Thua nao: Thai fermented soybean

•Up-to-date scientific information regarding Thai thua nao has been presented.•Fundamental data regarding fermentation of thua nao have been noted.•The nutritional quality of thua nao has been summarized.

Thua nao is a traditionally fermented food in Thailand. It is manufactured by fermenting cooked soybeans with naturally occurring microbes. There are also similar products including natto in Japan, kinema in India, and chongkukjang in Korea. In Thailand, thua nao is widely consumed, especially by people in the northern part. The product is generally regarded as a protein supplement and widely used as a condiment. Two major types of thua nao can be distinguished; fresh and dried forms. To date, scientific information on thua nao is scarce and thus this article aims to document the updated knowledge of Thai thua nao.