Evaluation experiments on brewer's yeast grown on molasses
1993
Hajdu, G. (Szeszipari Kut. Int. (Hungary))
During the fermentation process the enzymes of the brewer's yeast produce many byproducts that influence the taste, scent, and other characteristics of the beer. The most significant byproducts are: (1) diacetyl; it gives unpleasant pasteurized, sarcine taste to the beer. Diacetyl content reaches its maximum on the fifth day of the fermentation then it is gradually reduced to butanediol. (2) higher alcohols; they cause bitter taste and "rose" or "honey" scent. They are produced during the main fermentation and they don't decompose. (3) Esters; They are created mainly in the first part of the fermentation. Their amount is linked to the cell growth of the yeast. They don't decompose. (4) Aldehydes: They are responsible for the so called "green" taste. Their appearance is characteristic to the first part of the fermentation but they start to decompose from the fourth day. (5) Sulfur compounds; they have negative effect on the taste of the beer even in very small amount. A comparative experiment was carried out to determine how the same yeast strain (Ottakringer) grown on beer wort and molasses influence the quality of the beer. The sugar and the extract content, the cell number, the pH, and the amount of alpha-amino nitrogen and vicinal diketones were checked daily for nine days. The results have shown that the yeast previously grown on molasses needed two days adaptation period but the characteristics of the two raw beers were not significantly different
显示更多 [+] 显示较少 [-]