Physiological changes in peaches related to chilling injury and ripening

Firm-breaker (FB) and firm-mature (FM) peaches cv. 'Paraguayo' were either stood for 4 weeks at 2 degrees C or subjected to three cycles of 1 day of intermittent warming (IW) at 20 degrees C every 6 days at 2 degrees C. Normal postharvest ripening and post-storage ripening at 20 degrees C were also studied in order to relate postharvest physiology with the onset of chilling injuries (CI) (woolliness, gel breakdown and scald). As far as we know, both gel breakdown and scald have been described and reported on peaches for the first time. FB peaches were more sensitive to CI than FM ones. A high respiration rate and ethylene production in conventionally stored fruit after 2 weeks of storage, followed by a drop in ethylene production, was accompanied by the development of CI in fruit of both maturity stages. IW strongly reduced CI during storage. Periodic warming acclimatised chilled fruit to subsequent periods of chilling by allowing them to ripen due to the production of a suitable amount of ethylene, depending on their maturity stage at harvest. The increase in ethylene production during post-storage ripening could be related to the development of over-ripeness. (C) 1998 Elsevier Science B.V. All rights reserved.