Jalapeno and serrano peppers look almost like twins. Both are bright-to-deep green in appearance, although a serrano tends to be sleeker and longer than a jalapeno. There are many types of green chilies, but serrano and jalapeno peppers also are similar in terms of taste. However, make sure you know which pepper you've chosen before you dice one up for salsa or add it to your favorite ethnic cuisine. Even though they are mild compared to the fiery habanero or screaming hot ghost pepper, the contrast between a serrano chili and jalapeno lies in its temperament -- in this case, the heat.
Check the Chart, and the Nose
People have different tolerances to heat when it comes to hot peppers. One of the most trusted sources to consult when determining a pepper's effect on the taste buds is the Scoville Scale that measures heat units across the gamut of pepper species. According to the Scoville Scale, when compared with other peppers, both jalapeno and serrano chilies are midrange in regard to heat. However, serranos are hotter than jalapenos. The Scoville Scale gives jalapenos an average 2,500-8,000 heat units, while serrano peppers fall into the 8,000 to 22,000 range. The higher the number, the hotter the pepper.
If you don't have access to a Scoville Scale and you want to know which pepper is the hottest -- particularly if you have to choose between two serranos or two jalapenos -- conduct the less-scientific sniff test. The What's Cooking America website suggests cutting the pepper and holding it to your nose. The more intense the tingling sensation, the hotter the pepper. Alternatively, a mild pepper will not cause any sensation.
Controlling the Heat
When purchasing jalapeno and serrano peppers, look for smooth, thin skins and ensure they are firm to the touch. Both peppers have relatively thin skins, which means they do not have to be peeled or roasted prior to cooking. If the recipe calls for a jalapeno and you only have serrano peppers, don't despair. Serranos can be substituted for jalapenos, and vice versa. There also is a way to tone down the heat, even minimally. Prior to cutting into either type of pepper, don a pair of rubber gloves to prevent the oils from coming into contact with your skin. Slice the pepper open and remove the ribs and seeds if you want to reduce the pepper's heat.
Some Like It Hot
Although serrano peppers are considered spicy-hot compared to most jalapenos, you may be able to grow or buy varieties of jalapenos that possess varying degrees of heat. For example, Senorita jalapeno peppers are among the hottest, according to the Colorado Integrated Food Safety Center of Excellence website. Milder varieties of jalapenos include Fresno peppers -- that sport thinner walls than traditional jalapenos -- Sierra peppers and Mucho Nacho peppers.
Versatility In Cuisine
Serrano and jalapeno peppers are interchangeable when it comes to Mexican cuisine, particularly in salsa. However, those with a penchant for heat often choose the serrano. The jalapeno is often used in Indian curries and rice. Both serranos and jalapenos also can substitute for Thai chilies in traditionally spicy dishes such as in soups, noodles and rice. They also pair well in Thai shrimp or chicken dishes. Both types of peppers are generally used fresh, but also can be pickled.