Hydrogel microspheres may be used as delivery systems for bioactive compounds in food and pharmaceutical applications. In this study, hydrogel microspheres were prepared from whey protein isolate (WPI) and beet pectin (BP) by complex coacervation, which involved mixing the two biopolymers together at pH 6 and then acidifying to pH 4 to induce electrostatic complexation.  This processes led to relatively small hydrogel microspheres being formed (<i>d</i> &lt; 200 nm).  The influence of pH and thermal processing (90°C, 5 min) on the formation of the microspheres was also examined. Relatively small particles (<i>d</i> &lt; 200 nm) were formed at pH 4.0 where the two biopolymers had high and opposite charges and therefore strong electrostatic interactions. The microspheres were strongly anionic from pH 8 to 4, but they became less strongly charged at lower pH values.  The particle size was relatively small (&lt;550 nm) from pH 8 to 4, but increased appreciably at lower pH, which was attributed to reduced electrostatic repulsion.  The hydrogel microspheres were loaded with an anthocyanin-rich extract.  A higher encapsulation efficiency (EE = 55%) was observed when anthocyanin extract was heated (90°C, 5 min) with the WPI-BP solution before particle formation compared with non-heated systems (EE = 35%). A Trolox equivalent antioxidant capacity-assay was used to assess the antioxidant capacity of the anthocyanin-fortified hydrogel microspheres during storage for 7 days at 37°C. The results indicate that encapsulation of the anthocyanins within the hydrogel microspheres improved their stability.

Protein-polysaccharide-based hydrogel microspheres as delivery systems for anthocyanins

251st National Meeting (2016)

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