Food processing routinely exposes our food systems to often harsh thermal treatments, that are primarily aimed at reducing/eliminating microbial load, hence improving safety and shelf life¹. However, it has long been known that at these elevated temperatures, the available chemical pathways for spontaneous chemical reactions between food ingredients is substantially broadened, and their kinetics enhanced². Modern formulation strategies, i.e., the increased use of plant based ingredients in traditionally animal based products for health and environmental benefits, has substantially broadened the diversity of reactive chemical species in our food formulations. Amongst these, are phenolic compounds, generally regarded as beneficial to health thanks to their antioxidant properties, these microconstituents are present in almost all plant based ingredients, and have been found to interact strongly with other food ingredients, with a particular affinity to proteins³. Despite the above discussion, most studies on the interactions between phenolic compounds and proteins in food systems are still conducted at ambient conditions and may not necessarily reflect how these ingredients behave under a high temperature regime.

The outcome of recent, high temperature research, shows that phenolic acids interact chemically rather than physically with both plant and animal proteins at elevated (~90-140°C) temperatures and neutral conditions, permanently altering the protein and its functionality. In silico analysis demonstrates that thermally induced structural changes to the proteins appear to have a significant effect on the availability of binding sites for phenolic compounds and may facilitate covalent bond formation⁴. The present work summarises the current state of the art in this area and proposes experimental approaches that may better describe how protein–phenolic interactions evolve within the high-temperature regime. Key focuses involve adaptation of experimental setups to achieve in situ observation of bond formation in real time, rather than post processing. Further, making use of recent advancements in docking and molecular dynamics techniques that predict covalent bond formation can provide an additional mechanistic view of how these interactions may occur. Such understanding will enable a molecular level explanation of frequently reported effects to protein functionality upon covalent complexation with phenolics. Hence, facilitating the rational design of thermally processed foods where structural modification, digestibility, and antioxidant behaviour can be intentionally tuned.

References

1. Kubo, M. T. K.; Baicu, A.; Erdogdu, F.; Poças, M. F.; Silva, C. L. M.; Simpson, R.; Vitali, A. A.; Augusto, P. E. D. Thermal Processing of Food: Challenges, Innovations and Opportunities. A Position Paper. Food Rev. Int. 2023, 39 (6), 3344–3369. https://doi.org/10.1080/87559129.2021.2012789.
2. El Hosry, L.; Elias, V.; Chamoun, V.; Halawi, M.; Cayot, P.; Nehme, A.; Bou-Maroun, E. Maillard Reaction: Mechanism, Influencing Parameters, Advantages, Disadvantages, and Food Industrial Applications: A Review. Foods 2025, 14 (11), 1881. https://doi.org/10.3390/foods14111881.
3. Guan, H.; Zhang, W.; Sun-Waterhouse, D.; Jiang, Y.; Li, F.; Waterhouse, G. I. N.; Li, D. Phenolic-Protein Interactions in Foods and Post Ingestion: Switches Empowering Health Outcomes. Trends Food Sci. Technol. 2021, 118, 71–86. https://doi.org/10.1016/j.tifs.2021.08.033.
4. Ince, C.; Condict, L.; Ashton, J.; Stockmann, R.; Kasapis, S. Thermal Examination Implementing Supercomputer Simulations and Experimental Spectroscopy to Identify the Chemical Interactions between β-Lactoglobulin and Hexanal–an off-Flavour Compound. Food Res. Int. 2025, 117448.