Structured Segregated Model for Optimal Profit Control of Baker's Yeast Production

Abstract

In fed-batch production of baker’s yeast the profile of the sugar flow must regard the Crabtree-Effect and the oxygen transfer capacity of the reactor to avoid loss of yield. In this paper, optimal fed-batch control strategies are under investigation which also consider the final product quality. The optimization is carried out based on a mathematical process model that consists of three parts: The structured growth model can predict the growth kinetics in dependence of the operating conditions of the reactor; the age-distribution model for the budding process provides the fraction of budding cells (FBC) of the yeast population which is inversly correlated to the quality parameter fermentative activity; the cost model gives information on the economics of the process operation. New parts of the model are presented and simulation results with the model are compared with experimental data. The optimum operation of the Baker’s yeast fed-batch production is then investigated. Different from usual control trajectories, consideration of the quality criterion leads to a pulsed control of substrate flow. The optimum control predicted by the model was verified in laboratory-scale experiments.