Worku, Teshome (Ass.Professor)Mekonnen, Shimeles2018-07-172023-11-102018-07-172023-11-102017-06http://etd.aau.edu.et/handle/12345678/8819Black cumin seed (Nigella sativa) oil was used traditionally in different countries for many medical complains. The seeds are used for culinary purposes, medicinal treatment and also used as food additives. The oil can produce by different extraction methods. Among of those methods, solvent extraction is the most promising and effective process with minimum cost. When we are using solvent extraction process, the major problem is the uses of toxic chemical that is hexane as a solvent. These solvent produces photochemical oxidants in the ozone by reacting with other pollutants during extraction and recovery process and also a trace of hexane that is found in the oil affects the human health. This study mainly investigates and compares the effect of solvents, ethanol and hexane in the extraction process and optimization was done in the two factors named as, extraction time and seed to solvent ratio. The extraction process was carried out by using 3 level factor of the seed to solvent ratio (1:4, 1:6 and 1:8) and 4 level of extraction time (2hr, 4hr, 6hr and 8hr) using for each solvents using soxhlet extractor. The maximum yield of extraction for hexane solvent was found to be 35.725% with seed solvent ratio 1:8 and 4 hour and the minimum yield were 20.575% with the seed solvent ratio 1:4 and 2 hour of extraction time. Whereas using ethanol solvent the higher extraction yield was 35.51% with the factor of the 1:6 of seed solvent ratio and with extraction time 6 hour and the minimum result were 22.81%withthe seed solvent ratio 1:4 and 2 hours. The significance of each parameter was checked by using design expert software with the p-value<0.05 and identify the components and functional group of the samples by using GC-MS and FTIR and identified 23 components and 10 functional groups. The physical properties, density, specific gravity, viscosity and pH; the chemical properties such as Acid value, saponification value and Iodine value of the fixed oil was done before refining and after refined. Both of the experiment results has almost the same components and functional groups and there is no any significance effect in the environment and for the human health in ethanol solvent extraction. Therefore it is better to use ethanol as a solvent for extraction process rather than hexane. Key Words: Black cumin seed, HSO, ESO, solvent extraction, GC-MS, FT-IR.enBlack cumin seed, HSO, ESO, solvent extraction, GC-MS, FT-IRThesis