Immunological Study of Hydrophobic Polypeptides in Beer

Abstract

A panel of 15 monoclonal antibodies (mAbs) has been raised to a fraction of lager beer protein precipitated with ammonium sulfate at 40% saturation. The antibodies have been characterized in terms of their binding to a set of Octyl-Sepharose fractions of lager beer foam with increasing hydrophobicity (groups 1-5) by enzyme-linked immunosorbent assay and immunoblotting methods. The epitopes recognized were present in all of the lager beer foam fractions to some degree, and many of the mAbs bound to both high molecular mass (MM) (>3000 Da) and low MM (<3000 Da) material. Two antibodies, IFRN 1612 and 1613, bound primarily to the high MM material and preferentially recognized the more hydrophobic foam groups important in beer foam formation and stability. All of the mAbs recognized proteins present in malt, with much of the binding directed toward the material soluble in aqueous propanol from the highly modified crystal malt used in the lager beer production. Such a library of mAbs will be of use in investigating the contribution made by proteins and derived polypeptides, such as those from malt, to quality attributes such as foaming.