ABSTRACT
This study investigated different extraction techniques for production of antioxidants from chestnut shells (CS), a solid waste produced by the chestnut peeling process. Conventional and pressurized liquid extractions, ultrasound and microwave-assisted extractions were tested in presence of water as solvent, and the effect of the extraction time and CS concentrations were examined. The most efficient method was pressurized liquid extraction. The highest yields of antioxidant species, expressed in mg/mL of extract, were obtained for 10% CS after 60 min of incubation: 0.836 ± 0.018 for total phenols, 0.297 ± 0.003 for ortho-diphenols, 0.173 ± 0.002 for flavonoids and 0.545 ± 0.018 for tannins. Measurement of the radical scavenging activity indicated that all the extracts exhibited an antioxidant power stronger than that showed by commonly used antioxidants. HPLC analysis revealed only quantitative differences among the extracts, and gallic acid was the main simple phenol detected independently of the extraction method used. Its amount ranged from 159.66 ± 0.31 to 284.14 ± 0.72 μg/mL extract.
