Can Butter Go Rancid?

March 24, 2004 8:33 PM

Once again microbiologists & bacteria enthusiasts your wisdom is needed. My roommate is mad because I left the butter out overnight, he won't touch it and said I have to buy a new stick. But my grandma always kept her butter in a covered dish on the counter, not in the refrigerator. My question then, what are the facts here: does butter require constant refrigeration? How long till butter goes bad {packaged, refrigerated, covered dish} and in what ways, and at what risk?
posted by Brad to food & drink (14 comments total)

Can't speak to the microbiology, but during the cool months we leave our butter out on the counter in a covered butter dish all the time, tho in a household of four toast eaters a stick doesn't last more than two or three days. Haven't lost anyone yet. So I think your roommate is being a bit of a weeny.

I dimly recall that butter oxidizes when it goes rancid
posted by mojohand at 8:45 PM on March 24, 2004

It's safe. Even if it had a rancid taste, it wouldn't be dangerous, just yucky, and there won't taste rancid after one night.
posted by teg at 9:04 PM on March 24, 2004

If covered, I wouldn't be worrying about bacterial spoilage. There isn't enough available moisture in butter for them to grow fast.

However, butter goes rancid quite quickly in warm rooms or when exposed to sunlight. Some people (including me) are more sensitive to the taste of butter just starting to turn than others. I can't stand it when other people happily chow down.

Rancid fats aren't going to hurt you unless you make a habit of eating them, but they taste yucky.

Whether I side with your roommate depends on the temperature of your house.
posted by i_am_joe's_spleen at 9:07 PM on March 24, 2004

I'll second the bit of a weeny. My mother's family always had a butter dish out on the kitchen counter, and this was in the deep south where it was both hot & humid. Her family tends to die in their late nineties. I say if it tastes bad, don't eat it - you can be the taster for your roomate.

Of course I'm a strong believer in the five second rule.

On preview, I'm with i_am_joe's_spleen.
posted by skyscraper at 9:13 PM on March 24, 2004

... And the likelihood of spoilage is even lower if the butter was salted (most butter has salt in it to improve shelf life). Tell your roommate to grow a spine... our species has survived for millennia with all sorts of bacteria about.

My word.

*rolls eyes*

And a note to you: if you like softer butter, try using a butter bell (a crock pot that suspends butter upside down in a water jar)... it lets the butter soften, but keeps the airborne flavor killers at bay.
posted by silusGROK at 9:21 PM on March 24, 2004

Your roommate is too clean. We need a bit of grunge to survive. On the exceedingly slim chance that there could be anything at all wrong with the butter, he'll be a better man for it.
posted by five fresh fish at 9:43 PM on March 24, 2004

Q re: butter bell -- doesn't the butter just slide right out of the cup when the temperatures get summery? (In my house, that's up to 40c, but I'll take 25c as an upper limit with sensible use of air conditioning, eg. not running it all the time.)
posted by five fresh fish at 9:46 PM on March 24, 2004

My home stays at about 23c, and that's plenty cool enough for the butter to remain afixed within the bell... the water stays cooler through evaporation, and the mass of butter stays put through suction, mostly.

Great gadget... and not unsightly like those bread-crumb and grimey finger print-encrusted clear glass butter dishes.
posted by silusGROK at 9:55 PM on March 24, 2004

When I was a kid we'd always leave the butter out in its dish, its just not very spreadable from the fridge. You're doing him a favour.
Alternatively, buy him a new stick and hide a pube in it.
posted by biffa at 2:36 AM on March 25, 2004

My understanding (and I am not a nutritional scientist) is that rancid oils are a source of a metabolic byproduct called free radicals, which in turn damage cells and can be carcinogenic. I'm not entirely sure if the fats in butter oxidize so as to produce the same byproducts, but it seems prudent to me to keep the butter (and all other oils) in the refrigerator.
posted by Kat Allison at 5:13 AM on March 25, 2004

Another vote for the butter bell. It's primitive technology at its best. We call ours a "french butterkeeper" but it's the same thing.
posted by stupidsexyFlanders at 6:18 AM on March 25, 2004

I had always heard that ghee ("clarified butter") keeps even longer than regular butter.
posted by gwint at 11:35 AM on March 25, 2004

Ghee is done when a second foam forms on top of butter, and the butter turns golden.
Not sure the process name. Doing the first part and separating the foam from it. Thought it done so the butter will not scorch at high temperatures while cooking.
posted by thomcatspike at 4:38 PM on March 25, 2004

Kat: yes, but refrigeration is not necessary as long as room temperature is less than 20 °C or so.

Ghee keeps longer because you're removing the water and the proteins dissolved in it, thereby making the remaining butter fats a harsh environment for your average bacterium. thomcatspike is right, the point of ghee is that the non-fat milk solids in butter - caseins and whey and so forth - burn at higher temperatures. By using ghee or clarified butter, you get butter flavour and higher-temperature frying without unpleasant burnt notes.

Ghee and clarified butter are not really synonymous. Ghee is the Indian variant, which can be made at a higher heat. It thereby gains a nutty flavour and darker colour than its haute cuisine cousin, clarified butter, made at a temperature just sufficient to melt the original butter.
posted by i_am_joe's_spleen at 6:03 PM on March 25, 2004