Valorization of Agri-Food Waste from Pistachio Hard Shells: Extraction of Polyphenols as Natural Antioxidants

The agricultural processing industry usually generates a remarkable amount of by-products rich in bioactive compounds, which can be exploited for agri-food or nutraceutical applications. Pistachio’s hard shell is one the major from pistachio industrial processing. aim this work was evaluation shells as potential source natural antioxidants. We evaluated different extraction procedures by measuring total phenolic content, flavonoid content and antioxidative activity (DPPH•, TEAC ORAC). microwave-assisted ethanol extract turned out to most promising fractionated XAD-16 column chromatography, affording six fractions analyzed through HPLC/ESI-MS/MS 1H-NMR identify main constituents. Fractions Fr4–Fr6 demonstrated highest antioxidant activity. Gallic acid monogalloylglusose isomer are constituents Fr4. Both simple complex phenolics, such flavonoids hydrolysable tannins, were identified Fr5 Fr6; pentagalloylglucose kaempferol, well-known their activity, abundant results highlighted that proposed methodology an effective way recover compounds shell, making by-product with applications food healthcare sectors.