OXIDATIVE RANCIDITY OF AVOCADO OIL (HASS VARIETY) PRODUCED BY SCREW PRESSING AND SOLVENT EXTRACTION METHOD

Abstract

The avocados (Persea Americana) of Hass variety, collected from Aatmara, Dhankuta were subjected to oil extraction by screw pressing and solvent extraction. The extracted oil were analysed for physiochemical properties like melting point, specific gravity, refractive index, iodine value, saponification value and unsaponifiable matters. The oxidation rate at room temperature (RT) for 45 days was studied for both oil using acid value (AV) and peroxide value (PV) as stability indices at an interval of 9 days. The proximate analysis of avocado fruit showed 70.03±0.085% moisture, 22.61±0.020% fat, 1.19±0.303% protein, 0.59±0.01% minerals, 0.98% carbohydrate and 4.6±0.264% crude fiber. The melting point, specific gravity, refractive index, iodine value, saponification value and unsaponifiable matters were found to be 14.4±0.3°C, 0.875±0.01, 1.460±0.0005, 57.948±0.015 oil, 176.3±0.019 and 1.79±0.026 % for oil obtained by solvent extraction of dried pulp, and 15±0.2°C, 0.901±0.001, 1.461±0.001, 70.6±0.0 oil, 154.793±0.023 and 1.83±0.30% for oil obtained by screw pressing of dried pulp respectively. The oil yield was found to be 52.08% and 46.86% by solvent extraction method and screw pressing method respectively. AV and PV of both oil significantly increased (p < 0.05) with the increasing of storage time for 45 days. There was a significant difference (p<0.05) in increment pattern of oils. Both oils maintained their AV and PV within edible range till 45th day of storage at room temperature. Hence, avocado oil obtained by both processes are edible till 45 days of storage at room temperature