Regarding the assimilable nitrogen utilised during ethanol production under various aeration supply (Table 3), it was found that under the aeration condition, the nitrogen utilised in the EP medium supplemented with DSY and the metals was increased ∼37–52 mg l−1 , compared to that without aeration. More nitrogen utilised might be related to an increase in the final ethanol concentrations (Tables 2 and 3). Similar results were reported by Jones and Ingledew (1994), who found that supplementation of yeast autolysate into wheat mash under VHG fermentation significantly improved the rate of sugar utilisation and ethanol production.