12 January - 20 June 2016

Lipid digestion and curcumin bioavailability using Hydrogel-based bead encapsulation

A study published in Food Hydrocolloids has investigated three delivery systems on lipid digestion and curcumin bioavailability. While colloidal delivery systems have been found to potentially improve the bioavailability of curcumin, this study notes the main limitations of conventional oil-in-water emulsions is that they have limited scope for stability and release.

Curcumin, a bioactive agent in turmeric, has been reported to aid a number of biological activities including anti-oxidative, anti-inflammatory, anti-microbial and anti-tumour activities.  It is noted to have a low toxicity, even when ingested at relatively high doses however its use as a functional ingredient are limited due its physiochemical characteristics, as well as it being rapidly metabolised within the gastrointestinal tract.  Encapsulation has previously been reported to overcome these limitations.  A study published in Food Hydrocolloids has investigated three delivery systems on lipid digestion and curcumin bioavailability. While colloidal delivery systems have been found to potentially improve the bioavailability of curcumin, this study notes the main limitations of conventional oil-in-water emulsions is that they have limited scope for stability and release.  McClements et al. investigated delivery systems of curcumin loaded lipid droplets and encapsulation using two types of hydrogel beads (microgels); lipid-loaded alginate beads and lipid-loaded carrageenan beads. An emulsion was prepared using 9 mg curcumin with 30 mL of excipient emulsion (10% corn oil) held at 100 oC for 10 mins. The emulsion was stored at 4oC prior to encapsulation. The alginate beads had uniform spherical shape with diameters around 2-3 mm whereas the carrageenan beads had irregular shapes and diameters around 3-4 mm. The authors attribute these differences to the difference in the gelation mechanisms of the different polysaccharides. Using a simulated gastrointestinal tract that included mouth, stomach and small intestine phases, bioavailability was investigated.  The microstructure of the samples was analysed after each digestion stage. 

McClements et al. investigated the rate and extent of lipid digestion and found that the free lipid droplets digested quickly over the initial 10 mins, with 60% of the free fatty acids (FFA) being released during this time. The beads showed a much slower rate of FFA release. Alginate beads showed no lipid digestion in the first 30 mins with a subsequent slow release. Only a third of FFAs being released after the 2 hour measuring period. For the carrageenan beads, digestion started immediately and occurred over the whole of the period but was slow compared to the free lipid droplets with 46% of the FFAs being released in total.

McClements et al. measured both the amount and bioavailability of curcumin released for each delivery system and found that the free lipid droplets released more curcumin than carrageenan beads, which released more than alginate beads. With regards to bioavailability of the curcumin released, the researchers found the effective rates to be 57%, 25.5% and 12.5% for the free lipid droplets, carrageenan and alginate beads respectively.  They note that the relatively low bioavailability for beads is likely to be due, at least partly, to the fact that not all the lipids were digested and so curcumin remained within the undigested lipids.

The scientists suggest reasons why encapsulation may delay or prevent lipid digestion. They note that pancreatic lipase must adsorb to the surface of lipid droplets for digestion and while for the free lipid droplets this can occur rapidly, for the hydrogel beads, lipase and other components, must penetrate into the bead and diffuse through its matrix before reaching the lipid droplets.

In conclusion, McClements et al. note that it is important to ensure that any hydrogel beads used to encapsulate curcumin do not inhibit its release in the gastrointestinal tract so as not to prevent any associated health benefits but state that their work shows that use of an appropriate encapsulation bead may allow the controlled release of curcumin in different regions of the tract depending on where its release was required.

RSSL can analyse for curcumin in turmeric. For more information please contact Customer Services on +44 (0) 118 918 4076 or email enquiries@rssl.com 

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