Apple wash water validation

Adding sanitizer to apple wash water can be an effective tool to reduce cross-contamination.

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When apples are packed for fresh market, most packhouses wash the apples as they are packed. That means anything you can find on any one apple can end up in the wash water. When wash water picks up things like poop on one apple, it can spread it to every other apple that goes into the water. Scientists call this process of poop spread cross-contamination.

If you manage wash water in an apple pack house, you can prevent this cross-contamination by adding a sanitizer to the wash water. To be clear, the FSMA Produce Safety Rule does not specifically require you to add sanitizer to wash water. The PSR DOES require you to maintain the sanitary quality of the water used postharvest.

Sanitizer added to wash water does not sanitize the apples being washed, but it does prevent the apples from getting dirtier than before they went into the water. Recent work by Washington State University, Virginia Tech and Michigan State University has shown that maintaining label rates of sanitizer in apple wash water effectively prevents cross-contamination.

Using sanitizer in apple wash water can be tricky. A sanitizer is a pesticide. Like any pesticide, the label is a legal document. If someone does not follow the label, they are breaking the law. Only certain sanitizers can be used in apple wash tanks. They also need to be monitored and maintained at a certain concentration throughout operation to be effective at preventing cross-contamination. Too little sanitizer means that pathogens get through. Too much sanitizer can lead to an adulterated product.

For help with choosing the right sanitizer, learning how to monitor sanitizer levels or getting the right standard operating procedures in place, Michigan state University and the Michigan On-farm Produce Safety Team is here. Feel free to contact the Agrifood Safety Work Group at gaps@msu.edu or (517) 788-4292. You can also find your local produce safety technician on this site. 

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Article by Phil Tocco, MSU Extension Educator