Aspergillus sojae

Aspergillus sojae is a species of fungus in the genus Aspergillus. It is closely related to Aspergillus oryzae and is primarily used in the fermentation process of traditional Asian foods, such as soy sauce and miso.

Taxonomy

Aspergillus sojae belongs to the Aspergillaceae family. It is a domesticated species that has been selected for its ability to produce enzymes that are beneficial in food fermentation. The species was first described by Hideo Iizuka in 1917.

Morphology

Aspergillus sojae is characterized by its ability to grow on various substrates, forming a mycelium that is typically white to yellowish in color. The conidia, or asexual spores, are produced in chains and are usually spherical to elliptical in shape.

Industrial Use

Aspergillus sojae is widely used in the production of soy sauce, where it is responsible for breaking down proteins and starches in soybeans and wheat into amino acids and simple sugars. This process is essential for developing the flavor and aroma of soy sauce. The fungus is also used in the production of miso, a traditional Japanese seasoning produced by fermenting soybeans with salt and the fungus.

Fermentation Process

The fermentation process involving Aspergillus sojae typically begins with the inoculation of cooked soybeans and wheat with the fungal spores. The mixture is then allowed to ferment for several days, during which the fungus produces enzymes such as amylase and protease. These enzymes break down the complex carbohydrates and proteins into simpler compounds, which contribute to the umami flavor of the final product.

Safety

Aspergillus sojae is considered safe for use in food production. Unlike some other species of Aspergillus, it does not produce aflatoxins, which are toxic and carcinogenic compounds. The safety of Aspergillus sojae in food fermentation has been well-documented, and it is approved for use in food production in many countries.

Related Pages

• Aspergillus oryzae
• Soy sauce
• Miso
• Fermentation