There was a very long comments-discussion on an answer of Can you develop an immunity to chopping onions causing tears?, which triggered an automatic flag. I will delete the discussion from there, but the topic is interesting, so I would suggest that we continue the discussion here.
Content of the comments:
Eyes certainly do change as you age; it's plausible that something happens that's not specific to onions but still helps. – Jefromi♦ ↵ 19 hours ago
@jefromi Well, basic research indicates it is a reflex. I think anything deeper, and this is a medical or bio question, and no longer a culinary one. – SAJ14SAJ ↵ 19 hours ago
@Jefromi Can I ever attest to that! I'm blind as a bat, when the hell did this happen? – Jolenealaska ↵ 18 hours ago
@SAJ14SAJ I think we're quite happy to have biological/medical questions with culinary relevance here, just as we take plenty of chemistry ones. – Jefromi♦ ↵ 18 hours ago
@Jefromi Which is why I answered instead of voting to close as off topic.... but at some point, if we are going to investigate every chemical pathway and effect of the aging process, the culinary depth of the question will have been well exceeded. – SAJ14SAJ ↵ 18 hours ago
Here is a fun fact: syn-Propanethial S-oxide was the chemical of the week of the ACS: acs.org/content/acs/en/molecule-of-the-week/archive/… Who knew it was a celebrity! – SAJ14SAJ ↵ 18 hours ago
If the question's worth answering, it's worth answering completely. Maybe there's not an aging-related answer, but if there is one, I doubt it requires a ridiculously detailed examination of aging; it'd probably be a single physiological change that sometimes happens with age (maybe not for everyone). For example, some people end up with drier eyes. – Jefromi♦ ↵ 18 hours ago
@Jefromi That is an argument ad absurdem, otherwise every question would have to answered with the fundamental governing quantum mechanical equations. – SAJ14SAJ ↵ 18 hours ago
@SAJ14SAJ You are reading "completely" way, way too literally, making your resulting argument absurd. But it is no more ridiculous to say "aging eyes/tear ducts are often drier, resulting in less crying from onions too" than to say something about syn-propanethial-S-oxide. – Jefromi♦ ↵ 17 hours ago
@Jefromi: I rather disagree. An answer about syn-Propanethial S-oxide may sound a lot more obscure, but it's information about the onion. An answer about what happens to your tear ducts with age has nothing to do with food. – Aaronut♦ ↵ 12 hours ago
@Aaronut Fortunately we don't just answer questions about the fundamental properties of onions in isolation, we answer questions about humans using them in kitchens and eating them. – Jefromi♦ ↵ 12 hours ago
@Jefromi: The culinary use of onions does not encompass the effects of aging on human tear ducts. That's a question about biology, not cooking. – Aaronut♦ ↵ 12 hours ago
@Aaronut So you must think this question should be closed then. I would welcome an explanation on meta about this, especially if it makes it clear why this is bad but questions about taste perception and the nature of ingredients are about cooking (even if the explanations require chemistry or biology). – Jefromi♦ ↵ 11 hours ago
@Aaronut The answers (whatever they may be) come after the question. The question (despite the use of the word immunity) isn't a "health" question at all. It is a question about a completely normal (and perfectly healthy) response to a very typical culinary activity. – Jolenealaska ↵ 11 hours ago
@Jolenealaska No, I didn't really think there was anything wrong with the question. I just didn't agree that it was necessary or helpful to go into a series of hypothetical biological explanations about what might alter a reaction. This answer was at the appropriate level of detail, i.e. explaining the actual mechanism that causes crying from onions and how it might be a tolerance to the sensation but not to the chemical itself. – Aaronut♦ ↵ 10 hours ago
C'mon ... a 1999 article about onions? There was a group that showed that the process is not that simple, and even won this year's Ig Nobel for Chemistry – Joe ↵ 47 mins ago
Was 1999 a bad year for articles? Was it an uncredible source? Seriously, I read the new linked abstract (I don't have access to the full text), and while it expands the detail of the mechanism, it doesn't change anything fundamental--certainly nothing culinary, and nothing about the reflex reaction to the trigger of the tearing and burning sensation. Its import is that it might be possible to breed or engineer a tear-free onion, but that wasn't the point of the question. – SAJ14SAJ ↵ 44 mins ago
@SAJ14SAJ : see the Ig Nobel writeup : CHEMISTRY PRIZE: Shinsuke Imai [JAPAN], Nobuaki Tsuge [JAPAN], Muneaki Tomotake [JAPAN], Yoshiaki Nagatome [JAPAN], Toshiyuki Nagata [JAPAN, GERMANY], and Hidehiko Kumgai [JAPAN], for discovering that the biochemical process by which onions make people cry is even more complicated than scientists previously realized. The problem w/ 1999 is that it's dated, and been replaced with a more complete understanding of the process. (that there's other enzymes involved) – Joe ↵ 42 mins ago
upvote
flag
@Joe The ignoble site points back to the same abstract I already read. It may be slightly more complex, but it is not significant complexity in the context of this question, at least as described in the abstract. – SAJ14SAJ ↵ 39 mins ago edit
@SAJ14SAJ : but it still makes the part you quoted wrong. "The sulfenic acids, in turn, spontaneously rearrange to form syn-propanethial-S-oxide, the chemical that triggers the tears." They don't spontaneously rearrange, but are due to lachrymatory-factor synthase. – Joe ↵ 32 mins ago
@Joe Edited.... – SAJ14SAJ ↵ 19 mins ago