A Method for the Preparative Separation of Beer Proteins and Glycocompounds

J. Inst. Brew. 117(3), 435-439, 2011 The overall evaluation of foodstuffs and the numerical description of food qualities play an important role in scientific food research. Concentration and characteristics of beer proteins and glycocompounds can strongly influence the quality of the product. The quanti-qualitative studies of these molecules are therefore of crucial importance, but at the same time represent a difficult task as a consequence of all of the interfering substances present in the beverage. Recently, we have described a straightforward two-step method for almost pure protein and glycoprotein fractionated recovery from wine. The method represents an upgrade of the previously described KDS-precipitation (i.e., complexation of proteins with dodecyl sulphate, added as sodium salts, and subsequent insolubilization of the protein-detergent complexes by addition of potassium ions added as KCl). Here we present the application of the protocol to different beer samples. The protocol involves the successive precipitation by acetone of glycocompounds from the KDS supernatant. In this way, a fractionated preparation of proteins and glycocompounds from a few millilitres of beverage could be obtained and these molecules could be quantified. The obtained proteins and glycoproteins are almost free from interfering molecules and are directly utilizable for electrophoretic assays.