Lettuce is a popular vegetable in the produce section. Once you buy lettuce and take it home, you might not eat it for a few days. If it develops brown spots before you get around to eating it, you might not have to throw it out. However, be wary if the lettuce has sliminess and mold.
Lettuce should be stored close to 32 degrees Fahrenheit. However, lettuce freezes at 31.6 F, at which point the lettuce is easily damaged. Because lettuce loses water easily, it is stored best at a high humidity of 98 percent to 100 percent. Some types of lettuce have better storage times than others. At the most, lettuce can be kept up to four weeks if kept at the right conditions. However, if the lettuce is kept at a higher temperatures, such as 41 F, it will only keep for up to two weeks. Lettuce is also damaged by ethylene gas produced by produce such as apples, tomatoes, and peaches.
Your lettuce might have color changes or spots that do not indicate disease. Tip burn is when the parts of the tops of the leaves look brown and necrotic. Russet spotting are dark brown ovals caused by oxidation stemming from storage with ethylene gas from produce. Brown stains on the midrib are large and irregular in shape. They are caused by exposure to too much carbon dioxide. Finally, pink rib is the pink discoloration of the midrib caused by exposure to higher temperatures. However, lettuce with these disorders can still be eaten safely.
Lettuce that is unsafe to eat shows definite signs. Bacteria can begin to reproduce on bruised leaves. The buildup of bacteria causes a slimy texture. A fungal infection caused by sclerotinia also causes a slimy texture. Botrytis cinerea can thrive and cause a gray mold to be produced. You should take caution when finding these signs of lettuce disease.
Using Your Old Lettuce
If you have lettuce in your refrigerator that is about to go bad, consider using it for wilted lettuce salads. Rinse the lettuce to decrease the risk for contamination. Also, trim off any signs of discoloration to be safe.