3. Onion
Storing onions in the refrigerator for too long can cause them to become soft and even develop mold. Unpeeled onions need proper airflow for long-term storage, which is why keeping them in plastic bags inside the fridge is not recommended. Instead, they should be stored in a cool, dry, and well-ventilated place. However, peeled onions are an exception—these should be kept in resealable containers inside the refrigerator to maintain freshness.