Oxidative stability of pomegranate seed oil during INFOGEST in vitro digestion

Details

Supervisors

Debier, Cathy ; Vellemans, Sarah

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences agronomiques, à finalité spécialisée

Abstract

enOver the past decades, the prevalence of non-communicable diseases such as cancer, cardiovascular diseases, and diabetes has increased considerably. Among the potential dietary strategies to mitigate these conditions, conjugated linolenic acids (CLnA), a group of conjugated fatty acids, have gained attention due to their promising biological properties. Pomegranate seed oil (PSO) is of particular interest as it contains over 70% punicic acid (C18:3c9t11c13), one of the CLnA isomers. However, despite growing evidence of CLnA health eLects, their digestion mechanisms and oxidative stability remain poorly understood. The gastrointestinal environment may promote their oxidation, potentially aLecting nutritional eLicacy and safety. In this study, PSO and olive oil (OO, used as a control for its known stability) were subjected to the standardized INFOGEST in vitro digestion protocol under standard and reduced O2 conditions to assess oxygen's impact on lipid oxidation. Oxidation was evaluated by measuring primary and secondary oxidation products (peroxide value, PV; and p-anisidine value, p-Av) before and after digestion, as well as fatty acid losses by calculating a recovery index (RI). A bioaccessibility index (BI) was also calculated to assess digestion eLiciency and potential intestinal availability. Results showed an increase in PV and p-Av after digestion of PSO, particularly under standard O2 conditions (PV increased by 100% and p-Av by 85%). These increases were significantly more pronounced compared to OO. However, PV and p-Av values remained below the recommended limits for edible oils. Moreover, PSO may undergo an additional oxidation pathway, potentially leading to the formation of polymeric compounds not quantified in this study. RI analysis showed that CLnA exhibited lower recovery than other major fatty acids, suggesting greater degradation. Although oxygen conditions did not significantly aLect fatty acid RI due to high variability among replicates, individual replicate analysis revealed a consistent trend toward better RI under reduced O2 conditions, consistent with the lower PV and p-Av values observed. BI values further supported the hypothesis that oxidative losses occurred during digestion, suggesting that CLnA degradation may limit their nutritional impact.