In Silico Food Science. A ground-up Investigation into lipid structure and oxidative degradation

Lipid oxidation is a major problem resulting in the rancidification of oils and fats. Specifically, the oxidative degradation of lipids via a radical chain auto-oxidation reaction is a leading cause of rancidification. Several factors have been attributed to impact the rate of deterioration, including the type of lipid, presence and type of antioxidants, and if the lipid is present in an emulsion or as bulk oil. Unfortunately, there are still gaps in our understanding of lipid oxidation.

To address this knowledge gap, we adopted a multiscale computational approach, incorporating molecular dynamics (MD) simulations and density functional theory (DFT) calculations to investigate the fundamental mechanisms. We explored the inherent structural properties of flaxseed oil and its interactions with four antioxidants. To elucidate the behavior of triglycerides and antioxidants near and away from the water/oil interface, simulations were conducted in both bulk oil and water/lipid emulsions (Figure 1). The results unveiled structural features of antioxidants and lipids in proximity to the emulsion boundary, shedding light on differences in lipid oxidation rates.

To unravel the radical initiation and propagation processes at the atomistic level, DFT calculations were employed to explore the reaction mechanisms and associated reaction rates. The results show the initiation reaction is barrierless, indicating that initiation is solely limited by radical diffusion to the site. In comparison, propagation through molecular oxygen is unfavorable unless in the excited state, underscoring the importance of minimizing UV light exposure to decelerate oxidation. This work highlights molecular modelling can provide detailed structural and energetic information to lipid oxidization, and other similar problems relevant to food science.