Polyamines, Ethylene, and Physicochemical Changes in Low-Temperature-Stored Peach (Prunus persicaL. Cv. Maycrest)

Fruit firmness, free putrescine and spermidine levels, total soluble solids, titratable acidity, and ethylene production were determined in two ripening grade Maycrest peaches stored at 1 and 5 °C and when fruits were placed at 20 °C during 48 h. Storage at 1 °C of peaches resulted in significantly longer postharvest life than did storage at 5 °C. Titratable acidity of fruit stored at 5 °C tended to decrease during storage and soluble solids concentration to increase. Peaches maintained at 1 °C had lower ethylene emission than those stored at 5 °C. Fruits in stage 2 that were placed at 20 °C had the highest ethylene levels and they became over-ripe. A close and inverse relationship has been observed between ethylene and firmness. Putrescine and spermidine concentrations evolved in a similar way during storage at 1 and 5 °C in stages 1 and 2 and decreased in the fruits kept for 48 h at 20 °C except for stage 2 peaches stored at 5 °C, for which the spermidine levels increased. These fruits showed wooliness and became inedible. The increase observed in spermidine levels could be a consequence of this kind of stress.