Do "Butter Keepers" really work, and if so, how?

Recently, I’ve seen several of these Butter keepers or Butter Crocks advertised as a way to keep butter both unspoiled and spreadable. Do these things work? If so, how? I’d think that the microbes that spoil the butter would grow in the water too. It may make an air tight seal that lessens the accessablity of the microbes to the butter, but when the butter is out of the water being used, there are microbes around to get into the crock for later spoilage.

So, how does this work?

It’s mostly not microbial damage you have to worry about with butter–it’s rancidity (oxidation of the fats). Submerging the butter under water would keep it away from the air, exposing it to less oxygen, resulting in less oxidation, delaying spoilage. Oxidation is what turns flaxseed oil (a valuable essential fatty acid) into linseed oil (the medium for oil paint).

What toadspittle said. Microbes aren’t going to be able to grow in pure butter. The water activity is too low.

Interesting. When I think “spoiled”, I think microbes. I didn’t even think of oxidation.

Is spoilage often more caused by oxidation than microbes? Is it just the case with things like butter that are mostly fat?

Oh. Damnit, I should have realized that, Smeghead.

Hydrophobic, hydrophillic, fatty acids, membranes. mutter mutter.

Endorsement: I have a butter crock. I love having soft, spreadable butter at hand.

On the other hand, my mother leaves her butter out on the kitchen counter (in the butter box) overnight so it’s soft for breakfast, and I have never noticed any rancid overtones in it.

I suspect the biggest benefit of these devices is that they stabilise the temperature of the butter; all that stoneware and water takes time to equalise to the ambient temperature; so during the day, it will typically be warming up toward (but lower than) room temperature.

Pffft. I leave butter out for days and notice no ill effects, no keeper, not even covered.

Is rancid butter toxic, anyway?
My understanding is that generally speaking, fats can be kept for a long time without becoming inedible, and isn’t butter essentially pure fat?

Ponster and I keep our butter out in a ‘normal’ pottery pot with lid, no fancy water works. The only problems we’ve ever had have been when the weather has been hot (30°C /86°F +) and the butter has been* too* soft, almost melting - :rolleyes: It wasn’t a problem of taste or antyhing tho’ just it wasn’t the right consistency you know ?

I’d be tempted to try one of these - would the water act as insulation and keep the butter cooler ?

No, it will stabilize at the temperature of the room.

The average temperature of the room - which is likely to be a fair bit cooler than the peak daytime temperature.

Yes, I almost started this thread talking about my friend and his mother who both do this. Then I decided it wasn’t pertinent.

clairobscur, butter is basically pure fat which is why I was scolding myself for not remembering it when Smeghead pointed out that there wouldn’t be a lot of microbial growth.

Ugh. This was meant in reference to An Arky’s comment about leaving butter out for days. I just forgot to click the quote box.

Although, re-reading, I have to admit they cover the butter because they both use butter dishes.

According to Alton Brown, host of “Good Eats” on the Food Network, butter is 20% water.

Does the salt in butter help preserve it?

Butter is not pure fat, which is why you can burn it – there are still a lot of “milk solids” in it. Clarified butter is closer to pure fat – it has an essentially unlimited shelf life (unrefrigerated) and can be heated much more without burning.


Okay. Well, this thread is repeatedly showing how much I don’t know about food. Except that I like to eat it. Well, the thread isn’t showing that but I promise it’s true. I just don’t really cook. I kind of flail my way around the kitchen and end up with something edible.

Or, I go out and let someone else do the flailing.

See the famous thread, Where Do You Keep Your Butter?