Effect of Temperature, Moisture Content, Particle Size and Roasting on Shea Butter Extraction Efficiency

Abstract

The purpose of this study is to establish optimum extraction temperature, moisture content, particle size and the effect of roasting of shea kernels on extraction efficiency for optimum shea butter yield using low pressure (45kg/cm2) manual screw press. Extraction of shea butter is a major income generating activity in Ghana, particularly in the Northern Regions. It is estimated that about 80% of the shea butter produced in Ghana is processed by women using traditional aqueous extraction method. Commercial extraction using continuous screw press accounts for about 20% of production. Oil extraction rates for the traditional aqueous extraction method are relatively low. The traditional aqueous method involves roasting, milling, creaming and boiling, and relies on very low pressure, high moisture of 65-68% and temperatures of 100-140°C. In this study Intermediate Moisture Content (IMC) method was employed. The IMC method involves the use of a low pressure manual screw press to extract butter from shea kernels. The study established an optimum extraction temperature of 60°C and moisture content of 12% at which butter extraction efficiency was between 65.9% and 68.5%. The results revealed that oil extraction efficiency depends on the fineness of paste to be processed and that roasted kernels do not give higher butter yield than unroasted kernels. This is against the traditional belief that high shea butter yield can only be achieved when the kernels are roasted.