THE EFFECT OF STORAGE ON ASCORBIC ACID CONTENT OF GAMMA RADIATED POTATOES ^a

Abstract

The effect of ionizing radiations on the vitamin C content of foods is known to depend upon the level of radiations. Nickerson et al. (7) showed that high-voltage cathode rays of 2000 krep (1860 krad) caused 6 9 2 % loss of this vitamin in asparagus, broccoG, green beans, and spinach. Proctor and O'Meara (8) also demonstrated that high-voltage cathode radiations caused some loss of ascorbic acid in solutions, and to a lesser extent, in orange juice. Brownell and associates (2) maintained that even radiations of 10 krep (9.3 krad) reduced the ascorbic acid content of potatoes, and that the effects were more pronounced as the dosage level increased, but no data were given.On the other hand, Mickaelsen and Roer (6) reported that the vitamin C content was decreased in both radiated and non-radiated potatoes during the first seven months of storage at approximately 40" F, but was restored after this period, and that ascorbic acid levels of the radiated samples were higher than those of the controls.In the light of the present divergent views regarding the effect of storage on the ascorbic acid content of potatoes which had been subjected to ionizing radiations to inhibit sprouting, there appeared to be a need for further study. Cloutier et al. (3) reported the effect of storage on the carbohydrate content of two varieties of potatoes treated with gamma radiation. This paper reports data on the ascorbic acid content of the same set of samples. MATERIAL AND METHOD Two varieties, Katahdin and Netted Gem (Russet Burbank) were used. Details of experimental design, gamma radiation treatments, and storage conditions werc described by Cloutier et al. (3).Tubers were cut in quarters lengthwise. Each sample was a quarter of the same tuber which was used in the determinations of carbohydrates. Five replicates were analyzed for each treatment and for each storage period of each variety of potatoes, except for those samples remaining after 9 months of storage. In this case because of the relatively low variation between replicates previously obtained, only two replicates of 2% quarters of potatoes were used.Samples were blended in 20% meta-phosphoric acid with cracked ice in a Waring blender, and the blends diluted with distilled water to contain 2% meta-phosphoric acid.