Mechanically separated meat (MSM), a product also known as mechanically recovered/reclaimed meat (MRM) or mechanically deboned meat (MDM), is a paste-like meat product produced by forcing beef, pork, turkey or chicken, under high pressure through a sieve or similar device to separate the bone from the edible meat tissue. For the production of chicken and turkey MSM, most of the time, breast carcasses are used as they still contain parts of breast meat.
This paste goes on to become the main ingredient in many a hot dog, bologna, chicken nuggets, pepperoni, salami, jerky etc…
Mechanically separated meat has been used in certain meat and meat products since the late 1960s. This product can be contrasted with meat extracted by advanced meat recovery systems. The most common use of MSM is into hot dogs.
As for products using mechanically separated chicken and pork, FSIS ruled that they are safe to eat, but required them to be labeled as such.
Despite them being safe, FSIS states that no more than 20% of the meat in a hot dog come from mechanically separated pork.