Tomás G. Villa and colleagues explain that proteins from the barley and yeast used to make beer contribute to the quality of its foam (read more about beer foam and foam-stabilizing materials and terms like proteolysis here). The foamy head consists of bubbles containing carbon dioxide gas, which yeast produces during fermentation.
Proteins gather around the gas, forming the bubbles in the foam. Studies have shown that polypeptides, chains of amino acids, in beer - proteins - from the yeast stabilize the foam, preventing the head from disappearing too soon.
But until now, no one knew which yeast gene was responsible for making the foam-stabilizing protein.
The researchers identified the gene, which they call CFG1. The gene is similar to those already identified in wine and sake yeasts that also are involved in foaming. "Taken together all the results shown in the present paper make … CFG1 gene a good candidate to improve the foam character in the brewing industry," they say.
Published in Journal of Agricultural and Food Chemistry