Capsicum should be stored whole in the fridge for optimal freshness. Slicing it before storage leads to faster spoilage.
Storing capsicum whole helps to retain its moisture and prevent it from drying out. When you slice a capsicum, you expose the inner flesh to air, which accelerates the decomposition process. This can lead to the capsicum becoming soft, wrinkled, and developing an unpleasant taste. A whole capsicum, properly stored, can last for one to two weeks in the refrigerator. To store it correctly, place the whole capsicum in a perforated plastic bag or a crisper drawer. The perforation allows for some air circulation, preventing moisture buildup that can also cause spoilage. If you only need to use part of a capsicum, cut off only the portion you need and store the remaining whole piece as described above.
If you've already sliced your capsicum and want to store it, wrap the cut pieces tightly in plastic wrap or place them in an airtight container. Use them within a day or two to prevent them from becoming too soft and losing their flavor.