Monday, May 4, 2009
9-37
Ethanol production by fermentation using immobilized cells of Saccharomyces cerevisae in cashew apple bagasse
Alexandre Pacheco, Diego R. Gondim, and Luciana R. B. Goncalves. Chemical Engineering, Universidade Federal do Ceará, Campus do Pici, Bloco 709, Fortaleza, CE, Fortaleza, Brazil
Cashew apple, source high concentrations of reducing sugars, is a common pseudofruit in the Northeast of Brazil. However, only 12% of the total peduncle is processed and it does not play an important role to the economy of the state. Therefore, ethanol production from cashew apple represents an alternative for this residue. Cell immobilization improves productivity and provides a physical protection to the yeasts. In this work, cashew apple bagasse (CAB) was used for Saccharomyces cerevisiae immobilization. The support was prepared through a treatment with a solution of HCl 3% (v/v) at for 2.5 hours. Then this mixture was washed until neutral pH and dried. Deslignification with NaOH 2%(p/v), at 120 rpm, for 24 h was also conducted. Afterwards, the support was washed with water until neutral pH and dried at. Ten consecutive fermentations of cashew apple juice for ethanol production were carried out using immobilized yeasts. Before each cycle, samples were taken before inoculation and after 6 hours of fermentation. After that time, fermentation process was stopped and the support containing immobilized cells was washed with water and reused. A Neubauer-counting chamber was used to quantify the yeasts immobilized in CAB and optical density (OD, λ=660nm), to identify free cells growth. Reducing sugars consumption and ethanol production was analyzed by HPLC. High ethanol productivity was observed from the second fermentation assay until the tenth fermentation. Results showed that cashew apple bagasse was an efficient support for cell immobilization aiming at ethanol production.