Pilot‐plant fractionation of soybean glycinin and β‐conglycinin

A laboratory process for separating glycinin and β-conglycinin from soybean flakes was successfully scaled up to the pilot-plant scale (15 kg soy flakes). Average yields of the glycinin and β-conglycinin fractions were both 9.4% on a dry basis (db). The protein contents of glycinin and β-conglycinin fractions were 92.8 and 97.7% db, respectively. The glycinin and β-conglycinin purities were 90.4 and 72.7% of the protein content, respectively, which were very comparable to those of the laboratory-scale process. The total sulfhydryl plus half cystine content of the glycinin fraction was 37.8 mol/mol protein and 14.8 mol/mol protein for the β-conglycinin fraction. The native glycinin structure loss in the glycinin fraction was negligible. The native β-conglycinin loss in the β-conglycinin fraction was 10%, as estimated by rocket immunoelectrophoresis analysis. Hydrophobicity index value showed that hydrophobic properties of the pilot-plant protein fraction were ordered, from high to low: β-conglycinin fraction > glycinin fraction > intermediate mixture fraction.