Modeling cereal starch hydrolysis during simultaneous saccharification and lactic acid fermentation; case of a sorghum-based fermented beverage, gowé

•The parameters controlling the activity of α-amylase (including Ki) specified•Km and Vmax for the α-amylolysis of native and gelatinized starches compared•Global model of the simultaneous growth of LaB and of the activity of α-amylase•The use of the model shows the main levers for improving the quality of gowé.

Gowé is an acidic beverage obtained after simultaneous saccharification and fermentation (SSF) of sorghum. A previous paper focused on modeling the growth of lactic acid bacteria during gowé processing. This paper focuses on modeling starch amylolysis to build an aggregated SSF model. The activity of α-amylase was modeled as a function of temperature and pH, and the hydrolysis rates of both native and soluble starch were modeled via a Michaelis-Menten equation taking into account the maltose and glucose inhibition constants. The robustness of the parameter estimators was ensured by step by step identification in sets of experiments conducted with different proportions of native and gelatinized starch by modifying the pre-cooking temperature. The aggregated model was validated on experimental data and showed that both the pre-cooking and fermentation parameters, particularly temperature, are significant levers for controlling not only acid and sugar contents but also the expected viscosity of the final product. This generic approach could be used as a tool to optimize the sanitary and sensory quality of fermentation of other starchy products.

Graphical abstractSimultaneous saccharification and fermentation of malted cereal.Download high-res image (65KB)Download full-size image