Abstract
Red radish (Raphanus sativus L.) pigments are attractive natural colorants, because they resist heat and light and give foods an attractive red hue. The major limitation of using red radish colorants in food is their distinctly undesirable flavor resulting from the degradation of glucoraphasatin, which is a glucosinolate predominantly contained in radishes. In the present study, we developed a novel red radish cultivar, ‘Saint Rouge’, for odorless food coloring. ‘Saint Rouge’ was derived from ‘AD-1’, a red radish cultivar used for colorant and bred by introducing a gene conferring glucoraphasatin-less trait using marker-assisted selection. ‘Saint Rouge’ offers a ca. 1.2–1.9-fold greater index for the total color amount than that of the original ‘AD-1’. Meanwhile, the color tone of the extract was quite similar to that of ‘AD-1’. ‘Saint Rouge’ did not contain glucoraphasatin. Therefore, the amount of methyl mercaptan, dimethyl disulfide and dimethyl trisulfide, substances responsible for off-flavors and the sulfur-like odor of radish pigment extracts, was drastically lower in ‘Saint Rouge’ than in ‘AD-1’. These results demonstrate that ‘Saint Rouge’ is a breakthrough red radish cultivar for odorless food colorants.
