Dissolution of whey protein concentrate gels in alkali

The dissolution of whey protein concentrate (WPC) gels has been studied in detail, and the different mechanisms involved have been quantitatively analyzed. The NaOH diffusivity in gels has been determined at different pH at 22°C. Dissolution experiments of gels under several conditions have been performed and compared. Both heat-induced gels (HIG) and caustic-induced gels (CIG) have been studied as models to heat-exchanger fouling deposits. It is proposed that the constant dissolution rate observed at low pH is controlled by the reactions that break down the gel structure, particularly the β-elimination of intermolecular disulfide bonds. Alkali dissolution of CIG is reduced with increasing the gelation pH, as more crosslinks are present in the gel. It is proposed that a similar mechanism of crosslink formation may explain the low dissolution rates observed in HIG at dissolution pH above 13.1. NaOH diffusion is observed to limit the dissolution process at high temperatures and pH close to 13.