Effects of Gamma Irradiation on the Shelf Life and Nutritional Content of “Obubra” Water Yam.

Abstract:

The effects of gamma irradiation on the shelf-life and nutritional content of Obubra water yam in Cross River State, Nigeria were investigated. Two hundred tubers of a total of two hundred and fifty water yams were irradiated using gamma irradiation technology at doses of 50Gy, 100Gy, 125Gy 150Gy and 200Gy in order to test for the shelf-life elongation and nutritional content of the tubers after storage. fifty tubers of the water yam were kept as control (un-irradiated). Proximate analysis was done on the tubers after irradiation and also after storage, including those in the control group. Post-irradiation observation in a five month period revealed that the water yam tubers irradiated at dose level of 125Gy and 150Gy gives maximum shelf-life extension. Results further indicated that all the un-irradiated water yams sprouted by the end of the storage period. 80% of the irradiated water yams at 50 gray, 10% of the irradiated water yams at 100 gray sprouted within the storage period. None of the irradiated water yams at 125 and 150 gray sprouted. The results suggest that gamma radiation dose range of 125 – 150 gray effectively inhibit sprouting in water yams for 5 months and the 125 gray is more effective in preventing spoilage. The percentage weight loss (66%) in the un-irradiated was significantly (p ≤ 0.05) higher than the irradiated tubers There were no significant differences (p ≤ 0.05) in the average values of the ash, protein and carbohydrate content of the irradiated and un-irradiated water yam tubers. The results suggest that radiation processing preserved the quality of water yam tubers through sprout inhibition, reduction of weight loss, preservation of macro-nutrients such as protein, fibre, and carbohydrate content. The advantages of this technology are efficient energy and materials, easily controlled, no residues and its’ environmentally friendly be efficiently deployed to extend the shelf-life of water yam tubers and increase food security.