An original kinetic model for the enzymatic hydrolysis of starch during mashing

This paper presents a kinetic model for the enzymatic degradation of the starch during mashing for beer production. Based on a new set of experiments, an original reaction scheme for the hydrolysis of starch by alpha- and beta-amylases has been proposed. Here, the kinetics of the reactions involved in this scheme are described: starch gelatinisation, amylase activities and carbohydrate production. One originality of this model is the mathematical representation of the amylase activities temperature dependency. The model requires to know the initial composition of malt (starch concentration and amylase potential which are classically measured to qualify the raw material) and the operating conditions (temperature chart) to predict the evolutions of amylase activities, dextrins and fermentable carbohydrate concentrations during mashing. The model parameters have been estimated by fitting nine experiments performed on one malt variety. Five other experiments validate the model for different malt varieties. (C) 2002 Elsevier Science B.V. All rights reserved.