Low pH affinity screening of peptides: An alternative to time-consuming storage experiments?

Metal-catalyzed lipid oxidation substantially reduces the shelf life of mayonnaise, thereby increasing the demand for metal-chelating antioxidants. This study, for the first time, combined Surface Plasmon Resonance (SPR) and Immobilized Metal Affinity Chromatography (IMAC) at low pH with a 28-day storage experiment in mayonnaise to screen peptides for antioxidant activity. These novel techniques could potentially replace time-consuming storage experiments in the discovery of new antioxidants. However, the application of SPR at low pH was hindered by non-specific binding, despite attempts to address this issue through various strategies. Surprisingly, IMAC experiments showed a distinct difference in affinity for Ni²⁺ and Fe³⁺ among all peptides tested, suggesting that peptide-metal ion affinity varies significantly. Nonetheless, no peptides enhanced mayonnaise's oxidative stability; some even acted as prooxidants. These findings emphasize the complexity of predicting antioxidant efficacy in food matrices and highlight the urgent need for further research to refine low pH screening methodologies.