Unlocking the metabolomics and metagenomics code of phenyl moiety chromophore profiles underlying naturally occurring yellow color of dry-salted radish.

The aim of this study was to investigate the molecular basis and the role of biotic and abiotic factors in the development of naturally occurring yellow color of dry-salted radish by analyzing color, physicochemical properties, amino acid profile, glucosinolates and myrosinase activity, metabolomics and metagenomics. Results showed that metabolites of phenyl-containing amino acids (Trp, Phe, Try, carboline, indole, pyrrolidone), curcuminoids (curcumin, gingerol), polyphenols and flavonoids were the major chromophores for color of dry-salted radish. Additionally, chromophore formation involved assistance with pyrrole-containing compounds, glucosinolates and isothiocyanates. Low Aw (<0.7) was the key abiotic factor to facilitate the chromophore formation by enriching the genera of Lactiplantibacillus, Lacticaseibacillus, Pediococcus, Levilactobacillus and Halomonas, and promoted gene functions linked to metabolism of Trp, Phe, Try, curcuminoids, polyphenol, flavonoid, phenyl, pyrrolidone, transport of amino acid and ions, hyperosmotically responsive system. Capitalizing on this finding would empower the development of dry-salted vegetables with appealing and stable color.