Application of Biological Acidification to Improve the Quality and Processability of Wort Produced from 50% Raw Barley

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, ␤-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, ␤-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 ␤-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.

The Influence of Lactic Acid Bacteria on the Quality of Malt

“…All worts derived from acid treated malts showed similar viscosity levels, however ␤-glucan levels of the corresponding worts ranged from 93 ± 14 to 163 ± 27 mPas. Similarly no correlation between ␤-glucan levels and wort viscosities were obtained by Vis and Lorenz 48 and Lowe et al 29 . Viscosity and lautering performance.…”

“…The proteolytic activity of L. amylovorus FST 1.1, Lactobacillus plantarum TMW 1.460 and Lactobacillus amylolyticus TMW 1.268 was determined on skim milk agar plates as described by Lowe et al 29 . Clearing zones (halos) around the wells indicated proteolytic activity where a zone of 0.1-0.6 cm around the well indicated fair proteolytic activity, 0.6-1.5 cm around the well indicated good proteolytic activity and >1.5 cm around the well indicated very good proteolytic activity.…”

“…The production of ␣-amylase activity was tested on starch plates as described by Lowe et al 29 . The presence of a clear halo around a tested colony was taken as an indication of starch degradation and therefore the production of ␣-amylase activity, where a zone of 0.1-0.6 cm around the colony indicated fair amylase activity, 0.6-1.5 cm around the colony indicated good amylase activity and >1.5 cm around the colony indicated very good amylase activity.…”

Brewing with fractionated barley

“…Finally, more water uptake by the spent grains leads to higher extract loss (D.L. Lowe et al, 2004). A solution for the disadvantages described above could be the (partly) removal of those undesired components before the wet processing takes place.…”

“…In recent years, the partial replacement of the malted barley by unmalted barley was investigated (Doode, Wijngaard, & Arendt, 2005;Lowe, Ulmer, Van Sinderen, & Arendt, 2004;Steiner et al, 2012). The use of barley instead of malt in the brewing process has potential advantages, such as energy and water savings in the malting stage and a reduced raw material use due to the fact that no starch is used for germination.…”