Antioxidant activities of bioactive components in different species and parts of pitayas fermentation

The contents of total phenolics (TPC) and total flavonoids (TFC) and antioxidant activities (total antioxidant capacity, reducing power and hydroxyl radical scavenging activity) in different species and parts of pitayas (red flesh, RF;white flesh, WF;red peel, RP;white peel, WP) fermentation were determined. The correlation between phenolics contents and antioxidant activities was investigated. There were significant differences in the contents of total phenolics and total flavonoids and antioxidant activities among different extracts. The RP fermentation showed the highest contents of total phenolics (636.63 mg/L) and total flavonoids (452.42 mg/L), and total antioxidant capacity (the equivalent of V_C concentration of 169.32 mg/L), and reducing power (140.29 mg/L), and the strongest hydroxyl radical scavenging activity (96.65%). Each bioactive component demonstrated positive correlations with total antioxidant capacity, reducing power and hydroxyl radical scavenging activity, indicating that polyphenols mainly accountted for the antioxidant activities of pitayas fermentation.