Sihaiwang synthesis: peel scallion why tears? How can you avoid peeling scallion and tears? ~！ The unique odor of Allium comes from a volatile oil that contains an organic molecule called amino acid sulfoxide. Alliinase is released from peeled or ground onion tissue, which converts these organic molecules into hyposulphonic acid.
The sub sulfonic acid is then naturally recombined to form the chemicals propane mercaptan and sulfur oxide that can cause tears. After 30 seconds of tissue destruction, the formation of propanethionaldehyde and sulfur oxide reached a peak, and the chemical changes were completed about 5 minutes later. We can't be more familiar with the effect of this oxide on the eyes. The anterior surface of the eye - cornea - has several functions, one of which is to protect the eye from physical and chemical stimulation.
There are many ciliary nerve fibers with sensory ability distributed on the cornea. Ciliary nerve is a branch of trigeminal nerve which makes the front part of face and head produce touch, temperature and pain. There are also a relatively small number of autonomic motor fibers on the cornea that can stimulate the lacrimal gland. Abundant nerve endings are able to detect the syn propane mercaptan and sulfur oxide in contact with the cornea and cause the activity of the ciliary nerve, which the central nervous system interprets as a burning sensation, and the higher the concentration of this compound, the stronger the burning sensation.
This kind of nerve activity stimulates the autonomic nerve fibers by reflex. The autonomic nerve fibers return the signal to the eyes and command the lacrimal gland to secrete tears to wash away the irritant substances.