Interactions among cooling, fungicide and postharvest ripening temperature on peaches

Peach fruit (Prunus persica L. cv. 'Miraflores') harvested at the firm-ripe stage, treated or not with 2 g l(-1) iprodione, were cooled or not at 1 degrees C and ripened at 15 or 20 degrees C and 95% RH for 10 days. During ripening, weight loss, fungal development and changes in quality parameters (firmness, soluble solids content, titratable acidity, pH and ground and flesh color), and carbon dioxide and ethylene production were monitored. Cooling alone or combined with iprodione avoided Rhizopus nigricans decay during ripening at either ripening temperatures. A skin damage not previously reported on fungicide treated peach was observed at 20 degrees C. Cooled fruit ripened at 15 degrees C showed an anomalous respiration rate and ethylene production after the climacteric peak, a loss of firmness and a drop in titratable acidity after 7 days of storage, and reduced endo-polygalacturonase activity in presence of continuous pectinmethylesterase activity during the first week. Cooling before ripening at 20 degrees C led to the best flavor without excessive total losses. These results helped in the optimization of warming cycles during cold storage used to avoid chilling injuries development on peaches. (C) 2000 Elsevier Science Ltd and IIR. All rights reserved.