The acid is produced by Aspergillus oryzae (the genus Aspergillus or others), which is used for production of miso, soy sauce, and so on; it is an important substance which has an antibacterial effect and prevents the ingredients from rotting.
この麹酸は味噌やしょう油等の製造に用いられる麹菌（Aspergillus属等）が生成する、抗菌作用を持ち原料の腐敗を防ぐ効果がある重要な物質である。