Yes, lettuce is a highly perishable vegetable, meaning it is susceptible to rapid deterioration after being harvested. Its texture, flavor, and appearance decline quickly, making proper storage important for extending its usability. The delicate nature of its leaves contributes to this short shelf life.
Factors That Accelerate Spoilage
The primary reason lettuce spoils quickly is its high water content, which is around 95%. This makes the leaves crisp when fresh but also prone to rapid moisture loss, leading to wilting. After harvest, the lettuce leaves continue to respire, a metabolic process that uses up the stored sugars and nutrients in the leaves, hastening their decay.
Lettuce is also highly sensitive to ethylene, a natural plant hormone released as a gas by certain fruits and vegetables like apples, pears, and cantaloupes. Exposure to ethylene gas accelerates the decay process in lettuce, causing effects such as russet spotting, which appears as reddish-brown specks on the leaves. Mechanical stress from handling and processing can also damage the plant’s cells, leading to browning and a loss of textural quality.
Effective Storage Methods
Proper storage extends the life of lettuce by managing moisture and temperature. For whole heads of lettuce, like iceberg or romaine, the goal is to keep them crisp without getting too wet. Wrap the entire dry, unwashed head in paper towels to absorb any excess moisture and then place it inside a plastic bag. Store this in the crisper drawer of your refrigerator, which is designed to maintain a higher humidity level.
Loose-leaf lettuces and pre-washed greens require a slightly different approach. After washing, dry the leaves thoroughly. A salad spinner is excellent for this, or you can gently pat them dry with paper towels. Once dry, place the leaves in a hard-sided container lined with paper towels, layering more paper towels between the greens. This technique prevents the leaves from being crushed and absorbs condensation.
The ideal storage temperature for most lettuce is just above freezing, around 32°F (0°C), with 90-95% relative humidity. Colder temperatures can cause ice crystals to form within the leaves, resulting in dark, soggy spots once thawed.
Recognizing When Lettuce is Bad
Spoiled lettuce will often have a slimy texture, which is a result of bacterial decomposition. It may also develop a noticeably foul or sour odor. Dark, mushy spots or significant discoloration are other clear indicators that the lettuce should be discarded.
On the other hand, wilted lettuce may appear limp but will not have the slimy feel or bad smell of spoiled greens. This condition is usually due to simple water loss and is often reversible. You can frequently restore the crispness of wilted leaves by submerging them in a bowl of ice water for about 10 to 30 minutes. This allows the cells to rehydrate, making the lettuce usable for salads or sandwiches.