Process Biochemistry, Vol.34, No.8, 785-794, 1999
Beer volatile by-product formation at different fermentation temperature using immobilised yeasts
Beers produced by bottom-fermented yeast Saccharomyces cerevisiae entrapped in calcium pectate and kappa-carrageenan contained lower amounts of diacetyl and higher alcohols at all temperatures studied (from 5 to 20 degrees C). Eater formation was lower at temperatures from 5 to 15 degrees C and acetaldehyde formation at temperatures from 5 to 12 degrees C. The contents of total nitrogen and free amino nitrogen were higher at all temperatures studied due to lower amino acid uptake by entrapped cells. The character of beers produced by yeast adsorbed on DEAE-cellulose at different temperatures was similar to beers produced by free yeast. The concentration of diacetyl in beers fermented by entrapped yeasts decreased as the temperature was increased. In contrast, the diacetyl concentration increased with increasing temperature using free yeast and yeast immobilised on DEAL-cellulose. The concentration of acetaldehyde, higher alcohols and esters increased as the temperature was increased in all beers.