Elucidation of the Role of Nitrogenous Wort Components in Yeast Fermentation
C. Lekkas1, G.G. Stewart1,3, A.E. Hill1, B. Taidi2 and J. Hodgson2
1 International Centre for Brewing & Distilling, Heriot-Watt University, Edinburgh, EH14 4AS.
2 Scottish & Newcastle PLC, 2–4 Broadway Park, South Gyle, Edinburgh, EH12 9JZ.
3 Corresponding author. E-mail: G.G.Stewart@hw.ac.uk
J. Inst. Brew. 113(1), 3–8, 2007 | VIEW ARTICLE
ABSTRACT
The Free Amino Nitrogen (FAN) content of wort prescribes efficient yeast cell growth and fermentation performance. FAN consists of the individual amino acids, small peptides and ammonia ions formed during malting, the relative amounts of which vary. In this paper, the individual constituents of FAN were dissected and their effect on both ale and lager fermentations determined. The patterns of amino acid and small peptide uptake and the changes in extracellular protease activity revealed the dynamic environment that develops during fermentation. Lysine and methionine, previously identified as key amino acids in wort fermentation, were investigated further.
Key words:
Amino acids, beer flavour and stability, diacetyl, free amino nitrogen, wort oligopeptides, wort supplementation, yeast proteases.
Publication no. G-2007-0308-493 ©2007 The Institute & Guild of Brewing