Effect of γ-irradiation and post-irradiation cooking on thiamine, riboflavin and niacin contents of grass prawns (Penaeus monodon)

To determine the nutritional changes of grass prawns during ionizing radiation processing, the effects of irradiation doses, irradiation temperatures and the combined treatment of irradiation and cooking on thiamine, riboflavin and niacin contents of grass prawns were studied. Grass prawns were irradiated with different doses at refrigerated (4 °C) or frozen (−20 °C) temperatures. A domestic cooking procedure then followed irradiation. Our results indicate that radiation and post-irradiation cooking result in different changes in the vitamin contents. The loss of thiamine increased with the increase of irradiation doses and temperatures. In contrast, no significant changes were observed in either riboflavin or niacin even after irradiation doses were administered up to 7 kGy at 4 or −20 °C. Moreover, significant destruction of thiamine occurred and there was no change in riboflavin or niacin after post-irradiation cooking. The total loss of thiamine after the combined treatments appears to be simply the sum of the individual losses produced by the two treatments respectively.