Sunday, May 3, 2009
3-74
Ethanol production from cashew apple bagasse: improvement of enzymatic hydrolysis by microwave-assisted alkali pretreatment
Tigressa H. S. Rodrigues1, Maria Valderez Ponte Rocha2, Gorete Ribeiro Macedo3, and Luciana Rocha Barros Gonçalves1. (1) Chemical Engineering, Universidade Federal do Ceará, Campus do Pici, Bloco 709, Rua General Piragibe,347, Fortaleza, Brazil, (2) Chemical Engineering, Universidade Federal Rural do Semi-Árido, BR 110 - Km 47 Bairro Pres. Costa e Silva, Mossoró, Brazil, (3) Departamento de Engenharia Química, Universidade Federal do Rio Grande do Norte, Núcleo de Tecnologia, Lagoa Nova, s/n, Campus Universitário, Natal, Brazil
Energy consumption has increased steadily as world population has grown and more countries have become industrialized. The fossil fuels have been the major resources to meet the increased energy demand. Moreover, its inevitable depletion and the increased concerns of greenhouse gas emissions have resulted in a worldwide interest in exploring renewable energy such as fuel ethanol. Lignocellulosic materials appear as a feedstock and low-cost biomass that can be used as alternative raw materials for ethanol production. Cashew apple bagasse (CAB) is the result of the industrial process of cashew apple, a pseudofruit native of the Northeast region in Brazil , for juice production. Therefore, CAB appears as an alternative raw material for ethanol production. In this study, the objective was to evaluate the microwave-assisted alkali pretreatment and to investigate the effects of process parameters on enzymatic hydrolysis of CAB. Furthermore, the hydrolysate was fermented to ethanol using Saccharomyces cerevisiae. The microwave oven pretreatment was carried out with CAB presoaked in NaOH solutions with different concentrations (0.0, 0.2, 0.4 and 0.6 mol.L-1) for 15 and 30 minutes and power of 600W and 1000W. The enzymatic hydrolysis was carried out at 45°C using 2 and 16% (w/v CAB), 150 rpm and pH 5.0. Fermentation assays were carried at 30°C , 150 rpm, pH 5.0, and an initial cell concentration of 10.0 g.L-1. Results showed that microwave-assisted alkali irradiation is an efficient pretreatment method to enhance CAB digestibility.