Is Your Leftover Morning Coffee Safe to Drink in the Afternoon?
Experts weigh in on old joe
That delicious cup of morning coffee you just poured may provide the jolt you need to get your day started. Sometimes, though, that cup of coffee may sit around for hours before you have a chance to finish it.
The question is, can you still drink it? SafeBee interviewed several experts for their opinions.
Black coffee that’s been on hold for hours in a pot should not represent any kind of a health risk, according to Charles “Chuck” Gerba, PhD, professor of microbiology and environmental sciences at the University of Arizona’s School of Public Health in Tucson.
If you put milk in the coffee, the answer gets grayer. As a rule, you shouldn't consume milk that's been left unrefrigerated for more than two hours. But Gerba says milk in coffee that's been sitting on your desk for a few hours is unlikely to pose any health threat. "Caffeine is somewhat antimicrobial," he notes.
If you're using raw milk, you run a greater chance of bacterial contamination. "If the milk is not treated with the usual high temperature treatments such as pasteurization, the possibility of contamination is way greater," says Fernanda Haffner, a researcher in chemistry and food science at the University of Lorraine in France. But you can let coffee with pasteurized milk, she says, sit out for a few hours without worry.
Food safety coach Jeff Nelken, RD, agrees that coffee — even coffee with milk — is unlikely to support significant bacterial growth. He feels that you can safely consume coffee with milk two hours after it’s poured — with a caveat: “It depends where the milk came from and how it was stored,” he says.
If you got the milk from a coffeehouse pitcher or dispenser, “the milk may already have been sitting out at room temperature for several hours,” he says. And even pouring milk from the office fridge may not be a guarantee of safety, he says. “Office refrigerators are notorious for not having a thermometer, so do your office a favor and invest in a three dollar thermometer for the fridge." You’ll need one to make sure the temperature is no higher than 40 degrees F to store your milk safely, he says.
Nelken’s bottom line: If your old coffee has milk in it that came from a sufficiently cold fridge, bottoms up. Otherwise, you may want to toss it and get a steaming new cup.
(By the way, Nelken says you also need to be careful to wash your mug and spoon with soap and water – “I know that many office workers just rinse the mug and dry it with a paper towel -- yes, you, I see you out there!”)
Masking bad coffee
Of course, coffee connoisseurs might call you crazy for wanting to drink that hours-old brew.
As coffee cools, its flavor will change, according to Kevin Sinnott, author of "The Art and Craft of Coffee" and creator and host of the traveling consumer coffee festival CoffeeCon. Sinnott says that's in part because you're better able to discern all the flavors in a cup of room temperature coffee. Heat, as it turns out, can be a great way to mask bad coffee. "Tasting it at room temperature is like looking at your complexion in a bright, fluorescent light," Sinnott says. "It's designed to reveal all the flaws."
Coffee that left sitting out will also grow increasingly bitter as the water in it evaporates.
Once coffee is done brewing, Sinnott says that to preserve its flavor, it’s best to remove it from heat right away. He advises people to buy coffee makers that produce the amount of coffee someone consumes in a single sitting.
Related: How Much Coffee Is Too Much?
For for the ideal cup of joe, his advice is to make the coffee within an hour of grinding the beans. “Coffee’s ideal window of opportunity is two weeks from the time it’s roasted, an hour from the time it’s ground and 30 minutes from the time it’s brewed. The whole time cycle — it’s a moving target,” Sinnott says.
And as Sinnott points out, great coffee is not like a fine wine. “There’s no such thing in the coffee business as grind your coffee now and put it in your cellar,” he says. “No one says, ‘Oooh, let’s have that August roast.’”