POLYAMINES, ETHYLENE, AND PHYSICOCHEMICAL CHANGES IN LOW-TEMPERATURE-STORED PEACH (PRUNUS-PERSICA L. CV MAYCREST)

Fruit firmness, free putrescine and spermidine levels, total soluble s olids, titratable acidity, and ethylene production were determined in two ripening grade Maycrest peaches stored at 1 and 5 degrees C and wh en fruits were placed at 20 degrees C during 48 h. Storage at 1 degree s C of peaches resulted in significantly longer postharvest life than did storage at 5 degrees C. Titratable acidity of fruit stored at 5 de grees C tended to decrease during storage and soluble solids concentra tion to increase. Peaches maintained at 1 OC had lower ethylene emissi on than those stored at 5 degrees C. Fruits in stage 2 that were place d at 20 degrees C had the highest ethylene levels and they became over -ripe.,A close and inverse relationship has been observed between ethy lene and firmness. Putrescine and spermidine concentrations evolved in a similar way during storage at 1 and 5 degrees C in stages 1 and 2 a nd decreased in the fruits kept for 48 h at 20 degrees C except for st age 2 peaches stored at 5 degrees C, for which the spermidine levels i ncreased. These fruits showed wooliness and became inedible. The incre ase observed in spermidine levels could be a consequence of this kind of stress.