Antioxidant Activity, Total Phenolic and Total Flavonoid Content in Sixty Varieties of Potato (Solanum tuberosum L.) Grown in Ireland

Potatoes accumulate phenolic compounds, which may have health-promoting effects. In this study, the skin and flesh tissues of 60 varieties of potato planted in two trial sites were evaluated for total phenolics, total flavonoids and antioxidant activity. Higher levels of total phenolics, total flavonoids and antioxidant activity were found in the skin than in the flesh of tubers. Blue variety 'Congo' showed the highest values in both tissues, except antioxidant activity in the skin which was higher in variety 'Edzell Blue'. Maximum values in skin and flesh, respectively, were 12.6 and 3.6 mg/g gallic acid equivalents for total phenolics, 9.5 and 2.3 mg/g catechin equivalents for total flavonoids and 18.8 and 4.4 mg/g Trolox equivalents for antioxidant activity on a dry-weight basis. Strong positive correlations were found among total phenolics, total flavonoids and antioxidant activity. Site and year of cultivation significantly affected the three parameters studied.