In Your Food: The Chemical Treatment of Potatoes to Inhibit Eye Growth

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Home / In Your Food: The Chemical Treatment of Potatoes to Inhibit Eye Growth
Would you buy a potato with eyes all over it? Image by  ostephy

Would you buy a potato with eyes all over it? Image by ostephy

You pick up a can or jar of food to read the label to see what the content ingredients are. You’re satisfied, and make the purchase for your next meal. Sometimes, though, there is no list of ingredients – as when you buy an apple.

You can tell whether the apple has been waxed, and you are aware there may be traces of pesticide you will need to wash off, but there are times when you may be totally unaware of what else has been applied to such a food item.

Say for instance when you purchase a potato. Are you aware that after harvesting, the potatoes were probably sprayed with a chemical or chemicals? The potatoes may be in storage for four to six months or more.

During that time, untreated potatoes would develop “eyes.”

Who wants to purchase potatoes with eyes? Few enough people, apparently, that growers and grocers want to inhibit eye growth.

Inhibiting Eye Development in Growing Potatoes

One obvious approach is to inhibit eye growth in developing potatoes – while they are still in the ground. The currently popular chemical for the purpose is maleic hydrazide, also known as 1,2-dihydropyridazine-3,6-dione. Growers must apply care in not applying the hydrazide too early, or fewer tubers will develop.

Maleic Hydrazide - Image by Mrgreen71

Maleic Hydrazide inhibits eye growth in growing potatoes. Image by Mrgreen71

The EPA facts sheet for Maleic Hydrazide says, “Current use practice limitations prohibit treating crops within 7 days of harvest, and grazing or feeding forage or hay from treated areas to livestock.” This is doubtless of importance because the hydrazide doesn’t remain on the foliage or the outside of the potato, but penetrates through the phloem into tuber interiors.

Inhibiting Eye Development in Stored Potatoes

After cleaning and healing wounds from the harvesting process, producers can treat stored potatoes – oftentimes by misting – to prevent the growth of potato eyes or buds.

The chosen chemical for this process is chlorpropham, or isopropyl (3-chlorophenyl) carbamate. Other disciplines often employ carbamates as insecticides, preservatives and polyurethanes.

The EPA facts sheet for Chlorpropham indicates in its use for potatoes, that it is non-carcinogenic, but is not without risks, and that the tolerance value for post-harvest potatoes should be reduced from 50 ppm (parts-per-million) to 30 ppm.

What Happens When You Cook These Chemicals?

At least one study indicates that residues of maleic hydrazide after cooking is not significantly different than levels before cooking. Residues of chlorpropham were a little less for cooked potatoes than for raw ones, however you’ll eliminate most of the chemical if you remove the peelings, and avoid eating them.

Chlorpropham Image by Roland Mattern

Chlorpropham is non-carcinogenic, but isn’t exactly health food. Image by Roland Mattern

Wash Your Potatoes

As might be expected in the case of a commercial product, persons who profit from consumer use of that product will tend to minimize risks associated with it. Others who would profit if that product was put in a negative light are likely to overemphasize its failings. Government agencies generally maintain a stand more middle of the road. It is up to the informed public to determine the viewpoint they will adopt.

If you choose to purchase potatoes that have received treatments either during growth or after, it is a good idea to thoroughly wash the potatoes, especially if you’re planning to eat the skins.

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