Keeping quality of cold stored peaches using intermittent warming

Firm-breaker and firm-mature mid-season peaches (Prunus persica L. Batsch cultivar 'Paraguayo') were stored for up to four weeks at 2 degrees C or subjected to intermittent warming cycles of one day at 20 degrees C every six days at 2 degrees C. Several quality parameters were monitored during normal ripening at 20 degrees C and weekly during storage, with and without three days of subsequent ripening at 20 degrees C. After three cycles, intermittent warming avoided or strongly alleviated chilling injuries (particularly woolliness and lack of juiciness) especially in breaker fruit. Low temperature induced abnormal ripening in control fruit, which was detectable when chilling injury was already irreversible. In comparison to sound fruit, injured fruit showed an increased total soluble solids/titratable acidity ratio, a decrease in flesh firmness and in Hue angle flesh color during storage and an excessive loss of acidity in fruit of advanced maturity. Hue angle was a good maturity index only for sound fruit. Intermittent warming appears to maintain the quality of peaches by acclimatizing chilled fruit to subsequent periods of chilling by allowing a gradual ripening of the fruits (softening, enhancement of ground and flesh color, and maintenance of juiciness). (C) 1998 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.