Impact of Unmalted White Nigerian and Red Italian Sorghum (Sorghum Bicolor) on the Quality of Worts and Beers Applying Optimized Enzyme Levels

Abstract

Brewing with sorghum adjunct is well established in many countries, such as Nigeria. However, no brewing-related publications based on the use of unmalted sorghum grown in Europe are available to date. Therefore, the objectives of this study were to determine and compare the impact of 40% white Nigerian and red Italian sorghum on wort and beer quality adding optimized levels of exogenous enzymes. Brewing with sorghum adjunct was carried out in a 60-L pilot plant applying a double infusion mashing process. Worts and beers were analyzed with regard to processability, flavor and sensory characteristics, foam stability, shelf life, and gluten content (competitive ELISA). The substitution of 40% barley malt with white or red sorghum caused significant increases in wort pH as well as significant decreases in wort viscosity (calculated to 12.0% w/w extract), TSN, FAN, and total amino acids. Worts produced with 40% red sorghum contained higher levels of total polyphenols and total fermentable sugars than those produced with 40% white sorghum. Beers brewed with 40% unmalted sorghum exhibited significantly lower foam stabilities compared with 100% barley malt beers. However, white sorghum had a considerably less adverse impact on beer foam than red sorghum. The sensory analysis performed according to the Deutsche Landwirtschafts-Gesellschaft e.V. (DLG) scheme revealed no significant differences between 40% sorghum and 100% barley malt beers. Furthermore, the gluten content of beers was significantly reduced by replacing 40% barley malt with sorghum adjuncts. According to the Codex Alimentarius, red sorghum beer could even be labeled as a “very low gluten” beverage.

• Beer gluten content
• Beer quality
• Brewing
• Sorghum adjunct
• Sorghum cultivar
• Wort quality