Lesson 8 - Beer Properties End of Unit SAQ
This lesson enables you to test yourself on the material covered in the lesson on Beer Properties and to determine the level to which you have met the learning outcomes.
Suggested Response - Q4
** Discuss the role of gases produced and used in brewing on both beer foam and flavour.
Response:
Beer gas is integral to both beer flavour and foam. This applies to CO2 produced during fermentation and supplemented by added N2 or a mix of CO2 and N2.
CO2 is needed to generate and maintain foam through beading to replace decayed bubbles. CO2 bubbles tend to vary in size so are prone to disproportionation; smaller higher-pressure bubbles merge into larger lower-pressure bubbles. This leads to instability and bubble collapse.
N2 bubbles are smaller and more consistent than those of CO2 by virtue of lower solubility. Gas does not pass between bubbles, and therefore, disproportionation does not occur, resulting in a more stable foam.
N2 and CO2 produce different flavours in beer, CO2 produces an acidic tingle mouthfeel while N2 provokes a feeling of creaminess and smoothness. This can be exploited to accentuate the style, for example, a refreshing tingle to a weissbier or a smooth creaminess to a stout.