Production of nutraceutics from chestnut burs by hydrolytic treatment

• A multiproposal process was developed for the production of nutraceutics.
• Nutraceutical extracts were obtained by hydrolytic treatments.
• Soluble fiber precipitation showed time and temperature dependent.
• Extract from autohydrolysis liquors behaved as potent as synthetic antioxidants.
• Chestnut bur is a good source of antioxidant and fiber for food industry.

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 21.0 g gallic acid equivalents (GAE)/100 g ethanolic CB extract, with EC50,DPPH = 0.38 g/L. Ethanol-extracted CB were treated with water at 120 °C, and the soluble fraction was mixed with ethanol to precipitate 8.8 g soluble fiber/100 g CB, with a Water Retention Capacity of 2.4 g/g and an oil absorption capacity of 23.7 g/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 = 0.103 g/L) at a yield of 7 g/100 g CB. When the aqueous phase before the ethyl acetate extraction was treated with sulfuric acid, an additional antioxidant fraction (EC50,DPPH = 0.395 g/L) was obtained. The properties and characteristics of these extracts produced make them good candidates to be used as active ingredients.