Shimelis, Admassu (Assoc.Prof.)Kenbon, Beyene2020-12-092023-11-102020-12-092023-11-102017-11http://etd.aau.edu.et/handle/12345678/23918The purpose of this research was to determine the physicochemical characteristics, proximate, mineral and the phytochemical composition of pulp and seed of two avocado cultivars, namely Fuerte and Hass, produced in Wondogenet, Ethiopia with respect to the unripe and ripe. Furthermore, extraction of oil from Hass avocado pulp using soxhlet and ultrasonic extraction and some process parameter optimization were carried out. The percentage oil yield, analysis of chemical properties and fatty acid profile of extracted oil were done. The basic characteristics evaluated were weight (of the fruit, pulp, seed, peel and seed coat), Dry matter (DM), Total soluble solid (TSS), pH, Titratable acidity (TA), Moisture content (MC), ash, total lipid, fatty acid composition, protein and minerals. The concentrations of phytochemicals (total phenolics, flavonoids, tannin, and phytate) were also analysed. Hass avocado cultivar showed greater flesh to seed ratio (13.57±10.43) and had lower fruit weight (183.92±47.58g) than Fuerte cultivar. The highest pulp MC (77.82±0.19%), protein (2.92±0.04%), ash (0.42±0.01%), fat (22.80±0.00%) and crude fiber (4.50±0.09%) corresponds to UHP except MC which is to UFP. The analyses of the nutritional compositions demonstrated that the pulp of the Hass proved to be rich in ash, fiber, total lipid, protein and potassium content than fuerte pulp. The seed, in turn, had higher DM (48.4±1.02%), TA (2.88±0.02%), Mg (2.01 ±0.02%), Na (12.67±0.01%), and Ca (24.77±0.02) mg/100g, wet basis contents than its pulp. With regard to the contents of phytochemicals, the seed was superior to the pulp. The effects of three factors (particle size, solvent to sample ratio and extraction time) on the oil yield were considered. The optimum extraction conditions for soxhlet extraction were found to be at 8 h reaction time, particle size of 1.4mm and solvent to solid ratio of 20:1 with a maximum yield of 69.7%, while the optimum extraction conditions for ultrasonic extraction were found at 1.5 h reaction time, particle size of 2mm and solvent to solid ratio of 15:1 with a maximum percentage yield of 67.2%. The analyses of the oil characteristics demonstrated that the oil extracted by soxhlet extraction shows lower PV, FFA, MVM and Alkalinity than oil extracted using Ultrasonic extraction. The results of fatty acid profile displayed that the oleic and linoleic acid contents of the soxhlet extracted oil were higher than that of the Ultrasonic extracted oil while palmitic and butanoic acid were higher in ultrasound extracted oil. Generally, Hass avocado variety was found to be better interms of pulp to seed ratio, proximate composition and minerals. Ultrasound assisted extraction showed a promising oil yield regarding short extraction time and low solvent consumption; but its oil quality is lower than that of soxhlet extracted oil.en-USavocadocultivarfatty acidperoxide valueripeningsoxhletultrasonicThesis