Researchers at the University of Illinois have developed a decontamination technique capable of achieving a 4-log reduction in numbers of E. coli O157:H7 cells on spinach leaves.
The new technique combines chlorine washing with a continuous ultrasound treatment to destroy bacterial cells on the leaves much more effectively than chlorine washing alone, which typically achieves a 1-log reduction.
Although ultrasonic treatments have been tried before, the University of Illinois process uses three pairs of large-area ultrasonic transducer boxes to form a channel through which the leaves pass during washing. This ensures a continuous flow and uniformity of the ultrasonic field, so that all the leaves receive the same exposure. The technique has also been tested successfully with lettuce.
A report on the process is published in the journal Innovative Science and Emerging Technologies and can be accessed here.