Behavior of mono-, di-, and trihydroxyoctadecenoic acids during mashing and methods of controlling their production

The behavior of mono-, di-, and trihydroxyoctadecenoic acids was investigat ed during laboratory-scale mashing under various conditions with a view to controlling their production. Using a malt in which the lipoxygenase activi ty was at only a trace level (less than 0.01 U/g) or starting the mashing a t a higher temperature than that conventionally used (65 degrees C instead of 48 degrees C) significantly decreased the production of these hydroxy fa tty acids. Lowering the pH of the mash to inhibit lipoxygenase activity and preventing O-2 uptake by the mash using carbon dioxide were also effective in reducing the amounts of these acids produced during mashing. From the v iewpoint of industrial-scale beer production, the prevention of O-2 uptake by the mash was selected as an appropriate method for reducing oxidation du ring wort production without affecting the subsequent brewing process or th e taste of the finished beer. After introducing oxidation prevention proced ures, the content of trihydroxyoctadecenoic acids decreased by about 30% an d the foam stability and taste were improved in commercial products brewed using less than 25% malts.