The U.S. Department of Agriculture has identified five romaine lettuce varieties that are slower to brown after processing.
The lettuces brown less quickly after processing and are slower to deteriorate after harvest, according to a news release from the USDA’s Agricultural Research Service.
The researchers identified the location of genes associated with post-harvest deterioration and others are looking for the genes associated with browning. By doing so, it will speed up development of new varieties with longer shelf lives.
"The inability to evaluate for deterioration early in the process of developing new varieties has been a real impediment to breeding advances,” Ivan Simko, a research geneticist at the ARS Crop Improvement and Protection Research Unit in Salinas, Calif., said in the release.
Knowing the molecular markers allow breeders to select varieties that exhibit those traits, according to Simko, who led the study into deterioration.
Lettuce had a farm-gate value of more than $2.5 billion in the U.S. in 2017, according to the release, making it a top-10 value crop for the country.
Current efforts to control browning and prolong shelf life include modified atmosphere packaging and flushing salad bags with nitrogen gas to reduce oxygen in the bags. Those practices are costly and can lead to other problems such as off-odors.
"Our study was aimed at finding lettuces that possessed low browning potential without the need for limiting the oxygen supply," research food technologist Yaguang (Sunny) Luo, said in the release. Luo led the browning study and is with the ARS Food Quality Laboratory in Beltsville, Md.