Abstract
To determine the effect of pressure-shift-freezing, boiled egg was pressurized at 200 MPa and -18℃. The structure, texture and the amount of drip of this egg were compared to those of eggs frozen at atmospheric pressure in a pressure vessel at -18℃ and frozen in freezers (-18, -30 or -80℃). Freezing time was shortest to longest with amount of drip least to greatest when the sample was pressure-shift-frozen at 200 MPa and -18℃ < frozen in a -80℃ freezer < placed in a pressure vessel at 0.1 MPa and -18℃ < -30℃ freezer < -18℃ freezer, respectively. Ice crystals were smaller in the pressure-shift-frozen albumen than in the other treated albumen. As freezing temperature increased, the space that surrounded the yolk spheres became large due to formation of ice crystals. However, the rupture stress and strain of pressure-shift-frozen gel did not change greatly. Thus, pressure-shift-freezing was effective in improving the quality of frozen boiled egg.
