In a previous 2-part blog, we looked at capsaicin; the culprit behind a hot pepper´s bite. In the first entry we looked at its history, where it is found, why it is found in hot peppers, and how it is measured. Here is something we haven´t covered, though; how the Scoville scale works.

We are used to seeing lists crowning the Carolina Reaper as the hottest pepper in the world, with a measure of 2,200,000 Scoville units. People often confuse this number with the true hotness of this variety. However, this is the incorrect way of interpreting this value. 2.2 million is the highest value ever measured for an individual pepper of this cultivar, and the capsaicin content of a pepper may vary from fruit to fruit, even in peppers from the same plant. Capsaicin content can vary depending on the stress the plant is under; access to water, nutrition of the soil, and sunlight are all factors that affect the capsaicin content of the pepper.

In the second entry we covered the way capsaicin works and how it interacts with your body for that spicy high. We also talked about why we love peppers, and the endorphin and dopamine rush that your body supplies to try to counteract the pain and burn. This has caused people to dedicate themselves to the breeding of hotter and hotter chili peppers. Generations of selective breeding and controlled growing conditions have eventually led to the development of new cultivars like the Scorpion and Carolina Reaper peppers. This process has led to some very interesting developments on the phenotype of the fruit. In 2015, researchers at the New Mexico State University Chile Pepper Institute made a breakthrough discovery on how exactly these Super-Hot peppers manage to pack so much heat. To understand this incredible development, however, we need to talk about the anatomy of normal chili peppers. The fruit has several key parts we must look at more closely.

The key parts here are the placenta and the pericarpal tissue. In normal peppers (like the serrano in the picture), the heat is in the placenta, where it has glands that secrete the capsaicin. You can see that the placenta extends as ribs to the apex of the pepper. These ribs are the white part you find on the inside of a pepper. Now, here is the difference: the endocarp, mesocarp, and exocarp that form the pericarpal tissue normally has no heat, except for perhaps very light “capsaicin bleeding” into the flesh. In these Super-Hot cultivars however, capsaicin secreting vesicles were found in the pericarpal tissue of the fruit. If you´d like to take a look at it, you can find the research paper with the images here. It looks amazing under a microscope. These capsaicin vesicles are the secret behind the amazing level of heat in the peppers. Look at the amount of capsaicin on this Chocolate Congo endocarp. You can see the droplets of capsaicin on the surface.

It is not the only secret, however. Here is a Carolina Reaper; do you see how bumpy it is, and the way if folds into itself and then ends in a sting? These pleats and bumps increase the pepper´s surface area, successfully getting more capsaicin into the pepper.

The incredible amount of heat of these peppers do not mean that they do not have a special aroma or taste; in fact, behind all that heat, complex profiles linger. The Carolina Reaper is one of the sweetest and most fragrant peppers there is. The Ghost Pepper has a sneaking and building heat that makes you think it is never going to end. Each of these peppers have their own special something and are suited for different preparations. Get to know them!