Deferriferrichrysin (DF)
デフェリフェリクリシンでふぇりふぇりくりしんDeferriferrichrysin (DF) is a cyclic peptide produced by yellow koji mold (Aspergillus oryzae). The compound is normally colorless, but when it binds with iron it turns into reddish-brown ferrichrysin. When iron is present in sake, DF can act on it and cause the sake to become discolored.
Because all ordinary yellow koji molds produce deferriferrichrysin, it is difficult to prevent discoloration in sake completely. In recent years, however, this characteristic has been taken into account, and yellow koji molds that do not produce DF, developed through artificially induced mutation, have been commercialized. This offers a new approach to avoiding iron-related discoloration in sake.