Gelation of Whey Protein Concentrate in Acidic Conditions: Effect of pH

A whey protein concentrate was obtained in acidic conditions, and heat-induced gels were prepared from it at pHs between 3.5 and 4.25. Whey protein concentrate and gels were characterized through solubility assays in different extraction solutions and SDS−PAGE of the soluble protein components. Transmittance at 660 nm of heated protein dispersions and water-holding capacity of gels were also performed. Results show that protein solubility and water-holding capacity of gels decrease when pH approaches the p I, and gels present different electrophoretic patterns. Solubility of the protein components of gels in the presence or absence of denaturing and reducing agents indicates that noncovalent bonds are responsible for the maintenance of gel structure at pHs 3.5−4.0, but in the gel prepared at pH 4.25, disulfide bonds would also be involved in the structure of the gel.