Use of Aspergillus oryzae during sorghum malting to enhance yield and quality of gluten free lager beers

Abstract

Sorghum has been used for brewing European beers but its malt generally lower beer yields and alcohol contents. The aim of this research was to produce lager beers using worts from sorghum malted with and without Aspergillus oryzae inoculation. Worts adjusted to 15°Plato from the sorghum malt inoculated with 1% A. oryzae yielded 21.5% and 5% more volume compared to sorghum malt and barley malt worts, respectively. The main fermentable carbohydrate in all worts was maltose. Glucose was present in higher amounts in both sorghum worts compared to barley malt worts. Sorghum-A. oryzae beer had similar specific gravity and alcohol compared to the barley malt beer. Sorghum-A. oryzae beer contained lower amounts of hydrogen sulphide, methanethiol, butanedione, and pentadione compared to barley malt beer. Sorghum-A. oryzae lager beer had similar yield and alcohol content compared to the barley malt beer but differed in color, key volatiles and aromatic compounds.