EVALUATION OF PHYSICOCHEMICAL PROPERTIES OF JATROPHA CURCAS SEEDS FROM DIFFERENT PROVINCES OF GHANA, AND THE EFFECTS OF SPONTANEOUS SOLID STATE FERMENTATION ON THE CHEMICAL COMPOSITION OF THE SEED/KERNEL MEALS

Abstract

The study was conducted to determine the physicochemical properties of Jatropha curcas seeds from four different geographical locations (Nyankpala, Dambai, WA, and Techiman) of Ghana and the effect of spontaneous solid state fermentation on proximate and antinutritional composition of Jatropha whole seed and kernel meals. The data obtained was analyzed using the General Linear Model (GLM) of the Analysis of Variance (ANOVA) and where significant differences were found, the means were separated using Tukey Pair Wise comparison, at 5 % level of significance. The average whole seed, kernel, and shell weights were significantly different (p < 0.05) among the four seed samples. The average whole seed, kernel and shell weights ranged between 0.65-0.73 g, 0.41 - 0.45 g and 0.24-0.28 g respectively. The Jatropha seeds had dry matter content of(94.71-95.54 %), crude protein (18.21 - 18.97 %), lipid (36.52 - 38.58 %), crude fibre (14.14 - 19.04 %), and total ash (5.03- 5.71 %). The kernels were high in lipid (55.51 -56.83 %) and crude protein (23.08- 25.88 %). The mechanically defatted seeds have crude protein (27.33 - 29.61 %) while the kernel meal contained higher crude protein (63.39 - 64.35 %). The whole seed meals were also rich in macro-mineral Phosphorus (1.33 - 3.80 %), potassium (1.07 -1.71 %), calcium (0.54 - 0.87 %), and magnesium (1.35-1.58 %). The antinutrients crude phorbol ester (CPE), tannins, and phytic acid were present in whole seed meals and kernel meals but were higher in the seed meals. The CPE, tannins, and phytic acid concentrations in seed meals ranged between (4.87-6.07 mg/g) , (0.72-0.93 % tannic acid equivalent), and (8.11-9.82 % dry matter) respectively while in the kernel meals the CPE was (2.60 - 3.70 mg/g), and phytic acid (6.56 - 7.46 %). Tannins were negligibly low in the kernel meals (0.03-0.07 % tannic acid equivalent). The proximate and antinutrients composition were significantly affected by the fermentation processes. The dry matter, crude protein, and ash content significantly increased in all fermented whole seed meals as compared the control meals (unfermented) while lipid content reduced significantly in the fermented seed meals. Meals fermented for 14 and 21 days have significantly higher crude protein than those fermented for 7 days and the control. Crude phorbol ester and phytic acid in all fermented seed meals and kernel meals also reduced significantly (p < 0.05). Generally, meals fermented for 14 and 21 days have lower antinutrients than the control meals and those fermented for 7 days. It could therefore be concluded Jatropha kernels meals can be detoxified by solid state fermentation.