Kvasny Prum. 2003; 49(1): 3-10 | DOI: 10.18832/kp2003001

The effect of yeast strain on flavour stability of beer.Peer-reviewed article

G. BASAŘOVÁ, M. BLÁHA, P. VESELÝ

In model fermentations in 10 l glass containers, three strains of bottom brewing yeasts marked as no. 2 – medium deeply to deeply fermenting, no 7 – medium deeply fermenting, and no. 95 –deeply fermenting in the collection of the RIBM Prague,  were tested on 10 % and 12 % hopped wort. Strain no. 2 exhibited the highest formation of SO₂ and the highest maximum enzymatic activity 3-methylbutanal reductase which degrades 3-methylbutanal belonging to so-called components of stale taste at various temperatures (7 °C, 10 °C, 13 °C, and 18 °C). The lowest formation was detected in strain no. 95 and still slightly lower in strain no. 7. The value of maximum of SO₂ formation and 3-methylbutanal reductase activity increased proportionally with an increasing temperature of fermentation. The effect of enhanced pitching yeast on SO₂ formation during fermentation was not proven. It was proven that strain no. 7 had a shorter lag phase on the growing curve, steeper exponential phase, it achieved the growth maximum earlier similarly as the beginning of agglutination and sedimentation. Tests of hydrophobicity confirmed a hydrophile character of the tested strains. All of them had the value of hydrophobicity index HI over 50 %. This index was the lowest in strain no. 95. Lower SO₂ formation in strain no. 7 correlated both with the course of the curve of growth and slightly higher content of reserve polysaccharide glycogen in cells compared to strains no. 2 and no. 95 after completion of fermentation which occurred under the completely congruent conditions. Earlier and more intense agglutination and sedimentation of strain no. 7 corresponded to a lower level of mannan in its cell walls. Strain no. 7 exhibited during fermentation a slower absorption of amino acids and extent of their exploitation. The significant effect of yeast strain on oxidation and reduction capacity of fermented hopped wort or the effect of the yeast strain on secretion of total, oxidized and oxidizable polyphenols and anthocyanogens from solution during fermentation was not found. (In Czech, English summary only).

Keywords: yeast strain, beer, flavour stability

Published: January 1, 2003