Influence of sorghum grain type on wort physico-chemical and sensory quality in a whole-grain and commercial enzyme mashing process

Abstract

To determine the most suitable types of sorghum for whole grain adjunct in lager beer brewing, 14 cultivars of five different types: white tan-plant, white not tan-plant, red non-tannin, white tannin (Type II), and red tannin (Type III) were evaluated. The effects of grain type on wort physico-chemical and sensory quality with raw grain and malt plus commercial enzyme mashing were assessed. Tannin content correlated significantly and negatively with wort extract and fermentable sugars (p<0.001) and free amino nitrogen (FAN) (p<0.1). This is attributable to inactivation of the exogenous enzymes by the tannins during the mashing process. However, the Type II tannin sorghums had wort quality attributes closer to the non-tannin sorghum types, probably due to their relatively low tannin content (≤1%). Malting gave a great improvement in wort extract, fermentable sugars and FAN but substantially influenced wort sensory properties in terms of higher sourness, bitterness and astringency as well as the expected more malty flavour. Worts from raw red non-tannin sorghums were similar to those of white tan-plant sorghums in both physico-chemical and sensory quality. Thus, red non-tannin sorghums, in view of their better agronomic quality, have considerable potential as whole grain adjunct in lager brewing.