CHEMICAL-CHANGES AFTER IRRADIATION AND POSTIRRADIATION STORAGE IN TILAPIA AND SPANISH MACKEREL

Influence of gamma irradiation (1.5-10 kGy) and post-irradiation stora ge up to 20 days at 2 +/- 2 degrees C on some chemical criteria of til apia and Spanish mackerel were studied. Total volatile basic nitrogen formation was lower in irradiated fish than in the unirradiated. Irrad iation also caused a larger increase in thiobarbituric acid values whi ch continued gradually during storage. Some fatty acids decreased by i rradiation treatments at all doses. Thiamin loss was more severe at hi gher doses (greater than or equal to 4.5 kGy), whereas riboflavin was not affected. Alpha and gamma tocopherols of tilapia and alpha, beta, gamma, and delta tocopherols, in Spanish mackerel, decreased with incr eased dose and continued to decrease during 20-day post-irradiation st orage.