Oxidative behaviour, aggregation and structural properties of silver carp myofibrillar proteins with different molecular states subjected to freeze–thaw process

Summary Silver carp myofibrillar proteins (MP) with different moleculars states were constructed by the addition of NaCl and fracture degree of muscle fibres. Results showed that salt‐dissolved MP (P+) under unfrozen and oxidised state showed higher oxidation degree with higher carbonyl (3.42 nmol mg −1 ) and dityrosine contents (25.98 a.u.) ( P < 0.05) compared with saltless‐polymeric MP (P) and salt‐induced swelling MP (F+) due to addition of salt and broken muscle fibres. After oxidative and freeze–thaw process, P+ group also exhibited more cross‐linking as evidenced by turbidity (0.73), solubility (64.96%) and SDS‐PAGE, but unordered aggregates in P group increased probably due to severe frozen denaturation. Moreover, F+ group of salt‐induced swelling MP from intact muscle fibres suffered less structural damages with higher fluorescence intensity (668.41 a.u.) and higher α‐helix contents (15.56%). Overall, Fish‐ Hua of salt‐dissolved MP had a higher oxidation level and NaCl contributed to improve freeze–thaw stability of MP during freeze–thaw process.