EFFECT OF LOW-TEMPERATURE BLANCHING, CYSTEINE-HCL, N-ACETYL-L-CYSTEINE, NA METABI-SULFITE AND DRYING TEMPERATURES ON THE FIRMNESS AND NUTRIENT CONTENT OF DRIED CARROTS

Low temperature long time (LTLT) blanching (70C for 20 min) together w ith calcium treatment can be used to significantly improve the texture of rehydrated dried carrots when compared to high temperature short t ime (HTST) blanching (100C for 3 min). LTLT blanching allows pectin me thyl esterase to deesterify pectin, which can then react with calcium to form salt bridges. 0.3% L-cysteine-HCl was found to be most effecti ve in preventing ascorbic acid loss and obtaining a product with the h ighest rehydration ability, compared to pretreatments with 0.3 % N-ace tyl-L-cysteine and 0.1 % sodium metabisulphite. On the other hand 0.1 % sodium metabisulphite was most effective in preserving the carotenoi ds content of dried carrots. Ascorbic acid and rehydration ability wer e more adversely affected by long drying time than high drying tempera ture, while carotenoids were more sensitive to high drying temperature than drying time. Hence, 60C drying temperature was good for ascorbic acid and rehydration ability, while 40C drying temperature was good f or carotenoid and color of dried carrots.