Bioinformatically Predicted Antioxidant Peptides Derived from Plant, Microbial, and Marine Protein Sources: Effects on the Oxidative Stability of Low Fat Emulsion at pH 4 and Mayonnaise

The demand for functional ingredients from natural and more sustainable sources is increasing. In recent years, peptides have been investigated for their functions including their antioxidant activity and ability to prevent oxidation in food. Previously, we have identified antioxidant peptides (4-30 AA residues) embedded in potato, seaweed, single cell, and spinach RuBisCO proteins using bioinformatics, validated their radical scavenging activity using in vitro assays (e.g. DPPH) and tested selected peptides’ ability to limit lipid oxidation in 5% fish oil-in-water emulsions at pH 7. In this work, we evaluated the effect of the same selected set of peptides (0.05 wt%) on the oxidative stability of iron-mediated (50 µM) 5% fish oil-in-water emulsions stabilized with 1 wt% of Tween 20 at pH 4. Results showed that all the peptides had antioxidant effect compared to control emulsions without any peptides based on the formation of hydroperoxides, consumption of tocopherols and the formation of secondary volatile oxidation compounds. Different peptides did not have any effect on the physical stability of the emulsions. Based on the emulsion study, the four best performing peptides from each protein source were selected and their effects on oxidative stability of fish oil enriched mayonnaise were investigated. Two control samples were included, one with EDTA, which is a commonly used synthetic antioxidant in mayonnaise, and another one without any addition of antioxidants . Increase in peroxide value and volatile compounds (e.g. 1-penten-3-ol, (E,E)-2,4-heptadienal, and (E,Z)-2,6-nonadienal) formed during the storage showed that none of the antioxidant peptides prevented lipid oxidation to the same extent as EDTA; however, potato peptide provided the best protection among all peptides followed by the seaweed peptide .