摘要
为研究增稠剂对酸乳体系的影响机理,在原料——鲜牛乳中分别加入0.1%、0.2%、0.3%的黄原胶,发酵制作酸乳样品,同时作对照。采用流变仪测定各种酸乳的流变学特性,并用扫描电镜观察其微观结构。结果表明,4种酸乳样品均是正触变性流体,其触变环面积之比为1∶1.08∶0.64∶0.77。黄原胶添加量为0.1%、0.2%和0.3%的3个样品中,随着黄原胶加入量的增加,酸乳样品的表观黏度和剪切应力逐渐降低。电镜观察发现,未加入黄原胶时,酪蛋白相互凝聚成细密的立体网状结构;加入黄原胶后,酪蛋白凝聚物变成散乱的片状结构。因此,原料牛奶中加入0.1%-0.3%的黄原胶,既不能改变凝固型酸奶的正触变性流体特性,也不能增加其黏度。电镜显示,这是通过黄原胶大分子的空间位垒效应干扰酪蛋白间发生凝聚的方式,导致凝胶结构散乱,从而降低酸乳乳块的表观黏度和剪切应力。
In order to explore the effect mechanism of thicking agent to yogurt system, the yogurts were fermented by adding different amount of Xanthan（0.1%, 0.2%, 0.3% and CK）. The rheometer was used to measure the rheological properties of these yogurts. Scanning electron microscope was also used to explore its microstructure. The results showed that the entire 4 yogurt samples were positive thixotropic fluid and the area ratio of the 4 thixotropic rings were 1：1.08： 0.64：0.77. The apparent viscosity and shear stress decreased gradually with the increasing of xanthan in the added amount of 0.1%, 0.2% and 0.3%. The observation by electron microscope showed that the casein micelles aggregated and constructed cross-linked network structures when no xanthan added in the samples, while the casein curds became to the disheveled sheet structures in the samples added with xanthan. It was the conclusion of the investigation that the characteristic of positive thixotropic fluid of the 4 kinds of set yogurt could not be changed and the viscosity could not be increased by adding 0.1%-0.3% xanthan. The mechanism of these phenomena, it was considered that the extra added xanthan disturbed the aggregating styles between casein micelles with the space baffle effect of xanthan molecular and caused the dishevelment structure of casein micelles cluster and furthermore reduced the apparent viscosity and shear stress of yoghurt curds.
出处
《中国食品学报》
EI
CAS
CSCD
北大核心
2009年第3期43-49,共7页
Journal of Chinese Institute Of Food Science and Technology
基金
中国博士后科学基金资助项目(20070411100)
山东省自然科学基金资助项目(2007ZRB02217)
关键词
酸乳
黄原胶
流变特性
微观结构
机理
Yogurt Xanthan Rheological-properties Microstructure Mechanism
