Volatile Aroma Components and Antioxidant Activities of the Flavedo Peel Extract of Unripe Shiikuwasha (Citrus depressa Hayata)

摘要

The flavedo peel extracts of unripe Shiikuwasha (Citrus depressa Hayata) fruits were extracted using steam distillation (SD) or a cold-press (CP) system. Volatile aroma content and composition were determined using gas chromatography (GC) and each compound was identified using gas chromatography-mass spectrophotometry (GCMS). The major constituents of the extracts were monoterpene hydrocarbons (91.75-93.75% [709.32-809.05 mg/100 g of fresh flavedo peel]) including limonene (43.08-45.13% [341.46-379.81 mg/100 g of fresh flavedo peel]), y-terpinene (27.88-29.06% [219.90-245.86 mg/100 g of fresh flavedo peel]), and p-cymene (8.13-11.02% [61.47-97.22 mg/100 g of fresh flavedo peel]). The extraction process used was determined to be a decisive factor that affects the composition of key citrus aroma components, as well as the antioxidant activities of the Shiikuwasha fruit. Antioxidant capabilities of the extracts were examined by assay of l,l-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and β-carotene bleaching inhibition. The cold-press extraction system may better retain the total phenolic content of the flavedo peel and display superior antioxidant activities, compared to the steam distillation extraction method.