Absorption of Amino Acids From Wort by Yeasts

Abstract

The absorption of α‐amino acids from wort by various strains of yeasts followed a sequence which was almost independent of the conditions employed. The rate of absorption of arginine varied with the strain of yeast employed. The absorption of tryptophan and glutamic acid was affected by aeration. Proline, unabsorbed under “anaerobic” conditions was taken up during the latter part of the fermentation under aerobic conditions, and absorption was accompanied by the excretion of ninhydrin‐positive material as yet unidentified. The use of worts containing an amino acid concentration in excess of a certain maximum resulted in the production of beers containing appreciable concentrations of the less readily assimilable α‐amino acids.

Elucidation of the Role of Nitrogenous Wort Components in Yeast Fermentation

“…Addition of L-lysine enhanced yeast metabolic activity and shortened the fermentation time from 96 h to 48 h. Such an effect can be characterised as stimulatory, since a substantial increase in suspended yeast cell numbers also occurred. The majority of the amino acids were taken up during the first 43 h of fermentation, and the same effect was also observed for ammonia, which was taken up by 19 h. This confirms the classification of ammonia in group C by Jones and Pierce 11 , although the reasons for incomplete removal are not apparent. Elevated VDK levels were observed in lysine-supplemented fermentations.…”

Teff (Eragrostis tef) as a raw material for malting, brewing and manufacturing of gluten-free foods and beverages: a review

“…It is known that proline residues are responsible for the affinity towards proanthocyanidins and take part in the production of aromatic compounds and, in this way, influence beer quality. The difference in amino acid contents will affect beer flavors (Gorinstein et al 1999;Jones and Pierce 1964;Outtrup 1989;Perpète et al 2005). Amino acid contents also play a crucial role in yeast nutrition.…”

A Review of Flavour Formation in Continuous Beer Fermentations*

“…Events such as dissolved oxygen and substrate depletion trigger the selective and sequential assimilation of individual compounds, e.g. fermentable sugars and wort amino acids 42 , as well as the formation of metabolic by-products in a coordinated fashion. Thus the beer flavour results from a mixture of aerobic and anaerobic metabolic products produced during growth phases of different intensity.…”