American Journal of Chemistry 2012, 2(3): 137-141 DOI: 10.5923/j.chemistry.20120203.07 Effect of Irradiation on Sprouting of Water Yam (Dioscorea Alata) Using Different Doses of Gamma Radiation James Imeh 1 , M. Y. Onimisi 1,* , S. A. Jonah 2 1 Department of physics, Nigerian Defence Academy, P.M.B 2109 Kaduna, Nigeria 2 Centre for Energy Research and Training (CERT), Ahmadu Bello University, Zaria, Kaduna, Nigeria Abstract Water yam (Dioscorea Alata) tuber samples from Abuja, Nigeria were irradiated with gamma radiation of doses 60, 80, 100, 120 and 140 gray respectively at an average dose rate of 3 gray/min and some un-irradiated used as control. All were monitored during storage for 7 months. Results indicated that all the un-irradiated water yams sprouted by the end of the 3rd month of storage. 90% of the irradiated water yams at 60 gray, 30% of the irradiated water yams at 80 gray and only 10% of the irradiated water yam at 100 gray sprouted within the storage period. None of the irradiated water yams at 120 and 140 gray sprouted. The results suggest that gamma radiation dose range of 100 – 140 gray could effectively inhibit sprouting in water yams for 7 months. 80% of the un-irradiated water yams rotted while none of the irradiated water yams rotted within the storage period. The percentage weight loss (64.79±13.45%) 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 lipid, protein and carbo- hydrate 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 macronutrients such as protein, lipid, and carbohydrate content. Keywords Water Yam, Gamma Radiation, Sprouted, Preservation, Macronutrients 1. Introduction Yam is the second most important tuber crop in Africa next to cassava. Nigeria is the main producer of yam globally with 71% of world production[1]. Yams are annual or per- ennial tuber-bearing and climbing plants with over 600 spe- cies in which only few are cultivated for food and medi- cine[2]. The most cultivated species in Nigeria are the white yam (D. rotundata), yellow yam (D. cayenensis), water yam (D. alata) and trifoliate yam (D. dumetorum)[3]. The crop is of major importance in the diet and economic life of people in West Africa, the Caribbean islands, parts of Asia, and Oceania[4]. Yam is an elite crop, preferred over other root and tuber crops of West Africa and a choice during cere- monies and festivities[5]. D. alata is also referred to as greater yam, Asian greater yam and ten-month yam. It is more important as food in West Africa and the Caribbean than in Asia and the Ameri- cas where it originated, and has been competing with the most important native species, D. rotundata Poir. It was * Corresponding author: onimisimy@yahoo.com (M.Y. Onimisi) Published online at http://journal.sapub.org/chemistry Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved introduced to Africa some hundred years ago from Malaysia through agriculturists and by Portuguese and Spanish sea- farers[6]. It is next to D. rotundata in terms of volume of production and extent of utilization. D. alata is also known for its high nutritional content[7]. D. alata tubers have variable shapes, the majority being cylindrical. The flesh of the tuber ranges in colour from white to purplish[1]. The texture of its flesh is usually not as firm as that of white yam and less suitable than other species for the preparation of the most popular food products from yam (fufu and pounded yam especially) in the West Africa region. The production of the yam is seasonal, so storage is nec- essary before subsequent planting or for use as food. Fresh yam tubers are often difficult to store and are subject to deterioration by sprouting and microbial rot during stor- age[8]. Post-harvest losses usually range from 25 to 60%[9]. Loss of yam in storage due to sprouting is very high[10].Several inhibitory chemical growth regulators such as maleic hydrazide, Tetrachloronitro benzene, acetic acid, naphthalene have been used to retard sprouting in stored yam tubers. Apart from unavailability of the right type of chemicals and their toxicity nature, widespread adulteration of the available ones especially in Nigeria is a serious prob- lem[11]. There are several reports on how temperature and age of the tuber affects sprouting of yam[12]. Processing of