In vitro impact of whey and soy proteins on bioaccessibility of a CLnA-rich oil

Details

Supervisors

Debier, Cathy ; Vellemans, Sarah

Faculty

Faculté des bioingénieurs

Degree label

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

Abstract

The incidence of non-communicable diseases, such as cardiovascular diseases, cancer, obesity, and diabetes, tends to rise with both the aging population and unhealthy lifestyles. It is crucial to raise awareness among populations about the importance of a healthy lifestyle. At the same time, there has been a notable increase in scientific investigation into the relationship between nutrients and health. Over the past three decades, numerous studies have explored the health benefits of various nutrients, such as conjugated fatty acids, including conjugated linolenic acids (CLnAs), which have demonstrated a range of positive effects on health, particularly against non-communicable diseases (G.-F. Yuan et al., 2014). These CLnAs are polyunsaturated fatty acids characterized by 18 carbons and 3 double bonds, of which at least two are conjugated. CLnAs are found in exotic plant seeds oil, including pomegranate seed oil, rich in punicic acid (PunA, C18:3c9t11c13). While numerous studies have investigated the health implications of CLnA, their mechanisms of digestion and their bioaccessibility remain unclear. Furthermore, food matrix components, such as proteins, interact simultaneously with the lipid digestion process. Proteins can participate to the stabilization of emulsions, due to their good surface-active characteristics. The impact of proteins on the bioaccessibility of CLnAs has never been studied. This master's thesis aims to investigate the bioaccessibility of a CLnA-rich oil by using a standardized in vitro digestion protocol called INFOGEST. Following this, a detailed lipid fractionation protocol using solid phase extraction was implemented to offer a comprehensive analysis of various lipid fractions, including the absorbable fraction comprising free fatty acids and monoglycerides. The INFOGEST protocol, established through an international consensus among 440 multidisciplinary scientists, holds significant recognition and is regarded as a reliable method for exploring human digestion processes. In this study, the INFOGEST protocol was be used to (i) evaluate the bioaccessibility of PunA present in pomegranate seed oil in comparison to olive oil containing oleic acid (OA) as a control, and (ii) assess the influence of incremental concentrations of proteins (whey or soy protein) within the food matrix on the bioaccessibility of both PunA and OA. Images of lipid droplets were captured using epifluorescence microscopy at the end of in vitro digestion, aiming to assess the emulsifying power of increasing protein concentrations in the matrix. The results indicated comparable and high bioaccessibility levels for the major fatty acids in both olive oil (OO) and pomegranate seed oil (PSO): oleic acid (OA) for OO and punicic acid (PunA) for PSO. The varying protein concentrations (WPI or SPI) studied did not significantly affect oil bioaccessibility. Additionally, lipid droplet measurements post-digestion showed no discernible difference between oils alone and those with increasing protein levels, contrary to existing literature on oil-protein matrix digestion. This underscores the need for further exploration into the role of proteins in the digestion of CLnA-rich oils to better understand the emulsification process.