Impact of homogenization on the physicochemical properties of the cod protein gel

Cod cut offs, as a by-product of cod processing, is often discarded and wasted. A cod protein gel (CP-gel) was produced from homogenized steamed cod cut offs to turn the otherwise “waste” into treasure. The effects of homogenizing conditions on the physicochemical properties of the CP-gel were investigated by assessing the gel strength, water holding capacity (WHC), rheological properties and microstructure, combined with the visual appearance. After homogenization at 80 MPa with 15 passes, the particle size was reduced to 4 μm and resulted in a gel strength of 0.63 N. The WHC of cod protein gel increased by 41% as compared to the un-homogenized sample. The secondary structures of the microfibrillar proteins changed as evidenced by the increased α-helix content by 3% via homogenization. The reduced particle size allowed particle-particle interactions and promoted protein cross-linking via both hydrophobic interaction and hydrogen bond formation. A relatively smooth and honeycombed network structure was formed with improved gel quality and physical properties. CP-gel provides a potential to utilize cod cut offs to produce value-added products.