POSTHARVEST PERFORMANCE OF INTERMEDIATE MOISTURE PEACHES AND PRUNES AS AFFECTED BY PACKAGING AND STORAGE CONDITIONS

The postharvest performance of two intermediate moisture fruits, peach (Prunus persica (L.) Batsch ‘Giallone’) and prune (Prunus domestica L. ‘Stanley’), was evaluated. Fruit were washed, cut (peach into slices, prune into halves), stoned, dipped in 2% (w/v in water) acid solutions (ascorbic acid for peach, citric acid for prune), and sonicated in ultrasonic bath with a 45%(w/v in water) fructose solution. After this pretreatment, fruit pieces were dried with heat pump technology equipment. Semi-dried fruit pieces were packed in polypropylene trays sealed with a composite covering plastic film with a partial vacuum (P=450 mm Hg) air atmosphere. In order to test postharvest performance in both refrigerated and unrefrigerated conditions, products were stored at 4±1 or 18±1°C for 60 days. After 0, 20, 40, and 60 days in storage, visual and sensorial scores, colour, texture, a_w, sugars, phenolic content, antioxidant activity, polygalacturonase activity, and microbial growth were evaluated. Peach and prune pieces stored in unrefrigerated conditions showed serious decay symptoms already after 20 days in storage; whereas, semi-dried fruit pieces stored at 4°C preserved their physical, sensorial, biochemical, and microbiological properties until 40 days in storage. After 60 days in storage, only peaches still maintained minimally acceptable quality; on the contrary, prunes were unmarketable.