How to eat pineapple ＂sting＂ without being ＂hurt＂ by it!

　　It’s the season to enjoy pineapple at will, and its sweet fragrance is everywhere in fruit shops and mobile fruit carts on the street, which is irresistible! However, many people have had this experience: pineapple will "sting"! Not only will its coat and crown on its head prick hands, but its flesh will also sting its mouth! Our oral cavity will be strongly stimulated, resulting in tingling, acidity and itching of oral mucosa and gums. What’s more, it suffers from bleeding, inflammation, redness and swelling around the mouth and lips. This is why people often soak pineapples in salt water first — — Reduce the intensity of its "sting mouth".

　　Why do pineapples sting?

　　Because pineapple is so "smart", in order to prevent humans and other creatures from eating it, it not only wears a barbed armor, but also hides three heavyweight weapons in the flesh.

　　The first heavy weapon: calcium oxalate needle crystal

　　Calcium oxalate needle crystal is the physical killing means of pineapple. Under the microscope, the bundle of calcium oxalate needle crystal wrapped by pulp tissue cells is like countless dense needles. They have a very powerful characteristic: they are insoluble in water. So it is not easy to be dissolved by our saliva!

　　When we chew pineapple pulp, we will destroy the tissue cells of the pulp because of the grinding of teeth, which is equivalent to opening the door to these invisible sharp needles that originally locked them. Once these sharp needles are released into the mouth, they will mercilessly "plunge" into any mucosal tissue they touch. With our continuous chewing, calcium oxalate needle crystals can be "pushed" into our tongue, inner wall of mouth, throat and gums, which are soft, delicate and have no resistance.

　　The second weapon: bromelain

　　This enzyme can be extracted from the pulp, peel and even stem of pineapple. Little friends who often cook must be familiar with this enzyme, because it is an important "second party" of tender meat powder. The common tender meat powder is either papain or bromelain.

　　Proteases, as the name implies, can decompose protein. On the one hand, bromelain will activate the "PAR" protease "alarm" in oral epithelial cells and free nerve endings, and after being activated, it will awaken the nerve pathway that can trigger itching. On the other hand, bromelain itself does destroy the protein of our oral mucosa — — It is achieved by decomposing and "cutting" the connective proteins between cells.

　　In this way, the defense network of oral mucosal cells is "relaxed" and the barrier protection is weakened, which makes it easier for some pathogens to take an opportunity to trigger inflammation or immune response.

　　Knowledge small link:

　　In fact, many fruits and vegetables contain both calcium oxalate crystals and proteases, such as papaya, spinach and figs. When we eat these fruits and vegetables, we won’t have obvious irritation, because the calcium oxalate crystals they contain are not needle-shaped, but oval or dumbbell-shaped and other non-lethal irregular shapes, so they won’t hurt our oral mucosa.

　　But kiwifruit is an exception. Calcium oxalate crystals in kiwifruit pulp are also needle-shaped, and kiwifruit also contains cysteine proteolytic enzyme. Therefore, when we eat kiwifruit, we will feel tingling more or less. Therefore, kiwifruit is also a kind of fruit that can "eat people", but it is not as fierce as pineapple, probably because its weapons and equipment are not as good as pineapple.

　　The third weapon: organic acids

　　The sour taste produced by organic acids such as citric acid, malic acid and quinic acid contained in pineapple not only stimulates our taste receptors, but also stimulates the pain receptors in the oral cavity. Combined with the first two weapons of pineapple, the lethality is self-evident.

　　The "killer" to conquer pineapple

　　How many have you learned?

　　In order to conquer the killer of pineapple and make it a delicious dish for human beings, our ancestors summed up several stunts for us:

　　1. Salt water soaking: This is the most common treatment method, which is said to "destroy bromelain". However, this principle is controversial and unsolvable, because sodium chloride in table salt is not a heavy metal salt, so it can’t denature protein. At best, some organic acids in pulp can be dissolved in water by soaking in salt water, thus reducing the stimulating effect of organic acids. Moreover, it is a bit salty to be sweet — — A small amount of salty taste can increase the taste buds’ perception of sweetness, which makes us feel "Wow! So sweet and beautiful! "

　　Of course, some people support that salt can reduce the activity of bromelain, and tell us through laboratory research data that different concentrations of salt water can really improve the problem of pineapple sting to varying degrees. When the concentration of saline increased significantly (from 0% to 3.5%, and then to 7% and 10.5%), the activity of bromelain decreased gradually. But what is the principle, it seems that it has not been verified.

　　2. Pepper salting: This is a classic way to eat in Guangdong, Guangxi and Hainan. It is sweet, sour, salty and spicy, and it is very delicious. As for whether the pain caused by spicy taste overwhelmed the acupuncture pain of pineapple in the end, or whether capsaicin and salt together inhibited the activity of bromelain, it is hard to say. I really expect someone to study this topic well to solve my confusion.

　　3. Heating: As a protein afraid of heat, bromelain can’t continue to show off at high temperature. When pineapple pulp is heated above 60 degrees Celsius, bromelain will be inactivated and calcium oxalate needle crystals will be dissolved to some extent. This is also the reason why pineapple pulp in delicious foods such as pineapple goo old meat and pineapple rice won’t make us feel stung. However, after heating to this temperature, the crisp, tough and cool taste of the pulp may be discounted, and interested friends can try it.

　　However, there must be some friends who refuse to heat the pineapple and are too lazy to soak it in salt water. So, how can you enjoy the delicious pineapple and relieve the pain of your mouth? The following two items are for reference — —

　　1. Make a quick decision: don’t eat slowly for a long time, and don’t give pineapple black weapons a chance to kill you fully;

　　2. Rinse your mouth in time: rinse your mouth immediately after eating pineapple to reduce the residence time of calcium oxalate needle crystals and bromelain in your mouth. If you like, you can rinse it several times, and the effect will be better. Text/Liu Suiqian (popular science worker, clinical nutritionist, member of China Nutrition Society)