Fungal infection of barley and malt is known to be a direct cause of beer gushing. Our studies have indicated that small fungal proteins called hydrophobins act as gushing factors of beer. Small amounts of hydrophobins, at level of ppm, were found to induce gushing. We developed an immunological ELISA for detection of hydrophobins in barley and malt. The results of the hydrophobin-ELISA correlated with the gushing potential of the malts determined by the gushing test. The aim of the present work was to study hydrophobin levels at different stages of the barley-malt-beer chain. The amount of hydrophobins increased during malting, especially during the steeping and germination steps. The studies on the fate of hydrophobins during the brewing process showed that mashing released hydrophobins from the malt into the wort and despite some losses into spent grains, cold break and surplus yeast as well as during fermentation and filtration, a significant amount of hydrophobins was detected in final beer.
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