Effect of Ash and Sawdust of Shear Butter) (Vitellaria paradoxa ) Storage Treatments on The Tuber Nutrient of Some Sweet Potato [Ipomoea batatas (L.) Lam.] Cultivars

Abstract

Qualitative and quantitative postharvest losses of Sweet potato tubers occur due to pest, mechanical, physiological and lack of appropriate storage system of the crop. The objective of this study is to seek for a safe and cheap storage method which can preserve the tubers and retain much of the nutrients. Tubers of five sweet potato cultivars were stored in pits treated with ash and sawdust of Shea butter(Vitellaria paradoxa) for one hundred and fifty days (150) at the National Root Crop Research Institute (NRCRI), Kuru-Vom  (latitude 09^o 44’N and longitude 08^o 47’E), Plateau State, Nigeria. Trease & Evans (1999) methods of phytochemical screening were adopted for the plant materials. Proximate food analysis method by Association of Official Analytical Chemist (AOAC, 2000) was adopted. Data collected were subjected to analysis of variance (ANOVA) test using Genstat software version 14(2000) and the means were separated using new Duncan Multiple Range Test. Phytochemical screening of the plant materials showed presence of Alkaloids, Resins, Cardiac glycosides, Terpenes and Steroids. The tubers stored in sawdust appeared fresh almost as at harvest. Proximate food nutrients show decrease but not significant in carbohydrate and nitrogen free extract (NFE) in all the cultivars after storage. Ash treatment had more decrease in moisture than sawdust treatment and control. Protein decreased in the cultivars but the decrease was significant (P<0.05) in CIP4400168 and TIS87/0087 cultivars. Ex-Igbariam cultivar had significant (P<0.05) increase in crude fibre. Crude ash and phosphorus significantly (P<0.05) decreased while Lipids significantly (P<0.05) increased in all the cultivars respectively. Calcium significantly (P<.005) increased in TIS2544Rusanya1.5, TIS86/0356 and TIS87/0087 cultivars while CIP4400168 and Ex-Igbariam cultivars had significant (P<0.05) decrease. Tubers stored in sawdust of shea butter gave the best preservation result. The results are further discussed.

Key words: Ash, sawdust, shea butter (Vitellaria paradoxa), sweet potato, cultivar, storage treatment.