Production of nutraceutics from chestnut burs by hydrolytic treatment

Abstract

Chestnut (Castanea sativa) burs (CB) were processed by solvent extraction (with ethanol, toluene–ethanol or n-hexane) and/or isothermal autohydrolysis, and the potential as nutraceutics of the solubilized fractions of dietary fiber and antioxidants was evaluated. Among the studied alternatives, the most suited consisted on ethanol extraction, which yielded 21.0g gallic acid equivalents (GAE)/100g ethanolic CB extract, with EC50,DPPH=0.38g/L. Ethanol-extracted CB were treated with water at 120°C, and the soluble fraction was mixed with ethanol to precipitate 8.8g soluble fiber/100g CB, with a Water Retention Capacity of 2.4g/g and an oil absorption capacity of 23.7g/g. The mother liquors from the above precipitation stage were concentrated and extracted with ethyl acetate to yield an organic phase containing soluble phenolics with high antioxidant activity (EC50,DPPH=0.103g/L) at a yield of 7g/100g CB. When the aqueous phase before the ethyl acetate extraction was treated with sulfuric acid, an additional antioxidant fraction (EC50,DPPH=0.395g/L) was obtained. The properties and characteristics of these extracts produced make them good candidates to be used as active ingredients.