Improvement of the ethanol productivity in a high gravity brewing at pilot plant scale.

A 23 full factorial design was used to study the influence of different experimental variables, namely wort gravity, fermentation temperature and nutrient supplementation, on ethanol productivity from high gravity wort fermentation by Saccharomyces cerevisiae (lager strain), under pilot plant conditions. The highest ethanol productivity (0.69 g l(-1) h(-1)) was obtained at 20 degrees P [degrees P is the weight of extract (sugar) equivalent to the weight of sucrose in a 100 g solution at 20 degrees C], 15 degrees C, with the addition of 0.8% (w/v) yeast extract, 24 mg l(-1) ergosterol and 0.24% (v/v) Tween 80.