Morpho-chemical divergence and fatty acid profile of shea tree seeds (Vitellaria paradoxa) collected from different locations in Kwara State, Nigeria

Abstract

The present study characterizes seed-related traits, phytochemical, physiochemical parameters and fatty acid profile of shea (Vitellaria paradoxa) seeds collected from the Kosubosu, Fufu and Sare areas of Kwara State, Nigeria to determine the effects of microclimate on seed morphology, biochemical and oil constituents. Seed morphological data were analyzed for variability. Seed oil was extracted for phytochemical constituents, physicochemical properties, and fatty acid profiling by gas chromatography equipped with mass spectrometry (GC/MS). Results showed intra and inter-locational variations in seed characters. Most fruits had 1–2 seeds. Seeds were predominantly brown and very few were dark brown. Phytochemicals and physicochemical parameters of the seed oil varied with place of collection. Alkaloid, saponin, tannin and phytate contents ranged between 0.79–0.84, 1.20–1.26, 1.48–1.56 and 0.15–0.18 mg g–1 respectively. The density of the oil was less than that of water, acid value ranged from 10.58–13.56 mg KOH g–1 and iodine values were between 36.63 to 40.32 g I2 (100 g)–1. Saponification values lie between 160.39 and 184.14 mg KOH g–1; and free fatty acid was within 5.32–6.81 %. Peroxide, alfa-tocopherol, total phenol and oxalate values as well as viscosity of the oil also varied; however, refractive index was similar. Ethyl oleate and octadecanoic acids were present and most abundance in all the locations, while glycidol stearate was only found in Fufu samples with three other fatty acids. Five fatty acids were present in Kosubosu, while Sare had only two. The results obtained in the present study indicate that shea oil could be used for medicinal, nutritional and industrial purposes. Since seed characters, phytochemical, physicochemical and fatty acid compositions varied with the microclimate, environmental and micro-ecological conditions should be considered when collecting seeds for oil utilization.