Characterization of lyophilized alginate beads with Rosa canina L extract

Abstract

The aim of the present study was the characterization of lyophilized alginate beads with Rosa canina extract via determination of encapsulation efficiency, total polyphenol and flavonoid contents, antioxidant capacity, particle size, sphericity factor and polyphenol release in distilled water medium. Electrostatic extrusion process was carried out to obtain calcium-alginate beads with encapsulated R. canina extract, which further lyophilized in freeze dryer at -75°C and pressure of 0.011 mbar for 24 h and at -65°C and pressure of 0.054 mbar for 1 h. The total polyphenol content was evaluated spectrophotometrically using modified Folin-Ciocalteu method, whereas total flavonoid content was determined using colorimetric assay; antioxidant capacity was analyzed in ABTS and DPPH assays. Total polyphenol and flavonoid contents in lyophilized R. canina extract loaded beads were 68.9±0.4 mg gallic acid equivalents/g of lyophilized beads and 37.1±3.8 mg catechin equivalents/g, respectively. Thus, determined encapsulation efficiency of polyphenols was 55.1±0.3 %. In ABTS assay, antioxidant activity of lyophilized extract loaded beads was 10.7±0.1 mg Trolox/g, whereas in DPPH assay, IC50 of lyophilized beads was 4.11±0.02 mg/mL. The size of the lyophilized R. canina extract encapsulated particles with extract was 460.7±47.7 µm and sphericity factor was 0.12±0.08. In distilled water as a medium, most of polyphenols of lyophilized R. canina extract loaded beads were released in the first 30 min, and the maximum release plateau was reached at 90 min. Lyophilized R. canina extract loaded alginate beads developed in this study have potential to be used in food, pharmacological and cosmetic industries, with the aim to improve functionality, bioavailability and stability of the products.