The antioxidant capacity and macroelement content of several onion cultivars

The aim of this study was to determine the phosphorus, magnesium, sodium, potassium, and calcium contents, as well as the total phenolic content and antioxidant activity in white, yellow, and red onion varieties. It is evident from the results that the highest content of all of these macroelements except phosphorus was found in the cultivar Fireball. In this cultivar, the phosphorus content was the lowest of all cultivars. The total phenolic content ranged from 1.17 to 2.10 g of gallic acid equivalents kg(-1) and the antioxidant capacity ranged from 1.26 and 1.86 g of ascorbic acid equivalents kg(-1) of fresh weight and was slightly higher in red onion cultivars than in white and yellow cultivars. The significant influence of color was determined by total phenolic content, antioxidant capacity, and macroelements except phosphorus (P < 0.05). While the season had influence on phosphorus and potassium content and on antioxidant capacity, the growing season significantly influenced the total phenolic content of the onions.