Origin and mitigation of catechins-induced discoloration during pea protein isolation while inhibiting off-flavor formation

This study elucidates the mechanisms of catechin-induced discoloration during pea protein isolation via alkaline solubilization–isoelectric precipitation, where catechins are applied to inhibit off-flavor formation. Catechins were also combined with various mitigation strategies, including reduced protein solubilization pH, sodium bisulfite (SB), gallic acid (GA), Duralox®, and their effects were evaluated using untargeted metabolomics, lipid-oxidation markers (HODE, MDA) and volatile compounds. Untargeted metabolomics identified extractable catechin-derived oxidized dimers ( m / z 570–610) as compounds strongly associated with brown color development. Lowering solubilization pH reduced pigment formation but diminished catechins retention and increased free-radical signals. Catechins–SB combinations most effectively suppressed discoloration, lipid oxidation and formation of volatile off-flavors which was consistent with improved sensory attributes. GA offered additional protection but caused concentration-dependent darkening, whereas Duralox® showed limited efficacy. Overall, targeted antioxidant systems, particularly catechins–SB combinations, offer an effective strategy to control oxidation and improve sensory quality in pea protein.