While reusing brine is probably fine in many cases, it's tricky from a food-safety perspective. It seems like there are lots of threads on the internet these days about reusing "pickle juice," and there are great reasons to take your brine and use it in some recipe for salads, dressings, sauces, etc. that you'll consume soon after making (or at least sterilize by cooking).
But reusing brine to make more pickled foods? That's another issue entirely.
If you've made homemade pickles or canned goods, you know that most reputable recipe sources have huge disclaimers saying: "Warning! Always be sure to follow recipes exactly, and do not deviate from the given proportions."
If you make traditional lactofermented pickles, you need a certain salt concentration to inhibit growth of dangerous microbes in the first few days of fermentation. After that, the acidity created by fermentation will prevent anything bad from growing. If you make "fresh pack" pickles or refrigerator pickles, you depend on a certain concentration of acid (usually vinegar and/or lemon juice) and salt to prevent bacteria growth.
Particular concentrations of acids and salt are critical to keep your food safe, especially if you plan to store it for more than a couple days, even in the fridge. Refrigerator temperatures slow the growth rates of bacteria, but they don't stop a lot of bad things from growing completely. If you drop a bunch of fresh vegetables in old brine and come back in a month or two expecting pickles -- you'll probably have some great-tasting stuff. But it could also be carrying harmful pathogens.
The main problem is that brine has salt. Due to osmosis, salt will draw water out of things with high water content (like vegetables, eggs, fruits, and just any food you might think of pickling). If water is added to your brine as it "leaks" out of the added food, you reduce the salt concentration as well as the acid concentration, perhaps leaving an unsafe solution to make further pickles.
Pickling recipes know this and will build in extra salt and/or acid into most recipes, knowing how much water on average will come out of particular foods. By adding a second or third or fourth batch of food to that solution, the brine will become increasingly watery.
Boiling or heating the brine -- as suggested in other answers -- probably doesn't help much. Your pickling brine was already designed to prevent growth of pathogens, with proper concentrations of salt and acid. You shouldn't be worried about pathogens in the brine, but rather pathogens in the new food you're adding. Cooking your new food first can help, but that sometimes ruins the texture of many pickled foods.
Also, even boiling the food many not be sufficient if the reused brine gets too weak. Botulism bacteria, for example, has spores that are not destroyed even at boiling temperatures. With proper acidity (and salt), they won't grow. But if you mess with the recipe, they could. At even lower acid levels, you could grow all sorts of stuff, Listeria, for example. At refrigerator temperatures, it might take a few weeks or months to grow to dangerous levels, but long-term storage is exactly what people tend to do with pickles.
The only way to reuse brine safely would be to ensure that your new brine has the same characteristics as the old one: especially equivalent acidity and salt content. If you really know what you're doing -- i.e., are an experienced pickle maker and understand how to vary recipes while ensuring safety -- you might be able to calculate how much salt and acid to add to keep your brine safe while adding new food. (Trying to re-ferment lactofermented pickles is unreliable, so I'd discourage that route to obtain new acidity.)
In the vast majority of cases, reusing pickling brine won't result in any problems, especially if you keep it in the refrigerator and only put the new food in for a few days. Commercial brines, in particular, often have excess acid and salt beyond that necessary to ensure safety, so reusing them once may be unlikely to cause problems. But it's actually not a safe practice unless you know what you're doing, particularly if you store the new food for any length of time. Whatever you do, do NOT leave pickles made from reused brine at room temperature, even if you've heated the brine and resealed the jars. Without the guarantee of proper acidity, you could end up with botulism toxins or other dangerous spoilage bacteria.
Brining and marination do two different things, contrary to popular belief.
Brines allow salt (plus possibly a very few other small flavor molecules) to penetrate into meat, at a rate of about 2-2.5 CM per 24 hours. These deeply season your meat, change its texture, and help allow it to retain moisture when being cooked.
Marinades are a surface treatment, applying flavors to the surface of the food. In actual practice, they do not provide any flavor deep into the food (except possibly salt). Marination generally does not penetrate more than about 2 mm. They are mostly about the sauce adhering to the food.
Your best bet, if you want the best of both worlds is to:
- Brine the chicken in a simple unflavored brine (just water and salt and/or sugar)
- Marinate in a low salt marination for surface flavor.
You do not want to do the reverse, as the brine would essentially wash away the marinade. You do not want to mix the marinade and the brine, as it will not adhere, and will not penetrate, essentially wasting the marinade ingredients.
It may also be helpful to treat the food with a low salt dry rub for flavor, or baste it with a flavorful sauce as part of the cooking technique.
Best Answer
I think (as is so often the case with preprocessed meat) it will often depend on who you buy it from. I often buy kosher prepared birds (which are always pre-
brinedsalted) and I've never had any complaints. The nice thing about kosher preparation, is that it is done according to very specific rules, under strict supervision. It's not a factory process.On the other hand, I cannot abide the brined birds from major poultry companies. Their primary goal is to increase the weight of the bird, not the flavor.
Factory prep seeks to minimize time and cost. They will use cheap ingredients (largely just water and salt, with no added herbs) and they will use whatever process takes the least time, most likely injection, which has the added benefit that they can force more liquid (and therefore weight) into the meat than would normally come from absorption. They'll likely insta-freeze it, so wait time is probably not an issue, but freezing causes its own issues.
I would say, for best results, take your time. A nice leisurely soak, real salt, and no pressure on the meat. For best results (talking turkey here) look for "Natural" or "Minimally Processed": if it says that, you shouldn't have to worry about competing additives.