Influence of gamma irradiation on the colour parameters of dry smoked shrimps (Penaeus notialis)

Abstract

Shrimp meat is one of the safest forms of muscle protein consumed in Ghana and in the world at large. Shrimps obtained from three different sources were smoke-dried to a moisture content of 15% and exposed to ionizing radiations from a Cobalt 60 source (Hungary, SLL 515) at doses of 0 (control), 4, 8 and 10 kGy at a dose rate of 2.17 kGy / hour in air. The effect of gamma radiation on colour was monitored before and after gamma irradiation. The colour parameters for the samples and colour change due to gamma irradiation were in the ranges 31.87 – 33.34 (L*-whiteness/blackness), 8.19 – 8.97 (a*-redness/greenness), 18.51 – 20.22 (b*-yellowness/blueness), 20.35 – 22.12 (C-chroma), 65.44 – 66.49 (H o -Hue angle) and 23.53 – 105.88 (B.I-Browning Index). These values were also used for calculation of the total colour change (ΔE), chroma change (ΔC), hue angle change (ΔH) and browning index change (ΔB.I). There were significant differences (P< 0.05) for L*, a*, b*, chroma, hue angle, browning index and overall colour change of shrimps after exposure to gamma radiations. Gamma radiation proved to be an effective preservative method for extension of shelf life of shrimp as neither no peculiar nor recorded.