Aspergillus Black Mold on onions: what should be done with them?
This black mold belongs to the Aspergillus genus of fungi and is known as Aspergillus black mold. If your fingers do come into contact with it, a good wash with soap and water will do the trick. However, onions that have this mold are often bruised or damaged even to the center, so to be safe, you should simply throw out the contaminated ones.
Aspergillus black mold on onions grows in hot climates, such as farms in southern states. Farmers and quality inspectors are rarely aware of this type of mold growth as it is hidden within the onion skin and sometimes there are no visible signs of damage from the outside. Although mold is known to thrive in humid conditions, Aspergillus on onions has also been common in extremely hot desert locations where onions are grown.
A. niger is less likely to cause human disease than other Aspergillus species, but has been found to cause a disease known as aspergillosis when large numbers of its spores are inhaled. Some symptoms of aspergillosis are: cough, chest pains, fever and shortness of breath.
Severe cases can include shock, chills, delirium, coughing up blood, and blood clots. It’s also possible for the mold to reach your other organs and destroy healthy cells there, causing breathing difficulties, liver failure, or kidney failure.
Where Does Aspergillus Black Mold Originate?
Mildew can begin its attack even when bulbs are still in the fields. They can also multiply during storage and can start from a simple bruising of the bulb. That’s why it’s important to handle bulbs carefully during harvest and processing to minimize damage.
Some people simply remove the offending Aspergillus black mold until the onion is apparently clean when inspected. However, the tiny spores that remain are too microscopic to see. If you know the health problems associated with ingesting black mold, you’ll never think twice about throwing out contaminated onions.
If you’re growing your own onions, always store them in a warm, dry place to cure, such as in wire baskets on your kitchen counter or hanging from your dirty kitchen ceiling, and in a cool but dry place when you store them.
As a general rule of thumb, the temperature you will store onions in should be in the range of 32 to 40 degrees Fahrenheit. Any heat would cause deterioration, and any increase in humidity would only encourage the growth of Aspergillus black mold.
Farmers have tried various fungicides to control the growth of this mold on onions, but no particular fungicide has been found to be effective. And since there’s no sure way to tell if your onions are contaminated, you’ll have to risk this possibility for now.