Also referred to as hamburger, ground beef is simply beef that has been ground or finely chopped. The price of ground beef is determined by the cut of meat from which it was made and the amount of fat incorporated into the mix. High-fat mixtures are less costly but will shrink more when cooked. The least expensive product is sold as regular ground beef or regular hamburger. It's usually made with trimmings of the less expensive cuts such as brisket and shank, and can contain up to 30 percent fat. The moderately priced ground chuck is the next level of ground beef. Because it contains enough fat (about 15 to 20 percent) to give it flavor and make it juicy, yet not enough to cause excess shrinkage, ground chuck is the best meat for hamburgers. The leanest (around 11 percent fat) and most expensive of the ground meats are ground round and ground sirloin. Though they're great for calorie watchers, they become quite dry when cooked beyond medium-rare. Ground beef is sold fresh and frozen, prepackaged in bulk (usually 1 to 5 pounds) or in preformed patties. It may also be ground to order. The way it is used determines how the beef should be ground. In general, the finer the beef is ground, the more compact it will be when cooked. For instance, firm-textured combinations such as meatloaf or meatballs should be made with beef that has been ground at least 2 or 3 times. For hamburgers, however, where a light, juicy texture is preferable, the beef should be coarsely ground. Ground beef should be lightly wrapped before storing in the coldest section of the refrigerator for up to 2 days. To freeze, shape into individual patties or a large, flat disk and wrap with freezer-proof packaging. It can be frozen up to 6 months. See also beef; hamburger.