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Novel Approach for Immobilization of Dandelion Polyphenols: Implementation of Green Coffee to Alginate Delivery Systems

Recently, due to the low bioavailability and high instability of polyphenols, scientific community, as well as industry put much effort to find adequate solutions for polyphenolics protection, and revealed encapsulation technique as the most effective. Since bioactive profile of dandelion (Taraxacum officinale L.) is still insufficiently investigated, and data about its encapsulation are limited, the aim of this study was to characterize and immobilize dandelion leaves polyphenols in different alginate-based delivery systems using ionic gelation. In order to enhance the properties of alginate hydrogels, alginate (A) was combined with whey protein isolates (WPI), and green coffee (GC), which as material for delivery of bioactives has not been used before. Also, the influence of alginate concentration (4% and 5%) on the encapsulation efficiency of dandelion polyphenols was examined. Polyphenolic profile of dandelion leaves was determined using spectrophotometric and HPLC analyses. Obtained hydrogel particles were scanned for physico-chemical and morphological properties. Encapsulation efficiency was evaluated in terms of total polyphenols (TP) and hydroxycinnamic acids (HCA), while release kinetics of polyphenols was observed in simulated gastrointestinal conditions. HPLC analysis showed chicoric acid as dominant hydroxycinnamic acid in dandelion leaves (6.14 mg/g), followed by caftaric, chlorogenic and caffeic acids. Beads produced with lower concentration of alginate (4%) were characterized with smaller size, less hardness and lower elasticity. In general, the addition of additional coating to alginate increased particle size, where hydrogel beads produced with GC were the largest (2.66 and 2.80 mm). Morphology analysis revealed more spherical shape of hydrogels when higher concentration of alginate (5%) was used, where plain alginate beads were scanned as ones with the most regular shape. Encapsulation efficiency (EE) of TP and HCA was markedly enhanced after the reinforcement of alginate with WPI and GC. HCA of dandelion leaves were immobilized in a high content, where system A-WPI had the highest EE (98.99%), followed by A-GC (79.09%), when lower alginate concentration was used. The slowest release of HCA from formulated beads showed system enriched with GC (5%A), with continuously release during 140 min, up to 2.9 mg caffeic acid/g of bead. Implementation of green coffee to alginate, besides improving bioactive profile of obtained beads, showed very high potential for entrapment of dandelion polyphenols. These results encourage introduction of new, unused materials into delivery systems for encapsulation purposes.

alginate; dandelion; green coffee; hydroxycinnamic acids; ionic gelation

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