Characterization of a cold-gelling whey protein concentrate

Cold-gelling whey protein concentrates, produced by heat pre-treatment during manufacture, gelled without heating when dissolved at sufficient protein concentration and under suitable conditions of pH and ionic strength. A cold-gelling whey protein concentrate was dissolved at low concentrations in water or NaCl solutions of varying ionic strength, pH and with the addition of a reducing agent, dithiothreitol (DTT) for studies by rheology, light microscopy and atomic force microscopy. The cold-gelling whey protein powder was found to consist of large, micron-sized, drying-induced, weak aggregates consisting of primary disulfide-bridged aggregates of 20-30 nm in diameter. In dilute solutions under conditions of large repulsive forces (low ionic strength and pH far from the isoelectric point) the large aggregates dissolved slowly over many hours. In less good solvents, larger aggregates remained or were formed. (C) 1998 Elsevier Science Ltd. All rights reserved.