This work shows optimal conditions to use the amylases from A. niger in starch hydrolysis and alcohol production from manioc root starch. Bioreactors contained 10-20 g/L of manioc starch concentration, on 35-55°C, and at pH 4.8; they were made for the evaluation of the effects of starch concentration and temperature on hydrolysis yield. New models for starch hydrolysis kinetics were compared for substratum dependence ([S]) to the hydrolysis time (t) and hydrolysis conversion rate (V) dependences with the substratum concentration ([S]). Results showed that exponential models fitted better than other models. The appropriate models were [S] = e-k.t and V = e(Vmax. [S]/KM), while k, Vmax and KM are the kinetic, maxim velocity and Michaelis-Menten constants, respectively. Models proposed in this work have been compared to experimental data, and it may be possible to simulate the starch hydrolysis process by amylases and its scale-up. Results showed that exponential models were more appropriate to use than Michaelis-Menten model for V values higher than 0.3 g/L.min. At a V range lower than 0.3 g/L.min, both models were satisfactory predictives. For starch hydrolysis, the exponential models perceived that, at optimal conditions, the mean yield was 70%. After fermentation, an alcohol yield above 45% was obtained (the theoretical is 51.1%).
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