Enzymes are added into turbid juice to obtain negative pectin test and starch test，which is not only to ease processing but also to improve juice product stability. This step is normally called juice clarification in the industry. These enzymes mainly include pectinase, but other enzymes are also necessary in order to break down big molecules other than pectin. Sometimes additional UF flux boosting enzymes are also added to degrade resistant macromolecules that would otherwise block UF membrane.