Improved prediction of malt fermentability by measurement of the diastatic power enzymes beta-amylase, alpha-amylase, and limit dextrinase: I. Survey of the levels of diastatic power enzymes in commercial malts

Abstract

In this study, more than 1,000 commercial malting samples from Australia and elsewhere, primarily malted in 2005 and 2006, were analyzed for their levels of the diastatic power (DP) enzymes alpha-amylase, beta-amylase, and limit dextrinase. The survey showed that there was more variation within a variety for DP and DP enzymes than between varieties. The data were evaluated, and a micromalting experiment was conducted to ascertain whether the wide range of malt qualities observed was the result of customer specifications, environmental conditions under which the barley was grown, variety, or malting practices. The evaluation of malt used by two breweries over the course of a year suggested that the conventional brewery customer specifications for variety, Kolbach index, and DP are somewhat successful in constraining potential fermentability variation. The conditions under which barley for malting was grown were also plausible factors that could explain the observed differences in DP enzyme levels. However, micromalting barley sourced from different regions showed that malting conditions had a strong influence on the malt levels of alpha-amylase and limit dextrinase. When combined, the observations and conclusions of this study further support our previous recommendations that the routine measurement of individual DP enzymes would most likely improve the consistency and predictability of the potential fermentability of malts supplied to brewers.