What's Alum Used For?

[Chris Amirault]

I bought a little jar of alum at the store the other day, and now I have no idea what to do with it. If we can figure that out, I'll get a WikiGullet entry going about it. How do you use this stuff?

[patrickamory]

Pickling and shaving!

[NancyH]

I've only ever seen it used in Warner Bros Cartoons - usually to mess up a character's face and voice.

[runwestierun]

I keep it in the house for medicinal purposes, I have never used it in food. It gets rid of canker sores on the tongue. That probably wasn't the inspiration you were looking for...

[catdaddy]

Try this......http://www.ochef.com/1080.htm

[Will]

I believe it's used in often used in youtiao (lit. "oil stick"; the Chinese "creullers").

[Qwerty]

isn't that the stuff you add to pickles to keep them crisp? I'm pretty sure it is but I'm too lazy to look it up. But yeah, if you were making fermented pickles its what you add to help them stay crisper.

[kayb]

Yes, on the pickles. It's what gives them their "snap." Other than that, I have no clue.

[Blether]

It'll keep your fresh-from-the-sea uni in good shape till you can sell them to someone who lives a few days away.

[Kerry Beal]

You can use it to change the pH of your soil to make your hydrangeas another colour, as a styptic pencil to stanch the bleeding, an antiperspirant, a component of your baking powder or to kill your garden slugs. Might need a bigger bottle!

Oh yeah - and to make your pickles crisp!

Edited February 21, 2011 by Kerry Beal (log)

[nickrey]

You can mix it with salt to use for toothache.

It also used to be a primary ingredient in styptic pencils to stop bleeding from shaving cuts.

Not sure I'd like to use it in pickles though. It still has a question mark over it as a causative factor in developing Alzheimer's. Although I'm not big on correlational research, why risk it if you don't have to?

[technophile50]

Hydrobiologia 451: 11–17, 2001. Jellyfish as food Y-H. Peggy Hsieh1, Fui-Ming Leong2 & Jack Rudloe3

"Jellyfish have been exploited commercially by Chinese as an important food for more than a thousand years. Semidried jellyfish represent a multi-million dollar seafood business in Asia. Traditional processing methods involve a multi-phase processing procedure using a mixture of salt (NaCl) and alum (AlK[sO4]2 · 12 H2O) to reduce the water content, decrease the pH, and firm the texture. Processed jellyfish have a special crunchy and crispy texture."

"Extensive liquidation of the tissue occurs in the absence of salt, while disagreeable odors develop in the absence of alum."

[David A. Goldfarb]

Alum is used as a hardener in photographic processes, and the gelatin in photographic emulsions is a pure form of the gelatin used in the kitchen that comes from bones and hides, so the alum is probably hardening the gelatin in the jellyfish and in various other things, though I don't know that that would account for crispy pickles.

[Blether]

Talking of Wikis, apparently you can also use it as the acidifier in your baking powder, or for making bread white.