Effects of Temperature Change on the Physico-Chemical Properties of Sesame Seed Oil

Abstract

Heating is one of the most commonly used methods of food preparation in homes and industries and prolong use of oil for this purpose causes changes in its physical and chemical properties. The effects of changing temperature on various chemical and physical characteristics of sesame seed oil were studied. The oil was extracted using soxhlet apparatus with n-hexane as extraction solvent. The seeds of sesame (Sesamumindicum) were found to have high oil content. Both the chemical and physical characteristics were investigated within a temperature range of 25-290°C. At room temperature (25°C), the results revealed the chemical characteristics as follows: acid value (AV) (5.61mg/g); peroxide value (PV) (4.42 Meq/kg); free fatty acid (FFA) (5.89%). The physical characteristics were: moisture content (MC) (5.50%); density (0.99g/cm 3); refractive index (RI) (1.47). At elevated range of temperatures (170-290°C), there were corresponding changes in both chemical and physical parameters as follows: AV (5.61-5.91mg/g); PV (4.44-6.05 Meq/kg); FFA (5.91-6.06%); MC (3.98-0.71%); density (0.95-0.69g/cm 3); RI (1.46-1.40). The study showed that there was gradual increase in chemical properties with increase in temperature whereas, the physical properties decreased gradually with increase in temperature.