酸乳凝胶特性影响机理的探讨

Effect of fermentation temperature on the rheological properties of yogurt

探讨了不同发酵温度下酸乳的表观黏度与剪切速率及时间之间的关系,并对酸乳持水力、胶体脱水收缩作用敏感性等流变学特性进行了研究。结果表明,不同发酵温度酸乳的黏度随剪切时间的延长而变小,并最终趋于平缓,都形成了触变环。表明是触变体系,酸乳触变环面积(37℃>40℃>43℃)与黏度具有很好的相关性。酸乳的表观黏度随剪切时间的变化曲线符合幂函数y=kx-n的变化规律。37℃发酵酸乳的持水力达到最高值,分别较40℃和43℃发酵酸乳的高出18%和8%,而胶体脱水收缩作用敏感性值最小,比40℃和43℃发酵酸乳的分别低13%和5%。表明低温发酵酸乳的黏度大,乳清析出少,稳定性好。

The relationship with the viscosity of yogurt fermented at different temperature between shear rate and time were discussed in this paper. Water holding capacity and susceptibility to syneresis of yogurt were also studied. The results showed that： the viscosity of yoghurt fermented at different temperature became smaller with extended shear time firstly, then changed slowly. They ,all formed a thixotropic ring as the thixotropic system. The area of thixotropic loop （37℃〉40℃〉43℃）had a good correlation with viscosity. Viscosity with shear time curves conformed to a power function y=y=kx^n changing in the law. Water holding capacity of yogurt femaented at 37 ℃ reached the maxi mum value. It was 18% ,8% higher than that of yogurt fermented at 40℃,43℃Meanwhile, the susceptibility to syneresis of yogurt ferment ed at 37 ℃ reached the minimum value. It was 13% ,5% lower than that of yogurt fermented at 40℃,43℃. So it shows that viscosity is much higher for yogurt fermented at lower fermentation temperature which has less separation of whey and better stability.