Application of Biological Acidification to Improve the Quality and Processability of Wort Produced from 50% Raw Barley
Deirdre P. Lowe 1, 2, Helge M. Ulmer 1, 2, Douwe van Sinderen 2 and Elke K. Arendt 1, 3
1 Department of Food and Nutritional Sciences, National University
of Ireland, University College Cork, Ireland.
2 National Food Biotechnology Centre, National University of Ireland,
University College Cork, Ireland.
3 Corresponding author. E-mail: e.arendt@ucc.ie
J. Inst. Brew. 110(2), 133-140, 2004 | VIEW ARTICLE
ABSTRACT
In this study four strains of lactic acid bacteria (LAB) were
chosen to bioacidify a mash containing 50% barley and 50%
malt. The strains were isolated from malted and unmalted barley
and assayed for extracellular enzymatic activities (proteases,
amylases, β-glucanases). The biologically acidified mash was
compared to a chemically acidified mash, 100% malt mash unacidified
and 50% malt and 50% barley mash unacidified. Characteristics
such as pH, extract, colour, viscosity, total soluble nitrogen
(TSN), free amino nitrogen (FAN), apparent fermentability,
β-glucan and lautering performance of the resultant worts
were determined. A model lautering system replicating one used
in a brewery was designed and built in University College Cork
(UCC) to measure the lautering performance of the bioacidified
mashes. The new system was compared to the filtration method
used in EBC method 4.5.1. Overall the addition of LAB to bioacidify
a mash of 50% barley and 50% malt resulted in faster
filtration times, which correlated with decreased β-glucan levels.
Proteolytic LAB had a positive influence on the quality of wort
and resulted in increased FAN levels. Lighter colour worts were
observed along with increased extract levels.
Key words:
β-Glucan, biological acidification, lactic acid bacteria,
lautering, malted barley, unmalted barley.
Publication no. G-2004-0521-233 ©2004 The Institute & Guild of Brewing