A factor for increasing the color of Japanese sakes under fluorescent light

Abstract

Changes in color of Japanese sakes brewed in Hiroshima Prefecture were monitored under fluorescent light for 6 months. Nine samples of regular type sakes in brown bottles were under a ceiling lamp at room temperature, and twelve samples of Junmai type sakes -- seven samples in green bottles and five samples in brown bottles -- were directly lighted with fluorescent lamps at 10～15℃ in a refrigerator. None of regular type sakes showed any distinct increase in color during the storage. On the other hand, some samples of Junmai type sakes clearly showed an increase in color. None of the Junmai type sakes in brown bottles showed much increase in color. For the Junmai type sakes in green bottles, a difference could be observed in the extent of the increase of the color between the samples. It was found that there is a negative correlation between the amount of increase for the color during storage and the Fe ion content of the Junmai type sakes in green bottles. With experiments of adding Fe ion to a Japanese sake of the Junmai type, it could be observed that Japanese sakes containing more Fe ion showed less increase in color. It was suggested that Fe ion might reduce the increase in color of some Japanese sakes under fluorescent light, although it was well known that Fe ion itself causes a coloring of Japanese sakes after reacting with deferriferrichrysin..