Effects of Gamma Irradiation on the Sprouting and Proximate Composition of Cocoyam (Xanthosoma Specie)
Keywords:
Cocoyam, gamma ray, post-harvest, irradiationAbstract
Cocoyam (Xanthosoma species), is an important staple food crop in several tropical countries, particularly Nigeria, where it is vital to food security and rural livelihoods. Unfortunately, due to microbial spoilage, physiological deterioration, and poor storage conditions, many post-harvest losses diminish both the availability and the potential economics of the crop. The aim of this study was to examine the impact of gamma irradiation on both the cocoyam’s storage quality and its proximate composition over a 5-month period of storage. A total of 60 healthy cocoyam tubers was divided into 6 groups. Each group was exposed to gamma irradiation at the following doses: 0 (control), 5, 10, 20, 30, and 50 Gy, from a Cobalt-60 gamma source. Rot incidence, sprouting, and weight loss, along with the effects on proximate composition, were determined. Gamma irradiation was shown to diminish cocoyam spoilage in a dose dependent manner. The control had 100% spoilage, while samples with 30 Gy and 50 Gy completely prohibited spoilage for the entire duration of the study. Weight loss was also significantly reduced from 24.10% in the control to 4.55% at 50 Gy. Storage stability and the storage tubers’ survival were significantly improved with gamma irradiation at the higher doses. Sprouting was not observed in any of the samples, control or irradiated, during the entire storage period. This also indicated the natural dormancy of the tubers. Proximate analysis showed that irradiation improved a number of the nutritional parameters. Specifically, ash content increased from 1.07% to 1.68%, crude fibre from 3.00% to 3.85%, and protein from 6.38% to 8.63%, with a concomitant increase in carbohydrate content from 33.63% to 44.97%, along with a decrease in moisture content from 54.00% to 40.55%. The study showed that particularly at the higher doses, from 30 to 50 Gy, gamma irradiation was a viable post-harvest treatment.
