Pepper: a “cultural and military” species

A former luxury spice

While preparing dinner, you discover that the spice bottle of black pepper is empty, so you dig out a bag of loose black pepper and prepare to refill the spice bottle. However, the design of the spice bottle is really unreasonable, and the mouth of the bottle is quite small. With a slight shake of your hand, a few black peppercorns slip from the edge of the bottle and fall into the sink. You pick them up and throw them into the trash can. But do you know that the things you are throwing away at this moment were once a considerable fortune.

Pepper is a flowering vine plant. In fact, the dried fruit is the peppercorns we see in our daily life (hereinafter referred to as pepper). Walking around the market, we can see many different colors of pepper: black, white, green, red, etc. In fact, the different colors of pepper come from different maturity and processing methods. If you cook and dry the unripe pepper fruit, you can get black pepper; if you dry it without cooking, you will get green pepper; if you wait until the pepper fruit is almost ripe before processing it, and then remove the peel after drying, you can get white pepper.

Pepper cultivation began in ancient India 3,000 years ago. After Rome conquered Egypt in 30 BC, pepper's popularity in Europe rose sharply, and it was first served on the tables of the rich and powerful. The rich and powerful were extremely obsessed with this magical spice from India, and the price of pepper also rose all the way. Pepper was even used as hard currency for a time. At that time, the Roman Empire sent more than a hundred cargo ships to India every year on the monsoon, returning from the Arabian Sea to the port on the Red Sea with pepper. Then the pepper was transported to the Nile River by land or water, and then from the Nile River to Alexandria, and finally to Europe, where it was stored in a special spice warehouse. Such a laborious transportation of pepper continued until the fall of the Western Roman Empire in the 5th century AD. It is said that when the Visigoth King Alaric besieged Rome, he used one ton of pepper as one of the conditions for pardoning the city.

In the Middle Ages, pepper was still very valuable and was a rare delicacy for nobles to enjoy daily and when visiting relatives and friends. In 1194, when King William I of Scotland visited King Richard I of England, he brought 900 grams of pepper as a gift.

More than just spices

The earliest use of pepper was not to add flavor to food, but to slow down food spoilage and cover up food odors. Before the advent of refrigeration technology, food preservation was a headache. Meat would go bad and stink after a while, and food contaminated by microorganisms seriously threatened human health. Therefore, people used a lot of pepper to marinate meat to slow down the spoilage process of food, and the aroma of pepper also made slightly spoiled food less difficult to swallow. Although this way of food preservation is only derived from people's long-term practice and has no theoretical basis, studies have shown that the terpenoid compounds in pepper essential oil do have an antibacterial effect. Pepper essential oil is hydrophobic and can be integrated into the lipids on the cell membrane of microorganisms, disrupting the cell membrane structure and increasing the permeability of the cell membrane, thereby disintegrating bacterial cells.

Why do humans love pepper as a "preservative"? Biologists believe that behaviors that benefit humans are inherited in our genes, and our taste buds are no exception. Because spices such as pepper can inhibit the growth of microorganisms in food, people who like to eat spicy foods may be healthier, live longer, and leave more offspring. Not only that, this preference will also be passed down from generation to generation in culture, and spice lovers will often teach their descendants to use spices in cooking.

In addition to preserving food, pepper also has a long history of medicinal use. Pepper plays an important role in ancient Indian medicine. The earliest record of pepper medicinal use in India can be traced back to 3,000 years ago. Modern science has explained the ancient Indian tradition of using pepper as medicine. Scientists have found that a certain substance in pepper can not only enhance the digestive effect of digestive enzymes such as amylase and lipase, promote intestinal absorption, but also inhibit drug metabolizing enzymes, slow down the degradation of drugs, and improve the body's utilization of drugs. So, what exactly is this magical substance?

Pepper is made up of a variety of ingredients, including cellulose, lipids, and inorganic salts. However, the reason why pepper has many special properties is that piperine is indispensable. Piperine is an alkaloid that can irritate the mucous membranes in the nose and trigger nerve impulses - this is why smelling pepper makes people sneeze. Scientists have developed pepper spray based on the properties of piperine. Since its debut in World War I, tear gas such as pepper spray has transformed from a weapon of war to a powerful tool for controlling criminals. According to eyewitnesses, close contact with pepper spray feels like the whole person is "on fire". Some people even said: I would rather have all my toenails pulled out than be hit by another pepper spray. If pepper spray hits the face, people will first close their eyes involuntarily, and then instantly feel a blockage in the throat, accompanied by a severe burning sensation in the face and nasal cavity. All these painful feelings are because piperine stimulates the biological mucosa, and in severe cases, the discomfort will last for about a day. People who suffer from pepper spray usually temporarily lose their ability to move due to poor vision and intense pain.

Pepper can be used as food, medicine, and weapon. It is truly "capable of both civil and military affairs". In the thousands of years that pepper has been around, humans have gradually uncovered the mystery of this beautiful plant. However, to this day, humans cannot say that they have fully mastered the secrets of pepper. What is the deeper and more specific mechanism of action of pepperin? Can it inspire more inventions? While enjoying pepper, we should also continue to explore.

Pepper, Sichuan pepper, and chili pepper all make people feel hot, but their neurobiological mechanisms are different

Our nasal cavity and oral cavity are full of nerve endings. Under the stimulation of unsafe factors such as high temperature, sharp objects and hazardous chemicals, the nerve endings will transmit information and open the corresponding ion channels, thereby realizing the body's alertness to the environment.

Peppers are spicy, but the so-called "spicy" is actually "hot" (or "hot"). Peppers contain capsaicin. When capsaicin enters the mouth, it triggers the ion channels responsible for transmitting temperature signals, making us feel "hot and scalding". Have you ever drunk hot water after eating spicy hot pot? If so, you will feel that the glass of water is hotter than expected. This is because the ion channels responsible for high temperature alarm are opened by capsaicin at room temperature, and the threshold of temperature alarm is lowered, so even if the temperature does not feel high at ordinary times, it can trigger strong nerve impulses. Interestingly, birds cannot feel "spicy" because their high temperature alarm ion channels do not bind to capsaicin. Some people mix peppers into feed when raising birds, which can drive away squirrels and other food-stealing animals that are "afraid of spicy food" without affecting the birds' enjoyment of the meal.

Piperine in pepper works in a slightly different way. In addition to triggering the temperature-sensing channel mentioned above, piperine also triggers a channel responsible for sensing pungent chemicals. This channel is also activated when we eat pungent foods such as cloves, mustard, cinnamon, garlic and ginger.

The mechanism of action of Sichuan pepper is more complex, and it is more difficult for us to describe its "taste". This complex "taste experience" comes from a molecule called pepper, which not only makes people feel slightly "spicy" (more accurately, "hot"), but also produces a tingling sensation, which is what we call "numbness". Unlike capsaicin and piperine, pepper does not work mainly by "making the body feel hot", but triggers touch neurons, thereby activating the same ion channels activated by some anesthetics.