Has this happened to you? You were all set to cook some chicken breasts, but your recipe said they needed to marinate for several hours, or even overnight, and you hadn't done that, so you changed your mind and made a frozen pizza or ordered takeout instead.
If so, good news! Because marinating does practically nothing to chicken, so there's no need to fret about how long you do it, or even whether you do it at all.
There are three commonly stated reasons for marinating chicken: to tenderize it, to add moisture, and so that the meat will absorb flavors. And in fact, marinating does none of those things.
We'll examine each of these notions one at a time, and then talk about what you can do instead of marinating to make your chicken as tasty as possible. And if you're determined to marinate your chicken anyway, we'll discuss how to make it not be a complete waste of time (and ingredients).
Marinating Does Not Tenderize Chicken
How tender your chicken is has 100 percent to do with whether you overcook it. Or to put it another way, how tender your chicken is has 0 percent to do with whether you marinate it.
The idea that marinating tenderizes chicken (or anything, for that matter) stems from the mistaken idea that the acidic ingredients (vinegars, lemon juice, wine, etc) in the marinade somehow soften or "break down" the proteins in the meat, thus making it more tender.
But acid doesn't tenderize meat. And, conveniently, you already know this. Because you know that ceviche is made by marinating raw fish and seafood in acid. And what happens to that seafood? The acid denatures the proteins, causing the flesh of the fish and seafood to become firm, not more tender. In other words, it cooks it.
Now, the reason acid cooks fish but not chicken is because the collagen sheaths surrounding the protein fibers in chicken are much thicker than the ones in fish. So the acid can't actually reach the proteins in the chicken. But even if it could, it would have the opposite effect of tenderizing.
Yep, tender, juicy chicken is entirely a function of not overcooking it. And with white meat chicken (i.e. chicken breasts), overcooked means cooked to an internal temperature above 165 F. Cook it to 165 F and it'll be tender and juicy. Cook it above that and it'll be dry, tough and stringy.
And speaking of juicy chicken...
Marinating Does Not Add Moisture to Chicken
Marinade is primarily oil plus some acidic liquids like vinegar, citrus juice and/or wine, all of which are mostly water with a small amount of acid. And we've already shown that acid doesn't penetrate the meat. But what about the oil? Well, no, oil doesn't penetrate the meat either. Because chicken is full of water, and of course water literally repels oil.
Matter of fact, why is there even oil in marinade? We'll get to that later.
Which leaves water. And water will not penetrate the meat either. Remember, raw chicken is already full of water. Chicken is made up of millions of protein cells, each one filled with water. In that sense, chicken is like a sponge that's already fully saturated. You can't take a saturated sponge, drop it in a bucket of water and have it continue to absorb all the water in the bucket. It's the same with chicken. No matter what you soak it in or for how long, it won't absorb any more liquid.
Chicken Does Not Absorb Flavors
This means you can forget about the chicken absorbing flavors. If the marinade isn't penetrating the meat, then neither are the flavors in the marinade.
Marinating does apply a small amount of that liquid to the surface of your chicken. Most of it drips off when you take it out of the marinade, but a small amount does stay on, and that small amount will indeed add some flavor to the chicken, assuming your marinade was flavorful.
But it won't add more flavor than quickly dipping the chicken in the marinade before cooking it, or simply brushing some of that flavorful liquid onto the chicken during the last few minutes of cooking.
Indeed, this last method is probably the most effective.
Even more effective, though, is seasoning your chicken with a dry rub. With a dry rub, the seasonings will actually adhere to the surface of the chicken, rather than simply dripping off as a marinade does when you lift it out.
Making the Most of Your Marinade
So whether you soak it, dip it or brush it, your marinade is only ever touching the surface of your chicken. That means that whatever is left after most of it drips off needs to be as flavorful as possible.
And that is where the oil and vinegar in the marinade come in. Some flavor compounds are water-soluble, some are fat-soluble and others are soluble in acid. Which means your marinade is a medium for dissolving the flavors of the other ingredients in the marinade, the herbs, spices and aromatic vegetables like garlic and onion, and transferring them to the surface of your food.
So when you make your marinade, be sure to load it up with these ingredients. Indeed, rather than soaking the chicken, you'd be far better off letting your marinade soak overnight all by itself, thus allowing the flavors of the ingredients to be released into the liquid.
By the way, this also means you can serve that marinade as a sauce, which you can't do with used marinade since soaking raw chicken in it turns it into a food safety hazard. But if your raw chicken never touches the liquid, this isn't an issue.