POSTHARVEST CHANGES AND PERFORMANCE AT PROCESSING OF SOME SRI LANKAN VEGETABLES

Abstract

Attached

A natural convective solar dryer was constructed and it was found that the dryer was able to dehydrate vegetables while retainins 76.6% of p-carotene. This amount is significantly higher when compared with the p-carotene content retained in vegetables dehydrated by exposing to direct sun light. The latter process showing ~nly trace amount of p-carotene. The effect of pretreatments on the quality of prbcessed ve~etables were examined. Blanching was found to be an effective pretre~tment in retaininG ascorbic acid and p-carotene content of these ve~8t~~les. The retention of ascorbic acid was increased when the blanching solution contained 0.1% K~S ( Potassium meta bisulphite). In the case of frozen bittergourd, the retention of ascorbic acid was 87.7 % L: the s~,r;rplbelanched in 0.1 % KI"iS solution an~ at storage for 28 weeks at _18 0 C (-O.4 0 F). Cf these three ve'~atablcs, sLuke;ourd and ~idgegourd could be p.re ser-v ed by r'c rt.c rrtati cn , The I'e r-rnen tatLon VIas carried out b;:/ pr-o vi.di.ng the r;ro':jthof na tur-a Ll.y present lactic acid pro(ucinS orGanisms on these comodities and the process was able to reach the 1% acid in the media within 1~ iays of fsrmentation. Durin~ this period, the total solujle BUbar content was fOUDd to 6ecrease by 90.8 % in snake gour-d and 94.0 % ill rid,:,egourd. In the case of bittergourd, the f ern.en tati.on VIdS incomplete and the production of aci~ did not exceed 0.5 % during 12 days of fermentation. However, the development of a new product was possible by preserving bittergourd in acid-salt suspension. In this preservation, the ascorbic acid content was found to reduce gradually during storage, and at the end of the 6th month, the retention of ascorbic acid was 32.5 %. The variation of p-carotene in fermented vegetables was similar to frozen products. The overall results showed the possibility of preserving these three vegetables by freezing or fermentation. Dehydration possibilities exist with respect to bittergourd compared to snakegourd and ridgegourd.