Lemon zest is rich in essential oils, making it aromatic and flavorful, but these oils are sensitive to air. The aroma can dissipate if leftover zest isn't stored correctly.
To store the zest properly, put it in a small glass or plastic container with a tight-fitting lid. The less air that can seep in, the better. You can then freeze or refrigerate it.
Alternatively, place the lemon zest on a piece of plastic wrap, then fold and seal it tightly. Resealable bags will also work, provided you squeeze out as much air as possible.
Ensure that your container is dry so there's no mold growth or bacteria, and routinely check if the zest is drying, as preserving moisture is crucial for maintaining its flavor.