Myoglobin‐induced gel degradation in surimi: mechanistic insights into the structural disruption and oxidative aggregation of myofibrillar proteins via myosin binding

BACKGROUND The utilization of unwashed surimi presents a promising strategy for reducing water consumption and wastewater discharge during processing. However, the elevated levels of impurities, including water‐soluble proteins, proteases and lipids, in unwashed surimi contribute to gel deterioration during formation, resulting in inferior sensory quality compared to washed surimi products. Myoglobin, as a key water‐soluble protein component, plays a significant yet poorly understood role in this gelation impairment. Consequently, elucidating the mechanism by which myoglobin induces protein oxidation within the surimi matrix, along with determining its specific binding characteristics and molecular interaction sites with myosin, is imperative for addressing the quality limitations of unwashed surimi‐based products. RESULTS After three rinses, the Mb concentration was reduced to 16 μmol L −1 , improving gel quality ( P < 0.05)，the textural properties and whiteness of surimi were improved and gel strength was increased to 304.87 g·cm. The surimi formed a homogeneous and ordered gel network structure after rinsing. When different concentrations of Mb were added to MP, solubility decreased, particle size increased and total thiol content declined, reaching a minimum of 3.68 mol g −1 after 24 h of reaction ( P < 0.05). Myosin binds to Mb through hydrogen bonding and hydrophobic interactions, reducing thermal stability and surface hydrophobicity. The primary interaction sites are Lys94, Ala55, Thr91, Arg126 and Lys141 on Mb and Gln456, Ala1329, Glu1767, Glu1771 and Glu882 on myosin. CONCLUSION In conclusion, Mb induces structural changes in MP and promotes the oxidative aggregation of myosin, ultimately leading to gel degradation.