The speed at which flaxseed oil (a plant-based source of omega-3 fatty acids) is digested appears to depend on the delivery system and whether protein is present, revealed the research team, a collaboration between the University of Massachusetts and Nanchang University, China.
Using a simulated in vitro model of the human gastrointestinal tract (GIT), flaxseed oil encapsulated in nanoememulsions displayed a much more rapidly digestion than when hydrogel beads (HB) were used. The addition of protein (caseinate), slowed the digestion process and FFA release, compared with flaxseed oil on its own.
“The free lipid droplets in nanoemulsions were rapidly and completely digested in the simulated small intestine, while lipid droplets trapped inside microgels were digested more slowly,” observed lead researcher Professor David McClements from the University of Massachusetts.
“The rate and extent of lipid digestion was reduced when caseinate was added to either the nanoemulsion or to the microgel delivery systems, which was attributed to the ability of caseinate molecules to inhibit lipase activity,” he continued.
The ability to tailor the speed of digestion and release of omega-3 fatty acids may have a number of applications, propose the researchers.
“These results suggest that it may be possible to design delivery systems that can control the digestion and release of omega-3 fatty acids in different regions of the GIT. This type of delivery system could be used to control blood triglyceride levels, induce satiety, or control the release rate of hydrophobic bioactive agents,” wrote McClements.
Caseinate reduces oxidation, slows digestion
The researchers had previously discovered that the addition of caseinate enhanced the oxidation stability of omega-3 fatty acids encapsulated in nanoemulsions or HB. In this study, they investigated the effect on speed of digestion and FFA release of the two delivery systems either with or without the added protein.
“A GIT model that simulated the mouth, stomach, and small intestine stages of the human digestive tract was used to follow the potential gastrointestinal fate of the delivery systems,” the researchers explained.
The fractions of FFAs released in the simulated small intestine were measured for each different method.
The flaxseed oil in the nanoemulsions was rapidly hydrolysed in the simulated small intestine, with over 76% (without caseinate) and 65% (with caseinate) of FFAs being released within 5 minutes. With the HB delivery system, these proportions dropped to 37% and 22% respectively.
“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,” concluded the team.
Source: Food Research International
Published online ahead of print, doi: 10.1016/j.foodres.2017.07.039
“Encapsulation of omega-3 fatty acids in nanoemulsions and microgels: Impact of delivery system type and protein addition on gastrointestinal fate”
Authors: Fang Chen, David Julian McClements, et al