Effect of Extraction Methods on Physico-Chemical Properties of Oil from Cashew Nuts (Anarcadium occidentale)

Abstract

With a view to studying the impact of methods of extraction on properties of oil from cashew nuts, two extraction methods were adopted to obtain oils from cashew nuts. The methods are solvent extraction using n-hexane as extractive solvent and traditional hydraulic press methods. The physic-chemical properties of the extracted oil samples were analyzed and compared to each other. Percentage oil yields were 53.25% and 46.89% for the solvent extracted and hydraulic press oils respectively. The oil sample’s odour was not offensive at room temperature for either method. Specific gravity was 0.86g/kg for solvent extracted oil and 0.94g/kg for oil obtained through hydraulic press. Saponification value ranged from 85.5g/kg for hydraulic press oil to 96.62g/kg for solvent extracted oil. pH values for both samples were below 7.0, and the refractive index for both samples were 1.47. The relative density value ranged from 0.9 to 0.92 at 29°C (room temperature). Both oil samples were in liquid state at room temperature and boiling points varied from 94°C to 98°C for solvent extracted oil and hydraulic press oil respectively. The results showed that the method of extraction imposed significant changes on specific gravity, saponification value, iodine value, acid value peroxide value and relative density. However, no significant differences were recorded in parameters like free fatty acid, peroxide value and refractive index values