Antioxidant Properties of Sacha Inchi (Plukenetia volubilis) Shell Extracts as Affected by Solvents used for Prior Decolorization

Sacha inchi (Plukenetia volubilis) shell is a potential source of phenolics with antioxidative activity and its extract can be used to prevent lipid oxidation in some food matrices. However, the sacha inchi extract has been fully exploited due to the dark brown colour properties associated with pigments. Thus, decolourization of sacha inchi shells before extraction using solvents could be a means to bring about the extract with a lighter colour, which could be applied in foods without constraints. The effects of different solvents used for decolourization in sacha inchi (Plukenetia volubilis) shell powder on antioxidant properties were investigated. The solvents used were methanol, acetone, chloroform and propanol. The ethanolic extracts' total phenolic content (TPC) and total flavonoid content (TFC) decreased when solvents were employed for prior decolourization. Among all solvents, the ethanolic extracts from sacha inchi shell powder decolourized using chloroform (CHE) showed the highest TPC (9.94 mg GAE/g dry extract) and TFC (7.20 mg CE/g dry extract). Also, extracts from chloroform decolourized shell powder had the highest antioxidant activities (2,410.01, 111.60 and 4.58 µmol TE/g dry extract for 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, ferric reducing antioxidant power (FRAP), respectively, and 0.52 mmol EDTA /g dry extract for metal chelating assay) compared to other extracts. Therefore, chloroform was the appropriate solvent for decolourization, and the resulting extract had higher antioxidant properties than others.