Akazu

Akazu is a Japanese red vinegar made from sake lees (酒粕, sakekasu). This vinegar, also known as kasuzu (粕酢), is used primarily to season sushi rice, which is then called aka shari (赤シャリ). Because of the sugars and amino acids in the sake lees, akazu has a dark reddish-brown color.

Akazu is traditionally made from the yeast sediment left over from sake production. During the Edo period, rice vinegar was expensive, so akazu was used as a less costly alternative. Ironically, akazu is more expensive to produce today, since it is typically aged for three to five years to develop its full flavor. Akazu is often used in Edomae Sushi, a traditional style of sushi from Edo, now Tokyo. The vinegar gives sushi rice a deep, savory flavor rich in umami. Unlike rice vinegar (komezu), it does not require added sugar, because akazu is naturally sweet. The more akazu is used, the darker the rice becomes.