An interesting observation arising from the results is that guava has a potent primary
antioxidant property (measured by IC50 and FRAP) but its function as a secondary or
preventive antioxidant (measured by chelating power) is weak. Primary antioxidants scavenge radicals to inhibit chain initiation and break chain propagation. Secondary
antioxidants suppress the formation of radicals and protect against oxidative damage. On the
other hand, though banana does not have high TPC and AAC values, it is a potent secondary
antioxidant which contains active components that bind to metal ions strongly.