Protein haze (tanpaku kondaku)

Protein haze (tanpaku kondaku) refers to a state in which sake loses clarity and becomes cloudy white. It generally appears during storage after pasteurization (heat sterilization, known as hiire). The main cause is that enzymes produced by koji, particularly saccharifying enzymes, are denatured by pasteurization and then coagulate during storage. Protein haze responds to changes in temperature: it clears when heated and turns cloudy again when cooled. By contrast, cloudiness caused by hiochi bacteria (hiochi-kin, 火落菌) looks similar but does not respond to temperature. Protein haze is regarded as an important factor in the quality and production of sake.