US scientists at the Agricultural Research Service (ARS) of the US department of agriculture in Maryland have found that combining ultrasound with wash-solutions can enhance the safety of leafy green vegetables and salads.

ARS food technologist Yaguang Luo first focused on reformulating a new sanitising wash that works better than chlorine for the fresh-prepared market as the chemical does not eliminate all the organisms that can be present.

Luo has been collaborating with colleagues at the University of Illinois to test combining the use of several sanitising washes, including the new formulation, with ultrasound to improve food safety of fresh-cut salad leaves before bagging. They conducted a study to determine the effects of selected ingredients, with or without ultrasound, on the reduction of Escherichia coli populations on spinach.

The highest E. coli reduction was 4.5 logs - meaning the bacteria decreased from about 300,000 colony-forming units to less than 10. This reduction was achieved through combining the newly formulated wash solution treatment with ultrasound treatment.

The combination of a new wash solution with ultrasound can therefore potentially be used to enhance the microbial safety of leafy green produce before the bagging process, according to Luo.