Pectic Enzymes in the Clarification of Apple Juice

Pectinesterase of Sclerotinia arachnidis was purified by 44 times. The clarification of apple juice with the purified pectinesterase and the formerly purified endo-polygalacturonase of Aspergillus saitoi was examined. The coexistence of pectinesterase and endo polygalacturonase was necessary for the complete clarification of apple juice. During the clarification reaction rapid decrease of viscosity and resultant coagulation of the suspended materials in apple juice were observed. The coagulated materials slowly precipitated leaving clear juice.

It was suggested from the result of electrophoresis that the positive charge existed inside of the suspended materials. The decrease in viscosity was supposed to correlate to pectin’s depolymerization which would result in revealing of positive charge inside. The probable mechanism of coagulation was attributed to the electrostatic neutralization between positive charge thus appeared and negative charge of still undegraded pectin.