Management of barley-associated bacterial biofilms: a key to improving wort separation

Several bacterial groups are associated with poor wort filtration performance. In this study we characterized the shifts within the bacterial community during malting by next-generation sequencing. The aim was to reveal the bacterial groups involved in the decreased mash filterability caused by hus-damaged barley. Field emission scanning electron microscopy was used to visualise biofilm formation in the outer layers of barley. This study also investigated the impacts of bacterial biofilm suppression on extract recovery. The bacterial growth was suppressed with antibacterial treatment and modified by adding Lactobacillus plantarum VTT E-78076 (E76) starter cultures to steeping. In particular, barley-associated Leuconostoc was associated with decreased wort filtration performance. This study showed that development of biofilm containing extracellular polymeric substances (EPS) on the kernel surface layers during malting was a crucial factor influencing wort separation. The application of L. plantarum E76 successfully controlled the bacterial community during malting and improved wort filtration. Thus, improved wort separation and higher extract recovery could be obtained by management of barley-associated biofilms during malting. (C) 2018 The Institute of Brewing & Distilling