It is a good time to eat spicy food in the hot summer. However, some people love spicy food, while some places try their best to ban spicy food.The Danish Food Authority has asked South Korea's Samyang Foods to recall three types of spicy turkey noodles produced by the company.because the chili content is “too high and may cause acute poisoning to consumers.”
Coincidentally, Germany also banned the sale of a brand of devil pepper potato chips nationwide because a 14-year-old student suffered from food poisoning a few hours after eating them and eventually died.
It seems that chili peppers are living up to the old saying: “One man's meat is another man's poison.” What is the scientific reason behind such divisive evaluations?
Nobel Prize winner reveals the mechanism of spicy food
When you eat chili peppers, you will first feel a tingling sensation in your mouth, followed by a burning sensation, as if there is a blazing fire burning in your mouth. This real pain and illusory heat are the result of the capsaicin in the chili peppers and the capsaicin-specific receptor in our body, the vanilloid receptor type 1 (TRPV1). In addition, it is the study of capsaicin receptors that made American neuroscientist David Julius one of the winners of the 2021 Nobel Prize in Physiology or Medicine.
Back in the late 1990s, a team led by David Julius at the University of California, San Francisco, was actively analyzing how capsaicin causes the sensations we experience when we come into contact with it.
Through various experimental methods, he finally successfully identified and cloned TRPV1, demonstrating the basis of the body's perception of spiciness at the molecular level: TRPV1 is an ion channel activated by pain and heat (noxious heat ≥42°C), which specifically recognizes afferent neurons of noxious stimuli and is widely distributed in multiple tissues and organs of the body. When the mouth comes into contact with capsaicin, TRPV1 is immediately activated, generating electrical signals that are transmitted to the brain along noxious afferent neurons, and the brain interprets these signals as “painful” stimuli. From a scientific point of view, the feeling of spiciness is defined as “pain”.
In addition to pain, how does capsaicin make us feel hot? The heat produced by eating peppers or pepper-like substances is not the result of physical heating, but after we are spicy, we become more sensitive to heat.
When TRPV1 is activated by capsaicin, the threshold for temperature perception is also lowered. Even a body temperature below 42°C will induce TRPV1 to transmit harmful heat signals to the brain, causing the brain to have an abnormal perception of “heat”. Therefore, under the dual stimulation of capsaicin and temperature, the excitability of sensory neurons expressing TRPV1 receptors is also enhanced. In summary, our feelings are “abnormally” amplified, and our mouths are like “breathing fire”.
David Julius used capsaicin to identify TRPV1, an ion channel activated by painful heat. Source: nobelprize.org
Next, our body also responds to the stimulus, which is still related to the TRPV1 receptor. TRPV1 is a non-selective cation channel expressed in both neural and non-neural tissues. Its activation leads to a large influx of calcium ions, increases the calcium ion concentration in non-neural tissues, and mediates the release of a variety of neuropeptides, such as substance P (SP) and calcitonin gene-related peptide (CGRP).
The former can induce vasodilation, increase vascular permeability, lead to edema, stimulate mast cells to release inflammatory mediators, and induce leukocytes to release proteases and reactive oxygen species. CGRP relaxes arteries, regulates blood flow to the skin, and induces neurogenic inflammation. As a result, our body induces an inflammatory response out of “self-defense”, and we begin to sweat, have a runny nose, blush, swell, etc.
Spicy food: Pain and happiness
Since eating spicy food makes us feel painful and irritated, why can't humans stop eating it?
While records of chili pepper use date back to 7000 B.C. in Mesoamerica, the study published in Science reveals that humans were growing and eating domesticated chilies from the Bahamas to the Andes by 6000 years ago, even before the advent of pottery in some areas.
During the Age of Exploration in the 15th century, Columbus and other early explorers brought chili peppers from the Americas to the Old World of Europe, and then spread them around the world through sea routes and the Silk Road. Today, chili peppers have become an important part of the diet in many countries around the world, including West Africa, East Africa, India, Southeast Asia, parts of China, South Korea, etc.
For thousands of years, people have endured the burning pain of chili peppers while diligently incorporating them into their diet. Paul Rozin, a psychologist at the University of Pennsylvania, pointed out that about one-third of the world's population eats chili peppers every day. Why? In simple terms:I just like it.
So far, most scientists still cannot fully understand why humans love chili peppers so much. Scientists in different fields have given possible explanations from different aspects.
Biologists offer an evolutionary explanation for why eating chili peppers has become a cultural preference in certain regions.
Jennifer Billing and Paul W. Sherman of Cornell University in the United States analyzed more than 4,000 recipes from 36 countries around the world and found that there is a certain relationship between the average temperature of a region and the proportion of spicy food in the diet: the higher the average temperature of a region, the higher the proportion of spicy ingredients used in local cuisine, because hot weather can easily breed a large number of microorganisms in food, and spicy substances have a bactericidal effect, ensuring food safety. People in cold regions also prefer spicy food, which may be related to the physiological effect of spicy food producing a sense of heat and causing a rise in body temperature.
A study published in Bioscience, Biotechnology and Biochemistry in 2007 pointed out that consuming capsaicin can increase the core and surface temperature of the body, which can play a certain role in keeping out the cold.
In addition, genes also seem to play a role in the tolerance of spicy food.
A paper published in Physiology & Behavior in 2012 used Finnish twins as subjects. They first asked them to rate their preference for spicy food, and then used a quantitative genetic model to analyze the impact of genetic and environmental factors on the preference for spicy food. They found that people who did not like spicy food gave higher scores to the spiciness of spicy food, but rated the pleasure it produced lower. Genetic factors explained 18% to 58% of this preference, and the rest was due to environmental factors, indicating that the preference for spicy food may also have a genetic tendency.
The psychological theory of “benign maochism” also provides a reasonable explanation, helping to understand people's motivation to eat spicy food.
Benign masochism refers to individuals enjoying negative experiences that are misinterpreted by the body or brain as threats. Once the individual realizes that there is no real danger, the difference between cognition and physiological response instead produces a pleasant excitement. Therefore, humans' love of spicy food is an active behavior of seeking negative experiences.
Paul Rozin led a team to conduct research and verified eight types of experiences that belong to benign self-abuse, among which eating spicy food belongs to the burning pain category. When an individual eats spicy food, it sends a “false alarm” that the body is threatened, causing the body to make a series of defensive reactions, but at the same time the individual realizes that the danger does not exist, and the pain of eating spicy food turns into a stimulating enjoyment. In addition, the study also suggests that when the spiciness of the food consumed by an individual is just slightly lower than his or her tolerance, the most pleasant spicy eating experience may occur, but further verification is still needed.
How much spiciness can you handle?
People who love spicy food are often quite confident in their ability to tolerate spiciness. So, how to quantify and evaluate this ability? The Scoville Scale provides a detailed reference measurement.
In 1912, American pharmacist Wilbur Scoville designed a subjective evaluation method called the Scoville Organoleptic Test to measure the capsaicin content in different pepper varieties. He used his last name as the unit of capsaicin content, called the Scoville Heat Unit, abbreviated as SHU.
However, his experimental method mainly relied on the personal subjective feelings of the subjects. Later generations developed a more objective “high performance liquid chromatography” method to measure, but the capsaicin content unit SHU was retained and is still used today.
Taking the following table as an example, bell peppers contain no capsaicin at all, so their Scoville index is 0; jalapenos are between 2500 SHU and 10000 SHU, and the pepper with the highest Scoville index is also the hottest pepper in the world today – Pepper X, with a spiciness of more than 2.69 million SHU.
However, this pepper is an artificially bred variety, cultivated over 10 years by American pepper breeder Ed Currie, the creator of the Carolina Reaper pepper, which was once the hottest in the world. Through selective breeding, Ed Currie allowed the pepper hybrid varieties to gradually show the desired characteristics, and after more than ten generations of breeding, the characteristics were stabilized, ultimately producing the strongest spiciness.
However, consuming these super spicy peppers may cause serious physical discomfort, so please eat according to your ability.
Data source: wiki
If you are not familiar with SHU, which measures spiciness numerically, then my country, as a major spicy food consumer and chili producer, also has a traditional spiciness classification: “mild, medium, high, extremely spicy”, etc.
The slightly spicy taste is characterized by extremely slight irritation on the tongue and mouth, which most people can tolerate. When the spiciness is adjusted to medium spiciness, the tongue and mouth can feel a certain tingling and burning sensation, which is the taste of the home-cooked tiger skin green pepper. When eating highly spicy peppers, the tongue and mouth will have a significant burning sensation. People who are not good at eating spicy food may start to sweat, have a runny nose, sneeze, or even cry. As for extremely spicy peppers,For example, Yunnan's shabu-shabu chili peppers are rarely eaten directly by humans because the stimulation they produce is too much for most people to bear.
The above spiciness levels are mainly based on personal subjective feelings and lack certain uniformity and accuracy. In 2006, the School of Food Science and Technology of Hunan Agricultural University was commissioned by the National Standards Committee to formulate national standards for the spiciness of peppers and pepper products. Since then, local governments and companies have also begun to define spiciness more accurately.
In 2014, the Department of Food Science of Sichuan Tourism College and the Key Laboratory of Culinary Science of Sichuan Higher Education Institutions combined the Scoville Index, the content of capsaicinoids in food and the traditional concept of spiciness to rank 123 Sichuan dishes.Mild, Medium, Hot, Extra Hot 4 levels.
Top 20 spicy Sichuan dishes in the study, source: https://www.spkx.net.cn/
In 2020, the Institute of Urban Agriculture of the Chinese Academy of Agricultural Sciences and a team of enterprises published a paper in the International Journal of Food Properties on the use of the Li Spicy Unit (LSU) to measure the spiciness of hot pot condiments such as hot pot base. The team divided the spiciness of hot pot into six levels based on the unit of “degree”: slightly spicy (9°~29°), low spicy (30°~39°), medium spicy (40°~49°), high spicy (50°~59°), extra spicy (60°~69°), and extremely spicy (≥70°), to help consumers more intuitively choose spicy food that suits their taste and tolerance.
Scientific Tips for Relieving Spicy Food
Given that everyone has different tolerance to spicy food, if we unfortunately overestimate ourselves and our tongue becomes extremely spicy and the burning sensation is unbearable, how can we effectively relieve the spiciness?
The first effective method is to disrupt the binding of capsaicin to the TRPV1 receptor.
Since capsaicin is only soluble in oil and alcohol, but not in water, drinking water will not relieve the spiciness. Instead, it will spread the capsaicin throughout the mouth and even the throat, making the spiciness even worse.Take a sip of milk or other dairy products to help relieve the spiciness.
Dairy products not only contain fat, but also casein, which is a non-polar molecule that can bind to capsaicin, which is also a non-polar molecule, dissolve it and eliminate the burning sensation. Therefore, foods such as full-fat ice milk, full-fat yogurt or ice cream are all “experts” in relieving spiciness.
In addition, starchy foods can also play a certain role in alleviating the spiciness, such as rice, bread, potatoes, etc. Although starch cannot dissolve capsaicin, it can absorb capsaicin like a sponge, shortening the duration of the spicy taste and eliminating the spicy feeling. So if there is no milk, you might as well eat a few more mouthfuls of rice when you accidentally get spicy.
The second method is to interfere with the brain's perception of spicy food, such as sucrose.
On the one hand, the stimulation of spicy and sweet tastes acts on different receptor cells in the mouth. After activation, these cells will interact with each other and interfere with the brain's perception of spicy taste alone. On the other hand, after receiving sweet stimulation, the brain will release analgesic substances to relieve the stinging sensation caused by spicy taste.
The third method is to use acidic substances to neutralize alkaline capsaicin, such as lemon, sour plum, sweet orange, etc., which can alleviate the spicy feeling.
In addition, an article published in the journal Physiology and Behavior in 2018 made an interesting discovery: completely blocking nasal airflow can reduce the perception of capsaicin by 50%. The reason is that after the nostrils are closed, the surface temperature of the tongue will decrease, and the temperature reduction will reduce the possibility of activating TRPV1. Maybe in the future, when you are choked by spicy food, you can try pinching your nostrils and use physical methods to relieve the spiciness?
Samyang Spicy Chicken Noodles was once selected as the most satisfactory Korean instant noodle brand for Chinese consumers in the 2021 Korean Brand Awards, but now it has been unexpectedly banned in Denmark. After all, mainly due to health concerns, not everyone can accept instant noodles with a spiciness of more than 4,400 SHU, especially for children with more sensitive taste and digestive systems and frail adults, who will face a higher risk of adverse reactions including nausea, vomiting, gastrointestinal side effects, etc.
So, spicy food can add vitality to life, but at the same time, be careful not to add burden to your health.
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