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Summary Flavour binding or release behaviour from the meat matrix is very important for its sensory properties. The interaction between flavour substance (nonanal) and myofibrillar proteins (MPs) was investigated using protein fluorescence quenching at different temperatures. The results suggested that nonanal caused the fluorescence quenching mechanism of MPs combining dynamic and static quenching mode, and dynamic quenching played a dominant role. Nonanal mainly combined with tryptophan residues rather than tyrosine residues. The results of synchronous fluorescence spectra and circular dichroism (CD) revealed that the interaction between nonanal and MPs induced no significant conformational changes in MPs. The binding constant (K) and number of binding sites (n) (1.45–2.03) increased with temperature. The negative value of ∆G (−383.16 kJ mol−1 to −397.30 kJ mol−1) showed that the interaction of nonanal and MPs was spontaneous. The positive ∆H (180.18 kJ mol−1, 181.48 kJ mol−1) and ∆S (696.17 J mol−1 K−1, 688.32 J mol−1 K−1) indicated that the binding of nonanal to MPs driven by hydrophobic force.

Protein oxidation can alter the structure of myofibrillar proteins (MPs), which further affect the MPs gelling properties. Ionic strength can influence MPs oxidation. The objective of the study was to evaluate changes in structure and gel properties of MPs induced by hydroxyl radicals (•OH) under certain ionic strength and pH. MPs were very susceptible to •OH attack under 0.5 M NaCl (pH 6.25) due to their swelling structure, resulting in higher protein oxidation level. Oxidative alternation of MPs structure had a significant influence on gel properties and microstructure. The maximum of storage modulus (Gʼ) during the cooling stage was observed at 1.0 mM H 2 O 2. Results of SEM confirmed that the gel had a more compact and dense structure at 1.0 mM H 2 O 2. The results demonstrated that mild oxidative modification (H 2 O 2 ≤ 1.0 mM) induced MPs aggregation, which was benefit to the formation of gel elastic network. However, further oxidative modification (2.5 mM ≤ H 2 O 2 ≤ 10.0 mM) led to an excessively cross-linking of MPs, which made a negative effect on gel properties.

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