Much Ado About Washing Produce

We probably all splash our purchased fruits and vegetables with tap water before we prepare them for eating. But do we really know if this step is accomplishing anything? We have no idea when we choose a bright red pepper or a golden yellow apple what it has encountered in its short life so far. It may still have imperceptible bits of soil clinging to it harbouring harmful bacteria such as E. coli. It may have passed through the unwashed hands of a person sick with a contagious illness. It may have been sprayed with an insecticide or herbicide. Whatever the case, it definitely seems like a good idea to at least try to achieve produce that is reasonably clean.

By choosing organically grown produce we can limit much of the pesticides that we might be exposed to but unfortunately not all of them. Organic farmers are allowed to spray a very restricted list of synthetic pesticides that are deemed to be less toxic. Still, crops can be exposed to more than just these select few. There can be cross-contamination from neighbouring fields or persistent pesticides such as DDT lingering in the soil (1). Fortunately washing produce properly goes a long way towards removing dirt, chemicals and contaminants from the surface of our food.

There are a variety of products on the market advertised to efficiently clean pesticides off of our produce. Many of them when put to the test actually perform no better than plain water. Pesticides do not dissolve in water but using water, along with mechanical rubbing of the produce, can actually remove up to 80% of some pesticides tested (3). Other pesticides though are more resistant and persist on the food at higher levels. Utilizing fancy fruit and vegetable washes or even detergents or dish soap does not increase the removal of unwanted impurities.

Luckily science can point us in a more effective direction. Researchers found that soaking potatoes in water removes only between about 2 and 13% of pesticides but washing vegetables and then soaking for twenty minutes in plain white vinegar (5% acetic acid) removes up to 100% of four common pesticides (chlorpyrifos, DDT, cypermethrin, chlorothalonil). Unfortunately diluted vinegar worked only slightly better than plain water. Vinegar comes with some drawbacks. Large amounts are required which can be costly plus vinegar is difficult to rinse off and leaves its unmistakable taste lingering behind. Plain water was not very effective in this particular test. There was one test solution that did rise above the rest though. A 10% solution of salt (1 part of salt mixed with 9 parts of water) was at least as efficient at removing pesticides as vinegar and proved to be easy to rinse away after doing its work (4).

A different study compared plain water, a bleach solution and a baking soda and water solution in their ability to clean fruits and vegetables. The baking soda solution was a very weak mix of 1 part baking soda in 100 parts of water but it ended up to be a clear winner. After 12 to 15 minutes of soaking, pesticide residues were removed on both the surface and beneath the skin of apples (5).

Most people don’t have time to wash their vegetables for 15 to 20 minutes. Not to worry, these methods will still perform in less time, albeit not as well. Here is a good compromise. Fill a large bowl with water. Mix in a teaspoonful of baking soda or about half a cup of table salt and let the produce soak for a minute or two in the solution. Scrub lightly with a brush then rinse well. If you don’t even have time for this much cleaning, rinsing your produce under running water for at least 30 seconds will remove at least a part of the impurities that may be hiding on their surfaces.

The good news is that even if all we had to eat were fruits and vegetables exposed to normal pesticide levels, the health benefits from the consumption of these plant foods outweigh any potential risks from pesticides (2). When you bring your produce home, keep in mind the cleaning methods described above. Wash your foods the best way that you can in the time you have available and know that you are taking one more positive step for your health.

 

SOURCES:

1 Benbrook, M.C., Baker, B.P. Perspective on Dietary Risk Assessment of Pesticide Residues in Organic Food. Sustainability 6.6 (2014): 3552-3570.

2 Winter, C.K. Pesticide residues in imported, organic, and “”suspect”” fruits and vegetables. J Agric Food Chem. 2012 May 9; 60(18): 4425-4429.

3 Krol , W.J., Arsenault, T.L., Pylypiw, H.M., Incorvia Mattina, M.J. Reduction of pesticide residues on produce by rinsing. J Agric Food Chem. 2000 Oct; 48(10):4666-4670.

4 Zhang, Z-Y., Liu, X-J., Hong, X-Y. Effects of home preparation on pesticide residues in cabbage. Food Control Dec 2007; 18(12): 1484-1487.

5 Yang, T., Doherty, J., Zhao, B., Kinchla, A.J., Clark, J.M., He, L. Effectiveness of Commercial and Homemade Washing Agents in Removing Pesticide Residues on and in Apples. J. Agric. Food Chem. 2017; 65 (44):9744–9752.