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 every 8 days of storage at 0 degrees C, was followed. Cold storage increased PME activity until a constant level was reached, whereas PG decreased after 2 wk. 15 degrees C-IW had a similar effect to conventional cold storage. 20 degrees C-IW induced a different behavior, PG activity 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 20 degrees C-IW did. Chilling injury development during storage was associated with continuous PME activity and inhibition of endo-PG activity after the second week of storage, regardless of exo-PG activity.