structural:expansion, structural:scholar_edition, structural:reformatting, information:classification
Aspergillus kawachii (white kōji)

In addition to Aspergillus oryzae (yellow kōji), Aspergillus kawachii (white kōji) and Aspergillus luchuensis (black kōji), which are used to brew shōchū and awamori, have been used to brew sake since the 21st century.

From the 1980s, research was conducted to brew sake using Aspergillus kawachii (white kōji), which is used to make shōchū, and sake made with Aspergillus kawachii became popular when Aramasa Co, Ltd. released "Amaneko" using Aspergillus kawachii in 2009. Aspergillus kawachii produces about 10 times more citric acid than Aspergillus oryzae, and thus has a strong ability to suppress the growth of bacteria that damage the flavor of sake. It also imparts a sour, citrus-like flavor to sake. Because it produces so much citric acid, older sake-making methods such as kimoto or yamahai can produce a starter mash as quickly as modern sokujō. Kimoto and yamahai do not add artificial lactic acid, which allows them to be labeled "additive-free," giving them a marketing advantage when exporting.