It’s all about the heat: Peppers grow hottest in warm weather

Published 12:00 am Sunday, July 5, 2009

One of our callers last week wanted to know why the peppers from his garden were not as hot as he expected. Today’s column will discuss the factors that give peppers their hotness and how hotness is rated, as well as some types of peppers.

A pepper’s hotness is chemically different from its flavor. The source of the fiery sensation is a group of naturally occurring chemicals called capsaicins. The effects of capsaicins have been described as a slow burn on the tongue and mid palate.

Flavor, on the other hand, is associated with the pigments that give the fruit its color. Most peppers begin their development in some shade of green, then change to red, orange, yellow or purple as they ripen. Generally, the deeper the color, the stronger the flavor.

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Capsaicin content is dependent on many factors, including genetics, climate, geographic location and stage of ripeness. Our warm region generally produces hotter peppers. Warm nights seem to be responsible for higher capsaicin content. Capsaicin production in peppers begins at one month and increases with maturity.  

Wilbur Scoville, inventor of the Scoville Heat Index, ranked peppers in order from mildest to hottest. The index starts with zero — the mildest — and goes over 1,000,000 to indicate the hottest peppers. Using this index, it is not uncommon for the same type pepper — jalapeños, for example — to have a wide range of hotness depending upon their growing conditions. The Scoville Heat Index for jalapeños can range anywhere from 2,000 to 8,000, for example.

Gardeners wanting really hot peppers should first select a type of pepper genetically capable of producing the heat desired. Then, allow the peppers to stay on the plant until fully mature, to minimize watering near harvest time and to hope for sunny, dry weather. Less mature, overwatered peppers will result in a milder taste. Cloudy weather as few as three days before harvest can also reduce hotness.

Using the Scoville Index, one could probably either start with bell peppers or pimiento peppers. The index for bell peppers is zero and pimiento peppers have an index of about 500 — very mild. Beyond the jalapeño is the serrano pepper. Serranos look much like jalapeños, but are much hotter. On the Scoville Index, they will range from 10,000 to 25,000, which places them in the same heat range as cayenne peppers. Cayennes are usually dried and used in powder form.

Tabasco peppers used to make Tabasco sauce range from 30,000 to 60,000 on the Scoville index. One of the hottest peppers commonly used today is the habanero chili pepper — 150,000 to 350,000. The Naga Jolokia, however, is the hottest pepper in the world with a Scoville heat index of more than 1,000,000. It is said that just one seed from this pepper can burn for as many as 30 minutes.

Hot peppers are quite versatile in that they can be used fresh, dried or frozen and are a good source of vitamins. In fact, green hot peppers have more vitamin C per weight than citrus fruit, and red hot peppers have more vitamin A than carrots. Hot peppers are low in calories, too.

John C. Coccaro is county Extension director. Write to him at 1100-C Grove St., Vicksburg, MS 39180 or call 601-636-5442. E-mail him at