菠萝对口腔的刺痛感从何而来？

菠萝对口腔的刺痛感从何而来？
Where does the tingling sensation of pineapple come from?
菠萝之所以会对口腔产生刺激，主要是因为菠萝中含有的菠萝蛋白酶（蛋白质水解酶），可以切断蛋白质一级结构当中的肽键，使其水解为多肽。
The reason why pineapple can stimulate the mouth is mainly because the bromelain (proteolytic enzyme) contained in pineapple can cut off the peptide bonds in the primary structure of the protein and make it hydrolyzed into peptides.
吃菠萝时，菠萝蛋白酶就会破坏口腔黏膜的结构，导致口腔、食道出现明显的刺痛感、灼烧感，甚至会导致出血（与食用量有关）。

When eating pineapple, bromelain will destroy the structure of the oral mucosa, causing obvious tingling and burning sensation in the mouth and esophagus, and even bleeding (related to the amount of food).

盐水浸泡可以杀灭菠萝蛋白酶吗？
Can salt water soaking kill bromelain?
从原理来看，酶的根本是蛋白质，它由氨基酸构成，本身拥有大量的羧基（—COOH）、氨基（—NH2）和羟基（—OH）等官能团。自然界中能使蛋白质变性的因素（条件）主要有高温、紫外线、强酸、强碱、重金属盐、甲醛、乙醇、苯酚等。
From the principle point of view, the root of enzyme is protein, which is composed of amino acids and has a large number of functional groups such as carboxyl (-COOH), amino (-NH2) and hydroxyl (-OH). The factors (conditions) that can denature proteins in nature mainly include high temperature, ultraviolet rays, strong acids, strong bases, heavy metal salts, formaldehyde, ethanol, phenol, etc.
食盐的主要成分是氯化钠（Nacl），它是一种盐，但并不是重金属盐。
The main component of table salt is sodium chloride (Nacl), which is a kind of salt, but not a heavy metal salt.
氯化钠当中的钠离子非常稳定，几乎不会发生任何化学变化，它没有办法像其他离子一样与酶形成配位键，这样一来也就不能影响酶的结构形态（导致其不能和目标反应物结合，或是不能正常变性，或是替换掉酶中本来具有的金属离子，致其失活）。

The sodium ions in sodium chloride are very stable and hardly undergo any chemical changes. It has no way to form coordination bonds with enzymes like other ions, so that it cannot affect the structure and morphology of the enzyme (resulting in its inability to react with the target). The substance binds, or cannot be denatured normally, or replaces the metal ions originally contained in the enzyme, causing it to inactivate).

为啥用盐水泡菠萝会好吃？
Why is pineapple soaked in salt water delicious?
虽然从原理上来看盐水浸泡菠萝不能使菠萝蛋白酶变性失活，但用盐水浸泡菠萝同样会有其他不可磨灭的“功劳”。

Although in principle, soaking pineapple in salt water cannot denature and inactivate bromelain, soaking pineapple in salt water also has other indelible "credit".

其一，使用盐水泡菠萝，对于很多人（相信盐水可以让菠萝不扎嘴的人）而言，强大的心理暗示足以帮助大家起到止痛的作用，毕竟一次性吃不了太多菠萝。
First, use salt water to soak pineapple. For many people (those who believe that salt water can keep the pineapple from sticking their mouths), strong psychological hints are enough to help them relieve pain. After all, you can't eat too much pineapple at one time.
其二，食盐中的钠离子是第一主族的阳离子，它本身具有抑制苦味的作用，所以盐水浸泡之后的菠萝必然会更加香甜。
Second, the sodium ions in table salt are the cations of the first main group, and it has the effect of inhibiting bitterness, so the pineapple after salt water soaking will inevitably be more fragrant and sweet.
因此，用盐水浸泡菠萝也可以让菠萝不那么“咬嘴”，增加美味的和谐度。

Therefore, soaking the pineapple in salt water can also make the pineapple less "bite" and increase the delicious harmony.

来源：科普中国（ID：Science_China）

Source: Popular Science China (ID: Science_China)