Chicken is just about the ideal meal ingredient, at least for omnivores. It's inexpensive, endlessly versatile and almost everyone enjoys eating it. The only real downside to chicken is that it can be a bit bland, unless you're buying really good birds from an artisan producer. The answer to that is adding flavors to your chicken, either by seasoning it as you cook or by marinating it ahead of time. Those marinades almost always call for oil, and olive oil is an especially good option.
Marinate for Flavor
Most marinades contain oil, an acidic ingredient, and some combination of other flavorings. Each of those three things plays a specific part in the marinade. The flavorings are there to add flavor, of course. The acidic ingredient is a flavoring in its own right, and it also dissolves water-soluble flavor compounds so they can make their way to the chicken. The oil does the same for fat-soluble flavor compounds, and it also coats the chicken. That's important, because it helps the surface of the food hang onto all of those flavors. It also protects the chicken from the heat of cooking, and helps it brown on the grill or in your pan.
Choosing Olive Oil
There's no physical reason to choose one oil over the other for a marinade, because whichever oil you use will work just fine to coat your chicken and infuse flavors. Still, there are a couple of reasons to opt for olive oil. For one, a good olive oil will often have a distinctive flavor of its own. If you're shooting for some kind of Mediterranean flavor profile, a bold-flavored olive oil plays into that. The other, really good reason for choosing olive oil is that it's one of the healthiest dietary fats. It's made up mostly of monounsaturated fatty acids – usually abbreviated as MUFAs in nutritional literature, because that's a lot of syllables to type and sound out – and MUFAs have a lot of well-researched benefits on things like your cholesterol levels.
Constructing Your Marinade
To make up your marinade, you'll need just enough oil to thoroughly coat your pieces of chicken. You can use a bowl or other food-safe container, but marinating your chicken pieces in a zipper-seal bag means you'll need less marinade, and waste less oil. Your acidic ingredient can be lemon juice, wine, a mild vinegar or any other fruit juice you've got handy. Just a tablespoon or two is usually all you need. Too much acid can change the texture of your chicken. Finally, add any combination of spices and fresh or dried herbs that appeals to you. Whisk the ingredients together, pour them into the bag and add your chicken pieces. Squeeze out any unnecessary air, seal the bag and massage it for a moment or two to make sure the marinade covers the chicken evenly. Keep it refrigerated until you're ready to cook, ideally no more than an hour or two.
Thank Hard About Salt and Sugar
Two flavoring ingredients are less straightforward than herbs and spices, and those are salt and sugar. Sugar, and other natural sweeteners such as honey, won't always fit the flavor profile you're looking for, but if they do they'll help your food brown more quickly on the grill or in the pan. That can be a bad thing if your chicken scorches at the surface before it's cooked through, so use it warily. Salt in a marinade can actually absorb right into the chicken breast, so you can marinade and brine it at the same time. That's a good thing up to a point, because it means your chicken will taste well-seasoned and come out juicy when it's done. The problem is that chicken is often already brined when you buy it, so if you add salt to the marinade, it might come out really, really salty. If you don't know for sure, skip the salt.