A partially folded protein from barley just might hold the secret to a great mug of beer, a new study shows. To connoisseurs, the head of foam on a beer may be as important as its taste. A lipid-transfer protein from barley helps stabilize the liquid-gas interfaces in beer foam, but it cannot do so until after the brewing process, when it undergoes structural changes that haven’t been fully characterized. Now, a team led by Alan R. Mackie of the Institute of Food Research, in Colney, England, suggests that minor changes in structure, likely coming from a failure to refold properly after being boiled in the brewing process, make the protein a good stabilizer (Biochemistry, DOI: 10.1021/bi901328f). Previously, it has been suggested that the barley protein must be almost completely unfolded to be able to do the job, Mackie says. The work “provides yet another piece in the puzzle of how protein stability determines beer foam stability,” says Kresten Lindorff-Larsen of D. E. Shaw Research, who has previously studied the barley protein.