Tuesday, May 3, 2011
The work proposed for this dissertation refers to the comparative study of acid and enzymatic hydrolysis of starch in the ethanol production process from cassava flour as raw material starch. Ethanol production represents an alternative to environmentally friendly replacement for petroleum derivatives. Cassava constitutes an important agricultural product, and because of its high starch content, which can later be turned into glucose, cassava has been used as feedstock for ethanol production. In this work the first step was to characterize the raw material, employing physical-chemical analysis in flours of three different varieties of cassava grown in the city of Junqueiro, located in the State of Alagoas, Brazil. In the last stage tests were performed in 18 flasks were divided into nine trials involving acid hydrolysis and nine trial of enzymatic assays aimed at producing ethanol with three differents yeasts. The musts fermented resulted in alcoholic strength of 7.5 º and 8.3 º GL for acid hydrolyzed while enzymatic hydrolysates gave values between 10.7 º and 11.6 º GL. According to these results, there was a clear advantage of using enzymes in the hydrolysis process. The best variety of cassava flour was the variety-SE, despite the lower amount of starch conversion efficiency was adequate for completion of fermentation for the three types of yeast studied. The yeast-type C3 (12) and C1 (10) were better than commercial yeast when the alcohol content was above 10%, showing more resistance to ethanol intoxication.