Comparison of blue discoloration in radish root among different varieties and blue pigment stability analysis.

• Internal blue discoloration was assessed in 16 varieties of Chinese radish. • Among lighting types, blue light resulted in the fastest degradation of blue pigments. • Blue pigments degraded more slowly at pH 3–11 than at pH 13 and 1. • Radish blue pigments are more thermally unstable than other typical pigments. The internal blue discoloration of radish root after harvest is a physiological phenomenon that decreases the radish quality. Internal blue discoloration in the roots of 16 varieties of Chinese radish along with the stability of blue pigment under different light, pH, and temperature conditions were investigated. Among the varieties LB05-244 and LB05-240 displayed the greatest degrees of discoloration, while the Piton and Dense radishes exhibited the lowest degrees of discoloration. The light and pH conditions along with the storage temperature affected the pigment stability. The degradation of blue pigment occurred faster under blue light than under green, red, and white light and darkness. Blue pigment degraded fastest at pH values of 13 and 1. The blue pigments in radish exhibited thermal instability, with complete degradation occurring in 5 or 10 min at 90 or 100 °C, respectively. In conclusion, variety affected the discoloration. The pigment exhibited light, pH and thermal instability. [ABSTRACT FROM AUTHOR]