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 diacet yl 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 acet aldehyde formation at temperatures from 5 to 12 degrees C. The contents of total nitrogen and free amino nitrogen were higher at all temperatures stud ied due to lower amino acid uptake by entrapped cells. The character of bee rs produced by yeast adsorbed on DEAE-cellulose at different temperatures w as similar to beers produced by free yeast. The concentration of diacetyl i n beers fermented by entrapped yeasts decreased as the temperature was incr eased. In contrast, the diacetyl concentration increased with increasing te mperature using free yeast and yeast immobilised on DEAL-cellulose. The con centration of acetaldehyde, higher alcohols and esters increased as the tem perature was increased in all beers. (C) 1999 Elsevier Science Ltd. All rig hts reserved.