Determination of biomass
To determine yeast growth during the course of batch fermentations, the OD600 was monitored using a Shimadzu UV-1800 Spectrophotometer (Shimadzu Europe GmbH, Duisberg, Germany). When necessary, samples were diluted with deionised water to obtain readings in the 0.1–0.4 range. Samples were always maintained at 4 °C until OD600 and dry cell weight (DCW) measurements were performed. Final (96 h) DCW was determined in triplicate by filtering appropriate volumes of the cultures (4 to 10 mL, depending on the OD600 values previously determined) followed by 5 mL deionized water through a 25 mm, 0.45 μm pore size pre-dried and pre-weighed nitrocellulose filter (Millipore, Billerica, USA). Filters were heat dried at 70 °C until constant weight (12–24 h).