Encapsulation of omega-3 fatty acids in nanoemulsions and microgels: Impact of delivery system type and protein addition on gastrointestinal fate

•Flaxseed oil was encapsulated in nanoemulsions or alginate microgels.•Delivery systems were passed through mouth, stomach and small intestine stages.•Flaxseed oil was fully digested in nanoemulsions.•Flaxseed oil digestion was retarded when encapsulated in microgels.•Caseinate retarded flaxseed oil digestion in nanoemulsions and microgels.

Carefully designed delivery systems are required to encapsulate and protect omega-3 fatty acids in commercial food and beverage products, but then release them at the required site-of-action within the human gastrointestinal tract (GIT). Previously, we showed that the oxidative stability of flaxseed oil (a plant-based source of omega-3 fatty acids) encapsulated in nanoemulsion droplets or calcium alginate microgels (hydrogel beads) was improved using caseinate as a natural antioxidant. In this study, the impact of caseinate on the digestion of flaxseed oil encapsulated in these delivery systems was investigated using a simulated GIT. The flaxseed oil was incorporated into four delivery systems: nanoemulsions (NE); nanoemulsions mixed with caseinate (NE + C); hydrogel beads (HB); and, hydrogel beads containing caseinate (HB + C). The gastrointestinal fate of the flaxseed oil droplets depended on delivery system type and the presence of protein. The flaxseed oil in the nanoemulsions (NE and NE + C) was rapidly hydrolyzed within the simulated small intestine, with over 76% and 65% of free fatty acids (FFAs) being released in the first 5 minutes, respectively. Conversely, the flaxseed oil in the hydrogel beads (HB and HB + C) was digested much more slowly, with only around 37% and 22% being released in the same period. This knowledge may be useful for designing delivery systems to protect omega-3 fatty acids from oxidation in functional foods, while still allowing them to be released in the GIT.

Graphical abstractEncapsulation of omega-3 fatty acids in nanoemulsions and microgels: Impact of delivery system type and protein addition on gastrointestinal fate.Download high-res image (150KB)Download full-size image