Aspergillus oryzae is filamentous fungus that excretes enzymes to produce food, including alcohol. The major enzyme A. oryzae produces is an alpha amylase, which hydrolyzes (breaks down) starch into smaller chains of sugar units and which is critical for yeast fermentation. But there are other interesting enzymes that A. oryzae produces such as proteases, glucanases, or hemicellulases that encourage yeast growth and reduce viscosity in whole-grain mash. The fungus is grown either in a solid state or in a liquid culture and usually requires further processing to purify the enzyme for the purpose of alcohol production.
The use of A. oryzae to hydrolyze starch and promote fermentation of grains was discovered and perfected in China during the early Zhou dynasty, at the beginning of the first millennium bce, and has been a bedrock of Chinese alcohol production ever since. See baijiu and qu. In the mid-twentieth century, it was experimented with in some North America distilleries, particularly those of the Seagram company. See Seagram Company Ltd.
Today, purified sources of enzyme are sometimes used in place of malt or in conjunction with it in spirits that use grain in the fermentation process. For example, in producing vodka or some whisky categories, it is allowed to use enzymes that are produced by a fungus. This gives latitude to distillers to change ratios of malted and unmalted cereals and ultimately the flavors in the final product.
Huang, H. T. Science and Civilization in China, vol. 6, part 5, Fermentations and Food Science. Cambridge: Cambridge University Press, 2000.
Machida, M., O. Yamada, and K. Gomi. 2008. “Genomics of Aspergillus oryzae: Learning from the History of Koji Mold and Exploration of Its Future.” DNA Research 15, no. 4 (2008): 173–183.
Monterio de Souza, P., and P. de Oliveira Magalhaes. 2010. “Application of Microbial α-Amylase in Industry: A Review.” Brazilian Journal of Microbiology 41, no. 4 (2010): 850–856.
Willkie, Herman F., and Joseph A. Prochaska. Fundamentals of Distillery Practice. Louisville, KY: Joseph E. Seagram & Sons, 1943.
By: Don Livermore