A: The answer is sulfites.

Have you ever wondered why dried fruit such as apples and apricots that you buy at the supermarket maintain their luster but when you slice an apple at home it immediately starts to brown?

Do you glance at the wine label while sipping your pinot noir and wonder why “contains sulfites” should appear there?

A brief intro to sulfites follows.

What you need to know:

1. Sulfites are inorganic salts that have antioxidant and preservative properties. Examples that appear on food labels are sulfur dioxide, sodium bisulfite, sodium sulfate,  and potassium bisulfite.

2. Sulfites prevent discoloration of dried fruit, some  shrimp, and some potato products. They also prevent wine from spoiling by stopping bacterial growth.

3. Sulfites destroy vitamin B1 (Thiamin). Too bad.

4. Unfortunately for about 1% of the population, sulfites can cause severe respiratory reactions within minutes of consumption, especially for susceptible individuals such as asthmatics. For the other 99%, sulfites are considered safe. However,  people may develop sulfite sensitivity at any point in their lifetime, and scientists haven’t figured out the cause yet.

5. The FDA requires food manufacturers to disclose the presence of sulfiting agents in concentrations of at least 10 parts per million, but the threshold causing reaction mayactually be lower. Sometimes manufacturers recall products because higher levels of sulfites are found in their products. For example, just today, Goya Foods announced a recall of Dried Yellow Potato.

What to do at the supermarket:

Sulfites appear in the food label of dried fruit, wines, and other products such as canned fruit. Organic dried fruit do not use sulfites, and that’s why they look brown and less appealing. Some wines don’t use sulfiting agents either, but the difference is not visibly discernible.

If you are buying products in bulk at the supermarket, you can sometimes ask the produce manager to see the bulk package labeling.

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