Scientists using an ultrasound-chlorine washing combo made a clean sweep of the deadly E. coli pathogen from spinach leaves.
This way, it is possible to "reduce the total number of food-borne pathogenic bacteria by over 99.99 percent," said Hao Feng, professor of food science and human nutrition, University of Illinois.
"Combining technologies is the key to bridging the gap between our current capacity and what USDA would like to see. The use of ultrasound exposure during chlorine washing gives the industry a way to significantly enhance microbial safety," he said.
The USDA is looking for proposed technologies that can achieve a four to six-log reduction in pathogen cells (a six-log reduction would achieve a millionfold reduction in such bugs), the journal Innovative Food Science and Emerging Technologies reports.
The food processing industry can presently achieve a one-log or tenfold reduction. In comparison, the Illinois technique yields a four-log reduction, according to an Illinois statement.
If even part of a leaf escaped the full ultrasonic treatment, it could contaminate the rest of the produce, he said. Hao Feng and team have used the technique on iceberg and romaine lettuce, as well as spinach, with similar results.