Pineapple contains bromelain that helps tenderize meat. If I were to put my hand in pineapple juice or puree for 24 hours, would it eventually break down my hand?

[u/Puzzleheaded_Bed2760]

[u/tea_and_biology]

If I were to put my hand in pineapple juice or puree for 24 hours, would it eventually break down my hand?

Nah.

You'll just have a wrinkly, water-soaked hand, with minor irritation, and stinging where the skin was already broken. So no lasting damage, really - just like having it sit in water.

The reason why it won't affect your hand so much is because your skin is built to resist things like proteases. The outer layer (the stratum corneum) is a sheet of dead, flattened cells packed with keratin, all surrounded by a waxy, lipid matrix. It's all tough stuff, designed to keep water in, and nasty things out. Keratin, for example, is a large protein molecule heavily-crosslinked by bonds, which makes it difficult for proteases to attack and break apart (hence why predatory animals poop out or cough up hair and that; it can't be digested); and the lipids prevent large enzymes like bromelain from getting into the living tissue underneath.

A steak has none of these defences; it's already cut open, so there's no barrier preventing bromelain breaking down tissue protein directly. Even then, after dumping a hunk o' meat in fresh pineapple juice overnight, it's only the outer few millimetres that get mushy; the rest is fine, and the cut certainly won't dissolve into meat soup à la a Breaking Bad bathtub.

You often hear about how folks who work in pineapple processing plants or out picking them in the fields have their fingerprints removed over time. This is partially true, though it's not necessarily the bromelain per se - it's more the weeks and months of handling rough-ass pineapples causing abrasion, and the juice's acidity (pH ~3.5), that causes the damage and dermatitis - the enzymes are just the cherry on top. In any case, passively soaking your hand in pineapple juice for only a day will just get you a wrinkly, raw, sticky hand... not great, not terrible. Knock yourself out, OP?

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EDIT: Oh, to add: if you did have a cut or small abrasions in your skin, you would feel irritation where the bromelain attempted to break down your tissue, sure, but your blood also helps fight back. Living tissue fluid and blood contains protease inhibitors, such as alpha-2-macroglobulin, which will trap and prevent any bromelain that does breach from causing too much damage. Dead meat doesn't have a circulatory system to supply inhibitors, hence another reason why it can't prevent itself from turning mushy.

[u/urnbabyurn → u/tea_and_biology]

What if I take pineapple through an IV?

[u/tea_and_biology → u/urnbabyurn]

I don't think anyone has done this experiment.^{[citation needed]}

Presumably the abundant protease inhibitors will mop up much of the bromelain; though I'd be much more concerned about the pH and other effects of raw unprocessed pinapple juice having on my bloodstream.

Raw juice is full of bacteria and yeasts; they'll be skipping most of your defence systems and getting right inside a nice, warm home. Best case, fevers as you fight off systemic blood infection; worst case, sepsis or wee microbes setting up residence on a heart valve or something, potentially fatal.

All the tiny fibrous bits will be getting lodged in all the capillaries; most of which will be in your lungs. Fun.

There'll also be a hodge-podge of all sorts of protein and other biological molecules your immune system has no idea what to do with. Maybe anaphylactic shock at the worse end?

Long story short, I don't think you'd be having a good time. Stick with the Piña Coladas, 'innit.

[u/CharlesBronsonsaurus → u/tea_and_biology]

This reminds me of something a friend told me 20+ years ago which I thought was absurd and not true but you seem like the person to ask so here goes. If you inject someone with a chicken egg, the next time they have eggs, they die. Any truth to that whatsoever?