马铃薯果胶流变特性的研究

Study on rheological properties of potato pulp pectin

以马铃薯果胶(potato pectin extracted by chelating agent,PPCH)为研究对象,研究果胶溶液质量分数、剪切速率、温度、pH、金属离子等因素对马铃薯果胶流变学特性的影响。研究表明,PPCH溶液的黏度随溶液质量分数上升而增加。随着剪切速率的增大,PPCH溶液黏度下降,剪切变稀现象随着果胶质量分数的增加而更加明显,属于非牛顿流体。PPCH溶液流体行为受温度的影响。在剪切速率为50 s^-1时,温度10~47℃为时,PPCH溶液黏度随着温度升高而急速下降;温度为47~65℃时PPCH溶液黏度随着温度升高而缓慢波动,较难以用Arrhenius方程加以解释;温度为65~80℃时,PPCH溶液黏度随着温度升高而缓慢下降。在剪切速率为100、500 s^-1时,PPCH溶液黏度随着温度升高而缓慢下降。温度为10~47℃时,PPCH溶液活化能与剪切速率有较大的相关性,而温度为47~80℃时,活化能与剪切速率相关性较小。pH值对PPCH溶液流动性能有较大的影响。随着pH的升高,果胶溶液的黏度呈先增加后减小的趋势,在pH 4.0时,果胶溶液黏度最低,流动性最差。二价金属离子(Ca^2+、Mg^2+)可提高PPCH溶液的黏度,Ca^2+对于PPCH溶液黏度的增加幅度明显高于Mg^2+。

Rheological properties of potato pectin(PPCH)and the factors,such as pectin concentration,shear rate,temperature,pH value,metalions on rheological properties were investigated.The results showed that the increased pectin concentration resulted in the increase of solution viscosity.However,with the increase of shear rate,the solution viscosity was reduced.Moreover,the shear-thinning became more obvious with the increase of pectin concentration,which could be attributed to non-Newtonian fluid.The rheological behavior of PPCH solution was affected by temperature.At specific shear rates(50 s^-1),the viscosity of PPCH solution decreased rapidly with the increase of temperature in range from 10℃to 47℃.In addition,the viscosity of PPCH solution fluctuated slowly with the temperature increasing in the range from 47℃to 65℃,and the viscosity of PPCH solution decreased slowly as the temperature increase in the range from 65℃to 80℃.At specific shear rates(100,500 s^-1),the viscosity of PPCH solution decreased slowly with the increase of temperature.In the temperature range from 10℃to 47℃,the activation energy of PPCH solution had a greater correlation with the shear rate.In the temperature range from 47℃to 80℃,the activation energy had a smaller correlation with the shear rate.The rheological properties of the PPCH solution were influenced greatly by pH value.Besides,the viscosity of pectin solution increased first and then decreased with the increase of pH value.And at pH 4.0,pectin solution had the lowest viscosity and the lowest fluidity.Divalent metalions obviously improved the viscosity of PPCH solution.Compared with Mg^2+,Ca^2+could significantly increase PPCH solution viscosity.