Therefore, it is important to carefully describe the different stages of the beer production process, in order to optimize process conditions and beer flavour. To do so, in this study, a comprehensive fermentation model and optimization problem were formulated. This model includes a complete yeast growth model, production of ethanol and flavor related desirable and undesirable chemical species, including temperature dependency of such processes as well.
Beer flavor reflects the combination of a large number of chemical species, mostly resulting from the yeast metabolism. Therefore, in this work, the goal is to determine how an up-to-date industrial beer production should optimally operate. To achieve this, a two-step procedure is applied: (i) a comprehensive fermentation model is developed, including a yeast growth model, ethanol and by-products production (fusel alcohols, esters, VDKs, acetaldehyde and sulfidic compounds); and, (ii) a dynamic optimization problem is formulated and implemented with the objective of maximizing the conversion of substrate to ethanol, while dealing with the final allowable concentrations of the by-products as strict constraints.
Preliminary results show that each by-product flavor threshold affects process performance and beer flavor in a distinctive manner, which is also supported by published literature. Results indicate that the maximum acceptable concentrations of off- and on- flavors, like diacetyl and ethyl acetate, have considerable impact on the flavor profile, as well as on batch duration.
A comprehensive fermentation model was developed based upon kinetic models. Furthermore, in order to optimize the flavor profile and process conditions, a dynamic optimization was formulated and solved. Thus, we believe, that this work contributes to a comprehensive understanding of the impact of different chemical species (off- and on-flavors) on the optimal beer flavor profile, as well as in the optimization of process conditions.