Post-harvest handling practices and physico-chemical characteristics of shea (Vitellaria paradoxa) fruit in Uganda

Abstract

This study assessed the post harvest handling practices and physico chemical characteristics of shea butter in the parkland areas of Uganda. To investigate post harvest practices of shea butter (Vitellaria paradoxa) fruit, a total of 275 respondents were interviewed between July 2007 and January 2008. The collected socio-economic data were coded, entered in SPSS computer programme and analysed. In the same period, fresh shea fruit pulps were collected, dried and analyzed for proximate and mineral compositions. The shea butter oil extracted from the shea kernels of the shea fruit were also analysed for variability in physico chemical characteristics and fatty acid profile extracted by n-hexane solvent, traditional boiling and mechanical cold pressing methods. The proximate analysis showed that the shea fruit pulp, crude oil, crude fibre, crude protein, total carbohydrate, vitamin C and caloric value contents ranged between 1.5-3.5%, 10-15%; 3.1-4.2%, 61-64%, 85.59-124.86mg/100g and 248-256 Kcal/100g, respectively. The mineral composition of the shea fruit pulp consisted of calcium 35.18-95.58 mg/100g, potassium 42.04-63.55 mg/100g, magnesium 18.14-24.21mg/100g, sodium 7.07-18.12 mg/100gm and iron 3.41-3.76 mg/100g. The shea seed kernel butter/oil content ranged between 41-54% and the physico chemical characteristics such as colour, refractive index, viscosity, acid value, peroxide value, saponification value, iodine value and α- tocopherols ranged between orange to orange–yellow, 1.670-1.690, 2.4-2.8cP, 2.3-12.59mgKOH/kg, 2.10-2.50meq/kg, 160- 192mgKOH/g, 39.21-41.37 I2g/100g and 26.3-44.4mg/100g, respectively. The shea butter fatty acid profile: palmitic , stearic, oleic, linoleic and arachidic acid fatty acids ranged between 6.52-8.12%, 28.65-30.94%, 55.54-57.63%, 6.18-7.79% and 0.65-0.90%, respectively. The physico-chemical characteristics of shea butter extracted by n-hexane solvent extraction, traditional boiling and cold pressing methods for the colours, refractive index, viscosity, acid value, peroxide value, saponification value, iodine value and α tocopherols ranged between yellow-orange to yellow-red; 1.468-1.469, 2.4-2.8cP, 2.3-6.9mgKOH/kg, 2.2-5.09mEq/kg, 145-192mgKOH/kg, 36-38 I2/100, 34.4-45.5mg/100g while the fatty acid profile: palmitic , stearic, oleic, linoleic and arachinic acid fatty acids ranged between 6-8%, 29-31%, 55-57%%, 6-8%and0.65-0.98%, respectively. While the proximate and mineral composition of the shea fruit pulp makes shea fruits a potential nutritious fruit in the parklands, the physico-chemical characteristics and fatty acid profile of shea butter on the other hand make it a suitable raw material for food, cosmetic and pharmaceutical products. The quality of shea butter oil is also comparable to other edible oils such as soya bean oil (Glycine max). The indigenous post harvest handling practices of shea butter in Uganda is appropriate, however, there is a need to investigate further their influence on quality of shea butter..