Submitted to: American Society of Brewing Chemists Newsletter
Publication Type: Abstract Only
Publication Acceptance Date: 6/24/2001
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: The soluble proteins released during the malting of barley affect many aspects of brewing and beer quality. Their effects on quality are variable, both positive and negative. A goal of this research is to better understand how soluble protein is developed and determine how to control the hydrolysis of protein using parameters that are under the maltster's control. Specific objectives were to determine the effects of variety (Stander and Robust), growth year (1996 and 1997), steep moisture content (42%, 45% and 48%), green malt germination temperature 15C and 18C) and germination time (0,2,3 and 5 days) on soluble nitrogen, soluble/ total protein ratio (S/T), wort color, free amino nitrogen (FAN), and protease activity. All samples were pilot-malted, and all analyses except protease activity were performed on cold boiled wort. The protease activity assay was performed directly on ground malt. The experimental design was a randomized completed block design with 3 replications. Results were analyzed using procedures of the Statistical Analysis System. Germination time had the greatest impact on all analyses. Soluble nitrogen, S/T, FAN, color and protease activity values all increased with germination time. Increases in soluble nitrogen, S/T, and FAN were observed with increasing steep moisture. Soluble nitrogen, S/T, protease activity and color values all increased with increasing germination temperature. Variety did not have an effect on any of the analyses performed. The hydrolysis of protein during germination can be controlled with malting parameters. Adjusting malting parameters can independently control soluble nitrogen and S/T, FAN, color, and protease activity allowing for malt to be produced with differing soluble protein profiles.