Identification and Antioxidant Characterization of Caffeic Acid–Cysteine Adduct in Meat Products Supplemented with Dandelion Extract

Caffeic acid (CA), a catechol-containing phenolic acid, is readily oxidized to its quinone form during food processing and can form covalent adducts with amino acid residues in proteins. This study aimed to detect the presence of caffeic acid–cysteine adduct (CA-Cys) in meat products supplemented with dandelion extract, and further investigate its antioxidant properties and intestinal absorption characteristics. Compared with CA, CA-Cys exhibited stronger ABTS radical scavenging activity, greater ferric-ion reducing capability, and lower cytotoxicity in cultured cells. In the oxidative stress model induced by hydrogen peroxide (H2O2) in Caco-2 cells, CA-Cys treatment enhanced antioxidant enzyme activities in a dose-dependent manner. In the Caco-2 cell monolayer model, the apparent permeability coefficient and cellular uptake of CA-Cys were 4.32 × 10−5 cm/s and 0.85 ± 0.14 nmol/mg protein, respectively. These values were approximately 1.23-fold and 1.67-fold higher than those of CA, suggesting that CA-Cys may have significant advantages in intestinal absorption. These results indicate that adducts represent potentially beneficial substances for green food processing.