Onions

Keeping onions in the fridge may seem like the logical thing to do, but in reality, it’s not the best idea. Onions have a high water content, and refrigeration can cause them to become soft and mushy. Additionally, the humidity in the fridge can make them spoil faster. A dark, cool pantry or countertop is actually the ideal place to store onions.
One of the main reasons why onions shouldn’t be refrigerated is because they absorb odors. Placing them next to other strong-smelling items like garlic or cheese will result in cross-contamination of flavors.