Characterization of Soy Protein Concentrate Produced by Membrane Ultrafiltration

ABSTRACT The functionality of membrane processed soy concentrate was very similar to soy flour in terms of solubility and water hydration capacity. The high emulsifying activity index of soy flour is believed to be reflective of its higher solubility, while surface hydrophobicity is believed to be responsible for an equally high emulsifying activity index in acid precipitated soy isolate. The proteins of soy flour and membrane soy concentrate seem to have most of their hydrophobic residues buried in the interior, while they are exposed in acid precipitated soy isolate. Heating resulted in a decrease in solubility but improved the hydration capacity and emulsifying activity of both soy flour and membrane soy concentrate. The essential amino acid profile of concentrate was comparable to current commercial isolates manufactured by acid precipitation. The majority of the polypeptides present in soy flour were observed to be present in the concentrate. The membrane soy concentrate was determined to have the least soybean aroma when compared to both soy flour and acid precipitated soy isolate.