The Truth About Raisins and Pesticides

Or, why I am making my own raisins from now on.

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Homemade raisins are healthier and more delicious.
Homemade raisins are healthier and more delicious.

Raisins and photo by Melissa Breyer

Every year we report on the Environmental Working Group's Shopper's Guide to Pesticide in Produce, which lists the 12 items of produce with the most pesticide residue and the 15 items with the least. There are regular appearances made on both lists by a number of fruits and vegetables, but this year the USDA data revealed a surprise cameo: Raisins.

It was the first time since 2007 that the US Department of Agriculture included raisins in their tests for pesticide residues, and the results are "shocking," says EWG toxicologist and report co-author, Thomas Galligan, Ph.D. He writes:

"Of the 670 conventional raisin samples analyzed, 99 percent tested positive for at least two pesticides. On average, each sample was contaminated with more than 13 pesticides, and one sample had 26 pesticides."

EWG did not add raisins to their "Dirty Dozen" list of pesticide-tainted items because the organization does not include processed foods (even minimally processed ones like dried fruit) in the report. But because of the heavy pesticide load, they decided to see how raisins would stack up against fresh produce. According to Galligan, "after running the analysis again, we found that if raisins were included, they would rank No. 1. By a wide margin, raisins would rank higher than fresh grapes, which would rank seventh."

The bottom line, he writes, is this: "Raisins are one of the dirtiest produce commodities on the market – and even some organic raisins are contaminated."

According to the USDA data, pesticides were generally detected less frequently on organic raisins than their conventional cousins, but not always. For some pesticides, there was no differences between organic and conventional raisins. "Bifenthrin and chlorpyrifos were detected about as often, at comparable levels, on both conventional and organic raisins," Galligan writes. Among other pesticides, 77 percent of organic raisin samples were contaminated with bifenthrin and 62 percent with tebuconazole. "Both chemicals are developmentally neurotoxic in animals and are classified by the Environmental Protection Agency as possible human carcinogens," he adds.

I asked Dr. Galligan about the pesticide residue found on organic grapes. He explained to me in an email that organic raisins must be cultivated and processed without pesticides. But, "in the USDA dataset, a number of pesticide residues were detected on organic raisins. The exact sources of the pesticides remain unclear to us."

"Because of wide-ranging spraying of pesticides in conventional agriculture, some of these pesticides may have drifted from nearby farms, or there might have been cross contamination in processing facilities," he added.

Another problem with conventionally produced raisins is that they are usually fumigated with toxic gases to control pests during storage. The USDA does not test for fumigant residues, but EWG notes that they can remain in foods after treatment.

What Are the Safest Alternatives to Conventional Raisins?

EWG recommends organic raisins over conventional ones since they did prove to have fewer pesticide residues and they can not be fumigated. But there are some workarounds here as well. Namely:

Organic Fruits and Prunes

Dr. Galligan told me that, "Ultimately, for consumers trying to limit their dietary exposure to pesticide residues, organic foods are a better choice than conventional, and prunes, whether organic or conventional, would be an even better dried fruit option. Prunes had far fewer pesticides than both conventional and organic raisins according to the USDA’s tests.”

Prunes! What a smart idea. Here were the numbers on prunes:

  • Only 16 percent of conventional prunes tested positive for two or more pesticides, compared to 99 percent of conventional raisins and 91 percent of organic raisins.
  • The average conventional prune tested positive for just one pesticide, compared to more than 13 on the average conventional raisin and four on the average organic raisin.
  • The maximum number of pesticides detected on a single prune sample was four, compared to 26 on conventional raisins and 12 on organic raisins.
  • 50 percent of conventional prunes were free from detectable pesticides, compared to only one percent of conventional and organic raisins.

Make Your Own Raisins

While happy to start adding prunes to the mix, I am all about the homemade raisins. You can use fresh beautiful organic table grapes, or sad and old organic table grapes, like the ones pictured below left ... which turned into the raisins pictured below right, and at the top of this article. It couldn't be easier (even if it is not super speedy).

how to make raisins
Sad old grapes on the left, turned into happy raisins on the right.  Melissa Breyer

My method: Preheat oven to 225 degrees F. Lightly oil a rimmed baking sheet; alternatively use parchment or a Silpat. Spread out the grapes; roast for around 4 hours, checking in occasionally to make sure they are drying evenly.

It will all depend on the grapes you start with. Sometimes four hours is plenty of time, on other occasions, they may be more plump than you'd like (but pro tip: plump raisins are sublime). Sometimes I turn the heat off and let them sit in the oven for a few more hours as it cools down.

(Granted, four hours of roasting is not practical during warmer months; for those times, WikiHow explains how to make sun-dried raisins or use a dehydrator instead of the oven.)

The results are so good; tender and delicious. The batch above was made with muscat grapes, whose floral sweetness sweetened the pot. But whatever variety you use, freshly made raisins are such a far cry from commercial, conventional raisins. And given that making one's own gives control over grape variety, pesticide load, and local fruit sourcing, you may never want to buy regular raisins again.