QUALITIES OF TIGER NUT OIL AS INFLUENCED BY HEATING TEMPERATURE

Abstract

The effect of heating temperature on the oil yield and characteristics of tiger nut was investigated. The tiger nut samples was divided into four portions A, B, C and D. Samples B, C and D were heated at 100oC, 120oC and 140oC respectively for 30 minutes, while sample A, which was not heated served as the control for the experiment. The oil extraction was done using solvent extraction method and the extracted oil was characterized using standard methods. The results showed a percentage oil yield of 28.18%, 26.83%, 24.14% and 21.19% for samples A, B, C and D respectively. The acid (mg/KOH/g) and peroxide (m/mol/kg) values are 2.81, 2.53, 2.24, 1.40 and 2.8, 2.0, 1.0, 2.0 for samples A, B, C and D respectively. The free fatty acid (mg/KOH/kg) values are 5.61, 5.05, 4.49, 2.81 for samples A, B, C and D respectively for oil samples extracted. The oil yield, acid value, peroxide value and free fatty acid decreases with increase in heating temperature. The heating temperature however had no significant effect on the specific gravity, density, refractive index, saponification value and iodine value of the extracted oil. It can be concluded that tiger nut should not be heat treated above 100oC prior to oil extraction for optimum oil yield and reduction in peroxide value. However further research work should be carried out on tiger nut by heating at temperature below 100oC prior to oil extraction.