How To Keep Guacamole From Turning Brown

Few things are more frustrating than buying an avocado only to find it overripe by the time you’re ready to use it. But what’s even worse? Reaching for your leftover guacamole and discovering it’s turned an unappetizing shade of brown after a day in the fridge. How can you keep guacamole from turning brown so you can enjoy it later? Whether you’re hosting taco night, watching the big game, or simply craving the creamy, tangy goodness of guacamole, there are ways to keep this crowd-pleasing dip bright green. We spoke with a food scientist and chefs to uncover the science behind avocado browning and the best methods to preserve your guacamole’s freshness.

Why Avocados (and Guacamole) Turn Brown

“This browning process is the result of a natural chemical reaction involving an enzyme called polyphenol oxidase (PPO),” says Abbey Thiel, Ph.D., food scientist and founder of Abbey the Food Scientist.

Avocados contain plant compounds called polyphenols. When exposed to oxygen, these polyphenols undergo a chemical reaction that converts them into melanin, a brown pigment (yes, the same melanin found in human skin).

“Inside an intact avocado, PPO and a group of compounds called polyphenols are stored in separate parts of the cells. However, when the avocado is sliced or mashed, these cell structures break open, allowing PPO to interact with polyphenols and oxygen from the air. This triggers a series of chemical reactions that convert polyphenols into quinones, which then link together to form larger molecules called melanin. Melanin is a brown pigment, which is why the surface of the avocado darkens over time,” Thiel explains.

This process, known as enzymatic browning, isn’t unique to avocados. “It also occurs in other fruits and vegetables, such as apples and bananas,” adds Thiel.

How to Keep Guacamole From Browning

While brown guacamole is still safe to eat, it doesn’t look or taste as appealing as a fresh batch. Fortunately, there are several ways to delay the browning process before you store uour guacamole.

Add Acid

Adding a layer of lime juice on top of your guacamole can protect it from browning by slowing down the enzymatic process that causes that brown color.

“Applying lemon or lime juice to the exposed guacamole surface can significantly slow browning. The citric acid lowers the pH, reducing PPO activity and delaying browning,” says Thiel.

Chef Oscar Cabezas, executive chef of Teleferic Barcelona Restaurant Group agrees: “To keep guacamole fresh and bright, Add some lime juice or citric acid to your guacamole. It’s more than just a zesty flavor kick—lime is a natural preservative that slows oxidation.” 

Minimize Oxygen Exposure 

Creating a barrier between the guacamole and air will help the guacamole stay fresh. You can accomplish this either with plastic wrap or a thin layer of water.

“To prevent that ugly browning you need to minimize the exposure to air. For guacamole, you can do that by placing plastic wrap on top (just make sure it’s touching the guacamole) or packing it down tight in a container and then placing a thin layer of water or lime juice on top. Pour the liquid off before serving,” says Lisa Bryan, food content creator at Downshiftology, author of bestselling meal prep cookbook Downshiftology Healthy Meal Prep, and developer of the most popular guacamole recipe on the internet. 

While the water method is effective, it can sometimes leave your guacamole with a slightly wet texture or a brownish tint. Plastic wrap is a nearly foolproof alternative that keeps your guacamole fresh without altering its texture.

Try a Guacamole Saver 

If you want your guacamole to stay fresh for many days to come, invest in a guacamole keeper like the Progressive Prepworks Fresh Guacamole Keeper. This BPA-free container features a press-fit, silicone-lined lid that removes excess air as you press it down, ensuring a tight seal and minimizing oxygen exposure. The clear container also doubles as a serving dish.

Do Avocado Pits Keep Guacamole Fresh?

Placing an avocado pit in guacamole is probably the most popular method people use, thinking it will keep it from browning. While it may seem to work in some spots, the pit doesn’t release any special anti-browning chemicals.

“A lot of people believe that placing the avocado pit in the guacamole will prevent browning, but unfortunately, that’s a misconception and doesn’t work. It really only prevents the guacamole that’s right below it from turning brown, as again, it’s preventing the exposure to air,” says Bryan.

In other words, the pit acts as a physical barrier, much like plastic wrap or a layer of liquid. While it might help in a pinch, it’s not a foolproof solution.

Keeping guacamole from turning brown doesn’t have to be a challenge. Whether you opt for plastic wrap, a splash of citrus, or a handy kitchen gadget, these tips ensure your guacamole stays as appetizing as the moment you made it.