Lipases from Rhizomucor miehei (RmL) and Candida antartica (CaL-B) entrapped in surfactant free microemulsion-like ternary systems consisting of n-hexane, short chain alcohols (1-propanol or 2-methyl-2-propanol) and water, keep their catalytic activity at 30 degrees C, catalyzing efficiently the esterification of fatty acids or natural phenolic acids including cinnamic acid derivatives. High conversions (up to 95%) were obtained with both lipases entrapped in various ternary systems. Lipases catalytic efficiency and stability was influenced by the composition of the ternary systems used. Hydroxypropylmethyl cellulose (HPMC) microemulsions-based organogels (MBGs) formulated with various surfactant free microemulsion-like systems were used as a matrix for enzyme immobilization. These lipase-containing MBGs prove to be a novel solid-phase catalyst for use, under mild conditions, in non-polar solvents as well as in solvent free systems. CaL-B immobilized in surfactant free MBGs keep its catalytic activity for a storage period of 8 months, while the corresponding residual activity of immobilized RmL was decreased by 50%. The stability of enzymes in such surfactant free MBGs is higher than that observed in MBGs formulated with surfactant based w/o microemulsions. Lipases-containing surfactant free MBGs were used in seven consecutive batch syntheses of fatty esters with only 10-15% loss of activity. (c) 2005 Elsevier Inc. All rights reserved.