The use of gamma radiation for the preservation of kola nuts

Kola nuts wrapped with Mitragyna stipulosa (Akan: subaha) leaves and stored in baskets (traditional method) and irradiated with Co-60 gamma rays with absorbed doses ranging from 0.10 to 0.50 kGy at a dose rate of 0.171 kGy/hr to control kola weevils (Balanogastris kolae) during storage. The number of nuts per treatment ranged between 20 and 1353, and the ambient storage temperature fluctuated between 16.5EC and 37.5E C. Gamma radiation suppressed the development and emergence of kola weevils that destroy the nuts in storage. Whilst no live insects were found in the treated samples, up to 48 live weevils were counted per packet in the control treatment at 28 days in storage. Consequently, nut infestation in the control was about 98.4%. Fungal deterioration of both irradiated and unirradiated kola nuts was observed. Weight loss in kola nuts irradiated at 0.25 and 0.50 kGy and stored for 84 days after irradiation was 18.2% and 19.2%, respectively, whilst comparable loss from the control treatment was 39.9%. Weevils fed with treated and untreated nuts did not show any preferences and differences in growth. A panel of tasters did not detect any differences between treated and untreated nuts. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 2 No. 3 (2000) pp. 184-19