Malt derived proteins: Effect of protein Z on beer foam stability

The role of proteins, especially protein Z, on beer foam stability was studied. The results showed that both positive and negative proteins were enriched in beer foam. Contrary to previous results, proteins with lower surface hydrophobicity were preferred for beer foam stability. Among all proteins, protein Z was the most prevalent protein in beer foam and could be accurately measured using an enzyme linked immunosorbent assay. The quantity of protein Z was found to be positively correlated with beer foam stability. The addition of purified protein Z from barley (Hordeum vulgare) malt into the finished beer could enhance the beer foam stability. Therefore, proteins with lower surface hydrophobicity might be beneficial for beer foam stability, especially protein Z.