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Microwave hydrogravity pretreatment of Sargassum muticum before solvent extraction of antioxidant and antiobesity compounds

Flórez‐Fernández, Noelia, Casas, María P, Jesús González‐Muñoz, María, Domínguez, Herminia
Journal of chemical technology and biotechnology 2019 v.94 no.1 pp. 256-264
Sargassum muticum, adsorption, ambient temperature, antioxidant activity, antioxidants, bioactive compounds, biomass, ethanol, gravity, lipogenesis, macroalgae, phenolic compounds, resins, solvents
BACKGROUND: Microwave hydrodiffusion and gravity (MHG) of Sargassum muticum was proposed both for obtaining an aqueous extract and as pretreatment before ethanol extraction of bioactives. RESULTS: No significant differences in composition and properties between the aqueous phase drained during MHG processing at 600 W/7 min (MHG‐1) and at 600 W/5 min + 300 W/5 min (MHG‐2) were observed. The aqueous extract, accounting for less than 0.2% of the initial material, was refined by adsorption onto food grade resins to recover and concentrate the phenolic fraction, further eluted in 68% ethanol. The final product contained more than 50% phlorotannins and the antiradical capacity was higher than that of Trolox. Ethanolic extraction of the dried solids yielded 7% non‐volatile solubles, containing 5% phenolics and 1.2% fucoxanthin. After 12 months at room temperature in the dark, phenolic and fucoxanthin content, and antioxidant properties of the extracts were markedly reduced. The aqueous extracts from MHG‐2 and the ethanolic extracts from the dried solids showed inhibition of lipogenesis in 3TL1 cells when used at 100 µg mL⁻¹. CONCLUSION: MHG processing can be proposed both for the extraction of an aqueous fraction and for the conditioning of seaweed biomass before conventional solvent extraction of bioactives. © 2018 Society of Chemical Industry