EFFECT OF IRRADIATION ON VITAMIN-C CONTENT OF STRAWBERRIES AND POTATOES IN COMBINATION WITH STORAGE AND WITH FURTHER COOKING IN POTATOES

The vitamin C content of four varieties of strawberry was determined b efore 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 f rom the effects of post-harvest stress, were irradiated at a sprout in hibition dose of 0.15 kGy, followed by storage and cooking. Total asco rbic acid (TAA), ascorbic acid (AA) and dehydroascorbic acid (DHAA) co ncentrations were measured using the technique of ion-exclusion high-p erformance liquid chromatography. Results from analysis of the strawbe rry samples showed the DHAA content increased immediately following ir radiation and must, therefore, be taken into account when reporting vi tamin C levels in irradiated produce. In addition it was observed that whilst irradiation did affect the vitamin C concentration in all vari eties of strawberry, the change was small in comparison with the large variations observed between varieties. With regard to potatoes result s showed that, whilst irradiation, storage and cooking all had the eff ect of reducing vitamin C concentration, irradiated samples stored for 5 months had similar or marginally higher levels than their non-irrad iated counterparts. Cooking did not markedly reduce TAA content of irr adiated potatoes compared to non-irradiated potatoes and it was also n oted that microwave cooking was more destructive than boiling in light ly salted water.