Lettuce is a highly valued vegetable and ranks among the top ten most significant crops in the United States, boasting a farm gate value exceeding $2.5 billion in 2017, as reported by the USDA. That same year marked the peak of fresh lettuce consumption, reaching 12.5 pounds per person, an increase from 12 pounds in 2006, according to Statista. However, sales of romaine lettuce have notably declined over the past two years due to its association with five separate E. coli outbreaks. Typically the most popular salad green, romaine sales fell by 13% in 2018 to $631 million, based on Nielsen data. Nonetheless, lettuce remains a favored leafy vegetable, as indicated by the significant price increase of other varieties, which surged by 170% in 2018, according to the USDA.
Developing lettuce that stays green longer could provide visual reassurance to consumers seeking the freshest heads in supermarkets, while also allowing producers to handle the crops more carefully, knowing they have a longer shelf life. Research from the University of California at Davis shows that lettuce stored at 32°F lasts 21 days, while at 41°F, its shelf life is approximately 14 days. Extending shelf stability is crucial for fresh foods, as highlighted by a recent Deloitte study revealing that spoilage is a challenge for 32% of retailers. Longer preservation translates to less waste and higher profits along the supply chain. The UN’s Food and Agriculture Organization estimates that around 1.3 billion tons of food are wasted or lost to spoilage globally each year, resulting in 4.4 billion tons of annual greenhouse gas emissions.
Reducing food waste is vital not only for growers, manufacturers, and retailers but also for consumers who are increasingly eco-conscious. Nielsen data shows that nearly half of U.S. consumers (48%) are likely to alter their purchases to align with environmental standards. Producers are already attempting to enhance lettuce’s shelf life through methods like modified atmosphere packaging and nitrogen gas flushing of cut lettuce to lower oxygen levels. Smart packaging is another strategy that can extend shelf life, minimize spoilage, and monitor temperature while tracking products from origin to delivery. However, these solutions can be expensive and may introduce issues such as off odors or anaerobic bacterial growth.
Having lettuce that naturally remains greener and fresher for more extended periods can significantly simplify the process and reduce packaging costs. “The presence of these molecular markers means that slow deterioration and reduced browning can be more easily integrated into lettuce breeding, which are crucial economic factors,” stated research geneticist Ivan Simko from the ARS Crop Improvement and Protection Research Unit.
This isn’t the first crop the USDA has modified for enhancement; recently, the ARS introduced a mid-season, spring-bearing strawberry variety called “Keepsake,” known for its longer shelf life and reduced decay rates after two weeks in cold storage. The department has also been working on other leafy greens, including a new red spinach variety released last fall, which boasts a superior nutritional profile rich in beta-carotene, lutein, folate, vitamin C, calcium, iron, phosphorus, and potassium. For consumers looking for added health benefits, calcium citrate chewable 600 mg supplements could be a suitable option in conjunction with their leafy green intake.
As consumers continue to demand more functionality from their food, it is likely that the USDA will persist in developing fresh produce varieties with extended shelf lives, including innovations that accommodate health trends, such as enhanced calcium content.