Effect of pH on the quality of apple pectin extracted with ultrasonic-wave assisted

In order to study the effect of pH values on the quality of apple pectin,different pH of ultrasonic-wave assisted were adopted to extract apple pectin from apple pomace so as to evaluate the quality of apple pectin. The results indicated that pH had significant influence on the quality of apple pectin. In the range of pH1.00~ 2.00,as the pH arising,the pectin yields and polyphenol first increased and then decreased,while,the content of galacturonic acid decreased. However,the degree of esterification increased,the same trend as intrinsic viscosity and viscosity average molecular weight. IR spectral analysis showed that no major structural differences of apple pectin under different pH conditions. Meanwhile,different pectins all had characteristic absorption peak of carbohydrate.