The total betalain pigment content was measured on a UV/VIS
spectrophotometer (Lambda Bio20, Perkin-Elmer, Waltham, MA,
USA) following the method proposed by Jiratanan and Liu (2004).
The wavelengths of 535 and 476 nm were used for betacyanin and
betaxanthin analysis, respectively (Fernandez-Lopez and Almela,
2001).