Purification of conjugated linoleic acid isomers by selective esterification with Candida rugosa lipase

Ability of Candida rugosa for separation of two main conjugated linoleic acid (CLA) isomers including 9-cis،11-trans and 10-trans،12-cis was investigated in the mixture of free fattyacids of these isomers and L-menthol. In order to effectively separate two mentioned isomers، optimization of reaction conditions was conducted using response surface methodology (RSM). After data analysis by D-optimal design، the best reaction conditions for maximum esterification of 9-cis،11-trans isomer with L-menthol after just one step esterification were as follows: reaction time 23. 1 h، temperature 32. 6°C، enzyme amount 135. 4U، molar ratio of CLA oil to L-menthol at 1:1. 7 and pH at 7. 7. At this optimum point، the lowest amount of c9، t11-CLA isomer (6. 7%) was observed in free fatty acids fraction. This effective process for purification of CLA isomers using L-menthol could be applicable to produce food supplements.