Effect of solvent type and temperature variation on yield and quality parameters of oil extracted from eel fish (Anguilla marmorata [q.] gaimard) using soxhletation method

Abstract

Fish oil is a lipid, soluble in non-polar solvents such as ether, hexane, chloroform, petroleum ether, and benzene. Oil of eel (Anguilla marmorata [Q.] Gaimard) contains a high level of unsaturated fatty acids that have health benefits. The aim of this study was to determine the best solvent and optimal temperature required for the extraction of eel fish oil by the soxhletation method. Fish oil was extracted with the soxhletation method using n-hexane and diethyl ether as extraction solvent at 60, 70, and 80ºC for 5 hours. The extracted fish oil was analyzed for organoleptic properties, percentage yield, peroxide value, and free fatty acid content. The results of the organoleptic analysis showed that extraction with n-hexane at 60ºC produced the best oil and the highest percentage yield was obtained with diethyl ether at 60ºC. It was observed that the highest peroxide value was obtained for oil extracted with diethyl ether at 80ºC, while the lowest peroxide value was in the n-hexane at 70ºC. The highest free fatty acid level was found in the oil extracted with n-hexane and the lowest in diethyl ether at 60ºC. Analysis of the results indicated that the best condition for extracting eel fish oil was the use of diethyl ether at 60ºC, which produced a clear oil extract, with a typical aromatic odour of fish oil and a golden-brown colour, with a percentage yield of 36.49%, a peroxide value of 5.460 meq/kg, and a free fatty acid level of 41.595%.