How the chicken is processed depends on the supermarket. At many places you can just ask them what they do and they’ll be glad to tell you. That said, brining

How the chicken is processed depends on the supermarket. At many places you can just ask them what they do and they’ll be glad to tell you. That said, brining chicken prior to roasting is very common. I do it myself and it is almost essential for free range chicken which tends to have more blood near the bones, brining helps mitigate that. The other stuff is more or less just spice rubs. YMMV, depending on your supermarket. Roast chicken tends to go fast so I would be surprised if they need to use preservatives.