| This thesis was conducted to examine the physicochemical changes occurring in protein-stabilized emulsions during in vitro gastro-duodenal digestion, and how interfacial engineering could lead to differences in fatty acid release and the potential bioavailability of incorporated lipophilic molecules. Gastric behaviour of the oil-in-water emulsions was highly dependent on the type and concentration of protein along with susceptibility against pepsinolysis. At the same protein concentration, emulsions stabilized with whey protein isolate were more stable compared to soy protein isolate. The size and interfacial composition of the oil droplets, which plays a critical role in lipid digestion, was extensively altered during the duodenal phase due to the presence of bile salts (BS) and phospholipids (PL). The Inhibition of pancreatic triglyceride lipase (PTL) activity was observed in the presence of BS, PL, and the products of lipolysis. Inclusion of colipase (COL) and phospholipase A2 (PLA2) significantly reduced the inhibitory effect of BS and PL, respectively, although through different mechanisms. Positive correlations were observed between the extent of lipid digestion and bioaccessibility of incorporated lipophilic molecules. In addition, the physical and chemical properties of the encapsulated lipophilic bioactive compounds played a major role in the release and micellization behaviour. For example, highly lipophilic molecules such as beta-carotene and coenzyme Q10 tended to remain in the oil phase. In contrast, vitamin D 3 and phytosterols solubilized more readily and extensively into the aqueous micellar phase during digestion. This research supports a better understanding of how to tailor the composition of oil droplet surfaces in food emulsions which will aid in optimizing lipid digestion and, as a result, delivery of lipophilic nutrients. |
