Effect of Ohmic heating combined with glycation on the structure and immunoreactivity of tropomyosin from Litopenaeus vannamei

This study investigated the mechanism of tropomyosin (TM) immunoreactivity reduction in Litopenaeus vannamei through ohmic heating (OH) combined with glycation. The screening of five common monosaccharides (glucose, xylose, ribose, galactose, and arabinose) and treatment times (0–120 min) revealed that galactose-treated TM samples subjected to OH (50 V/cm, 100 °C) for 60 min exhibited the lowest immunoreactivity. Following the OH–galactose treatment of purified TM and shrimp meat, the IgG/IgE binding capacity of purified TM decreased to 45.65% and 27.16%, respectively. The shrimp meat treatment group exhibited a further reduction in immunoreactivity to 39.99% and 25.75% due to the binding of endogenous sugars in meat with TM during treatment. Structural analysis revealed that there was a decrease in α-helix content, with a transition to β-sheet and random coil conformations, accompanied by reduced intrinsic fluorescence and increased surface hydrophobicity, indicating changes in the secondary and tertiary structures. Notably, the unique rapid volumetric heating characteristics of OH effectively drove these extensive structural modifications. After treatment, the content of amino acids decreased, accompanied by a reduction in the content of allergenic epitope peptides. Furthermore, the gastrointestinal digestibility of the sample was enhanced post-treatment, thereby facilitating human digestion and mitigating potential allergic risks. Molecular docking results demonstrated that galactose primarily binds to TM via glutamate-mediated interactions, which effectively masks the critical antigenic epitopes.