A peeled avocado that is exposed to air will undergo oxidation, one of the main reasons avocados turn brown. To keep it fresh, keep the peeled fruit in an airtight container in the refrigerator. Or better yet, peel it right before you plan to eat it. A few other techniques will keep an avocado green until you're ready to eat it.
Fresh Peeled Avocado Storage
Use containers with tight-fitting lids, zippered storage bags, cling film or wax paper to help keep an avocado fresh after it's peeled. All of these supplies help by reducing air exposure. Cover the exposed surface with lemon or lime juice to protect it from turning brown. You may use other citrus, although orange, tangerine and grapefruit can alter the avocado's flavor. Vinegar keeps an avocado green, but use it sparingly to avoid giving it a sour taste. For picnics, camping, outdoor weddings and other events, keep the fruit on block ice or reusable frozen packets in a cooler to preserve its freshness and safety.