In order to cook properly, food has to be fully submerged in water in a pot or a sous vide machine. Some foods can rise to the surface once they’re placed in the water. That can be problematic in a couple of ways.

If any portion of the food rises above the surface of the water, it’s in danger of not cooking all the way through. Chelsea Cole, author of “Everyday Sous Vide,” told Tasting Table that food that is not fully submerged is also in danger of bacteria growth. When left at temperatures between 40 F and 140 F any bacteria present in food can multiply rapidly.

To prevent this, it’s critical that your food remains fully submerged. If you’re cooking eggs in a plastic bag, any air left in the bag will create air bubbles that will lift the bag to the surface. There’s a simple trick to keeping the bag submerged, even if you don’t have a vacuum sealer.

The water displacement method will keep eggs submerged as they cook. It removes air from the bag before you seal it. Place your eggs in the plastic bag. Place the bag in the sous vide machine or the pot. As you lower the bag in the water, the pressure from the water will force excess air out. Seal the bag before the water reaches the top. With little or no remaining air trapped inside, your bag of eggs should stay fully submerged.