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Influence de la structuration de l'interface colloïdale sur la formulation et la biodisponibilité d'acides gras d'intérêt nutritionnel

Abstract : Recent epidemiologic studies show an insufficient intake of polyunsaturated fatty acids (PUFA) in occidental countries. Besides, the sensibility of PUFA to oxidation is one of the major causes of organoleptic and nutritional quality deterioration in food products. Moreover, lipids in food products are often in an emulsified stage. Therefore, industrials that care to formulate PUFA enriched food products adopt technological strategies to protect and stabilize the lipids while improving their bioavailability. One of those strategies consists in looking for stable emulsified systems that already exist in nature, extract tensioactive molecules of interest and mimic the lipid state. In this context, several studies deal with oil bodies (OB), that are natural occurring structures for lipid storage in oleaginous plants, composed of proteins (OBP) and phospholipids (PL).Therefore, the main objective of this PhD work is to manage emulsion formulation only based on canola (oil, PL and OBP). This goes through: 1) an understanding of the interactions between PL and OBP; 2) a study of the stability of the emulsions under storage and gastrointestinal conditions, and finally, 3) an investigation of the influence of the emulsion interfacial composition on the bioavailability of PUFA in rats.The spectroscopic studies of the model PL:OBP interactions showed favorable interactions for stabilizing the emulsions based on anionic PL, unsaturated PL and OBP. These results allowed choosing an adequate canola lecithin. The PL:OBP interactions, modulated by the pH and the PL:OB ratio, influences the formation of the emulsions, the quantity of OBP adsorbed at the interface and the physical stability of emulsions with a pronounced creaming in emulsions rich in proteins. The PL:OBP synergy at the interface seems to be a decisive factor to slow down the oxidation of the emulsified canola oil. The emulsion behavior in conditions that mimic that of the gastrointestinal track, shows that the presence of OBP at the interface favored the emulsion flocculation at acid pH (mimicking that of the stomach). However, the flocculation was reversible when the pH was adjusted to a value close to that of the intestine. OBP also increased the activity of the pancreatic lipase in vitro. Finally, the presence of PL and OBP at the interface increased the lymphatic bioaccessibility of the PUFA in rats.On the whole, we showed that it is possible to manage emulsion formulation only based on canola products. This could be of peculiar interest for clean labeling or vegan nutrition by subtracting synthetic emulsifiers or emulsifiers from animal origin, respectively.
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Christine Bourgeois. Influence de la structuration de l'interface colloïdale sur la formulation et la biodisponibilité d'acides gras d'intérêt nutritionnel. Chimie théorique et/ou physique. Université de Bordeaux; Université Laval (Québec, Canada), 2018. Français. ⟨NNT : 2018BORD0379⟩. ⟨tel-02090577⟩

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