Evaluation of the in vitro impact of phytosterols on the bioaccessibility of fatty acids in pomegranate seed oil

Details

Supervisors

Debier, Cathy ; Vellemans, Sarah

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

enIn recent decades, the significant increase in mortality from non-communicable diseases such as cancer and diabetes has highlighted the challenges posed by an ageing population and unhealthy lifestyles. In this context, scientific interest in bioactive compounds of dietary origin has grown significantly, notably in conjugated linolenic acids (CLnA) (18-carbon polyunsaturated fatty acids with three double bonds, at least two of which are conjugated) found mainly in certain vegetable oils. Punicic acid (PunA; C18:3c9t11c13), the main CLnA in pomegranate seed oil (PSO), constitutes 80% of its fatty acid content, making PSO a promising functional oil. Despite the potential health benefits of CLnA, only a few data are available concerning their digestion and bioaccessibility. A recent study conducted in our laboratory by Sarah Vellemans showed that PSO exhibits high overall bioaccessibility, comparable to that of olive oil (OO), although oleic acid (OA) showed lower bioaccessibility in PSO. Compositional analysis revealed that PSO contains approximately three times more phytosterols than OO, raising the hypothesis that these compounds may influence fatty acid bioaccessibility. This master's thesis aims to study the impact of phytosterols on the bioaccessibility of OA in PSO. To this end, in vitro digestion using the standardized INFOGEST protocol was carried out on phytosterol-enriched OO, at concentrations equivalent to those naturally present in unenriched PSO, and on phytosterol-enriched PSO. Lipid classes of the digestates were then separated by solid-phase extraction (SPE), allowing quantification of fatty acids in absorbable fractions. The results of this study showed that phytosterols were well incorporated into the enriched oils, without altering the fatty acid profile of the lipid matrices. Most of the fatty acids were highly bioaccessible, notably OA in OO and PunA in PSO. Significant differences in bioaccessibility were observed for OA and LA between OO and PSO. No significant difference was observed between phytosterol-enriched and unenriched oils (both OO and PSO) for the same fatty acid. This study also showed that the bioaccessibility of PunA did not decrease despite the addition of phytosterols. These findings suggest that the phytosterol concentrations used did not significantly affect fatty acid bioaccessibility in OO or PSO. Furthermore, although OA and LA were less bioaccessible in the PSO matrix, the high bioaccessibility of PunA is encouraging and supports the potential of PSO as a functional dietary oil.