Kinetic study of ethanol fermentation from sugarcane bagasse enzymatic hydrolyzate concentrated with molasses

Nowadays many efforts are being made to develop new technologies using renewable resources, as is the case of second generation ethanol production. Among several challenges concerning process development and sustainability features, a robust second generation (ethanol production from lignocellulosic feedstock) fermentation is necessary.

Development of ethanol production process from sugarcane bagasse is desirable since it improves productivity, yields and row material use efficiency, mainly when associated to first generation (ethanol production from sugarcane juice). In the current state-of-the-art of second generation, further studies are required for better understand the process behavior. A key issue is the investigation of possible changes in the kinetic of ethanol fermentation by Saccharomyces cerevisiae when the hydrolyzate is used as fermentation media.

In this work, a kinetic model for ethanol fermentation process from hydrolyzed bagasse was developed considering the effect of temperature. Fermentation media was a mixture of hydrolyzate obtained from enzymatic saccharification of acid-catalysed hydrothermal pretreated sugarcane bagasse and molasses. Experiments were performed with temperature ranging from 30 to 36^oC in batch mode with Bioflo 115 of 1 L fermentor (New Brunswick Scientific) with stirring, temperature control, pH (Mettler Toledo) and capacitance (Aber instruments) probes. The accuracy of a mechanistic kinetic model is evaluated, not only by their precision in describing experimental observations, but also by the challenges involved in the estimation of their parameters. The model used to describe the fermentation achieved a good prediction of cell, substrate and ethanol concentrations.