Protein source and storage time influence the digestibility of caprylic and docosahexaenoic acids enriched plant-based oil-in-water emulsions

The physical and oxidative stability of oil-in-water emulsions, together with their digestibility, are critical parameters for their functionality and performance. However, although the effects of long-term storage on the stability of plant-protein-based emulsions are well documented, little is known about how it affects lipid digestion. This study thus aimed to determine the effect of 28-day mild storage on the bioaccessibility of caprylic acid (C8) and docosahexaenoic acid (DHA; C22:6) in oil-in-water emulsions, using either pea protein isolate (PePI) or potato protein isolate (PoPI) as emulsifier. Throughout storage, both PePI and PoPI emulsions coalesced although the average droplet size of both emulsions remained <2 μm. PePI emulsions retarded the formation of primary lipid oxidation products compared to PoPI emulsions (3.7 versus 7.7 mmol/kg oil at the end of the storage). The bioaccessibility of C8 was higher for PePI emulsions (35-40 w/w %) compared to PoPI emulsions (15-25 w/w %) at the start of the intestinal digestion (p < 0.05). After storage, the bioaccessibility of C8 significantly decreased (p < 0.05). Digestibility should thus also be considered when determining the shelf-life of food products, especially if they are designed to promote health.