Obtenção de etanol a partir de malto-dextrina de mandioca pelo processo de sacarificacão simultânea à fermentação (SSF)

Abstract

A study was conducted to obtain ethyl alcohol from the maltose-dextrins of cassava by using saccharification and fermentation simultaneously. An incomplete factorial (33) design with three equidistant levels was used: substrate concentration (10; 15 and 20g/l), concentration of the yeast Saccharomyces cerevisiae (10; 15 and 20g/l) and the enzyme amyloglucosidase concentration (500; 1250 and 2000 AGI/l). The experiments were conducted at 35° ± 1oC, initial pH of 4.5 ± 0.1 and 135 ±5 rpm agitation. The productivity (g/l.h) and yield (%) were analysed using response surface methodology with 95% fermentation process development. The results showed that the most contributing variable was the enzyme concentration. Mathematical models were obtained from the data for productivity and yield. A compromising solution between the two responses was developed from the response surface graphs where the yeast concentration was fixed at 15g/l. Likewise the best simultaneously estimated responses within the experimental region are as follows: productivity from 3.28 to 3.32 g/l.h and yield from 88,26 to 89, 72%. Such variations correspond to the following concentration of substrate and enzyme respectively. 127.5 to 132.5 g/l and 1887.5 to 2000 AGI/l. The response surface graphs were of value when economic limitations were imposed by the relation between enzyme and substrate.