Study on Protein Recovery Process of Silver Carp Surimi Rinsing Water

Rinsing water from the production of sliver carp surimi was applied as the research object. The effect of different settling time, temperature, acid species, pH, flocculant species and their addition on the supernatant permeability, protein recovery yield and protein polyacrylamide gel electrophoresis (SDS-PAGE) of recovered proteins from surimi rinsing water were investigated. The results showed that, when adjusted the pH to 5.5 with hydrochloric acid prior to settlement, settlement at 4℃ for 60 min was benefit for protein recovery from rinsing water. The protein recovery yield and light transmittance of the supernatant of rinsing water were increased to by 65.8% and 50.1%, respectively, when adjusted the pH to 5.5 with hydrochloric acid prior to settlement, and the values were higher than those of acetic acid and citric acid. Furthermore, protein recovery yield and light transmittance of the supernatant of rinsing water were increased to 85.8% and 87.8%, respectively, with the presence of 0.6 mg/mL chitosan. The SDS-PAGE results showed that the molecular weight of the recovered protein from surimi rinsing water was mainly distributed at 35, 42, 48, 63, 100, and 190 kDa. After a series of treatments, the protein content gradually increased (except for the band at 190 kDa), and multiple new protein bands were generated around 25.0~28.0 kDa. Accordingly, the appropriate conditions for protein recovery from the surimi rinse water were that the pH was adjusted to 5.5 with hydrochloric acid, 0.6 mg/mL chitosan was added, following by settlement at 4℃ for 60 min. This research could provide theoretical basis and practical guidance for protein recovery and waste water purification from surimi rinsing water industrially.