These days many restaurants and home cooks rely on commercial meat extracts and bases for making their sauces and soups. The pioneer of mass-produced meat extracts was Justus von Liebig, inventor of the mistaken theory that searing meat seals in the juices, who was motivated by the equally mistaken belief that the soluble substances in meat contain most of its nutritional value. However, they do contain much of its savory flavor. Today, meat extracts are made by simmering meat scraps and/or bones in water, then clarifying the stock and evaporating off more than 90% of the water. The initial stock is more than 90% water and 3–4% dissolved meat components; the finished extract is a viscous material that is about 20% water, 50% amino acids, peptides, gelatin, and related molecules, 20% minerals, mainly phosphorus and potassium, and 5% salt. (There are also less concentrated fluid extracts, and solid bouillon cubes that have various natural and artificial flavors added.) Because gelatin would make such concentrated material too thick to work with, manufacturers intentionally break it down into smaller molecules by extending the initial cooking by several hours, and by pressure-cooking the clarified stock (at around 275°F/135°C for 6–8 minutes; this step also coagulates the remaining soluble proteins). In order to limit browning reactions and keep the extract light in both color and roasted flavor, much of the water evaporation is done at temperatures below 170°F/75°C.
