By Heath Goldman for Food Network Kitchen
Heath Goldman is a culinary editor at Food Network.
Make a big batch of guac (see a detailed step-by-step here), and a couple of hours later, the once-vibrant green surface has turned a murky greenish-brownish colour. The next day, the leftovers are even browner. It seems like leftover guacamole is destined for brownness. We’re here to dive into the science of why that happens and whether those less than appealing leftovers are bad for you.
The Best Guacamole
Simple ingredients in perfect proportion make this Mexican dip a crowd-pleasing favourite for any event. We decided not to use tomatoes and included both onion and garlic for extra zip. A healthy dose of fresh lime juice balances and brightens the flavors.
Why Does Guacamole Turn Brown?
To understand if brown guac is bad for you, it’s helpful to discuss what’s going on when guacamole turns brown. When an avocado is cut, an enzyme in the flesh reacts with oxygen, turning the layer of guacamole that’s in contact with oxygen an unpleasant brown colour. This is called oxidation. A similar reaction occurs in apples when you cut them. It’s important to note that the reaction is a visual one — the flavour and nutritional benefits of the guacamole remain unchanged.
Is Brown Guac Bad for You?
Although brown guacamole isn’t the most appealing, it’s completely safe to eat (as long as you’ve stored the guacamole in the refrigerator, and it isn’t more than three days old).
"While a bit off-putting to look at, brown guacamole is totally safe," confirms Food Network’s nutritionist, Dana Angelo White, MS RD ATC. "The flesh of the avocado oxidises quickly — much like a cut apple — which changes the color. The addition of citric acid, like from lime juice in your guac can help delay this process but will not completely prevent it," she says.
The Best Way to Prevent Guacamole from Browning
If you want to save your guac for later, store it in the fridge with citrus juice squeezed over it. Smooth the surface with the back of a spoon so there are no bumps or ridges and press a sheet of plastic wrap directly against the guacamole. Then wrap the entire bowl tightly with more plastic wrap to keep as much oxygen away from your dip as possible.
