Relationship between levels of diastatic power enzymes and wort sugar production from different barley cultivars during the commercial mashing process of brewing

The fermentable carbohydrate composition of wort has a direct influence on yeast fermentation efficiency and resultant beer quality. In this study, the relationship between diastatic power enzymes (DPE) and their wort sugars products during the course of small-scale, emulated commercial mashing was investigated. Malts derived from 13 barley cultivars were mashed and assayed at five time points during mashing for the levels of DPE and fermentable sugars. Comparisons of the patterns of DPE activity and wort sugar production showed that the activity levels of β-amylase and limit dextrinase (LD) during mashing were variable between the 13 cultivars, in comparison to the level of α-amylase and resultant composition of wort sugars. Moreover, comparison of peak DPE activities indicated that α-amylase correlated positively and significantly with LD, while no obvious correlation was found between β-amylase and either α-amylase or LD, indicating that activity pattern of α-amylase and LD was closely related during mashing. Multiple linear regression models, based on levels of the DPE as various time points during mashing, thermostability of β-amylase and malt Kolbach index, were able to explain 42.9%, 91.9%, 94%, and 73.2% of wort maltotriose, maltose, glucose, and fermentable sugar composition, respectively. A combination of these insights into the dynamics of starch hydrolysis during mashing will assist brewers in malt cultivar selection and the adjustment of mashing conditions so as optimize the sugar content for the efficient production of high quality beer.