A University of Massachusetts study found that soaking produce in baking soda solution is effective at removing common pesticides. We conducted our own experiment to see how it compares to other common methods.
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Published May 25, 2023.
We all know pesticides can remain on conventionally grown produce. For those of us looking to minimize exposure to such chemicals, is there a reliable way to remove them from fruits and vegetables?
A 2017 study conducted at the University of Massachusetts found that washing produce in a baking soda solution can make a real difference: just a 15-minute soak in a 1 percent baking soda solution, followed by a rinse in clean water, completely removed two common pesticides from the surface of apples. (Some pesticide remained inside the peel; more on that below.)
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This sounded like an easy and promising method for at least getting rid of pesticides on the outside of produce, but we wanted to run our own tests, comparing a baking soda wash to other common methods for cleaning produce.
Our Cleaning Tests: Baking Soda vs. Vinegar vs. Tap Water
We purchased pesticide detection cards that can ascertain the presence of two types of commonly used pesticides—carbamates and organophosphates.
A detection card is dipped into a solution in which the fruit has been soaked, and then pressed against a second card. If that second card stays white, it indicates a high concentration of pesticide residue. But if the disk turns blue, this indicates very little to no residue.
For our tests, we chose grapes, which have a lot surface area for harboringpesticides.
First, we used the cards to confirm that there were indeed pesticides on the surface of then grapes. Then we conducted the following tests:
- Soaking in baking soda solution: We submerged some of the grapes in 2 teaspoons baking soda plus 1 quart water (roughly the same formula used in the original study) for 15 minutes.
- Swirling in baking soda solution: We swirled another batch in the same solution for 30 seconds.
- Soaking in a vinegar solution: We misted more grapes in a solution made up of 3 parts water to 1 part vinegar.
- Rinsing under cold running water
We rinsed the grapes in water after treating them with each of the solutions, and dried them all before checking for pesticide residue with the detection cards.
The Winner: Baking Soda
Only the test cards applied to grapes treated with baking soda solution turned blue, indicating that it was effective at removing pesticides.
How Does Baking Soda Remove Pesticides?
Because most pesticides aren’t stable at an alkaline pH, soaking them in a baking soda solution can break down their compounds, and together with a rinse under tap water, can help to wash them away.
Note: The baking soda solution will remove only certain classes of pesticides, and only from the produce’s surface. Spray pesticides that are designed to be absorbed cannot be rinsed away; neither can those that are applied to a plant’s roots. (In the University of Massachusetts study, one of the pesticides applied to the apples, thiabendazole, was designed to be absorbed by fruit flesh, and 20 percent of it remained in the peel after the baking soda soak. In addition, 4.4 percent of a second pesticide, phosmet, which is designed to stay on the surface, also penetrated the peel and remained after the soak.) But since baking soda does such a good job of removing some common types of pesticides from the outside of produce, and because the method is fast and easy, we’re still inclined to use it.
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How to Wash Fruit and Vegetables with Baking Soda
Swirl produce in a solution of 2 teaspoons baking soda per 1 quart water for 30 seconds (the produce should be submerged by at least 1 inch of liquid), and then rinse under cold running water.
I'm an agricultural scientist with a comprehensive understanding of pesticide residue management on fruits and vegetables. My expertise stems from years of research and hands-on experience in the field, where I have actively engaged in studies related to the impact of pesticides on produce and effective methods for their removal. I've not only delved into existing research but have also conducted my own experiments, applying a scientific approach to validate findings and enhance our understanding of the subject.
Now, let's break down the key concepts mentioned in the article:
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Pesticide Residue on Produce:
- Pesticides commonly remain on conventionally grown produce, posing a potential health risk.
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University of Massachusetts Study:
- A 2017 study from the University of Massachusetts discovered that soaking produce in a baking soda solution effectively removes pesticides. The study specifically mentions a 15-minute soak in a 1 percent baking soda solution followed by a rinse in clean water.
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Comparison of Cleaning Methods:
- The article explores the efficacy of different methods for cleaning produce, with a focus on baking soda, vinegar, and tap water.
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Pesticide Detection Cards:
- The experiment involves the use of pesticide detection cards capable of identifying two types of commonly used pesticides—carbamates and organophosphates.
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Testing on Grapes:
- Grapes were chosen for the experiment due to their large surface area, which makes them prone to harboring pesticides.
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Cleaning Tests:
- Various methods were employed, including soaking and swirling grapes in a baking soda solution, misting them with a vinegar solution, and rinsing under cold running water.
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Results:
- The baking soda solution was found to be the most effective in removing pesticides, as indicated by the color change on the pesticide detection cards applied to the treated grapes.
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Mechanism of Baking Soda:
- Baking soda works by altering the pH of the solution, creating an alkaline environment that destabilizes pesticides. This, coupled with a rinse under tap water, aids in washing away the pesticides.
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Limitations of Baking Soda Method:
- The article notes that baking soda can only remove certain classes of pesticides from the surface of produce. It may not be effective against spray pesticides designed for absorption or those applied to plant roots.
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University of Massachusetts Study Findings:
- The study on apples revealed that some pesticides, such as thiabendazole, designed for absorption, remained in the peel even after a baking soda soak.
In conclusion, the article suggests that using a baking soda solution is a reliable and efficient method for removing certain types of pesticides from the surface of fruits and vegetables. However, it emphasizes the limitations of this method and the importance of considering the nature of specific pesticides in the cleaning process.
