Chili peppers can bring tantalizing spice to our dishes. However anyone who touches these fiery red fruits will feel a strong burning sensation. This unique sensory experience often leaves people bewildered and even in pain. Why does touching chili peppers cause intense burning?
Pain Sensation
Some of you may wonder, "Why do my hands burn when they don’t have taste buds, unlike my tongue?" Here’s where I need to clarify this common misconception. Spiciness isn’t a taste; it’s a pain sensation.
When spicy food enters the mouth, "the pain-related fibers that control the tongue and are sensitive to heat are activated, causing neurons to react as if there is heat stimulation in the mouth" (Christian H. Lemon, 2022). Since spiciness causes our nerves to “feel overheated,” it’s no surprise that any skin touching chili peppers, not just our taste buds, can sense the burn.
Taste buds in different areas of the tongue are responsible for recognizing specific tastes, as shown in the picture. However, spiciness is not a sensation in a specific part of the tongue, but a pain sensation that can be felt on all skin surfaces.
Capsacin
The protagonist of this article, capsaicin is the main potent irritant in pepper.
They binds to sensory nerve receptors in our skin, triggering a series of chemical reactions that make us feel heat, pain, and inflammation. The nerve receptor it mainly "attacks" is called TRV1. Most mammals have this nerve receptor, and the more common "lucky ones" are birds. They do not have the TRV1 receptor, so birds are excellent helpers for pepper sowing.
Note that capsaicin itself does not generate heat, but it makes the areas of our body that come into contact with it feel like they’re experiencing high temperatures.
This explains why, even after washing away capsaicin with water, we still feel a burning sensation in our mouth.
More interestingly, this reaction mechanism is not just meant to cause discomfort but is also part of a "chemical war" between plants and animals. Capsaicin evolved as a self-defense mechanism in chili plants to deter animals from eating their fruits.
Measuring "Spiciness"
So, how do we measure the spiciness of chili peppers? This brings us to a specific standard for gauging heat—the Scoville Heat Units (SHU).
The Scoville Heat Units were invented by American pharmacist Wilbur Lincoln Scoville in 1912. It measures the spiciness of chili peppers by diluting their extract. Specifically, the Scoville Heat Units indicate how many times a unit of chili extract needs to be diluted until no heat is detected.
For example, sweet bell peppers have a SHU value of 0 because they have no spiciness. In contrast, extremely hot peppers like the Carolina Reaper can have SHU values over 2 million, putting them on par with pepper spray.
As you may have noticed, this testing method is quite subjective. After all, "no heat detected by the tester" varies with each individual’s tolerance to spiciness and is not a highly reliable standard.
But the good news is that with technological advances, scientists have adopted a new method to identify heat—high-precision liquid chromatography (HPLC). This method can separate compounds in a mixture, helping us identify and quantify the proportions of each component.
If you ever eat a Carolina Reaper, good luck going to the bathroom later…
So, does capsaicin only hurt us?
Not really, it also has benefits like weight loss, pain relief, and cancer prevention (Wahyuni, Ballester, Sudarmonowati, Bino, & Bovy, 2013). Since the discovery of capsaicin’s medicinal value, this devious substance has been welcomed by more and more people. According to researches, capsaicin can inhibit angiogenesis and tumor metastasis by inducing cell apoptosis and inhibiting the expression of vascular endothelial growth factor (VEGF)。
In addition, capsaicin can inhibit the growth of prostate cancer by reducing the expression of androgen receptors and preventing tumor occurrence by inhibiting NADH oxidase.
These studies show that capsaicin has significant potential in cancer prevention, and because of its natural source, it has relatively few side effects and has become an important component in many cancer prevention and treatment programs. At the same time, capsaicin has also been shown to have anti-inflammatory properties. It can regulate a variety of inflammatory mediators such as IL-1β, IL-6, IL-8 and IL-10, which makes it also widely used in the treatment of chronic inflammatory diseases.
Independent Research
Recent studies have shown capsaicin can alleviate oxidative stress, regulate lipid and energy metabolism, and exhibit significant anti-inflammatory properties.
Using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS), capsaicin has been demonstrated to scavenge free radicals and reduce oxidative stress responses. It stimulates fat breakdown and oxidation while inhibiting fat synthesis, reducing body weight and fat mass.
Additionally, capsaicin enhances calorie expenditure and fat oxidation, aiding in weight loss. Its anti-inflammatory properties inhibit the expression of inflammatory genes and proteins.
Capsaicin also has a notable impact on gut microbiota, improving glucose tolerance and insulin sensitivity. These findings indicate that capsaicin offers numerous health benefits, particularly in antioxidant, weight loss, anti-inflammatory, and gut health regulation (Peng et al.).
So, what should we do if we get burned by chili peppers?
Treatments to pepper burn
Use Dairy Products
Drinking milk or yogurt is an effective way to relieve the heat. The casein in dairy products can bind with capsaicin, helping to neutralize its effects and reduce the burning sensation. This method is more effective than drinking water, as water cannot dissolve capsaicin and may spread it to other parts of the mouth.
Eat Fatty Foods
Such as butter, cream, or peanut butter. Fat can dissolve capsaicin, helping to alleviate the burn.
Drink Sugary Beverages
Sugar can also help reduce the heat, so drinking some sugar water or sugary beverages might be helpful.
Apply Vegetable Oil or Olive Oil
If your hands are burned, you can apply vegetable oil or olive oil to the affected area, then wash with soap and warm water. The oil can help dissolve and remove capsaicin.
Capsaicin, the compound responsible for the fiery heat in chili peppers, plays a significant role in culinary and medicinal fields. While it can cause a burning sensation upon contact, understanding its effects and how to manage them can enhance our enjoyment of spicy foods. Capsaicin brings not only unique flavors to our dishes but also offers potential health benefits, including pain relief, weight management, and cancer prevention.
By mastering how to handle capsaicin, we can appreciate its contributions to our meals and health without being overwhelmed by its intensity. Ultimately, with the right knowledge and precautions, we can enjoy the flavorful and beneficial aspects of capsaicin, adding both spice and health to our lives.
Reference
Charles Oluwaseun Adetunji, Olaniyan, O. T., Мaksim Rebezov, Mohammad Ali Shariati, Oluwatosin Ademola Ijabadeniyi, Olulope Olufemi Ajayi, Inobeme, A., Modupe Doris Ajiboye, Wadzani Palnam Dauda, Ghazanfar, S., Juliana Bunmi Adetunji, & Uchenna Estella Odoh. (2023). Roles of nutrigenomics in drug discovery and development. Elsevier EBooks, 277–299. https://doi.org/10.1016/b978-0-12-824412-8.00016-3
da Silva, G. (2020, June 11). What makes pepper spray so intense? And is it a tear gas? A chemical engineer explains. Findanexpert.unimelb.edu.au. https://findanexpert.unimelb.edu.au/news/12428-what-makes-pepper-spray-so-intense%3F-and-is-it-a-tear-gas%3F-a-chemical-engineer-explains
Thermo Fisher Scientific. (n.d.). HPLC Basics - US. Www.thermofisher.com. https://www.thermofisher.com/ca/en/home/industrial/chromatography/chromatography-learning-center/liquid-chromatography-information/hplc-basics.html#:~:text=High%2Dperformance%20liquid%20chromatography%20(HPLC
Peng, Zifang, et al. “Recent Advances in Analysis of Capsaicin and Its Effects on Metabolic Pathways by Mass Spectrometry.” Frontiers in Nutrition, vol. 10, 28 July 2023, https://doi.org/10.3389/fnut.2023.1227517.
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