Effective strategies to maximise dextrin formation in brewing

Abstract

Why was the work done: Dextrin is the non-fermentable product of starch hydrolysis and plays a role in enhancing the perceived palate fullness of beer. Therefore, increasing dextrin formation is a promising strategy to improve palate fullness, particularly in non-alcoholic and low-alcohol beers. How was the work done: This study investigated the impact of adjusting the mashing profile of a 100% barley malt mash on the dextrin content and molecular weight distribution in the wort. Mash thickness, heating rate, and mashing-in temperature with and without the addition of a thermostable α-amylase were adjusted during mashing to evaluate the impact on dextrin content and molecular weight distribution. To benchmark this work, the dextrin content and molecular weight distribution was determined in five pilsener beers and their non-alcoholic counterparts. What are the main findings: With the exception of one non-alcoholic beer which contained 72 g/L, the concentration of dextrin ranged from 15 to 30 g/L in the five commercial pilsner-type beers and their non-alcoholic equivalents. The molecular weight distribution of dextrin among the beers was similar, with 85-98% of the dextrin population characterised by a degree of polymerisation below 35. Various strategies were applied during mashing to evaluate the impact on the content and the molecular weight distribution of dextrin. A strategy that promoted dextrin formation was mashing with a lower water-to-grist ratio. This resulted in delayed starch gelatinisation influenced by increased solid extract content in wort. Furthermore, at a low water-to-grist ratio, faster mash heating (up to 2°C/min) or isothermal mashing at temperatures below 72°C had no impact on dextrin formation. Isothermal mashing at 78°C supplemented with thermostable α-amylase increased the dextrin level in wort up to 60 g/L, while the molecular weight distribution of dextrin was similar to that found in commercial beers. Why is the work important: This study demonstrates that increased dextrin formation is achievable in beer but requires significant changes to the mashing process. These insights will enable brewers to enhance the palate fullness of beers, especially those which are non-alcoholic or low in alcohol.