Direct Determination of Wine Proteins

Abstract

The inadequacies of current methods of measuring proteins in white wines are briefly discussed, and measurement by gel column analysis, with ultraviolet detection at 280 nm, is proposed as being well suited to their determination. A rapid automated procedure for direct analysis of residual wine proteins is described. The concentrations found varied greatly, to a maximum of 840 mg per liter protein. Molecular weights of protein constituents were considered to be in the range 10,000-50,000. About half of total wine protein is apparently bound to a minor quantity of grape phenolics, and this portion is thought to be responsible for protein haze. Bentonite fining is not selective between the two fractions.