Impact of high-pressure shift freezing on physicochemical and functional properties of egg edible parts

Effects of high-pressure shift freezing (HPSF) at 200 MPa/-20 degrees C on physical, functional and thermal properties of egg white and egg yolk from three egg types were studied. The phase transition time in HPSF was shorter compared to atmospheric freezing (about 25% for egg yolk and 56% for egg white) due to the high degree of supercooling. The effect of freezing on functional properties seems to be related to different degrees of protein denaturation depending of the freezing/pressure level. Partial protein unfolding (suggested by higher free sulfhydryl) was observed after freezing at atmospheric pressure, especially for egg yolk. On the other hand, higher protein aggregation due to lower thermal denaturation enthalpy (50% in egg yolk and 70% in egg white) was found in HPSF samples, supported by decrease of protein solubility, disappear of electrophoretic bands and increase in viscoelasticity (G ' and G '' values).