A kinetic growth model for Saccharomyces cerevisiae grown under redox potential-controlled very-high-gravity environment

A growth kinetic model for redox potential-controlled very-high-gravity (VHG) fermentation was developed. The model is semi-empirical and two important VHG fermentation operating conditions including glucose feed and redox potential level were incorporated in the model. The model consists of a substrate inhibition term and a product toxification term. A two-step parameter-estimating strategy was proposed and implemented. In the first step, the first few experimentally collected data points were used to estimate parameters relating to the substrate inhibition term; in the second step, the complete data set was used to estimate parameters relating to the product toxification term. The developed growth model could fit the original data with an R2 value >0.95. Three operating diagrams were constructed by using the results generated from the developed model. Each respective diagram could be used to select the best operating condition for the shortest fermentation time, the highest final ethanol concentration, or the highest fermentation efficiency.

► We report the development of the first available growth kinetic model specific to redox potential-controlled very-high-gravity (VHG) ethanol fermentation process.
► We propose and implement a two-step parameter-estimating strategy to estimate kinetic parameters pertinent to yeast growth, ethanol production, and glucose consumption.
► We validate that the parameters obtained by using the proposed strategy could result in a high accuracy of data prediction (R2 > 0.95).
► We construct operating diagrams to select the best fermentation conditions towards high fermentation efficiency, short fermentation time, and low residual glucose after fermentation.