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Characterisation of barley‐associated bacteria and their impact on wort separation performance
Author(s) -
Laitila Arja,
Manninen Jenny,
Priha Outi,
Smart Katherine,
Tsitko Irina,
James Sue
Publication year - 2018
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/jib.509
Subject(s) - brewing , bacteria , steeping , food science , population , chemistry , starch , biofilm , biology , fermentation , genetics , demography , sociology
Wort separation is one of the rate‐limiting steps in the brewhouse. It is a complex process, influenced by barley components such as proteins, β ‐glucans, residual starch and lipids. Filtration performance may also be influenced by microbial biofilms forming on the outer layers of the grains. This study aimed to identify the main barley‐associated bacteria influencing wort separation efficiency. Next‐generation sequencing was applied to characterise indigenous bacterial communities associated with Overture barley from different geographical locations as well as the bacterial population dynamics during laboratory‐scale malting. In order to study the weakened filtration performance potentially caused by induced bacterial biofilm formation, a small portion of barley (5–12%) was subjected to mild husk damage prior to steeping. The bacterial communities were dominated by Gammaproteobacteria, accounting for >70% of the total bacterial population. Bacterial growth induction significantly decreased wort filtration performance. A content of ~12% of injured grains decreased the rate of wort separation by up to 25%, with over 10% lower extract yields. This study showed that bacteria associated with barley are one of the key factors influencing wort separation. © 2018 The Institute of Brewing & Distilling