Juice characteristics related to woolliness and ripening during postharvest storage of peaches

The effect of up to three cycles of intermittent warming (IW) for one day at 20 degrees C every 6 days of storage at 0.5 degrees C on the development of woolliness and on the changes in juice characteristics during post-storage ripening of "Paraguayo" peaches at two ripening stages was studied. By subjecting the peaches to IW, woolliness was strongly reduced concomitantly with a sudden reduction in flesh firmness due to normal fruit ripening. During post-storage ripening, extractable juice and juiciness only decreased in conventionally stored (CS) fruit as a result of woolliness. However, the liquid phase of the juice extracted (clear juice) decreased in IW but not in woolly CS fruit. Clear juice reduction appeared to be related to normal advanced ripening, with differences between woolly and sound fruit associated with the ripening stage during storage. The technological and physiological implications of these quality indices, mainly related to ripening, senescence, and woolliness, are discussed. These results support the hypothesis that IW maintains cellular membrane integrity and helps the recovery of pectolytic enzymatic activity. It has been stated that the incidence of woolliness was more closely related to the juice release mechanism than to the clear juice content.