The secret to optional foam in the head of freshly poured brew has been discovered by researchers.
Cornell's Karl J. Siebert, principal investigator and author of "Recent Discoveries in Beer Foam, said bitter compounds found in hops, like iso-alpha acids, are important to brewers.
He said dissolved gases in the beer - carbon dioxide and, in some instances, nitrogen - play a role.
Fascinating as foam is to chemists, it's of vital importance for the sensory experience of beer appreciation, insists Siebert, formerly a longtime research chemist in the industry, including at the former Stroh Brewery Co. in Detroit.
The study is set to be published in the Journal of the American Society of Brewing Chemists.