STUDIES ON EXTENSION OF SHELF-LIFE OF RAWA BY GAMMA-IRRADIATION

Semolina, a wheat product, popularly termed as rawa, was packed in 500 g pouches prepared individually from high density polyethylene (HDP), biaxially oriented polypropylene : low density polyethylene laminate (BOPP/LDP), polyester : low density polyethylene laminate (PET/LDP) an d irradiated using a Cobalt-60 source at doses of 0.15 to 0.50 kGy. At the end of six months' storage at room temperature, the unirradiated rawa developed infestation, whereas the irradiated samples were comple tely free of any infestation, thereby indicating a complete destructio n of all stages of the insects due to irradiation. There was no signif icant difference in the moisture content and the total bacterial as we ll as mould counts of the irradiated and unirradiated rawa. Gamma irra diation significantly decreased the gelatinization viscosity of rawa. In sensory evaluation tests, irradiated rawa scored the same on a 9-po int Hedonic scale, thereby showing that overall acceptability of the r awa was not altered due to irradiation upto 0.25 kGy. Amongst the pack aging materials used, BOPP/LDP was found to be better, because of its comparatively higher resistance to penetration by insects. Gamma irrad iation at 0.25 kGy could thus be recommended for effectively extending the shelf-life of rawa, prepacked in pouches made from BOPP/LDP lamin ate, for six months.