Structure formation in protein-polysaccharide mixtures upon pressure treatment

In recent years high hydrostatic pressure has been evaluated as a food processing alternative to classical heat treatment. High hydrostatic pressure can cause changes in protein conformation leading to denaturation, aggregation and gelification of proteins. In the presence of polysaccharides, e.g. high methoxy pectin, denaturation of whey proteins leads to phase separation. Microscopy and rheology were used to describe the behaviour of incompatible mixtures of whey proteins and high methoxy apple pectin upon combined high pressure and temperature treatment. Room temperature and a pressure greater than or equal to 400 MPa, or heating the proteins above their denaturation temperature (80 degrees C) at ambient pressure (holding time 10 minutes), resulted in the formation of polydispersed gelified microparticles. If high pressure was combined with higher temperatures (greater than or equal to 40 degrees C) pectin and whey protein separated into two bicontinuous phases.