搅拌型酸奶流变学特性的研究

Preliminary Study on the Rheological Properties of Stirred Yogurt

以市场上流行的6种搅拌型酸奶为研究对象，对其流变学特性及质构特性进行了初步的研究。结果表明：6种酸乳的剪切应力值在升速和降速过程中都能形成触变环，表观粘度在升速过程中随剪切应力的增大而逐渐降低，降速过程中随着剪切速率的降低而升高；酸奶在16r／min的剪切速率下，转速和相应的表观粘度符合幂率定律，进一步发现搅拌型酸奶具有时间触变性，是一种正触变性流体。由触变环的面积可知，6种搅拌型酸奶的触变性大小：S5〉S4〉S2〉S1〉S3〉S6，触变性的大小对样品的口感有非常重要的影响。此外，酸奶的流变学分析得出口感较好的酸奶粘度值应在540．56～674．25mpa·s范围内；酸奶质构分析发现口感较好的酸奶硬度在33．9-39．9g范围内。

This study mainly investigated on the popular stirred yogurt on market, having a preliminary research on the rheological properties and texture profile analysis of stirred yogurt. The results showed that six samples could produce thixotropic loop in the processes of acceleration and deceleration. The apparent viscosity decreased during rotor running up and increased in the process of speed down.When the shear rate was 16 r/min, the relation of the speed of rotator and corresponding apparent viscosity adapt to power law. We can further find that the stirred yogurt was a kind of positive thixotropic liquid. The order of their thixotropic was number 4〉number 5〉number 2〉number 1〉number 3〉number 6, the size of thixotropic loop had an important influence on taste. By the rheology study of stirred yogurt,when the the viscosity of the sample was in the range of 540.56-674.25 mpa＇s, the sample had a good taste; by analysis of texture, when the hardness of the sample was in the range of 33.9-39.9 g, the sample had a a good taste.