NITROGENOUS CONSTITUENTS OF BREWING MATERIALS: VIII. FRACTIONATION OF THE NITROGEN COMPOUNDS OF WORTS AND BEERS. FOAM-STABILIZING ACTIVITY OF THE FRACTIONS

Open Access
Publisher Website
Google Scholar
Abstract
Hopped and unhopped infusion worts and the derived beers have been fractionally precipitated by means of metallic salts in presence of ethanol at various pH values using modifications of the methods used by Cohn and later by Schmid for blood serum proteins. The final solution obtained after removing the various precipitates was found to contain only a small proportion of the undialysable nitrogen compounds originally present, and it was submitted to the ion-exchange procedures described earlier in this Series. In this way, the whole of the nitrogen was accounted for. The various protein fractions were mixtures and, in addition, contained polysaccharide. It is perhaps significant that, with the exception of a precipitate produced by chilling alone, no fraction contained an amount of polyphenol comparable with that normally encountered in beer haze. The precipitated fractions contained the bulk of the foam-stabilizing activity of the original materials, this activity being confined to fractions amounting to less than 14% of the total solutes.