牦牛酸奶加工工艺参数优化及其品质分析

The processing parameter optimization of yak yogurt and its quality analysis

为开发出一种品质优良、营养丰富、口感细腻的牦牛酸奶产品,该研究以牦牛奶粉为原料,通过响应面试验优化牦牛酸奶的最佳加工参数如下:牦牛奶粉复水比为1:8,蔗糖添加量为7%,杀菌条件为85℃/15min,发酵时间8 h。在此条件下获得的牦牛酸奶质地醇厚、口感细腻、酸甜适中,持水力57.53%、黏度9065 mPa·s、酸度95.41°T、硬度45.21 g、黏性26.16 mJ、内聚性0.51、弹性0.95 mm、乳酸菌活菌数2.74×106 CFU/mL。为明确牦牛酸奶风味成分特点,采用全二维气相色谱/质谱联用仪(comprehensive two-dimensional gas chromatograph/mass spectrometer,GC×GC-MS)对其进行测试分析,并与普通酸奶及3种市售酸奶进行对比。结果表明,牦牛酸奶中风味物质最多,有180种,包括烯烃类、烷烃类、醇类、醛类、酯类、酮类、醚类、酚类、胺类、酸类以及呋喃类物质,其中含有10种牦牛酸奶特有的风味物质。

The yak yoghurt with good quality,rich nutrition and delicate taste was developed by using yak milk powder as raw material and the optimum processing parameters of yak yogurt were optimized by response surface test as follows:the rehydration ratio of yak milk powder was 1:8,the addition amount of sucrose was 7%,the sterilization condition was 85℃/15min,the fermentation time was 8 h,and the post-ripening time was 24 h.The yak yogurt achieved under the above conditions has a mellow texture,delicate taste,moderate sour and sweet;Yak milk pH 4.6,water holding capacity 57.53%,viscosity 9065 mPa∙s,acidity 95.41°T,hardness 45.21g,adresiveness 26.16 mJ,cohesioness 0.51,springiness 0.95 mm,number of viable lactic acid bacteria 2.74×106 CFU/mL.Moreover,integrated two-dimensional gas chromatography/mass spectrometer to detect and analyze them were used to determine the volatile components of yak yoghurt,respectively.Compared with ordinary yogurt and three kinds of commercial yogurt,yak yogurt contains 180 kinds of flavor substances,including olefins,alkanes,alcohols,aldehydes,esters,ketones,ethers,phenols,amines,acids,furans,etc.,of which 10 kinds of unique flavor substances are found.