Comparison of pectolytic and proteolytic activities of six clarifying commercial preparations. Incidence of secondary enzymatic activities on proteins in Champagne musts

Abstract

In order ta estimate c1arifying aptitude and the effects of prefermentation treatment by commercial pectinases, polygalacturonase (PG), pectin Iyase (PL), pectinmethylesterase (PME) and proteolytic activities of six pectinases samples were studied. PG activity is preponderate and proportional to the relative protein concentration.

These one, submitted to both SDS-PAGE and isoelectric focusing technics, show molecular weights ranging from 20 ta 100 kDa and isoelectric points ranging from 3.00 ta 7.40. Total protein of Champagne grape varieties Chardonnay (CH) and Pinot noir (PN) - were submitted to an isoelectric focusing. All of the pI's ranging from 3.30 to 4.55 (CH) and from 3.30 to 4.90 (PN). Proteases are put in evidence in commercial pectinases using fluorescamine- casein as substrate. However, they seem to have no incidence upon must proteins.