Cold plasma precipitation of sarcoplasmic proteins from surimi wastewater: Differential structural modifications of...

Cold plasma (CP) can induce partial precipitation of sarcoplasmic protein (SP) in surimi wastewater, resulting in a biphasic distribution of SP. Comparative investigation of changes in total SP and unsedimented SP during CP treatment aids in elucidating the response mechanism of SP to CP. CP etching disrupted the higher-order structure of SP, leading to enhanced intrinsic fluorescence and concurrently inducing an increase in the relative content of β-sheets. The resulted soluble aggregates undergo further cross-linking under oxidative promotion to form initial precipitates, with significantly enhanced hydrogen bond and disulfide bond contents. When the CP acidified solution approaches the protein's isoelectric point, both conformational transition and covalent bond formation undergo secondary intensification. The results from gel electrophoresis and molecular docking indicated that the degree to which different protein molecules in the SP respond to reactive substances is the key factor triggering the selective precipitation of SP by CP.