The most recent development in the area of sausage casings is the
use of co-extruded alginate, collagen or alginate–collagen hybrid
casings. In the co-extrusion process, a thin layer of collagen, alginate
or alginate–collagen hybrid coating is extruded onto the meat batter
as it is being extruded from the stuffer. In the case of collagen, the
collagen fibers are oriented into a woven structure by counter-rotating
concentric cones on the extruder (Embuscado & Huber, 2009). The coated
sausage then enters a brine bath to dehydrate the casings and increasetheir tensile strength. The alginate casings are cross-linked in a calcium
chloride bath, while the hybrid alginate–collagen casings are first
cross-linked with calcium salt and then liquid smoke (mainly the
aldehyde component) for protein–protein cross-linking. Alternatively,
the collagen casings go through a sodium chloride bath prior to being
cross-linked with liquid smoke.