Microencapsulated bioactive compounds may boost availability: Rat study

The study, published in the Journal of Functional Foods​, examined the distribution of the three bioactives (resveratrol, fish oil and tributyrin) in different formulations after oral administration to rats. The authors, from the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia detected the bioactives and their respective metabolites by using of radioactive tracers, finding that microencapsulation had no effect on gut transit of the compounds, but did increase levels in the liver and blood - thus indicating an increase in bioavailability.

The researchers demonstrated that microencapsulation could be used “for the effective delivery of a mixture of bioactives within a single emulsion formulation.”​

“The results provide information regarding the effects of microencapsulation on the distribution of the bioactive mixture and their degradation products when delivered within a single formulation,”​ said the authors, led by Dr Mary Ann Augustin from the Division of Food and Nutritional Sciences, at CSIRO.

Bioactive benefits​

The researchers explained that there is a “strong demand”​ for natural bioactives –which are suggested to help maintain health and reduce the risk of disease. Dr Augustin and her colleagues said fish oil, butyrate, resveratrol, and resistant starch are ingredients “that are of particular interest” ​because they all may have benefits has been for improving cardiovascular and gastrointestinal health.

The authors said that an important aspect of the delivery of bioactives is their bioavailability on ingestion. They explained that some of the “challenges in the delivery of sensitive ingredients into functional foods may be potentially met with the use of microencapsulation.”​

They said that microencapsulated delivery via an emulsion-based system has the potential to protect bioactives from oxidation, and mask the taste of undesirable components.

The new study investigated the release and availability of the three bioactive compounds in a single delivery vehicle, using radioactive ‘tracer’ compounds in either a non-encapsulated or one of two microencapsulated preparations.

“A growing trend is the co-delivery of range of bioactive ingredients … it is recognized that a wide range of therapeutic effects are obtained when there is an additive or synergistic effect between different bioactives,”​ said Augustin and co-workers.

The researchers used an oil-in-water emulsion system stabilized by a heated mixture of a milk protein, glucose and a modified resistant starch as the single delivery vehicle for fish oil, tributyrin and resveratrol.

Study details​

The researchers explained that the major difference between the microencapsulated preparations was the method resveratrol dispersion. They said that the first formulation resveratrol was directly mixed with the oils prior to homogenization, whereas in the second resveratrol was dispersed in a solid fat particle which was then dispersed in a fish oil/tributryin mixture prior to homogenization.

The authors observed that the time-course of transit, and relative distribution along the rat digestive system, were not altered by microencapsulation.

“As a percentage of the relative distribution along the GI tract tissue walls, the majority of the radioactivity from the bioactives was associated with the walls of the small intestine,” ​said the authors.

Augustin and colleagues reported that microencapsulation increased the levels of the radioactivity from the bioactives in the blood and liver, which is “consistent with an increase in the bioavailability of agents.”​

They concluded that an emulsion “is an effective delivery system for a mixture of fish oil, tributryin and resveratrol,” ​adding that microencapsulation of such bioactives in an emulsion does not affect transit through GI tract, but may increase increases levels in blood and liver.

Source: Journal of Functional Foods​
Published online ahead of print, doi: 1016/j.jff.2011.01.003​
“Effects of microencapsulation on the gastrointestinal transit and tissue distribution of a bioactive mixture of fish oil, tributyrin and resveratrol”​
Authors: M.A. Augustin, M.Y. Abeywardena, G. Patten, R. Head, et al​