Trace the difference driven by unfolding-refolding pathway of myofibrillar protein: Emphasizing the changes on structural and emulsion properties

[Display omitted] •Obvious pH-shifting response was found after unfolding-refolding process.•TFI and CD confirmed pH-shifting changed MPs secondary and tertiary structure.•AFM images showed pH-shifted MPs distribution was spherical rather than fibrous.•pH-shifting effectively improved the emulsion properties of PSE-like chicken MPs.•Refolding stage is not the reverse process of unfolding. The effective strategy of pH-shifting to improve the emulsifying properties of myofibrillar proteins (MPs) extracted from pale, soft and exudative (PSE)-like chicken was investigated. To determine the mechanism of improvement, changes on structural and physicochemical properties were clarified by tracing the difference driven by unfolding-refolding process. According to the results of tryptophan fluorescence intensity and circular dichroism spectroscopy, it is found that unfolding-refolding process markedly changed MPs secondary and tertiary structure. The atomic force microscopy images showed MPs appeared to have fibrous-like appearance at pH 7.0, however, exhibited as spherical shape after pH-shifting. Both emulsifying activity index and emulsifying stability index increased after pH-shifting. These results systematically illustrated the changes on structural and emulsion properties of MPs during unfolding-refolding process. It proved that the strategy pH 11.0–7.0 could more effectively promote MPs emulsifying properties, whose mechanism was simultaneously the transformation in MPs structure and potentially formation of highly-soluble particle.