You have a bowl of delicious homemade guacamole, created with the most perfectly ripe avocados, tangy lime juice, fresh seasonal tomatoes, onion, and coriander for flavour. But you can't finish the bowl (bummer!), and you want to put the rest in the fridge to enjoy later. Usually, this means a brown, bad-tasting mess after it's been in the fridge too long. Instead, use this simple trick to save leftover guacamole without it turning brown.
First, in order to know how to prevent your guac from turning brown, you need to understand why it happens in the first place. An enzyme in the avocado reacts with the oxygen it's exposed to, and that sad, gross colour is the result — the same thing happens to apples.
In order to prevent oxygen from touching your precious guac, try this simple hack: Smooth out your guacamole in the bowl, then pour a thin layer of water on top. It sounds weird, but guacamole is dense enough and fatty from the avocados so the water won't affect the texture or taste. Store your bowl in the fridge, and when you're ready to chow down, grab a bag of tortilla chips and pour out the water. Give it a good mix, and start dipping — the water doesn't make it soggy at all!
Why not use cling film, you ask? While that can protect your guac from coming in contact with air, you have to press the plastic into the surface perfectly, because even just a teeny amount of space will lead to browning. Plus, a lot of cling film is porous, allowing oxygen to seep through.
The water trick works like a charm, and it's so easy to do. Keep this in mind next time you make a big batch of guac or want to prep for a party ahead of time.