Fed-batch ethanol fermentation at low temperature as a way to obtain highly concentrated alcoholic wines: Modeling and optimization.

Graphical abstract Highlights • Kinetic parameters of the Andrews-Levenspiel model correlated with temperature. • Fed-batch fermentation validated with kinetic model obtained in batch process. • Modeling of fed-batch ethanol fermentation with viable cells and high substrate feed. • Modeling of ethanol fermentation considering substrate and product inhibition. Abstract The effect of product inhibition on yeast hinders the production of wine with ethanol concentration above 80.0 g L−1 (∼10°GL) in the industrial ethanol production process commonly performed at 34 °C. Lowering the fermentation temperature is a way to produce wines with higher ethanol contents. In this work, batch fermentations were carried out at temperatures of 28, 30, 32, and 34 °C, with initial substrate concentration of 180.0 g L−1, using industrial yeast under conditions reproducing those found in industry. The Andrews-Levenspiel hybrid kinetic model, considering viable cells, showed an excellent fit to the experimental data. Kinetic parameters were determined for the different temperatures. The model was used to simulate fed-batch fermentations at different temperatures, with the same total substrate concentration, resulting in satisfactory descriptions of the process behaviors. A new optimization strategy to obtain the maximum possible ethanol production, based on the C Emax parameter of the Andrews-Levenspiel kinetic model, provided ethanol production of up to 134.7 g L-1 (17.1°GL) at 28 °C and 305.4 g L−1 substrate. A modification was made to the Andrews-Levenspiel kinetic model, relating the n parameter to the final ethanol concentration (C Ef), in order to enable the model to describe the behavior of fed-batch fermentations performed with high substrate concentration and at temperatures from 28 to 34 °C. [ABSTRACT FROM AUTHOR]