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The potential of rosemary polyphenols encapsulation in different alginate-based delivery systems using ionic gelation

Rosemary (Rosmarinus officinalis L.), culinary and medicinal plant, due to its rich bioactive profile, especially polyphenolic antioxidants, has recently become of great interest as functional food ingredient. However, polyphenols reveal remarkable instability in the gastrointestinal tract after oral consumption, likewise during food processing and production. Therefore, the aim of this study was to examine the encapsulation potential of polyphenols from rosemary extract in alginate-based delivery systems using ionic gelation. In order to formulate delivery systems with enhanced encapsulation efficiency and slower release profile of polyphenolics, alginate (A, 2%, w/v) was combined with whey protein isolates (WPI), and natural materials which still have not been used for encapsulation purposes, cocoa powder (CP) and carob (C), respectively. Obtained hydrogel beads were evaluated for physico-chemical and morphological properties. Encapsulation efficiency (EE) was determined in terms of total polyphenols (TP) and hydroxycinnamic acids (HCA). The release kinetics of TP and HCA from beads was accompanied in simulated gastric (SGF) and intestinal (SIF) fluids. Among alginate beads encapsulating rosemary polyphenols, A-WPI beads resulted with the smallest particle size (1.7 mm), while the addition of CP and C provided larger particles (2.2 and 2.1 mm). In comparison to plain alginate beads, which were characterized with regular, spherical shape, the addition of other materials provided irregular beads and appearance. HCA, as the most representative polyphenolic group, were encapsulated in a high content, from 52.32% (A) to 91.16% (A-CP), indicating that introduction of an additional carrier to alginate improved its encapsulation properties. The same pattern was observed for release kinetics of TP, where A-CP and A-C had the most extended release of TP in SGF, followed by gradually release in SIF up to 140 min. Formulated carriers proved to be effective materials for immobilization of rosemary polyphenols, with potential of usage in various functional food products.

Alginate; Encapsulation; Ionic gelation; Polyphenols; Rosemary

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