Researchers at the University of California, Riverside, have been studying the effectiveness of disinfectant washes as a means of killing foodborne pathogens on spinach leaves and other salad vegetables.
Spinach and other leafy greens may become contaminated with pathogens such as Salmonella and E. coli while growing in the field, either through dirty irrigation water or contact with animals. A number of recent foodborne disease outbreaks have been traced back to contaminated spinach and other greens. Commercial crops are therefore washed before packing and sale, often using a chlorine solution as a disinfectant.
The researchers tested the effectiveness of commercial chlorine washes and found that they should work much better than they actually do at the concentrations typically employed. The main reason for this seems to be the unevenness of the spinach leaf surface.
They then developed a model for the flow of chlorine solution across the leaf surface and found that some areas were exposed to concentrations up to 1,000 times less than others. This means that bacteria on certain parts of the leaf may be protected and survive, acting as a reservoir for cross contamination during processing, according to researcher Dr Nichola Kinsinger.
Dr Kinsinger presented the results of the study at the 250th National Meeting & Exposition of the American Chemical Society last week and more information can be found here.