Well, it makes sense that the metallic parts through which the meat goes through will contaminate it with tiny amounts of metals. Aajonus also said that metallic mincers will contaminate it.
Regarding knife, it is metals, and it is difficult to process lamb breast, which are extremely high in fat.
i do some mincing on an inexpensive home machine.
- are you asking about commercial or home mincing machines?
- what kind of contamination are you referring to, metal leaching from the mincing machine, metal particles or
chilling fat and muscle to near freezing will make mincing easier but the fat still builds up inside the machine.