PROXIMATE COMPOSITION AND PHYSICO-CHEMICAL PROPERTIES OF THREE AVOCADO (Persea americana) VARIETIES IN UMUAHIA, NIGERIA

Studies were carried out on oil extraction and proximate analysis of pulp and oil from three varieties of ripe avocado (Persea americana) namely; Brogdon, Russel and Choquette. Solvent extraction of oil was done using three different solvents namely; ethanol, hot water and chloroform. The Brogdon variety gave the highest yield and ethanol was the best solvent for extraction. The proximate analysis of the avocado pulp showed that the Brogdon, Russel and Choquette varieties had moisture contents of 67.87, 69.35 and 67.34%, respectively. Ash content was 1.05, 1.00 and 1.07% while crude fibre was 4.65, 4.00 and 4.80% for the Brogdon, Russel and Choquette varieties, respectively. The fat contents are 18.77, 14.67 and 16.27%, respectively and their crude protein content was 2.76%, 2.38% and 2.56% for the Brogdon, Russel and Choquette varieties. The physical and chemical characteristics of the extracted oil were determined. Results showed that the physical characteristics of the oils from the Brogdon, Russel and Choquette varieties were respectively: melting point (21.72, 20.64 and 21.33°C), refractive index (1.43, 1.41 and 1.42), specific gravity (0.91, 0.91 and 0.92), moisture content (1.03, 1.25 and 1.35%), flash point (237.55, 248.00 and 255.44°C) and smoke point (178.89, 181.33 and 187.33°C). The chemical parameters of the Brogdon, Russel and Choquette varieties were; saponification value (181.78, 182.78 and 182.58 mgKOH/g), iodine value (89.48, 90.55 and 90.45 mgKOH/g), acid value (0.83, 0.79 and 0.69 mgKOH/g), free fatty acid (1.58, 1.54 and 1.30%) and peroxide value (3.28, 2.88 and 3.00 mg/kg). The physico-chemical characteristics and proximate composition of the oil shows that it has some industrial potential and utilization of this oil will reduce dependence on the popular vegetable oils like groundnut, coconut and palm oil for domestic use.