Like many other products, such as bologna and liver sausage,
hot dogs and Frankfurters are created by"meat emulsion," although as the FAO
notes,"meat batter" might be a more accurate term.
While it is unlikely that the practice of putting sausages in some sort of bread only happened recently(bread being a staple food throughout history and sausages being relatively popular in many cultures), the first recorded instances of sausages being sold encased in bread come from around the 1860s
where various German immigrants sold Frankfurters with milk rolls and sauerkraut on the streets of New York City.