PECTOLYTIC ENZYME-ACTIVITY DURING INTERMITTENT WARMING STORAGE OF PEACHES

Pectin enzyme evolution in peaches intermittently warmed at 15 degrees C (15 degrees C-IW) and at 20 degrees C (20 degrees C-IW) for 24 hr e very 8 days of storage at 0 degrees C, was followed. Cold storage incr eased PME activity until a constant level was reached, whereas PG decr eased after 2 wk. 15 degrees C-IW had a similar effect to conventional cold storage. 20 degrees C-IW induced a different behavior, PG activi ty increasing and PME activity decreasing after 2 wk of storage. This different behavior seemed to be related to the development of chilling injury, since 15 degrees C-IW did not alleviate chilling injury but 2 0 degrees C-IW did. Chilling injury development during storage was ass ociated with continuous PME activity and inhibition of endo-PG activit y after the second week of storage, regardless of exo-PG activity.