含量始终显著高于4℃成熟干酪;成熟时间少于6个月时,12℃成熟干酪的感官品质优于4℃成熟干酪。因此,原料乳热处理和成熟温度的提高能增加干酪中总游离氨基酸含量,降低其硬度和黏聚性,缩短干酪成熟时间,改善其品质。该研究为低脂牦牛乳硬质干酪的生产提供了理论指导。

Fat reduction of cheese meets the health demand of consumers.Production technology is one of the economical and simple ways to improve the quality of low-fat cheese.In this experiment,low-fat yak milk hard cheese was made under the conditions of raw milk heat treatment(without heat treatment,65℃for 30 min,75℃for 1 min,and 85℃for 15 s)and ripening temperature(4℃and 12℃),respectively.The physicochemical and quality indexes of the cheese were determined at different ripening times(0,1,3,and 6 months).The results showed that with the increase of heat treatment temperature of raw milk,the yield,moisture,and total free amino acid contents of cheese increased,and the NaCl content showed a decreasing trend.The hardness of the cheese in the three heat treatment groups was significantly higher than that in the non-heat treatment group,but the hardness decreased with the increase of heat treatment temperature.The difference in elasticity between different heat treatment groups was small.The cohesiveness of the cheese treated at 85℃was significantly lower than that of the other three groups at the later ripening stage.In the whole maturity period,the sensory quality scores of the 85℃treatment group were higher.The hardness of cheese matured at 12℃were always significantly lower than that at 4℃,but the contents of NaCl and total free amino acid were always significantly higher than that at 4℃.When the ripening time was less than 6 months,the sensory quality scores of 12℃ripened cheese was better than 4℃ripened cheese.Therefore,the increase of heat treatment and ripening temperature of raw milk can increase the content of total free amino acid in cheese,reduce the hardness and cohesiveness,shorten the ripening time and improve the quality of cheese.This study provided theoretical guidance for the production of low-fat yak milk hard cheese.