Effect of washing, packaging material and storage period on the quality of sweetpotato roots

Abstract

Sweet potato storage hardly happens in Kenya since most farmers harvest the roots piecemeal on demand. Moreover, many traders have little knowledge on the appropriate conditions for storage. There exists very little information on stability of nutrients of these roots during storage. Kabode (orange fleshed) and Kenspot 2 (white fleshed) varieties of sweet potato were harvested and subjected to similar storage conditions for 21 days to monitor changes in moisture content, starch, reducing sugars, beta carotene and vitamin C. Half of the samples were washed while the similar half were unwashed before storage. Samples were stored both under room temperature 22-24oC, relative humidity 60-70% and at temperature of 12-13oC, relative humidity 80-90%. There was moisture loss of up to 82.9% (Kabode) and 53.2% (Kenspot-1); starch loss of up to 29.7% (Kabode) and 23.7% (Kenspot 2); reducing sugars increased up to 286% (Kenspot 2) and 148.4% (Kabode); beta carotene loss of up to 100% (Kenspot 2) and 79.6% (Kabode) as well as vitamin C loss of up to 56% (Kenspot 2) and 62% (Kabode) at the end of 21 days of storage. Significant (p?0.05) higher losses were recorded in samples stored at room temperature (22-24oC) with relative humidity 60-70% compared to samples stored at 12-13oC with relative humidity ranging 80-90%. Sweet potato storage shelf life can therefore be enhanced by storing the roots in temperatures 12-13oC at 80-90% relative humidity conditions which slow down metabolic reactions responsible for nutrient degradation. Relevant stakeholders in the sweet potato value chain should work together towards designing and establishing sweet potato roots storage chambers to increase the commercial viability of the enterprise.