2nd Nov 2018
Why is the head on a pint of stout white when none of the ingredients are white ? I can understand why the head on an Irish Coffee is white because of the cream but not Guinness ? This was a question from one of my learners this week when I was teaching a lesson on ‘Gasses in Beer – Nitrogen and CO2’. It got me thinking for a while. Well its all to do with reflection and absorption of light. What is observed is what happens when light enters foam and is scattered in a particular way.