3.4. Visual appearance
The unirradiated control samples of tiger prawn consistently showed some brown patches during the storage period of 56 days, while some of the samples treated with 0.5 and 1.5 kGy also showed brown patches indicating melanosis. Exposure with doses 2.5 kGy and above reduced the brown (in the web version) patches in stored tiger prawns thereby improving their appearance (Fig. 7). Irradiated fresh water prawns and those irradiated with 0.5 kGy also showed brownish integument. Irradiation with higher doses minimised such discolouration (Fig. 8). Reduced melanosis in irradiated brown (in the web version) shrimps (Penaeus aztecus) has been also observed by Novak, Grodner, and Rao (1967).