Aspergillus carbonarius polygalacturonases purified by integrated membrane process and affinity precipitation for apple juice production

Aspergillus carbonarius, when grown by submerged and solid-state fermentation, produces different
molecular forms of polygalacturonase (PG; EC 3.2.1.15), among them a 42 kDa PG with a high specific
activity of 7000 U/mg protein. When the enzymes were purified by integrated membrane process
(IMP) and alginate affinity precipitation (AAP), the two processes concentrated different forms of the
enzyme. The AAP process selectively purified and concentrated the high active PG whereas the IMP
yielded different PGs and also amylase and protease. Evaluation of the AAP enzyme preparations for apple
juice preparation under conditions usually employed commercially demonstrated that the high activity
PG did not result in good juice clarity. With IMP processed enzymes, juice yields and clarity were similar
to that obtained with commercial PG from A. niger.