The shelf-life of conventional surimi and recovery of functional proteins from silver carp (Hypophthalmichthys molitrix) muscle by an acid or alkaline solubilization process during frozen storage

The shelf-life of conventional surimi and isolated proteins that modified by acidic pH (2.5) and by using alkali pH (11) from silver carp (Hypophthalmichthys molitrix) was studied during months of storage at -18±2 °C. For conventional surimi, three washing steps were used. In the third stage of washing, 0.2% NaCl was used to withdraw more water. The result showed that isolated protein by alkaline pH has a higher efficiency. In the obtained result of percent yield and the recovery of protein product, isolated proteins showed higher values than conventional surimi. Isolated protein by using acid-aided processes had lower lightness and whiteness score, compared with alkaline-aided process and surimi prepared by a conventional washing method during frozen storage. The concentration of myosin heavy chain and actin were varied with solubilizing pH. Also, the lowest downfall of protein and the best surimi quality were found in produced samples with alkaline-acid aided process.