Antigenic Beer Macromolecules an Experimental Survey of Purification Methods

Abstract

The macromolecules of an antigen-rich beer fraction X were characterized by column chromatography. Elution profiles of protein, carbohydrate and immunochemicaliy distinct antigens were recorded after separation on gels of Sephacryl, Sephadex, Sepharose, DEAE-Sephadex, SPSephadex, Bio-gel HT hydroxylapatite. Con A-Sepharose, and two types of antibody-Sepharose. The elution patterns demonstrate that beer antigens, originating from barley or yeast macromolecules, can be separated from carbohydrates, from 'proteose-like' material and from each other in a few preparative chromatographic steps. Affinity chromatography on a column of im mobilized antibodies towards fraction X indicated that the antigenic material constitutes about 25% of the fraction. More than 20% of the protein in fraction X seems to originate from a distinct barley protein Z.

Fractionation of protein components from beer by density gradient centrifugation

“…The precipitate was redissolved in 3% EDTA, dialyzed extensively against distilled water and lyophilyzed. The yield was about 1 g of brownish coloured powder and this protein fraction corresponds to "fraction x" used in previous studies (8,11). It contained 25% (w/w) of protein and 70% (w/w) of carbohydrate.…”

“…Beer proteins are a heterogeneous group of substances varying widely in isoelectric points and molecular weights, and also to some extent in firmly bound carbohydrates and polyphenols (1,3,6,11,13,17). Hence, it is understandable that even the combined use of several protein fractionation methods has failed to produce beer protein fractions which meet the criteria for homogeneity (1,13,17).…”

125th Anniversary Review: The Non-Biological Instability of Beer

“…Minor hop resin components may also be important 139 . Of the hydrophobic polypeptides, the most studied have been Protein Z 66,78 and Lipid Transfer Protein 1 (LTP1) 142 . The importance of hydrophobicity was especially highlighted in the latter instance by the observation that LTP1 is not especially foam active when isolated from grain, but that its foaming abilities are greatly boosted by boiling, with the attendant denaturation and exposure of the hydrophobic interior 22 .…”

Turbidity and Haze Formation in Beer - Insights and Overview

“…The content of only 2 mg/L protein is enough to form haze 19 . Only about 20% of the total grain proteins are water-soluble.…”