DEVELOPMENT OF POLYGALACTURONASE ACTIVITY AND SOLUBILIZATION OF PECTIN IN PEACHES DURING RIPENING

SUMMARY –Polygalacturonase activity, water‐soluble pectin, total pectin, molecular weight distribution of water‐soluble pectin, and fruit firmness were determined during ripening of freestone peaches. Polygalacturonase activity was not present in unripe peaches, but it developed during both tree and postharvest ripening. The development of activity paralleled the formation of water‐soluble pectin characteristic of freestone peaches. Fruit firmness began to decrease before polygalac‐turonase was detected, but the peaches softened rapidly after the appearance of the enzyme. Application of gel filtration revealed that the molecular weights of peach pectin range from about 100,000 to several million and decrease progressively during ripening. The results indicate a role for polygalacturonase in pectin solubilization during ripening of peaches.