When you take some chicken out of the fridge to cook it, you might find yourself giving it a quick sniff to see if it smells all right. If it does, you continue. If not, you start to wonder: is this chicken still good?
This little ritual, repeated millions of times in kitchens everywhere, is something we do out of habit, almost a reflex. But can taking a whiff of chicken tell you if it's gone bad? And what does "bad" mean, anyway?
What Makes Chicken Go Bad?
To begin with, when your chicken (or any food, for that matter) goes bad, it's because of bacteria. Bacteria are very tiny, very simple organisms that live on our food, which they eat, and where they also reproduce. As a result of them inhabiting and eating our food, they produce changes in that food that cause it to go "bad."
There are two kinds of bad: there's smelly-bad, and then there's might-make-you-sick bad. What's important to note is that these two kinds of bad are caused by completely different sorts of bacteria.
And, since avoiding the might-make-you-sick kind of bad (aka food poisoning) is a far more crucial concern, we'll address that one first.
Chicken That Might Make You Sick
Food poisoning is caused by certain bacteria that—either because of toxins they produce or because they attack the cells in our digestive tracts cause the various symptoms that we identify as feeling sick—nausea, diarrhea, and so on.
Examples of these microbes (known as pathogens) are Salmonella and E. coli. Salmonella happens to be the most common cause of food poisoning, and it's particularly prevalent in uncooked poultry.
There's both bad news and good news when it comes to chicken that is contaminated by one of these pathogens. The bad news is, there's no way to tell that it's contaminated: not by looking at it, not by smelling it, and not by touching it. These bacteria are completely undetectable.
In other words, a piece of chicken that's contaminated with Salmonella will not only appear to be completely "fresh," it can, in fact, be absolutely fresh.
The good news, however, is that bacteria of this type are incredibly easy to kill. All you have to do is cook the chicken.
The standard guideline, as given by the FDA, is that chicken should be cooked to an internal temperature of 165 F for at least 30 seconds, and doing so, will reliably kill any harmful bacteria that it might harbor.
This makes it extremely easy to ensure that your chicken won't make you sick. Just cook it thoroughly. Now, there are quality issues with cooking chicken to that temperature—specifically chicken breasts, which when they reach 165 F are considered overcooked, meaning they'll be dry and stringy. But from a food-safety perspective, they're considered safe.
Fortunately, by extending the duration, you can lower the target temperature. For instance, an internal temperature of 150 F for 2.7 minutes is the same, food safety-wise, as 165 F for 30 seconds. Likewise, 145 F for 8.4 minutes.
And, since 145 F happens to be the ideal temperature to cook chicken breasts to ensure that they're tender and juicy, all you have to do is make sure that they maintain that temperature for at least 8.4 minutes. For more on that, here's an article on the right temperature for cooking chicken breasts.
Chicken That Smells Bad
Spoilage, on the other hand, is another thing altogether. Spoilage—meaning the changes that take place in food that cause it to smell bad, feel slimy, change color, and so on—is also caused by bacteria, only it's different bacteria.
What happens is, like all living organisms, these bacteria eat food and excrete waste. And, in many cases, it's this cycle of eating and excreting that causes the changes in the food that we recognize as spoilage. In other cases, it's the dead bacteria themselves (since their life cycle isn't particularly long).
But what's important to know is, chicken that smells bad can't actually make you sick—assuming you cook it properly, in accordance with the guidelines we described above. Now, whether you would want to cook spoiled chicken is another matter, but the point is, you could. And, it wouldn't hurt you. You'd just be eating smelly chicken.
Most of the changes known as spoilage occur on the surface of the food, so if you have some chicken breasts that feel slimy, your first step should be to rinse them thoroughly in cold water.
As for the smell—spoiled chicken smells, well, bad. As in ammonia, or rotten eggs, or just plain pungent. Even fresh chicken smells like something, but it shouldn't smell funky. If yours does then it's probably spoiled. (Note: One of the reasons sauces were invented was to mask the off-flavors and aromas of meats and poultry that had gone slightly bad.)
How to Keep Your Chicken From Going Bad
The best way to ensure that your chicken doesn't go bad is to cook it and eat it the same day you bring it home. And, if you're not going to do that, you should freeze it the same day you bring it home.
You can learn more about how to keep your chicken from going bad, but in general, if you get into the habit of either eating it or freezing it on the first day, you'll be fine.