A clean-label antioxidant strategy: Structure-function relationships in soy protein-catechin complexes and their application in steamed porcine longissimus lumborum meatball

This study investigated the influence of catechin concentrations (0, 2, 4, 6, 8, 10, 12, and 14 g/100 g, based on SPI) on the structural characteristics, emulsifying properties, gelation behavior, and thermal stability of soy protein isolate-catechin (SPI-C) complexes, as well as their effects on the quality of steamed porcine longissimus lumborum meatballs. The incorporation of catechin was found to induce conformational changes in SPI and promoted strong molecular interactions, predominantly driven by hydrophobic forces. Compared with SPI, SPI-C complexes exhibited reduced sulfhydryl content and surface hydrophobicity. Notably, 10 g/100 g catechin demonstrated the highest encapsulation efficiency, loading amount, and emulsifying indexes, along with the maximum thermal denaturation temperature of 160.4 °C. Although the peroxide value and thiobarbituric acid reactive substances of meatballs decreased significantly with increasing SPI-C complex levels during short-term storage (24 h), the optimal concentration (8 g catechin/100 g SPI) yielded the lowest total volatile basic nitrogen value (8.35 ± 0.01 mg/kg) and preserved the highest springiness and moisture content. These findings indicated that the SPI-C complex possessed a stable structure and superior functional properties, effectively enhancing the oxidative stability and water-holding capacity of meatballs, thus offering a promising clean-label antioxidant strategy for meat-based products. • Catechin and SPI cross-linked predominantly by hydrophobic interactions under non-covalent conditions. • Catechin improved the emulsifying and gelling properties of soy protein. • Soy protein-catechin complexes improved edible and storage quality of meatballs.