Processors that use waterjets to cut lettuce may have an advantage over those using blades.

A University of California-Davis study involving Salinas, Calif.-based Fresh Express found improved fresh-cut lettuce longevity and quality using Baxter Springs, Kan.-based KMT Waterjet’s cutting system.

“KMT has long felt that waterjet cutting produce would be better than using blades,” said Bob Pedrazas, KMT marketing manager. “Instead of a compression cut like a blade, which causes a certain amount of damage to the cell structure of the produce — especially as the blade dulls — a waterjet cut is an erosional process that would not do as much damage.”

For the first of two tests in the study, Fresh Express conventional whole head hearty romaine lettuce was harvested and stored overnight at 36.5 degrees Fahrenheit and held on ice until stored or packaged.

Lettuce was cut to a 2-inch by 2-inch size using a dull knife, a sharp knife, a fuzzy nozzle waterjet (at 35,000 psi) and a sharp nozzle waterjet (at 55,000 psi).

The study found no notable differences among cutting treatments until after 12 days storage in plastic bags at 36.5 degrees Fahrenheit.

By 18 days, however, lettuce cut using the sharp nozzle exhibited overall better visual quality with less discoloration, while the fuzzy nozzle proved to be the worst cutting treatment.

Lettuce cut with the sharp nozzle also exhibited the lowest bacteria count during testing over the course of the study.

Waterjet cutting offers enhanced food safety, reducing the possibility of cross-contamination associated with blades that can pick up and spread pathogens to items it cuts, Pedrazas said.

For the second part of testing under similar conditions using thinner romaine, lettuce cut with the waterjet sharp nozzle showed superior overall visual quality and color by 12 days.

Another round of testing with Fresh Express is planned for August.

Among fresh-cut suppliers using waterjets to cut produce are Dole, San Antonio-based Fresh from Texas Inc., Moore, Okla.-based Vaughn Foods and Oviedo, Fla.-based Duda Farm Fresh Foods, which has been using KMT waterjets to cut celery for five years, Pedrazas said.