The 3 ways to prevent oxidation in food are to cook the food, blanch the food and store the food in airtight containers.
Oxidation in food is when a chemical reaction occurs with the food's chemicals when they are exposed to oxygen in the air.
The oxidation causes the food to break down and lose it's nutritional value.
Oxidation in the food is basically a chain reaction which causes the foods molecules to lose electrons and it then changes the food's chemical composition.
The oxidation in food can lead to off odors, off flavors and discoloration and changes in the foods texture.
Foods that are more prone to oxidation are foods that contain edible oils such as butter.
Other factors that affect food oxidation are packaging, processing and storage of the food as well as the foods ingredients.
Blanching or cooking the food can prevent the food from oxidating by inactivating the enzymes and the microorganisms which cause it.