几种代可可脂巧克力浆的流变性

Rheological Behaviour of Chocolate Pastes Composed of Cocoa-Butter Replacers

本文研究了可可粉与三种代可可脂组成的巧克力浆的流变性。三种代可可脂的流动活化能均与可可脂颇为接近。代可可脂ＳｕｐｅｒＹＺ－２／可可粉的特征粘度明显较低，在可可粉体积分率较低时，三种可可悬浮体均呈牛顿性，但当＞０．２时具有明显剪切稀化特征。悬浮体粘度服从—通用流变模型，当超过某一临界值而悬浮体有屈服应力时该模型自动转化为Ｃａｓｓｏｎ方程。屈服应力与颗粒体积分率的关系服从四参数方程，实验求出了全部模型参数。

The rheological behaviour of cocoa pastes consisted of three cocoa butter replacers (CBR) and cocoa powder was studied. The flow activation energy for these CBR was approximately same as the value of cocoa fat. The intrinsic viscosity of Super YZ-2/cocoa powder was obviously lower than the others. It was found that all cocoa suspensions exhibited Newtonian property at low volume fraction of particle, but shear thinning if >0.2. The viscosity of cocoa suspensions followed a general model which reduced to Casson equation if yield stress existed when was beyond a critical value. The yield stress can be represented by a equation with 4 parameters. All model parameters of cocoa suspensions were also determined.