Betalain Content of Different Varieties, Growth Stages, and Parts of Beet (Beta vulgaris L.)

Abstract

Beet (Beta vulgaris L.), belonging to the family Amaranthaceae, contains a large amount of betalain, a markedly antioxidant pigment. However, few studies have been conducted to examine the betalain content in different varieties in Japan. Beet is usually harvested when the diameter of the taproot (edible root) has reached approximately five to six centimeters. However, few standards for its shipment to market have been established, and only limited information on the appropriate period to harvest beet crops containing the highest betalain content is available. The present study, involving four varieties of beet: ‘Detroit Dark Red’, ‘Saffron Yellow’, ‘Gorgo’, and ‘Rivolta’, with taproots of different colors, was conducted to examine differences in the betalain content among the varieties, and changes in the betalain content in red beet (‘Detroit Dark Red’) at six different growth stages. ‘Detroit Dark Red’, a type of red beet, contained the highest betalain content. The betalain content on a fresh weight basis in ‘Detroit Dark Red’ was the highest when the diameter of the taproots had reached approximately five to six centimeters, indicating that betalain intake from ‘Detroit Dark Red’ harvested around this period would be optimal.