A MODEL FOR THE PREDICTION OF FERMENTABLE SUGAR CONCENTRATIONS DURINGMASHING

A model describing the hydrolysis of starch catalysed by alpha- and be ta-amylase in mashing was developed. The model was included in a simul ation program that helps the planning of the mashing temperature profi le. Measurements from laboratory scale mashings with different tempera ture profiles were used for estimating the model parameters for a Finn ish malt made from the two-row barley variety Kymppi. An estimate for the proportion of gelatinized starch at different temperatures was als o obtained. The model predictions for glucose, maltose and maltotriose concentrations were compared with independent measurements not used i n the parameter estimation. The prediction errors for the final total concentration of fermentable sugars in wort (glucose, maltose and malt otriose) were +0.6 to -5.6% (3 mashings) when Kymppi malt was mashed. For the other two malts tested on the laboratory scale the prediction errors were -1.1 to -9.9% (4 mashings) and in the industrial scale mas hings +4.6 to -2.6% (7 mashings). The model predicted the concentratio ns of active alpha- and beta-amylase to a sufficient accuracy in all e xperiments. Estimating the model parameters for the mashing conditions and the malt used would make the model predictions for fermentable su gar concentrations more accurate.