Pressurized and heat-treated surimi gels as affected by potato starch and egg white: microstructure and water-holding capacity

The influence of potato starch and egg white on water-holding capacity (WHC) and microstructure of surimi gels induced by high pressure (400 and 650 MPa, 10 min) was compared to heat-induced (90°C, 40 min) gels. Gels were made from Alaska pollock and Pacific whiting surimi with salt (2 g/100 g) alone; salt plus 4 g/100 g potato starch; salt plus 1 g/100 g egg white; or salt plus both 4 g/100 g potato starch and 1 g/100 g egg white, treated by high pressure or heat, and then examined by scanning electron microscopy (SEM). Final moisture content was adjusted to 78 g/100 g and WHC was determined using a centrifuge method. SEM demonstrated that the surimi-egg white has a fibrous and homogeneous network structure, whereas surimi-starch exhibited a compact network. When potato starch was added alone or in combination with egg white, the integrity of some starch granules was maintained after pressure treatment, suggesting that high pressures at the 400 and 650 MPa levels do not affect the structure of potato starch. Additive treatment increased WHC of Pacific whiting surimi gels at 400 and 650 MPa with egg white, holding more water than heated gels.