Publication date: January 2019Source:Renewable Energy, Volume 130 Author(s): Erika C.G. Aguieiras, Daniele S.N. de Barros, Roberto Fernandez-Lafuente, Denise M.G. Freire Cottonseed meal is a co-product from the cotton industry that is produced in large quantities worldwide. The aim of this work was to add value to this by-product through the production of Rhizomucor miehei lipases and application of the dry fermented solid in esterification reactions between oleic acid and ethanol or methanol and transesterification of a vegetable acid oil. Reactions were carried out in a solvent-free system and conversions higher than 85% were obtained in 4 h in the esterification reactions. The reusability of the biocatalyst was evaluated and the washing of the biocatalyst with solvent (ethanol) was necessary to recover the activity of the lipase, being obtained conversion of 74% in relation to the initial conversion after 4 sucessive reactions. The dried fermented solid was also able to catalyze the production of ethyl and methyl esters by simultaneous transesterification/esterification reactions of macaúba acid oil, with production of an ester content of about 76% after 24 h. This is the first time that fermented solids produced in cottonseed meal without any supplementation are used as biocatalyst of esterification and transesterification reactions.