The search for safer spinach

| December 10, 2012 | 0 Comments

Food poisoning outbreaks associated with fresh produce seem to have become more common in recent years, especially in the USA. Just last month 28 cases of E. coli O157:H7 infection in the New York area were linked to contaminated organic spinach and Spring Mix. The reason for the apparent increase in such outbreaks remains unclear, but it is probable that several factors are important. One may be the growing demand for vegetables requiring minimal preparation. Today’s consumers are unwilling even to wash salad ingredients and want them in ready-to-eat form, so that growers and processors must deal with any contamination in the supply chain. Regular reports of produce-related outbreaks demonstrate that this is not always effective.

A solution already widely applied by the produce industry is to decontaminate fruits and vegetables by applying an antimicrobial wash, usually chlorine. Unfortunately this doesn’t work terribly well in terms of reducing microbial numbers and there are enduring concerns about chlorine residues on produce. The problem has spawned many research projects aimed at improving decontamination methods and learning more about how pathogens survive on plants.

One such project at the University of Illinois has been looking again at the chlorine wash, but in combination with an ultrasound treatment to remove E. coli O157 from spinach leaves. The researchers focused on ensuring that all leaf surfaces receive an even exposure to the treatment and have achieved 4-log reductions. This represents a big improvement over the performance of chlorine washes used in isolation. At present the technique has only been applied as a pilot system, but if it can be as effective at the industrial scale it could be a very useful tool for produce suppliers.

But, back in September, this blog observed that prevention is better than cure when it comes to food contamination. Although this latest decontamination technique seems to work quite well compared with many in current use, is such sophisticated technology really the most cost effective way to deal with the problem? A ‘silver bullet’ treatment has great appeal for the produce industry, but simply improving measures for keeping animals out of vulnerable crops might be a better option.

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