Antioxidant Activity and Phenolic Composition in 'Beauregard' Sweetpotato Are Affected by Root Size and Leaf Age
2007
Padda, M.S. | Picha, D.H.
Phenolic acids are considered important antioxidants that may help to prevent many human chronic diseases. The antioxidant activity and phenolic content of sweetpotato [Ipomoea batatas (L.) Lam.] roots and leaves of different sizes and ages, respectively, were quantified. Small roots (approximately equal to 4 g root weight) had a higher antioxidant activity and phenolic content compared with full-sized marketable roots (approximately equal to 300 g root weight). Phenolic content in marketable roots was significantly higher in the cortex tissue than in the internal pith tissue. The highest total phenolic content [chlorogenic acid equivalents (10.3 mg·g-1 dry weight)] and antioxidant activity [Trolox equivalents (9.7 mg·g-1 dry weight)] was found in cortex tissue of small-sized roots. Sweetpotato leaves had a significantly higher phenolic content and antioxidant activity than roots. Young, immature unfolded leaves had the highest total phenolic content (88.5 mg·g-1 dry weight) and antioxidant activity (99.6 mg·g-1 dry weight). Chlorogenic acid was the major phenolic acid in root and leaf tissues with the exception of young immature leaves in which the predominant phenolic acid was 3,5-dicaffeoylquinic acid. The results suggest that small-sized roots, which are typically discarded in the field, and young immature leaves may be concentrated sources of phenolic antioxidants.
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