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Effect of irradiation on vitamin C content of strawberries and potatoes in combination with storage and with further cooking in potatoes

Graham, W.D., Stevenson, M.H.
Journal of the science of food and agriculture 1997 v.75 no.3 pp. 371-377
strawberries, potatoes, food irradiation, ascorbic acid, dehydroascorbic acid, cultivars, storage, cooking, boiling, baking, microwave cooking, ionizing radiation
The vitamin C content of four varieties of strawberry was determined before and after treatment with ionising radiation at doses of 1, 2 or 3 kGy and after storage for 5 and 10 days at 6 degrees C, and also in potatoes which, having been allowed a period of one month to recover from the effects of post-harvest stress, were irradiated at a sprout inhibition dose of 0.15 kGy, followed by storage and cooking. Total ascorbic acid (TAA), ascorbic acid (AA) and dehydroascorbic acid (DHAA) concentrations were measured using the technique of ion-exclusion high-performance liquid chromatography. Results from analysis of the strawberry samples showed the DHAA content increased immediately following irradiation and must, therefore, be taken into account when reporting vitamin C levels in irradiated produce. In addition it was observed that whilst irradiation did affect the vitamin C concentration in all varieties of strawberry, the change was small in comparison with the large variations observed between varieties. With regard to potatoes results showed that, whilst irradiation, storage and cooking all had the effect of reducing vitamin C concentration, irradiated samples stored for 5 months had similar or marginally higher levels than their non-irradiated counterparts. Cooking did not markedly reduce TAA content of irradiated potatoes compared to non-irradiated potatoes and it was also noted that microwave cooking was more destructive than boiling in lightly salted water.