Natural casing is made of the longest small intestine in animal viscera, usually pig small intestine, but also cow small intestine, horse small intestine and sheep small intestine.

Making small intestine into casing requires complicated processing, not only cleaning and removing undigested food residues, but also removing inner mucosa and outer intestine skin. Therefore, the thickness of casing is much thinner than that of normal animal intestine, and meat can be poured into it.

The advantage of natural casing is good air permeability. Therefore, after the sausage is properly dried and smoked, the smoked ingredients can be attached to the sausage to get their favorite flavor, and the casing can be eaten directly.