Semi-dynamic in vitro digestion of sourdough bread enriched with flaxseed oil coacervates

Food structure and addition of encapsulated compounds can impact the gastro-intestinal digestion of food. Flaxseed oil was encapsulated by complex coacervation using soluble pea protein and gum arabic as shell materials, dried by either spray or electrostatic spray drying and incorporated into sourdough dough before baking. Three bread formulations were prepared using spray-dried (B-SD), electrospray-dried coacervates (B-ES) and free ingredients used in the encapsulation (B). The standardised semi-dynamic INFOGEST in vitro digestion method was used. Cumulated protein/free NH2 release and cumulated free fatty acids (FFA) release were used to assess protein and lipid digestion. Coacervates were resistant to bread preparation since they were visible in B-SD and B-ES. The total release of protein, free NH2 and FFA by the end of intestinal digestions ranged between 41.58-45.23%, 1.08-1.22 µmol/g protein and 22.26-63.54%, respectively. There were no significant differences between formulations. There was a statistically significant increase (p<0.5) of about three times in FFA release between the oral and gastric phases. Our findings help to understand the behaviour of coacervates when incorporated into solid food. In this study, the delivery structures did not affect in vitro digestion and may be used to increase the polyunsaturated fatty acid content by 50%.