Baudoinia compniacensis is a black fungus that frequently grows on warehouses where barrels (or permeable clay jars, in the case of baijiu) of spirits are aging, feeding on the ethanol vapors known as the angels’ share. See angel’s share. Antonin Baudoin was the first to identify the mold, originally called Torula compniacensis, in the 1870s. It was renamed in the 1990s after it was discovered that it is not in fact a Torula fungus at all (it is related only to a fungus that grows in Antarctica).
It is believed that the fungus can use nutrients other than ethanol and that ethanol alone is not sufficient to provide adequate support for it. (The fungus being millions of years old and large-scale ethanol production being a relatively recent phenomenon, this must be the case.) The angel’s share will vary widely depending upon the alcohol strength of a barreled spirit and the materials, temperature, humidity, airflow, and other influences of a warehouse environment, and there seems no simple formula by which to predict Baudoinia growth, due perhaps to the sheer complexity of all these variables.
The mold is essentially harmless, and indeed some distillers believe it adds to the character and aromas of their aging spirits; many point to its vigorous growth as an endorsement of the quality of their spirits. Not everyone is a fan, though: in 2013, some Louisville, Kentucky, residents sued the Brown-Forman company, saying the mold was unsightly and that removing it from their cars and homes involved frequent cleaning, shortening the life of those objects. See
See also ethanol.
Rogers, Adam. Proof. New York: Houghton Mifflin Harcourt, 2014.
By: Doug Frost