Pectin degrading enzymes and their inhibitors in brined amla (Phyllanthus emblica) and lemon (Citrus limon (L.) fruits during storage

Abstract

Softening of fruits during brining is one of the problems a pickle industry has confronted due to pectinolytic enzymes. Endogenous pectin degrading enzymes and their inhibitors present in these fruits have an impact on the texture attributes of the brined fruits during storage. In this study for the first time, the diffusion of these enzymes and their inhibitors into the brine from the brined fruits and their impact on the brined fruit texture was investigated. Pectin methylesterase (PME) units in brined fruits, in brine and a total in fruit + brine declined during storage with 91.18% and 88.15% decrease in brined amla and lemon respectively whereas polygalacturonase (PG) units significantly increased in brined fruit, in brine and total in fruit + brine during storage with 75.86% and 62.34% increase in brined amla and lemon fruits respectively by 60th day of storage. Pectin methylesterase inhibitor (PMEI) units in brined fruits significantly decreased by 55.24% and 36.22% in brined amla and lemon respectively whereas it increased in its brine and the total in fruit + brine remained constant during storage. Polygalacturonase inhibitor proteins (PGIP) units in brined lemon fruits significantly decreased by 56.06% whereas it increased in its brine and total in lemon fruit + brine remained constant during storage. The results suggest that the progressive softening of both fruits in brined conditions during storage can be majorly attributed to the action of increasing endogenous PG activity and in lemons due to decreasing levels of PGIP during storage.