Comparison of brewing performance using 100% unmalted grains: Barley, wheat, oat, and rye

Beer is traditionally produced from barley malt; however, it is possible to produce beer solely from unmalted grains with the addition of exogenous enzymes, leading to reduced industrial cost and carbon footprint. While there are several studies on production of beer using various levels of unmalted grains as adjuncts, brewing performance using 100% unmalted grains remains mostly unknown. Grains of interest include barley, wheat, oat and rye in the Danish market and, in particular, it is interesting to produce gluten-free beer using oat as a raw ingredient. The aim of this study was to investigate the brewing potential using 100% unmalted barley, wheat, oat and rye in comparison with a control brew using all-barley malt. To address this, a series of brews were carried out at lab-scale applying commercial enzymes (Ondea Pro), and comparisons were made between selected quality attributes of different worts and beers. These included fermentable wort carbohydrates, free amino nitrogen and viscosity of worts, degree of fermentation, concentration of ethanol, higher alcohols and esters, as well as beer color. Consequently, it is anticipated that this study not only provided a greater understanding of processability using various types of 100% unmalted grains, but also revealed specific needs when making production brews with these raw grains, potentially paving the way to process optimization and new products in the future.