Hydrothermal fractionation of Sargassum muticum biomass

Sargassum muticum is an invasive brown alga which could be regarded as a renewable resource susceptible to fractionation and integral valorization. S. muticum biomass was processed according to a scheme consisting of conventional alkaline extraction of alginate, ultrafiltration to concentrate antioxidant compounds lost in the waste streams and autohydrolysis of the solid residue remaining after alginate extraction. The effect of temperature during non isothermal autohydrolysis was optimized to maximize yields and antioxidant activity of the solubilized fraction. The overall solubilization yield reached 88% of the initial material and the solubilization yield from the alginate-exhausted solid up to 82%. The waste fraction concentrated by membrane technology and that solubilized during autohydrolysis showed radical scavenging and reducing activities comparable to commercial antioxidants. The solid insoluble by-product from the autohydrolysis stage could be potentially useful for agricultural purposes.