Mrs. Dolphinboy and I like to make a big pot of coffee over the weekend. We rarely drink it all and by thursday or friday the following week there is often some left in the decanter (pot). It’s been sitting at room temperature for 3-4 days by this time yet we continue to reheat cups of it and drink it.
Does coffee go bad after a while or could we leave it out for a week with no ill effects? Should we just keep it in the fridge instead?
I don’t see that it can go ‘bad’ any more than boiled water can go ‘bad’. Although I’m astonished that you don’t notice the taste declining with each reheat. But that’s an aside.
I would think coffee sitting around at room temperature for 3-4 days would have a lot of “crud” in it. And the oils in the coffee would start developing a nasty flavor, although I don’t think it would be unhealthy.
Coffee is fairly acidic which would probably keep too much in the way of nasty things like bacteria from growing in it, but after a couple of days sitting out, it would taste pretty nasty (although apparently that doesn’t bother you).
It can get moldy if you leave it out long enough. Some coffee got left in out in my lab a couple of times, and you could see little patches of mold floating on top after about 7-10 days, IIRC.
Anyway, coffee that’s more than a few hours old tastes nasty.
Anything left exposed to air is going to collect bacteria and fungus spores. Reheating the coffee and swirling it around (pouring, etc.) will probably kill off some of the bacteria and fungus and hide the rest, but after 3-4 days, you’re probably drinking a nasty concoction of flora and fauna, whether or not you can see or taste it.
Personally, I won’t keep brewed coffee for more than a day. If I feel bad about throwing out a whole pot, I might put it in the fridge for the next day, but if I forget and leave it out, out is where it goes in the morning.
Well… after a couple of weeks you can see funny fungus swimming around, and it gets even more interesting after a month or two… but I have never tried it under that situation. If you reheat it enough you’ll kill bacterias, but you’ll lost the real taste after hours in my opinion.
When I worked at a Red Roof Inn 20 years ago, we had coffee and donuts for the guests in the morning. I would make the last pot at 10am. The Polish houskeepers would let it sit and they would drink it around 3pm when they left. They said they liked it thick and strong.
Other than a loss of flavour I can’t see the harm. You can keep ice coffee for awhile. And if you reheat it it should kill the germs. Like I said it will taste “different.”
Coffee left out in my house, whether in the pot or in an unattended cup, gets moldy within two days.
:eek: Bleh! Why not get a 4 cup coffee maker and make it as needed???
Just information: four cup coffee makers make only two servings. 
We have coffee in a box from a local restaurant. How long do you think that would keep, in the refrigerator, say? How long do you think they keep it before we get it?
The fridge may actually be a bad place to keep coffee. While people disagree, I would recommend at very least that you wrap it up EXTREMELY well - just because coffee that has absorbed food odors is probably not going to taste real good.
If the coffee’s ground, ideally you shouldn’t keep it for very long - if you’re spending serious money on it, don’t let it sit ground for over a week, and keep it tightly closed. Even whole beans don’t last that long - their flavor changes after the roasting process. It’s hard to say how long it’s been sitting at the restaurant before you purchase it, but it starts to decline in flavor soon after roasting; whole beans won’t go rancid or lose flavor as fast as ground coffee, but don’t keep it too long.
As for letting brewed coffee sit for several days, I have been known to let it sit for a day or two with no ill effects beyond the rather revolting flavor of old coffee (which sometimes is acceptable when you just need your fix) but longer than that? Eww. Coffee gets moldy. Toss it or else stick it in the fridge, in something covered. The oils will certainly begin to go rancid (i.e. oxidize) do to exposure to air fairly quickly, but if you can stand the taste, it’s probably ok to let it sit for about a day, or to refrigerate it for several days. I do this with iced coffee in the summer.
Well, it’s in a box, like a wine box. The liner is mylarized maybe. I’ll let you know the next time one’s finished.
I once left coffee in a pot over the weekend, and it was moldy.
Most of the time I’ve left coffee in the pot it has grown mold within two-to-five days. Brew a new pot when you’re ready. Please.
What about muffins, pies, or cakes, left out two days?