Beyond impurities: The role of minor components in oil stability

Oil refining process is used to partially remove pigments, traces of metals, and impurities to increase oil stability and improve its taste and aroma. Other minor components (MCs) such as free fatty acids (FAs), mono- and di-acylglycerols and alcohols are not removed during this process. The current research aims to investigate the organization of MCs in bulk oil and their influence on oil stability. Canola oil was subjected to a stripping process to remove all MCs. Subsequently, glycerol-monostearate, stearic acid, stearyl-alcohol, and octadecane were added to the oil while their effect on the stability of the unsaturated triacylglycerols in canola oil was examined. Molecular dynamics simulation was employed to gain insights into the molecular interactions between the MCs and oxidation products.

Analysis of peroxide value curves revealed three distinct regions: induction, exponential, and decomposition periods in all samples. However, the different MCs influenced each of these regions differently. Moreover, within the exponential region, two sub-regions were identified based on low and high peroxide values, indicating a change in the rate of oxidation. The presence of MCs affected the transition time between these sub-regions, which was attributed to the formation of mutual hydroperoxide-MC micelles. This transition was accompanied by a significant increase in viscosity and a decrease in the content of unsaturated FAs. Molecular dynamics simulations demonstrated that hydroperoxides formed hydrogen bonds with the polar head groups of the MCs, exhibiting varying bonding tendencies. This suggests that these molecules can impact the formation, organization, and decomposition kinetics of the oxidation products.

In conclusion, the findings of this research shed light on the intricate interactions between minor components and oxidation processes, potentially paving the way for more effective strategies in the food industry to enhance oil stability, reduce waste, and ultimately contribute to improved global food quality and sustainability.