THE STABILITY OF VITAMIN-C (L-ASCORBIC-ACID) IN BOTTLED AND CANNED ORANGE JUICE

The stabilizing effect of two levels of cysteine and sodium metabisulphite on vitamin C (L-ascorbic acid) in bottled orange juice kept at room temperature was investigated. Although increasing the level of either chemical stablizer from 200 to 400 ppm had a significant stabilizing effect (p < 0.05), this did not prevent decline of ascorbic concentration with storage time. The descending order in effectivness to stablize vitamin C was 400 ppm cysteine, 200 ppm cysteine, 400 ppm sodium metabisulphite and 200 ppm sodium metabisulphite. The level of the vitamin in refrigerated canned juice without added stablizer was, on the whole, higher than in bottled juice. Independent regression analysis on ascorbic acid level and storage time data indicated that ascorbic acid depletion with time was almost linear, with correlation coefficients greater than 0.890 for all cases. Their use for predicting the storage time for complete ascorbic acid depletion in orange juice is discussed.