拉伸温度对纤丝干酪流变学特性及微观结构的影响

Effect of Stretching Temperature on Rheological Characteristics and Microstructure of String Cheese

摘要:

用小型单螺杆拉伸机制作纤丝干酪，研究拉伸温度对纤丝干酪流变学性质和微观结构的影响。扫描电镜观察结果表明，干酪凝块经过拉伸过程后由无定型的三维结构转变为近乎平行排列的线性纤维状结构，拉伸温度越高蛋白质网络结构越致密。这一结果与通过离心法测定纤丝干酪可榨乳清含量结果一致，说明经过热烫拉伸处理后酪蛋白矩阵持水力增大，且拉伸温度越高酪蛋白矩阵持水力越大。干酪从25 ℃升温至80 ℃的动态流变学温度扫描结果表明，拉伸温度低于50 ℃时制作的纤丝干酪加热后流变学性质不稳定。干酪从0.1~10 Hz动态流变学频率扫描结果表明，纤丝干酪表现出较强的粘弹性以及剪切稀化特性，且随着拉伸温度的升高，这种特性表现的愈加明显。TPA分析结果表明，拉伸温度对纤丝干酪硬度影响最显著。

Abstract:

String cheeses were provided by a small-scale single screw extruder, and the effect of stretching temperature on the rheological characteristics and microstructure of string cheese was observed in this research. Scanning electron microscopy of string cheese indicated that cheese microstructure changed from amorphous three-dimensional into a near-linear parallel fibrous structure after stretching, which exhibited a more dense protein network structure at higher temperature. This microstructural change was consistent with a reduction in the level of serum expressed by centrifugation and suggested that after the stretching treatment the water holding capacity of the casein matrix increased with the rise of temperature. Dynamic measurement of the viscoelastic changes on heating the cheese from 25 to 80 ℃ showed that rheological properties of string cheese were unstable below 50 ℃. Dynamic measurement of the viscoelastic changes on the string cheese from 0.1~10 Hz frequency sweep displayed that it had stronger viscoelastic and shear thinning properties, and the performance was more obvious with increasing stretching temperature. TPA results revealed that cheese hardness was affected by the stretching temperature significantly.