Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
If the mold is unhealthy and may pose a threat to our health; hence we should consider it impure and refrain from using it.
Responding to your question, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Are molds on food impure?
As far as I can learn from the experts, the foods that have molds may have invisible bacteria growing along with it; they may cause allergic reactions. Some of them may produce poisonous substances and toxins that may have spread throughout the food and make us sick.
If the above is correct, we should avoid using such foods.
The Prophet taught us to keep the foods covered.
How to prevent mold on foods
Then, I came to read this recommendation on how to prevent mold on foods.
“When serving food, keep it covered to prevent exposure to mold spores in the air. Use plastic wrap to cover foods you want to stay moist (fresh or cut fruits and vegetables, and green and mixed salads). Empty opened cans of perishable foods into clean storage containers and refrigerate them promptly.”
Prophetic instructions on food storage
I told myself that we strictly follow the Prophetic instructions on washing our hands, face, and surfaces that come into contact with filth, and take care in preparing, serving, and keeping the foods we consume. It would go a long away in keeping ourselves safe and healthy.
The Prophet (peace be upon him) was once ready to start the prayer, and yet he told his companions to wait; then, he went home and returned, saying: I forgot to place the lid on the cooking pot!”
In conclusion, if the mold is unhealthy and may pose a threat to our health; hence we should consider it impure and refrain from using it.
Almighty Allah knows best.