Today let look at GRAS (generally regard as safe) microbes – Aspergillus oryzae. The reason that I got to know it because my friend from china told me they used A.oryzae to ferment porcine blood to serve as high-nutrient blood meal for livestocks. What a case that open my eyes, not only reduce cost, but also reduce environmental pollution! In China, this is a very common practice, but in Malaysia it seemed not that practical.
In my living area, Soy sauce manufacture is carried out by traditional Chinese methods. Most of the factories are small-scale enterprises, producing less than 100 kiloliters per year.
Traditional soy sauces are made by mixing soybeans and grain with mold cultures such as Aspergillus Oryzae and other related microbes and yeasts (the resulting mixture is called “koji” in Japan; the term “koji” is used both for the mixture of soybeans, wheat, and mold; as well as for only the mold). Historically, the mixture was then fermented naturally in giant urns and under the sun, which was believed to contribute additional flavors. Today, the mixture is generally placed in a temperature and humidity controlled incubation chamber
Family member of Aspergillus oryzae
A. flavus and A. parasiticus are known to produce the potent carcinogen aflatoxin. ( this is the thing that making the livestock farmer terrified)
A. oryzae and A. soji have been used for producing food grade amylase and fermentation of oriental foods for centuries (Sooriyamoorthy et al., 2004; Geiser et al., 1998).
They are defined by the production of spore chains in radiating heads which range in color from yellow-green to olive brown. ( like the shape of nuclear explosion)
They are are highly aerobic and are found in almost all oxygen-rich environments, where they commonly grow as molds on the surface of a substrate, as a result of the high oxygen tension. Commonly, this fungi grow on carbon-rich substrates such as monosaccharides (such as glucose) and polysaccharides (such as amylose). Aspergillus species are common contaminants of starchy foods (such as bread and potatoes), and grow in or on many plants and trees. Members of the genus are also sources of natural products that can be used in the development of medications to treat human disease.
Use and application
1) Generally, It is used in Chinese and Japanese cuisine to ferment koji. Koji is a culture prepared by growing either Aspergillus oryzae mold on cooked grains and/or soybeans in a warm, humid place. Koji serves as a sourceof enzymes that break down (or hydrolyze / digest / split)natural plant constituents into simpler compounds whenmaking miso, soy sauce, sake, amazake, and other fermentedfoods. Its fragrant white (or red) mycelium, which lookssomewhat like the surface of a tennis ball, has a delightfularoma resembling that of mushrooms. It is also used to saccharify rice, other grains, and potatoes in the making of alcoholic beverages such as huang jiu, sake, and shōchū.
2) An inexpensive and readily available agro industrial substrate such as rice bran can be used to produce cheap commercial enzymes like protease, lipase and amylase by solid-state fermentation.
3) Also, production of enzyme, antibiotic in various industry fields.
In conclusion, A. oryzae is long considered safe in food industry and recently being selected as eligible candidate of probiotics
All About the little Microbes 