IDENTIFICATION AND CHARACTERIZATION OF BEER POLYPEPTIDES DERIVED FROMBARLEY HORDEINS

Two groups of hordein-reactive antibodies (cross-reactive in barley wi th B/C monomers or subunits from the B/D-hordein aggregates) were used for the analysis of malt, wort and beer. A number of additional lower molecular weight hordein-derived polypeptides were present in water e xtracts of malts and worts. and protease inhibitors or higher mash-in temperature had a stabilising effect on certain hordein-derived polype ptides. The solubilisation profiles of hordein polypeptides monitored by specific immunological methods were clearly different from total wo rt polypeptides monitored by the Bradford method. There were also diff erences between the profiles for the two groups of hordein-derived pol ypeptides with the solubilisation of polypeptides recognised by antibo dy with specificity for the subunits from the B/D aggregates being esp ecially temperature dependent. Beer samples mainly contained hordein-d erived polypeptides of lower molecular weight than barley hordeins wit h polypeptides in the B and C molecular weight regions being lost duri ng the brewing process. Beer polypeptides (Mr > 50,000) were recognise d by antibodies cross-reactive with the subunits from the B/D aggregat es in barley. A number of lower molecular weight polypeptides (Mr < 30 ,000) were recognised by antibodies with specificity for B and C horde ins; a subset of the latter antibody group bound to a specific Mr 23,0 00 beer polypeptide.