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Tips for improved shelf life and food safety when washing fresh fruits and vegetables


By Annalisa Hultberg, Extension Educator, Food Safety

Harvest is well under way, and crops are coming in strong in many areas with our intense heat. As you prepare your products for sale, many are rinsed to remove soil or cooled in water to crisp them up. While rinsing produce can cool it and remove that soil, it also can spread contamination that might be present on the exterior to other produce, making a small problem a bigger one.  

For example if a melon or lettuce leaf had fecal contamination from a bird or rabbit, and that produce was put into a bulk washing tank, the pathogens in the feces can spread to the other pieces via the water. Contamination can also be introduced from workers hands or from dirty wash tanks or tools.  Illness from the bacteria can include diarrhea, vomiting, fever, nausea, and can even be more serious for some individuals with compromised immune systems.  

Some basic steps can go a long way to reduce the potential risks of contamination in your postharvest washing, and also have the added benefit of improving shelf life and storage quality of your product.  Here are some tips to think about as you rinse your fresh produce to ready it for sale.


1. All water used for washing, cooling and other postharvest use must be like drinking water. 

First, consider the quality of the water you are using to wash your produce.  Well (ground) water should be tested at least annually for bacteria. Municipal water does not need to be tested. Surface water like streams and ponds should never be used for postharvest applications like washing produce, since the water quality is highly variable and this water is vulnerable to bacteria and pollutants from animals, runoff, flooding and other sources of contamination.

Test well water at least annually for presence of generic E. coli. Results should indicate not detectable in 100 ml.  When you call the lab, they might say that a potability or drinking water test is generally for total coliforms.  Coliforms are an indicator of the water quality and of bacterial contamination in the well, but E.coli is better as it is a direct indicator of fecal contamination, and therefore the likelihood that there will be harmful pathogens in the water. The FSMA Produce Safety Rule requires testing for the presence of generic E. coli.  Tests are about $35- $40 each. 

To find a lab: Minnesota Department of Health Accredited Labs database or for more information about water testing and to find a lab, see Testing Water for FSMA Produce Safety Rule

Taking a water sample from a well head 

2. Don't wash unless needed

Not all produce should be washed before it goes to the customer. Herbs and berries are typically not washed until right before consumption, as washing begins the process of degradation and will result in lower quality produce with a shorter shelf life. Of course many crops do need to be washed to remove field soil and/or to hydrocool and crisp up. However sometimes washing can actually increase the risk of contamination, as water spread pathogens readily, moving fecal contamination around via the water. So, washing should be done with care and only when needed.

Consider the crop before washing. Do the peppers, cabbage, tomatoes or eggplant need to be washed? Depending on the crop, how it was grown (on plastic much for example, or in a high tunnel), on the rainfall, perhaps no postharvest cleaning is needed at all. Sometimes they are simply dusty and a light rub with a clean towel or paper towel is all that is needed.