Fish gelatin combined with chitosan coating inhibits myofibril degradation of golden pomfret (Trachinotus blochii) fillet during cold storage

• Chitosan and fish gelatin were combined for coating refrigerated fish fillet.
• Mechanism for molecular changes of protein molecules was investigated.
• Chitosan with 7.2% gelatin preserved myofibril in length.
• The coating inhibited the degradation of myosin light chain and myoglobin.

Coating of gelatin and chitosan can improve fish fillet’s quality, but the mechanism is not clear. Chitosan/gelatin coatings significantly prevented deterioration of golden pomfret fillet at 4 °C. Chitosan with 7.2% gelatin group showed the best effect on preserving the length of myofibril, which remained greater than 15 μm at day 17 of storage, while for control, chitosan and chitosan combined with 3.6% gelatin group, it was 5.03, 10.04 and 9.02 μm, respectively. The MALDI-TOF MS result revealed that the coatings slowed down the protein deterioration of fillet. On days 13 and 17, the myosin light chain and myoglobin in control group degraded, while the two proteins still existed in chitosan/gelatin coated groups. Overall, the chitosan with 7.2% gelatin coating had the best effect on preserving fillet’s quality during storage. The coating may exert its protective effect via inhibiting myofibril degradation within fillet.