解淀粉芽孢杆菌GSBa-1凝乳酶对羊奶干酪成熟特性的影响

Effect of Bacillus amyloliquefaciens GSBa-1 Rennet on Ripening Properties of Goat Milk Cheese

为探究解淀粉芽孢杆菌GSBa-1凝乳酶制备的羊奶干酪(干酪B)成熟特性的变化,以采用商业凝乳酶和同批次羊奶制作的干酪(干酪A)为对照组,比较两组干酪在60d成熟期主要组分、质构特性、微生物指标及风味物质的变化。结果表明,两组干酪得率相差不大。成熟期间干酪的水分、蛋白质及脂肪含量呈先上升后下降趋势,干酪B始终高于干酪A;干酪游离氨基酸总量在成熟期间呈先下降后上升趋势,且干酪B中苯丙氨酸、天冬氨酸、异亮氨酸、甲硫氨酸、丝氨酸含量高于干酪A。成熟前期干酪B质构特性优于干酪A。干酪A成熟后乳酸乳球菌数量增加了(5.22±0.02)%,干酪B无显著变化(P>0.05)。成熟期内,两组干酪中挥发性风味物质种类和含量均增加,但干酪B中的壬酸、辛醇、2-庚酮、2-壬酮、二甲基砜使羊奶干酪风味独特、浓郁。因此,GSBa-1凝乳酶具备替代商业凝乳酶用于羊奶干酪生产的潜力,可对干酪风味的形成和品质的提升起到一定促进作用。

To explore changes of the ripening properties of goat milk cheese made with Bacillus amyloliquefaciens GSBa-1 rennet(cheese B),commercial rennet and cheese prepared with the same batch of goat milk(cheese A)were used as the control group.Changes in main components,texture properties,microbial indicators and flavor substances were analyzed during the 60-day ripening of cheeses.The results showed that there was no significant difference in the cheese yield between the two groups.The moisture,protein and fat contents of cheese increased first and then decreased,and contents of cheese B were always higher than those of cheese A.The total contents of free amino acids increased first and then decreased,and the contents of phenylalanine,aspartic acid,isoleucine,methionine and serine in cheese B were higher than those of cheese A.The texture characteristics of cheese B in the early stage of ripening were better than cheese A.The number of Lactococcus lactis of cheese A increased by(5.22±0.02)%after ripening,and cheese B did not change significantly(P>0.05).During cheese ripening,the types and contents of volatile flavor substances in the two groups of cheese increased,but the nonanoic acid,octanol,2-heptanone,2-nonanone and dimethyl sulfone formed by cheese B gave goat milk cheese unique and rich flavor.Therefore,GSBa-1 rennet had the potential to replace commercial rennet in the production of goat milk cheese,and could promote the formation of cheese flavor and the improvement of quality.