Potencial amilolítico do grão de milho maltado no processo de sacarificação do mesmo cereal

Abstract

RESUMOObjetivou-se avaliar o potencial de sacarificação do malte de milho para produção de álcool deste cereal. Para tal, foi realizada germinação do grão de milho a 20 ºC por 5 dias. O potencial amilolítico do malte de milho foi otimizado por meio de . Termos de indexação:Amido, enzimas amilolíticas, fermentação alcoólica e sacarificação. ABSTRACTThe aim of this research was the production of maize malt and the evaluation of its use for alcohol production. The maize grain was allowed to germinate at 20°C for five days. The amylolitic potential of malt was optimized through a Complete Factorial Planning 2 2 with three central points, where the study variables were the temperature of incubation and the substrate concentration [S]. The sacarification was performed through a Planning of Mixture with three central points, where the study variables were the malt concentration and [S] during six 6 hours. The fermentation was carried out using the best sacarification condition, in a five-liter reactor and a two-liter working volume. The pH was maintained at 4.5 -5.0. The Brix was corrected to 14º. The sterile hydrolyzed product was inoculated with 5.0 g.L -1 Saccharomyces cerevisiae. The system was submitted to two hours of initial aeration (170 L O2 .h -1 ) and kept at 30°C. During the fermentation process, analyses were made to determine the cell concentrations (g.L -1 ), reducing sugars (mg.mL -1 ), alcohol (g.L -1 ) and °Brix. The temperature of incubation and substrate concentration were significant factors (p<0.05) in the determination of the amylolytic potential under the conditions of study utilizing 20% of substrate and incubation at 70°C. The central experiments with 50% malt presented the best kinetic parameters with a volumetric rate of ethanol formation of 2.81 g ethanol .L -1 .h -1 , which correspond to 8.0 ºGL, and a substrate conversion in cells of 0.127g cells .g glucose -1 .