Sacha inchi (Plukenetia volubilis L.) shell: An alternative source of phenolic compounds and antioxidants

Sacha inchi seed (SI) is known as a rich source of oil with high content of polyunsaturared fatty acids of the ω-3 and ω-6 type (~85% of total fatty acids). However, few studies have focused on the use of by-products from the seed. The aim of this study was to characterise the main phenolic families present in SI shell and to evaluate the best extraction solvent for the extraction of phenolic compounds (PC) and antioxidant capacity (AOXC). The PC content corresponded to 74.5 ± 5.1 mg g^-1 of which 93.1% were condensed tannins and the remaining compounds corresponded to free and bound phenolic acids, hydrolyzable tannins, flavonoids and flavanoids. Protocatechic and p-coumaric acids but also hydroxycinammic acid derivatives of ferulic and o-coumaric type and lignan derivatives were identified. Acetone containing solvents favoured the extraction of higher amounts of total PC and AOXC. This study highlights the potential use of SI shell as a novel and alternative source of PC antioxidants for the nutraceutical and/or functional food industries.