DEHYDRATION OF PEACHES WITHOUT SULFUR-DIOXIDE

The experimental drying behaviour of clingstone peach halves dehydrate d without sulphites was investigated. Fruit treatments such as peeling and peeling followed by blanching led to greatly increased drying rat es in comparison to unpeeled halves during isothermal dehydration. Sup erficial product temperature during dehydration was also affected by f ruit treatment. Drying rates during isothermal dehydration were found to increase as linear air velocity increased from 2 to 4 m.s(-1). Frui t size had a pronounced effect on drying rates, with halves obtained f rom the smallest fruit (54 mm.), showing the highest rates. Experiment al drying studies were also done under simulated counter-flow conditio ns (58 degrees --> 67 degrees C). Relative humidity influenced drying rates and fruit temperatures to a large extent in simulated counterflo w dehydration studies. Objective colour measurements of dried products subjected to different treatments before drying and dehydrated under different conditions are presented. Enzymatic browning reactions can b e controlled during dehydration by selecting dehydration conditions fa vouring low superficial product temperature and water activity.