By Harold McGee
Emulsified sausages are a special kind of cooked sausage, best known in the form of frankfurters or wieners and so called for their presumed origins in Germany (Frankfurt) or Austria (Wien). Italian mortadella (“bologna”) is similar. These sausages have a very fine-textured, homogeneous, tender interior, and a relatively mild flavor. They’re made by combining pork, beef, or poultry with fat, salt, nitrite, flavorings, and usually additional water, and shearing the ingredients together in a large blender until they form a smooth “batter,” which is similar to an emulsified sauce like mayonnaise: the fat is evenly dispersed in small droplets, which are surrounded and stabilized by fragments of the muscle cells and by salt-dissolved muscle proteins. The temperature during blending is critical: if it rises above 60°F/16°C in a pork batter, 70°F/21°C in beef, the emulsion will be unstable and leak fat. The batter is then extruded into a casing and cooked to about 160°F/70°C. Heat coagulates the meat proteins and turns the batter into a cohesive, solid mass from which the casing can be removed. Due to their relatively high water content, around 50–55%, emulsified sausages are perishable and must be refrigerated.