Avocados are one of the best food sources of flab-fighting fats, but it’s unlikely that you’ll eat an entire avocado in one sitting. So how do you keep that leftover avocado from turning brown?

Well, let’s first talk about why avocados turn brown. Like apples or potatoes, the flesh of an avocado oxidizes when exposed to air. Once you cut into an avocado, you’ll never be able to completely stop the oxidation process; however, you can dramatically slow it down with a few quick tips:

1.) Cut the avocado with a ceramic or plastic knife. Metal accelerates the oxidation process.

2.) Rub a little lemon or lime juice, which contain the powerful antioxidants ascorbic and citric acids, around the exposed flesh, and you’ll significantly delay the browning effect.

3.) No lemon or lime? Use oil. Oil is another great buffer to oxygen, and you can use it in place of lemon or lime juice when you don’t have any handy.

4.) Store as air-tight as possible. Again, avocados turn brown due to oxidation, which is accelerated by exposure to air. So, storing them in an air-tight container only makes sense.

5.) Water. Huh? That’s right, this one works especially well for guacamole. Place your leftover guac in a plastic container and press down to remove any air pockets. Add a half-inch of water on top and seal with an air-tight lid. The water creates a barrier between the avocado and the air, keeping your guacamole fresh for 24 hours or more! When you’re ready to enjoy some more, just drain the excess water and stir. Give it a try!