Efficacy of alginate and chickpea protein polymeric matrices in encapsulating curcumin for improved stability, sustained release and bioaccessibility

The present study compares the ubiquitously used alginate with seldom used chickpea protein as matrices for encapsulating curcumin, in terms of stability, in vitro release and bioaccessibility. Alginate and chickpea protein particles prepared via ionic gelation and isoelectric precipitation methods, respectively, were in the submicron range showing high encapsulation efficiencies of above 90%. Encapsulated particles stored in dark refrigerated conditions displayed greater stability of curcumin. In vitro release of curcumin from both encapsulated particles exhibited pH-dependent slow controlled release. However, alginate particles were more promising due to a protective role performed at gastric pH. The release profiles of curcumin from alginate and chickpea protein particles were best described by First order and Weibull models at pH 2 respectively, while those were well described by Higuchi and Zero order models at pH 6.8 respectively. Accordingly, release of curcumin from both encapsulated particles displayed diffusional controlled release at pH 2 while that from both particles showed diffusion-swelling controlled release at pH 6.8. Bioaccessibility of curcumin from both matrices after intestinal digestion was around 50% while that of free curcumin was approximately 18%. Overall, results point to alginate having an advantage over the chickpea protein matrix for safe efficacious oral delivery of curcumin. Thus, encapsulation of curcumin in alginate may be a promising method for the engineering of curcumin incorporated food with enhanced properties.