For beer drinkers, a frothy head is one of the key features of an ideal brew. Now, scientists say they have found a gene in yeast that makes the protein responsible for producing that beloved foam.

"This report represents the first time that a brewing yeast foaming gene has been cloned and its action fully characterized," wrote the Spanish and Australian researchers in the Journal of Agricultural and Food Chemistry.

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The gene, called CFG1, directs the manufacture of a protein in the cell walls of the common beer-making yeast Saccharomyces cerevisiae. The proteins, which are released during fermentation, are averse to water so they orient themselves on the insides of gas bubbles. This adds surface tension to the bubbles, helps them resist the draining of liquid and overall, makes the foam stable.

The formation of foam in beer depends not just on proteins but also on all sorts of other factors, including metallic ions and long carbohydrate molecules.

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But with the discovery of the first gene in brewing yeast that is involved in producing and stabilizing beer foam, science has taken another step toward creating a precise molecular recipe for the perfect beer.

"Taken together," the researchers wrote, "all the results shown in the present paper show the CFG1gene to be a good candidate to improve foam character in the brewing industry."

That's good news for beer-lovers everywhere.

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