Ingredients, Functionality, and Safety of the Japanese Traditional Sweet Drink Amazake

The sweet drink amazake is a fermented food made from Aspergillus oryzae and related koji molds in Japan. There are two types of drinks called amazake, one made from koji (koji amazake) and the other made from sake lees, a by-product of sake (sakekasu amazake). The sweetness of koji amazake is from glucose, derived from starch broken down by A. oryzae amylase. The other, sakekasu amazake, depends on added sugar. The main components are glucose and sucrose, but they also contain more than 300 other ingredients. Koji amazake contains oligosaccharides and ergothioneine, and sakekasu amazake has a resistant protein and α-ethyl glucoside, which are characteristic ingredients of each amazake. However, there are also common ingredients such as glycosylceramide. Functionality is known to include anti-fatigue, bowel movement, skin barrier, and other effects on human health. In particular, the bowel movement-improving effects have been well studied for both amazakes. These functions result from ingesting approximately 100 mL per day, but human clinical trials have clarified that this amount has no effect on blood glucose levels and weight gain. In the future, the identification of substances associated with each function is required.