Ethanol Production by Fermentation Using Immobilized Cells of Saccharomyces cerevisiae in Cashew Apple Bagasse Alexandre Monteiro Pacheco & Diego Romão Gondim & Luciana Rocha Barros Gonçalves Received: 22 May 2009 / Accepted: 15 September 2009 / Published online: 2 October 2009 # Humana Press 2009 Abstract In this work, cashew apple bagasse (CAB) was used for Saccharomyces cerevisiae immobilization. The support was prepared through a treatment with a solution of 3% HCl, and delignification with 2% NaOH was also conducted. Optical micrographs showed that high populations of yeast cells adhered to pre-treated CAB surface. Ten consecutive fermentations of cashew apple juice for ethanol production were carried out using immobilized yeasts. High ethanol productivity was observed from the third fermentation assay until the tenth fermentation. Ethanol concentrations (about 19.82–37.83 g L -1 in average value) and ethanol productivities (about 3.30–6.31 g L -1 h -1 ) were high and stable, and residual sugar concentrations were low in almost all fermentations (around 3.00 g L -1 ) with conversions ranging from 44.80% to 96.50%, showing efficiency (85.30–98.52%) and operational stability of the biocatalyst for ethanol fermentation. Results showed that cashew apple bagasse is an efficient support for cell immobilization aiming at ethanol production. Keywords Cashew apple . Ethanol . Saccharomyces cerevisiae . Cell immobilization . Alcoholic fermentation Introduction Immobilized cell system has been suggested as an effective means for improving ethanol fermentation, since it is possible to increase process productivity and minimize production costs [1, 2]. The immobilization of cells leads to higher cell densities with consequent increases in reaction rates and productivity. As a result, shorter residence time and smaller reactor size can be employed. Ethanol production by immobilized yeast cells has been extensively investigated [2–7]. For industrial purposes, an important choice criterion is the carrier cost which, combined with the interest in by-products recycling, has been leading to an increasing search for Appl Biochem Biotechnol (2010) 161:209–217 DOI 10.1007/s12010-009-8781-y A. M. Pacheco : D. R. Gondim : L. R. B. Gonçalves (*) Departamento de Engenharia Química, Universidade Federal do Ceará, Campus do Pici, Bloco 709, 60455-760 Fortaleza, Ceará, Brazil e-mail: lrg@ufc.br