酸奶对玉米淀粉流变特性的影响

Effects of yogurt on the rheological properties of corn starch

目的考察含有活性乳酸菌的酸奶对淀粉黏弾特性的影响。方法以玉米淀粉为原料,分别加入1%(V/V)的酸奶,并在37℃保温1 h;用流变仪研究发酵后玉米淀粉的流变学性质。结果剪切流变曲线服从Herschel-Bulkley模型(R2>0.90)。屈服应力τ0、粘度系数k增加,流动指数n减小(n<1),显示发酵后的玉米淀粉仍然是非牛顿、屈服假塑性流体。震荡流变曲线显示添加酸奶的样品组的贮能模量G’与损耗模量G’’均大于空白组、且均随着剪切频率的增大而增大。结论经乳酸菌发酵的玉米淀粉,具有更高的黏弹特性。

Objective To investigate the effect of yogurt containing active lactic acid bacteria on the viscosity characteristics of starch.Methods Corn starch was used as the raw material,1%(V/V)yogurt was added respectively and keeping them at 37℃for 1 h.The rheological properties of corn starch after fermentation were studied by rheometer.Results The shear rheological curve obeyed the Herschel-Bulkley model(R2>0.90).The yield stressτ0 and the viscosity coefficient k were increased,while the flow index n was decreased(n<1).It was shown that the fermented corn starch was still a non-Newtonian,yielding pseudo plastic fluid.The oscillating rheological curve showed that the storage modulus G’and loss modulus G’’of the sample group with yogurt added were higher than those of the blank group,and both increased with the increase of the shear frequency.Conclusion Corn starch fermented by lactic acid bacteria has higher viscoelastic properties.