Extending Shelf Life of Romaine Lettuce Through Modified Atmosphere Packaging and the Effects for Food Safety and Quality

Foodborne related disease outbreaks have been on the rise since 1998. For example, in 2019, approximately 75,233 pounds of salad products were recalled due to contamination with E. coli O157:H7. Investigations concluded there was a single grower that supplied romaine lettuce. Outbreaks in 2019 associated with romaine lettuce caused were over 167 people sick with 85 hospitalizations.

Moving forward to prevent future outbreaks, control strategies need to be developed for romaine lettuce. The U.S. FDA has put together a plan, but it will also depend on the work of the farmers to follow guidelines. Additionally, studies by scientists will also be needed to fully understand how certain pathogens, like E. coli O157:H7, can remain on the produce. E. coli O157:H7 deals with different stresses along the supply chain; for example, E. coli O157:H7 can survive on the edible portion of the harvested lettuce for extended periods and adapt to different stresses like temperature changes. Modifying the atmosphere is one control strategy that does help with food quality, but other measures need to be taken to prevent future outbreaks and protect food safety.

Romaine lettuce is a widely consumed product in the US. Consumers are looking for a product that is fresh, convenient, retains its nutrients and, has good sensory qualities. Romaine lettuce is also a highly perishable product resulting in flavor loss, discoloration, decay, softening, shrinkage, and vitamin loss. The use of modified atmosphere packaging (MAP) can extend shelf-life and limit these effects, to provide a fresh product to the consumer. Romaine lettuce is typically packaged with passive MAP. Passive MAP is generated by relying on the natural process of product respiration and the film permeability by relying on the natural respiration rates to attain the desired gas composition over time. Thus, the objective of the study reported here was to conduct a review of MAP and to understand how MAP can help the quality and safety of romaine lettuce.