Optimization of solvent requirement for refining of karanja (Pongamia glabra) oil by liquid- liquid extraction

Abstract

An improved detoxification method using liquid-liquid extraction of karanja (Pongamia glabra) oil is developed. Only 2 stage extractions [using oil and HCl (1:0.35 w/v)] followed by 3 extractions [using oil and alkaline MeOH (1:2 w/ v)] can completely detoxify oil. After HCl extraction, if alkaline isopropanol (IPA), dimethylformamide (DMF) and acetonitrile are used for extraction, total HCl and corresponding solvent requirement would be (w/v) 1:1.0, 1:6.0; 1:0.2, 1:1.2; and 1:0.4, 1:1.6 respectively. When only acetonitrile is used, 5 stage extraction using oil: acetonitrile (1:0.5, w/v) per batch makes total acetonitrile requirement 2.5 times (v/w) of oil for complete detoxification. Physicochemical characteristics of refined oils are acceptable. Overall oil yield (75-80% w/w) is obtained when alkaline MeOH, IPA and DMF are used, but higher yield (85-88%, w/w) is obtained when acetonitrile is used.