The Effects Of The Initial Cell Concentration On The Alcoholic Fermentation Of Cassava

Abstract

Cassava is being considered in Brazil as the main alternative to sugarcane for the production of ethanol for imdustrial and fuel purposes, and efforts are being made to improve this technology. Among the possible improvements one of the most important is the increase in the saccharification and fermentation yields and productivities when these operations are accomplished simultaneously. In this work, using Saccharomyces cerevisiae, ethanol fermentations from Cassava starch were carried out as a function of cell concentration ranging from 0.3 to 15.0 g/l. The main conslusions were that ethanol productivities and yield were not affected by the initial cell concentration unless this was below 0.3 to 0.6 g/l (dry base). Average ethanol productivities of about 4.0%/h were consistently obtained with ethanol yields ranging from 85 to 90%. Concerning reaction rates, it was found that unless very low values of initial cell concentration were used, the saccharification became the limiting step of the overall process.