You can cook a brisket in the oven for eight hours, but unless you're cooking a whole brisket, you probably won't need to. Even at low oven temperatures, most briskets cook in three to four hours. Keep the meat covered and check it frequently.
Brisket comes from the front portion of the steer, just under the shoulder. Part of the chuck, a whole brisket can weigh 15 pounds or more. Brisket is a complicated cut of meat, made of many overlapping layers of muscle. It's typically divided into two portions: the front cut, which is long, flat and lean, and the second cut, which contains more fat and marbling. Both cuts need long, slow cooking to become tender and juicy.
To cook a brisket in the oven for several hours, salt and pepper it generously and brown it in some oil on the stovetop. Preheat the oven to 275 degrees Fahrenheit. Place the brisket in a large Dutch oven or roasting pan and add a braising liquid, such as red wine, broth, beer or fruit juice. Cover the pan with a lid or aluminum foil, which prevents moisture loss so the brisket stays juicy. Baste the brisket with the braising liquid every 30 minutes to one hour -- an especially critical step for long cooking times. Add more liquid if necessary. The brisket should be partially covered, but not submerged in liquid.
Take Its Temperature
The cooking time for a brisket doesn't matter nearly as much as the temperature of the meat. The U.S. Department of Agriculture suggests 145 degrees Fahrenheit as the minimum safe cooking temperature for beef, but for a truly tender brisket, cook it until it reaches 185 to 195 degrees Fahrenheit. At this high temperature, the connective tissue in the meat breaks down, becoming tender, flavorful and moist. Insert a meat thermometer into the thickest portion of the brisket after two or three hours. Once the brisket reaches the right temperature, there's no reason to cook it more. Doing so can cause it to dry out or toughen.
Keep It Safe
One of the challenges with long cooking times is keeping food safe. Meat is particularly tricky. If the oven temperature is too high, the brisket will dry out. If the oven temperature is too low, the meat may not cook quickly enough to prevent bacterial growth. Bacteria multiplies when the temperature of food ranges between 40 and 140 degrees Fahrenheit -- sometimes multiplying in as little as 20 minutes. Because of this, the U.S. Department of Agriculture recommends cooking meat at an oven temperature no lower than 325 degrees Fahrenheit. This oven temperature is probably too high to cook brisket for eight hours. James Peterson, author of "Meat: A Kitchen Education," recommends cooking brisket at 275 degrees Fahrenheit. Cooking at this low temperature ensures a moist, juicy brisket, but it may increase your risk of food borne illness.