The present work evaluated the ethanol volumetric productivity during fermentation of worts with elevated original extract, for high gravity brewing by continuous process using yeasts immobilized on brewer's spent grain. Worts with different original extract (14.3 ºP, 15.2 ºP and 19.6 ºP) were prepared from a wort of 22 ºP elaborated with malt and high maltose adjunct in an adjunct:malt ratio of 1:2.8. The fermentations were performed in a bubble column reactor, at 15 ºC, using a dilution rate of 0.04 h-1 and a constant gas flow of 250 mL/min (200 mL/min CO2 and 50 mL/min air). According to the results, the ethanol volumetric productivity increased when the original extract concentration of the wort was increased, the maximum value (2.09 g.L-1.h-1) was attained for the wort with 19.6 ºP. This value represents an increase of 345% when compared with the productivity (0.47 g.L-1.h-1) of the discontinuous fermentation of worts with 20 ºP. It was thus concluded that beer production by continuous fermentation of worts with elevated original extract can obtain expressive gains in the ethanol volumetric productivity when compared with the discontinuous process.
beer; continuous process; immobilized yeasts; brewer's spent grain; concentrated worts; productivity
