Ultrasound-assisted production of emulsion-filled pectin hydrogels to encapsulate vitamin complex: Impact of the addition of xylooligosaccharides, ascorbic acid and supercritical CO2 drying

Abstract

Emulsion-filled hydrogels are a promising approach to encapsulate lipophilic bioactive compounds and protect them throughout storage. This study aimed to investigate the chemical stability of a vitamin complex (β-carotene, cholecalciferol, α-tocopherol, and ascorbic acid) in lentil protein emulsion-filled pectin hydrogel produced using high-intensity ultrasound (HIUS) as homogenization technique. The impacts of HIUS nominal power, the addition of xylooligosaccharides (XOS) and ascorbic acid on the viscoelastic properties, chemical stability, microstructure, color, lipid oxidation and antioxidant activity of the formed emulsion-filled hydrogels were evaluated. Overall, the hydrogels showed shear-thinning behavior. The addition of ascorbic acid had no significant effect on the rheological properties. The samples processed at 900 W for β-carotene and ascorbic acid contents and 600 W for cholecalciferol and α-tocopherol contents after 21 days of storage had maximum retention capacity. The presence of ascorbic acid contributed to the improved antioxidant activity, thus reducing the lipid oxidation in the samples. The FT-IR spectra showed no conformational difference before and after HIUS processing, indicating no degradation of the vitamin structures and XOS used. The emulsion-filled hydrogels were then dried to form aerogels using supercritical carbon dioxide (SC-CO2) technology. The concentration of pectin used influenced the drying of aerogels. Emulsion-filled hydrogels and aerogels with improved stability of the complex vitamins were produced.