Why does butter stay unspoiled outside the fridge considering that it is a dairy product?

It’s basically all saturated fat. Saturated fat doesn’t spoil on its own. The reason milk and other dairy stuff goes bad is because of the moisture, sugar, and protein allowing bacteria to reproduce.

Thank you @incendiary_dan! All this time I was wasting fridge space.

Just remember to keep bugs off of it. Unless you eat bugs, but frankly fruitflies aren’t worth the trouble.

I wonder about the same thing. My mom keeps her butter on the dining table and never puts it in the refrigerator. AND she keeps her house at 80F all the time. Needless to say, I always bring my own butter when I visit her.

And I’m still going to keep my butter in the fridge, regardless what anyone says about it not being necessary…

@HungryGuy, do you really bring your own butter? I keep my butter in the cabinet or in the microwave, often uncovered. I’ve eaten unrefrigerated butter my entire life and I’ve never gotten sick from it. I’ve never found a bug in it, either, for that matter.

@ANef_is_Enuf – Yes, I really bring my own butter. I also bring my own butter when I visit my cousin who uses only margarine and doesn’t provide butter for guests. Everyone in my family has their finicky preferences, and nobody is offended by each other providing for their own preferences.

I’d bring my own butter too, if margarine were the only alternative. Stuff’s bad for you, hydrogenated oils.

True, it is the fat. Back in days of old, during war time one way they would preserve meats for the soldiers is to rub fat all over it, then the air doesn’t get to it, and it lasts longer.

I’ve heard that in ancient Ireland, they used to make something called “bog butter”, which was in large part meat. I guess it was preserved in saturated fat and stuck in bogs to preserve it. They just found a large amount of it that was still good after a couple thousand years. @JLeslie ‘s comment reminded me of that. I’ve also heard of pemmican, a trail food made from dried, shredded meat, tallow (rendered animal fat), and sometimes dried fruits and nuts, being found 400 years old in pueblos in the southwest. Again, still good.

Butter might not spoil quickly but the flavor does change and I don’t care for that flavor. It’s one of the things from my early childhood I don’t miss.

I don’t know how hydroginated oil margarine is still out there

The fat in butter is resistant to bacterial action, but about 20% of the butter is water. That water contains plenty of stuff to support bacterial growth. The only reason that doesn’t happen is that the butter is an emulsion in which the water is dispersed in very fine droplets suspended in a matrix of solid fat. This means that even if bacteria began to grow in one of the droplets, it wouldn’t be able to migrate to neighboring droplets, because each droplet is isolated by a wall of fat.

Butter manufacturers try to get the dispersed water droplets as small as possible, because large droplets could allow for considerable bacterial growth even within a single droplet. The smaller the droplets, the less risk of spoilage.

I’ve had unrefrigerated butter that became somewhat rancid before, but I think it was unpasteurized.

The majority of butter most people buy nowadays is salted butter rather than sweet butter. Since salt is a preservative, that helps things greatly.

I do think that it seems to lose its flavor when room-temperature, though…

I’ll plan to continue my tradition of leaving the current stick out, but refrigerating the rest.

Butter Bells are a good way to keep the air away from room temp butter so it stays non-rancid longer.

Even some good quality hard cheeses can live outside the ‘fridge. I’ve taken chunks of Parmesan and aged Gouda camping for a week.

I keep the current stick in the refrigerator, and the rest of the box in the frizzer.

It does get rancid after a while, even if it doesn’t grow bacteria or mold. That said, when I was growing up we always had butter out on the counter. We lived in cool climates, though, and it was eaten rather quickly.

It might not spoil, in the sense of getting mold, but it does go rancid. I would never recommend leaving butter in the cupboard.

You can read about butter rancidity here.

The idea of eating room temperature butter turns my stomach. If you want it soft, just put it out an hour or 2 before you are going to eat it, but then return it to the fridge.

My mother always kept the butter out of the fridge, but I can’t stomach the thought of that. Ever since the food-safety portion of my home-ec class, I’ve been a nut about food storage and preparation.

@incendiary_dan is exactly right. Because the water content of butter is so low, bacteria won’t grow in it. Oils and fats do oxygenate, though. I think the word is ‘rancid’. It doesn’t make them too harmful, but the smell and taste is bad. Sunlight and warmth increase the speed at which fats go rancid and some fats go rancid faster than others due to their stability.

Interesting that most refrigerator doors have a “butter garage” built-in.

I buy spreadable butter. That way it can be kept in the fridge but spreads easily and tastes like butter.
Rancid butter taste, eugh

Butter will spoil eventually, if kept outside of the fridge. It just takes much longer and most people use up a block of butter before it turns rancid. But rancid butter is horrible.

No way! I even prefer my butter sliced thinly on whatever it is I’m eating, not even into spreading it. I would never leave it out, the thought of that makes me not want to eat the butter I’m about to eat now!

@augustlan Me too, I always keep butter in the fridge. I keep almost everything in the fridge.

I am so glad that this question was asked. I love to be able to spread butter, but I thought it would spoil if left out. I have a butter bell, but have been nervous to use it. Now I think I will fill it up tonight and stop worrying.

I keep one stick out in a covered butter dish and the rest in the fridge. (-: And no; I’ve never seen a bug in it.

So, some are saying it gets rancid and moldy, etc. and some are saying no it doesn’t. What are the sources you are using either way?

Please ignore the above. I see the 2 links.

@flo Even oil gets rancid.

@JLeslie I know much less about the topic than everyone else here. I have flagged the last 2 posts since they are about links, (websites) which I noticed later.

I posed the question maily because I have never seen those who didn’t refridgirate having visible adverse effects, so I was just curious. But there should be a definitive answer to it.

If you want to study organic chemistry and long chain fatty acids and Iodine numbers that will give you your definitive answer.

Butter is a reverse emulsion, which means that it contains both fats and liquid. The liquid is from the milk it is extracted from and the milk fats act as the emulsifier, combining the fats and liquids and keeping them in a stable form. All fats are made up of long chain fats and each have different properties. Some fats are more stable than others, in that they don’t react with air so they are very stable. Butter is a saturated fat and saturated fat, though they have a reputation of being bad for you, are the most stable and, therefore, they keep much better.

@cazzie I just think this is something every expert should have the same answer for. Like 1+1 is 2 right?

@flo…. so…. what part isn’t answered for you? You can leave butter out of the fridge for a relatively long time in a temperate climate without fear of spoiling.

@cazzie How about the answers that say it does get rancid?

Flo, it doesn’t get rancid like the same day you leave it out or anything, any more than bread goes moldy the same day you buy it. You can leave butter out for a number of days and it will still be good. But nothing stays good forever, and it does eventually go rancid. There are ways to preserve it longer (like a butter bell, for example). Does that make sense?

A simple experiment might be to buy some butter, and leave a stick of it out. You can see for yourself how long it takes butter to go rancid in your local environment.

@laureth thank you. The anecdotal evidence is one thing and then the empirical one. But it is not a huge need to know really.

Butter has changed over the 36 years of my married life. It used to go rancid fairly quickly on the table, just as the milk spoiled in about six hours left out. But now, I cannot remember tasting rancid, even slightly rancid butter, for years. However I just saw my first black dots of mold on a butter in a jar I had at room temperature for a week. No, THAT butter, mold and all was not rancid, as I started to use it and tasted it on my toast. It did not turn red yellow, did not smell strong, and did not taste rancid. It was whitish still, it was mild smelling and had big black mold dots on it like a piece of moldy bread. I am not sure how manufacturers are preserving butter, but it is not what it used to be. It is a different substance. Butter is not butter. It is not even Ghee.

@MOMANNB6 Good point.

I think the manufacturers of butter add margarine without warning. It is difficult to detect margarine in the mass of butter, because of they identity in many features. Pure butter get rancid in a few days. I remember it from my childhood in Tashkent, where margarine was not known that time.