Flower Colour and Antioxidant Activity of Violas (viola × Wittrockiana) As Edible Flowers

Edible flowers represent rich sources of nutritional and phytochemical compounds. Violas (Viola x wittrockiana) have been confirmed to be non-toxic as food products. Based on the wide variety of flower colours, major differences may exist in antioxidant concentrations among flowers of different colours. This study examined the differences in concentrations of antioxidant components in viola flowers of eight different colours: white, red, dark red, orange, yellow, light blue, light purple, and dark purple. Flower fresh weight, petal length, petal colour (measured using a chroma metre), ascorbic acid concentration, total anthocyanin concentration, total polyphenol concentration, and DPPH radical-scavenging activity were analysed. The violas used in this study had a wide range of colours, with different lightness and chroma values. Ascorbic acid, total anthocyanin, and total polyphenol concentrations were higher in red, dark red, and dark purple flowers. In contrast, these concentrations were lower in white and light-coloured flowers. The DPPH radical-scavenging activity was also lower in white and light-coloured flowers. Therefore, red, dark red, and dark purple flowers rather than white and light-coloured flowers of violas represent rich sources of antioxidant components and their consumption may provide various health benefits.