Toward a Spatiotemporal Model of Oxidation in Lipid Dispersions: A Hypothesis‐Driven Review

Abstract

Unsaturated lipids are prone to get oxidized through a sequence of reactions known as lipid oxidation. From a phenomenon considered at the beginning as a mere chemical process and described by the triptych of initiation, propagation, and termination, the vision of lipid oxidation has progressively evolved to further integrate the physical dimension of the phenomenon. Despite tremendous research efforts, however, this sequence of reactions is not yet well understood, especially in lipid dispersions where many facts are still inexplicable and unpredictable under the current paradigm. Here, the aim is to suggest that the main reason why a better understanding has not already been achieved is that the reactional network is not yet organized in a coherent spatiotemporal framework. The novel concepts and hypotheses proposed in this article may help redirecting a significant part of research efforts toward the establishment of a spatially and temporally resolved model of oxidation in dispersed lipids. Practical Application: Predicting how oxidation spreads in lipid dispersions represents a goal of crucial importance for academia but also for industry. Such prediction models would indeed greatly help food manufacturers prevent oxidation by using the most adapted antioxidative strategies for their specific products. To achieve such an objective, it is proposed that the first thing to do is to go beyond the extremely reductive and narrow framework in which this chemical process has been locked in. Indeed, while lipid dispersions are composed of a multitude of lipid colloids, researchers usually consider oxidation at the sole level of an individual droplet or membrane. Instead, lipid oxidation is advocated as a dynamic trafficking of chemical species within large communities of different colloidal objects such as droplets, membranes, or micelles dispersed in water—a system that dubbed “colloidal ecosystem”. This might represent a scale complementary to the scales of individual colloids or molecules that were the sole consideration so far to try to represent lipid oxidation. Only then can one hope to effectively apply modeling and “omics” approaches, as is explained in more details in this article.

Quantitative and Predictive Modelling of Lipid Oxidation in Mayonnaise

“…This meant that on the weight basis, the effects of EDTA and GA were similar and that f0 is not only sensitive for radical scavenging effects (GA) but also for the chelation effect (EDTA) in the early stages of lipid oxidation. This latter observation is in line with recent work that describes that in the early state of oxidation, LOOH can be generated via LH radicals as well as iron redox cycling [12,25].…”

“…In this work, lipid oxidation in food emulsions is accelerated by storage at elevated temperature (50 °C), where literature suggests that inter-droplet transport and diffusion mechanisms are not rate limiting [ 12 , 13 ]. We hypothesize that the main mechanisms at play are the known free radical mediated reactions and we also attribute a colloidal role to reverse micelle formation, which has been shown to play a part in lipid oxidation kinetics [ 14 , 15 ].…”

Radical Scavenging Activity of Olive Oil Phenolic Antioxidants in Oil or Water Phase during the Oxidation of O/W Emulsions: An Oxidomics Approach

“…On the other hand, significant differences were observed among the different emulsified systems: OPAs decreased the levels of hexanal, mainly when added in the water phase. Hydroperoxides have well-known surface activity [ 10 , 39 ]: antioxidants in the water phase could be more effective in slowing down both hydroperoxide decomposition and hydroperoxide-dependent initiation of oxidation [ 10 , 40 ]. Different results were observed for pentanal ( Figure 5 D) and 1-pentanol ( Figure 5 E): these compounds increased at 14 days after a lag phase and showed the lowest increase in O emulsions.…”

“…Moreover, several contributions have recently suggested the expansion of traditional analytical patterns to a wider range of oxidation products to better understand oxidative phenomena [ 5 , 6 , 7 ]. Three distinct viewpoints by Paradiso, Villeneuve, and Laguerre discussed the need for a new step to study lipid oxidation in emulsified systems by focusing on different aspects [ 8 , 9 , 10 ]. They stressed the importance of investigating some crucial parameters, up to now underestimated, that may govern antioxidant efficiency like the role of the transport of reactive species by surfactant micelles, the impact of smaller droplets in poly-dispersed systems, the application of multiparametric approaches to the analysis of oxidation reactions, and the development of spatially and temporally resolved models for lipid oxidation.…”

Quantitative Spatiotemporal Mapping of Lipid and Protein Oxidation in Mayonnaise

“…Whereas the effects of various ingredients that delay lipid oxidation in food emulsions have been widely studied at the ensemble level [ 6 , 8 , 13 ], there is scarce or even ambiguous support for current hypotheses on the spatial and temporal heterogeneity of lipid oxidation [ 14 ]. Variation in oil droplet size has been proposed as a factor in the spatiotemporal heterogeneity of lipid oxidation.…”