The Ascorbic Acid Content of Potato Tubers

The Ascorbic Acid Content of Potato Tubers

“…9A), the samples transferred to 1° C. and held in air showed the initial rise and subsequent fall (Eig. 9 A) which are characteristic of potatoes transferred from 10 to 1° C. at this stage in the storage period (Barker & Mapson, 1950). The samples subjected to pure oxygen immediately after transfer to 1° C. gave values falling on a curve closely similar in form to that obtained for the values in air.…”

“…The initial increase in ascorbic acid at i ° C. and the subsequent prolonged decrease (Fig. 5 A) were generally similar in form to those observed previously (Barker & Mapson, 1950). When the potatoes had been at 1° C. for i week, eighteen samples were removed from the trays and placed in sealed jars, through which currents of air were passed.…”

“…The techniques employed to determine the contents of ascorbic acid, dehydroascorbic acid and sugar have been described previously (Barker & Mapson, 1950;Barker, 1936). The content of reduced glutathione was estimated by the method reported by Guthrie (1937)-In general, only the values obtained for the content of ascorbic acid will be considered in this paper.…”

“…The potatoes* used were again of the variety King Edward VII, and the methods of selection, grading and storage were similar to those already described (Barker & Mapson, 1950)-For studying the influence of anaerobic conditions or of an atmosphere of pure oxygen, separate samples, each of from eighteen to thirty-six potatoes, depending on the particular experiment, were placed in sealed jars, through which passed a current, at the rate of about 2 l./hr., of air, nitrogen or pure oxygen as required. The samples could thus be held for periods of several weeks with complete exclusion of oxygen.…”

“…Reference has been made above to the high content of total ascorbic acid of 6 6 mg./g./ioo g. fresh weight, which was attained after some 40 days in air at -0-6 C. Special tests using the 'continuous-flow' method (Harris & Mapson, 1947) gave no evidence that this high reducing value was due to substances other than ascorbic acid (Barker & Mapson, 1950).…”