POLYGALACTURONASE AND PECTINMETHYLESTERASE ACTIVITIES IN DEVELOPING HIGHBUSH BLUEBERRIES

Polygalacturonase (PG, E.C. 3.2.1.15) and pectinmethylesterase (PME, E.C. 3.1.1.11) activities, berry size, and texture were measured in fruit of developing highbush blueberries (Vaccinium corymbosum L.). Peak PME activity occurred in red berries and preceded peak PG activity, which was observed in blue-red fruit. Extensive softening occurred with the transition in berry color from red to blue-red. Both peak enzyme activities and maximum softening occurred by the time the fruit were almost-equal-to 70% of their maximum fresh weight.