The Kitchen Staple That Prevents Guacamole From Prematurely Browning

Whether you're making guacamole to serve a crowd, spread on a sandwich, or just to have as a snack with some chips or crackers, there's no doubt that it's a superior dip when it comes to taste. However, if there's one big bummer about being a guacamole fan, it's that it only remains fresh for a few hours at best. Even when refrigerated, its vibrant green hue turns brown and looks totally unappetizing. Next time you're going to make a batch of guac, break out the lime juice to keep it green and tasty for another day, instead of sadly scraping it into the trash (and it works for cut avocado halves, too).

Luckily, if you're planning on mashing up an avocado for your favorite guacamole, you probably have limes on hand too, since lime juice is a staple in classic guac recipes. Add the amount of lime juice you normally would to your recipe, but set aside a few limes to do some heavy lifting later. When it's time to store your guacamole, your goal is to limit its exposure to air, as oxygen is the culprit behind browned guac. First, transfer it to an airtight container, and spread the dip with a spoon so that it is evenly distributed. Now it's time for the limes to come to the rescue. You'll want to add a protective blanket of lime juice to the top of your dip — just enough so that you can see a thin layer of liquid covering the whole surface. Secure the container's lid and put it in the fridge.

Once an avocado's flesh is no longer protected by its peel, oxidation causes it to turn that unappealing color in just a matter of hours in a process called enzymic browning. This also happens to a variety of other fruits when they are peeled, like bananas, for example. Avocados contain an enzyme called polyphenol oxidase, which produces melanin when oxygen is present, and results in browning. The key to preventing this chemical reaction is to give your guac a protective layer that oxygen can't fully penetrate. Enter lime juice.

The acid in citrus fruits like limes helps to slow the oxidation process by lowering the pH of the guacamole. Enzymic browning happens when the pH rises, so keeping it lower for as long as possible also means it stays that beautiful green color. Don't be mistaken though. This does not make your guacamole immortal — it simply delays the chemical reaction. Try to get that layer of lime juice over your guac as soon as possible after making it. After storing it in an airtight container in the refrigerator, aim to eat the leftovers within a day or two.