Several lipases of Candida rugosa ATCC 14830, obtained in different fermentation conditions and with different proportion and number of isoenzymes, were immobilized in microemulsion-based organogels (MBGs), gelled with hydroxypropylmethyl cellulose (HPMC) as biopolymer, and lecithin or AOT as surfactants. Lipase factor (LF) obtained from initial reaction rate profile is useful parameter to explain the catalytic activity of these crude enzymes in esterification reactions. This parameter is valid for the characterization of native or immobilized enzymes, due to the catalytic behaviour of the lipases immobilized in the MBGs is similar to that described for native enzymes. Lipases hosted in MBGs obtained from microemulsions with lecithin as surfactant are more active than those obtained with AOT in esterification reactions. Esterification of fatty acids in organic media and LF values can be used to evaluate the amount of lipase in different crude enzymes. (C) 2004 Elsevier Inc. All rights reserved.