over cooking and under cooking when braising

11.3  Over cooking or under cooking

If not compensated by countermeasures, the opening of the oven door and the resulting loss of temperature and moisture content of the air circulating inside can lead to increased evaporation from the meat surfaces. In the case of tough meats such as beef, bison, and deer, the result can be a hardened, shell-like, overcooked or burned outer crust, while inner layers of the meat may still be undercooked or raw; with soft meats such as poultry, the result can be a thorough drying from the surface to the bone, as in the case of the traditional American turkey.
To prevent this, the easiest solution is to place the meat in a closed oven bag, which traps evaporating moisture and does not let it disseminate into the oven space and then out to the kitchen. The meat is "auto basted" when the air trapped inside the bag reaches the point of its maximum possible moisture content, and the resulting precipitate forms into drops on the surfaces of the meat or the wall of the bag. The drops roll down to the lowest point of the closed space, where the meat sits and cooks in the resulting juices. This technique often requires very minimal or no added liquids other than what the meat already contains, for loss of moisture is virtually negligible from inside the bag.
However, oven bags lose their advantage if they are opened even one time during the cooking process, and seasoned cooks, who prefer adding flavoring, natural oils (herbs), or aromatics in different times and portions during the process, generally use alternate practices to avoid drying out the meat. For instance, they allow extended cooking time, administer increased amounts of juices, coat the meat with moisture rich fruits or fat-rich cuts, such as bacon, or actual fat, place moisture rich fruits and vegetables around the cooking meats, and if possible, use a convection oven.