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, β-glucanases). The biologically acidified mash was compared to a chemically acidified mash, 100% malt mash un-acidified 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.