Food - Drink
Here's Why Your Lettuce Is Turning Red
The lettuce family contains many colorful varieties, some of which are naturally pink, red, or purple, but the widely-used standard iceberg or romaine lettuce will always be green. When iceberg or romaine lettuce turns red in the fridge, it's the side effect of a chemical reaction that can be prevented in a few ways.
When lettuce leaves are cut or damaged, their cell walls absorb oxygen, releasing an enzyme within the plant that produces red-colored compounds. In addition, all fruits and vegetables emit ethylene gas as they ripen, and lettuce has a higher sensitivity to this gas, resulting in an unappealing red hue.
Though red lettuce is still safe to eat, it will have lost some flavor and nutritional value. To prevent lettuce from turning red, keep it away from fruits and vegetables that emit high levels of ethylene, such as tomatoes, avocados, bananas, and produce that's in the middle of ripening; also, store your lettuce in an airtight container.