How to Keep Leftover Avocados Green
It's quite common to use half of an avocado and save the rest for later. Is it possible to keep the leftover half from turning brown?
A few companies have designed gadgets that claim to keep leftover avocados green. (In our past tests they didn’t succeed; see Food Storage Gadgets under related content.) But if you start asking around, you’ll find that nearly everyone has a solution. We put together a list of the most oft-cited methods—leave the pit in the avocado; rub lemon juice on the cut side; wrap it tightly in plastic wrap; seal out air by coating the cut side in oil—and started testing.
We know that cold slows enzymatic action, and when fruits and vegetables brown, it’s an enzymatic process. Could we slow it down by refrigerating the avocados? Because each individual avocado browns at a different rate, we cut four avocados in half and put half of each in the refrigerator overnight. As we expected, the next day all the halves in the refrigerator were greener than their unrefrigerated mates. Once we’d established that chilling helps, we sliced four more avocados in half, treating one half of each with one of the aforementioned methods. We refrigerated them. At the 24-hour mark, all the treated halves were the same color as their corresponding untreated halves—obviously, none of these four methods made any difference.
Looking for other ideas, we called our science editor. Armed with his advice and three more cases of avocados, we spent two weeks doing everything from boiling avocados to dipping them in solutions made from crushed vitamin C tablets. Nothing worked, though we did inadvertently figure out how to make avocados brown faster. (You salt them.) We kept trying. Eventually, we were able to get nearly perfect green color at the 48-hour mark by leaving the avocado cut side down in a bowl of lemon juice and water. The drawback? The avocado was a little tart and slightly soft.
At this point, a colleague showed up to work one day with a box of vacuum-sealed peeled, pitted, and halved avocados from the grocery store. They were bright green—and stayed that way for a week in the fridge. What if we vacuum-sealed our own avocados? It worked (and cost less than buying them vacuum-sealed). A bowl of vacuum-sealed guacamole also stayed green for a week.
THE BOTTOM LINE: Vacuum sealing will keep leftover avocado halves and guacamole green for up to a week. Storing cut avocados submerged cut side down in lemon water in the refrigerator will maintain color for up to two days but may slightly affect texture and flavor.