You're whipping up a big batch of your killer guacamole recipe the night before your big Super Bowl party, and everyone is looking forward to it. Just one problem — how on Earth are you going to keep it from turning that unappetizing grey-brown color before kickoff? Keeping your guacamole green is a task every host can accomplish.

Avocados, along with other fruits and vegetables that contain the enzyme polyphenol oxidase, turn a dull shade of drab once oxygen in the air comes in contact with their flesh. This phenomenon is known as oxidation. So basically, fighting to keep your guacamole green, is waging a battle against air, but science can help. Here are four ways to keep your guac looking fresh and delicious.

Method #1: Top with lime juice and plastic wrap

Limes contains loads of ascorbic acid (vitamin C), which helps combat the polyphenol oxidase enzyme. This method is the same reason why we squirt lemon juice on freshly cut potatoes and apples. Place your guacamole in a bowl and top with a a shallow but visible layer of fresh lime juice. Cover the surface by pressing plastic wrap directly into guac. When ready to eat, remove plastic wrap and pour off excess lime juice, or stir it in for extra zing.

Method #2: Top with sour cream and plastic wrap

Not a fan of tart lime juice? Sour cream can act similarly to ascorbic acid, so if you prefer smoother guac, spread a thin layer of sour cream on top of your guac and cover with plastic wrap pressed directly on the surface. The next day, either scrape off the sour cream or stir it in.

Method #3: Top with plastic wrap

No extra limes or sour cream on hand? Use plastic wrap alone. Press plastic wrap on top of the surface of the guac. It can be trickier than if you topped the guac with lime or sour cream because you have to make sure there are absolutely no air pockets, or you'll have brown spots on the surface where the plastic wrap didn't touch.

Method #4: A Guac Keeper

Use the a product designed to keep air out like the Prepworks Fresh Guacamole Keeper. The plastic container has an airtight seal and keeps air out for days. Plus, it doubles as an easy serving bowl for guac, salsa or other dips. $12.99 on EverybodyShops.com. (seen in photo)

How to keep your homemade guacamole green