Design of shea nut rotary roasting machine used for shea butter production in Ghana

Abstract

Shea nuts are dominantly grown in the Northern region of Ghana. Studies have shown that shea nuts undergo hydrolytic destruction during traditional post- harvest processing and storage. Due to poor infrastructure, local women in the area go through extreme measures of stress to process shea nuts into shea butter coupled with their inability to control moisture, a factor for the high yield of shea butter. The sole aim of this paper is to propose the design of a rotary roaster for shea butter production in references to the oil quality and yield. A preliminary study was conducted on the shea nuts in relation to their thermal pre-treatment in terms of oil quality and yield in which certain physicochemical properties like free fatty acid values, acid values, and peroxide values were examined. This aided the design of the rotary roaster, which uses pellets of firewood as its fuel source. The machine is designed for a capacity of 60 kg/batch to reduce fresh shea nuts moisture content from 40% to an appreciable amount so as to increase the oil yield. The proposed materials for the construction of the machine are local materials that are affordable and will make the manufacture of the rotary roaster affordable for the local women in the Northern region of Ghana