LILLE 2024

Brewers are confronted with the impact of more extreme weather conditions (or climate change) on barley growth, observing increasing starch gelatinisation temperatures for malt. In addition, high levels of small starch granules are found in modern malts while their presence was commonly accepted to be neglectable. This is detrimental to the mashing process because the higher gelatinisation temperatures of small granules result in reduced fermentable sugar production. Balancing starch behaviour and enzyme stability and activity during mashing is thus becoming more critical. Besides, current analytical methods to determine starch gelatinisation behaviour are often static, while the mashing process is dynamic, due to the constantly varying temperature and composition of the mash. The analytical methods, therefore, do not provide sufficient information to understand and optimise starch hydrolysis during the mashing process to maintain a constant wort composition. Here, we combine recent knowledge on the gelatinisation behaviour of small and large starch granules and the thermal stability of the amylolytic enzymes to design a toolbox to maintain a constant, yet tuneable wort.

The production of wort for beer is a challenging process. Next to high yields and high wort concentrations, a fast process with the maximum of capacity and a low water consumption is desired. For high gravity and ultra high-gravity worts, brewers usually use mash filters. Using a mash filter usually means very defined demands on the milling system. For this reason, alternative ways of milling were investigated in this study to improve the brewhouse KPIs.
The results show great increasing in different topics. The brewhouse capacity was increased significantly whilst the losses were only marginal. Typical mash filters having a nominal load of approx. 30 kg/m2 for hammer mill grist, with a new mash filter design and the new milling strategies, loads up to 39,3 kg/m2 were gained. Next to the common KPIs the efficiency coefficient for kg extract per minute was introduced. This key value [kg/min] has shown an increase up to 180% compared to a standard hammer mill process. In general, first wort concentrations of more than 25°P were achieved. The solution was an adaption of a roller milling procedure instead of a hammer milling to save energy and to enhance the flexibility in the brewery.

In recent years, we have researched the importance of starch granule proportions and their gelatinisation behaviour in order to maintain high resource efficiencies during the mashing process. Direct proof of the importance of these parameters is however still lacking. We hence set out to develop a model describing the relation between wort characteristics, starch properties and amylolytic enzyme activities in barley malt. To this end, 21 micro-malted barley samples were mashed on a lab scale. Conversion of starch to fermentable sugars ranged from 74 to 91%. Based on our 2nd degree factorial model (R2 = 0.88), we found that amylose content, α-amylase and limit-dextrinase activity were the main drivers for fermentable sugar yield. The proportions of small starch granules, on the contrary, had a significant negative effect on the production of fermentable sugars. Starch content and β-amylase activity, although standard malt quality traits, did not significantly impact fermentable sugar yield. The results in this work show that current malt quality traits regarding starch and amylolytic enzymes should be re-evaluated, to secure resource efficiency in the brewing industry.