Drying characteristics and antioxidant properties of Java plum seed and skin waste

Java plum seeds and skin wastes recovered after passing fruits through a pulper were separated manually and dried in tray/fluidised bed drier at 50, 70 and 90EsC or in freeze drier at -55°C at 4.4 torr. Drying behaviour of java plum seeds and skin followed falling rate period and described adequately by Page's model. Drying rate constant was higher for fluidized bed drier varying from 0.00163 to 0.255406 h-1 for seeds and 0.002042 to 0.004258 h-1 for skin followed by tray and freeze drier. Anthocyanin content of freeze dried java plum skin was 1944 mg/100g dry basis but high drying temperature resulted in lower anthocyanin retention in tray and fluidized bed driers. 'L' and ‘b’ value of java plum seeds increased but ‘a’ value decreased. Free radical scavenging activities of fresh java plum seeds and skin were 92.41 and 93.42% respectively which decreased after drying.