Effect of Protease Treatment during Mashing on Protein-Derived Thiol Content and Flavor Stability of Beer during Storage

The ability of a protease added during mashing in a pilot-scale brew to release protein-derived thiols as antioxidants and thereby improve flavor stability during storage was investigated. The protease treatment resulted in increased protein-derived thiol concentrations in fresh beer produced at a pilot scale compared with a control beer without protease treatment, and electron spin resonance lag phase analysis also demonstrated improved oxidative stability of the protease-treated beer. However, the protease treatment also resulted in high sulfite levels and, therefore, it was not possible to conclude that the improvement in oxidative stability was solely a direct effect of increased levels of protein-derived thiol concentrations. The development of papery character and volatile linear aldehydes was inhibited when the protease-treated beer was stored at 35°C but the protease treatment also resulted in increased concentrations of free amino acids in beer, resulting in a more fruity aged or vinous character...