The gas environment of germinating barley in various microbial states during malting

Abstract Steeped barley was germinated in laboratory scale solid-state fermentors at various oxygen partial pressures. Experiments were performed with sterile living barley and with barley colonized by the natural microflora. On line monitoring of CO 2 concentration in the off-gas of the reactors reflected the metabolic activity more accurately than heat production measurement. When colonized by micro-organisms, the respiratory activity of germinating barley increased with the oxygen level in the air. However, CO 2 profiles of sterile barley did not alter at different oxygen concentrations in the inlet air of the reactor. It is concluded that the germination phase of malting can be optimized by controlling the oxygen supply to the barley based on CO 2 production measurements and taking into account microbial aspects.