Immobilized lipases from Candida antarctica for producing tyrosyl oleate in solvent-free medium
Abstract
Two immobilized lipases from Candida antarctica have been compared for the direct esterification of tyrosol with oleic acid in equimolar conditions and in the absence of organic solvent. Candida antarctica lipase B was immobilized on octyl-silica agglomerates and compared with commercial Novozym 435. Reduction of tyrosol particle size to 0.1 mm significantly increased the reaction rate with both immobilized lipases, and reduced pressure improved the final tyrosyl oleate yield up to 95% (w/w) in both cases. Immobilized lipases were recovered and reutilized in three consecutive trials with negligible inactivation. Under optimum conditions, a product mixture comprising more than 95% of tyrosyl oleate (w/w) was attained in less than 2 hours. Finally, the index of antioxidant activity obtained, according to the Rancimat method, indicated that tyrosyl oleate was slightly more effective than tyrosol as an antioxidant in a low polar matrix.