Archive · 7 Aug 2025
Onion Fungus: Is Black Powder on Your Onions Safe?
Sometimes onions get a black, dusty coating.
This is usually caused by a type of fungus called Aspergillus niger.
This fungus likes to grow in warm, damp places, like where onions are stored if the air doesn't move around well.
If the black powder is just on the outside, you can peel the onion and wash it, and it should be okay to eat.
But, if the onion smells moldy, feels slimy, or has black spots inside, it's best to throw it away.
People with breathing problems or weak immune systems should be careful around the fungus.
Black powder on onions is typically caused by the fungus Aspergillus niger.
The fungus thrives in warm, moist, and poorly ventilated storage conditions.
Peeling and washing onions with minor black powder contamination is generally safe.
Onions should be discarded if they smell moldy, feel slimy, or have internal discoloration.
Those with weakened immunity or respiratory issues should be cautious of fungal spores.
- Who
- The fungus affects the onions.
- What
- Black powder on onions caused by Aspergillus niger.
- When
- The fungus grows when onions are stored in warm, moist conditions.
- Where
- Onions are prone to the fungus when stored in humid environments.
- Why
- Fungus thrives in humid conditions.
Safe Consumption
Unsafe Consumption
Safe vs. Unsafe Onion Use
Safe Consumption
Peeling and washing onions with minor black powder contamination is considered safe.
Unsafe Consumption
Onions should be discarded when they smell moldy, feel slimy, or show internal discoloration.
- Cause of Black Powder
- Aspergillus niger fungus
- Ideal Conditions for Fungus
- Warm, moist environments
- Safe to Eat?
- Yes, if peeled and washed (minor contamination)
- When to Discard
- Moldy smell, slimy texture, internal discoloration