Keeping lettuce safe from farm to table

VINCENNES, Ind. — Researchers at Purdue University are studying ways to reduce foodborne illness in lettuce.

According to preliminary results of one study, chlorine dioxide is not a good choice for sanitizer in lettuce bubbling systems.

Using peracetic acid as a sanitizing solution, and washing greens for 10 minutes in a bubbler, is a promising combination to reduce contamination.

Foodborne illness in produce can be traced back to leafy greens about 25% of the time.

“We’re looking at how we can treat these products in a post-harvest environment to minimize the risk of contamination from anything coming from the farm,” said Scott Monroe, food safety educator with Purdue Extension, at the Southwest Purdue Ag Center’s field day.

Their research involved setting up 16 individual wash stations. Ten percent of the lettuce was artificially inoculated and divided up amongst the stations.

“We used a control of no sanitizer, chlorine dioxide, peracetic acid and chlorine,” Monroe said. “We ran the system for one of four times: 5, 10, 15 or 20 minutes.

“We’re seeing that peracetic acid seems to have the most promise as a sanitizing solution. It looks like about 10 minutes is optimal for wash time.”

When researching food safety, Monroe said these six steps are followed:

1. Assessing the risk.

2. Identifying the risk.

3. Developing a plan to mitigate that risk.

4. Implementing the plan.

5. Monitoring.

6. Trying something different if that plan doesn’t work.

“Our goal is to do this research so we can advise growers as to what we think the best practice is and how to use these systems to minimize the risk of a foodborne pathogen getting into the system,” Monroe said.