Casings 1. Natural casings –for “traditional” products –consist of submucosa layer (mostly collagen) of G.I. tract –outside (fat) and inside (mucosa) layers are removed –highly perishable, salted to reduce spoilage –salt will dehydrate, may harden collagen somewhat

– quality/size is variable –size variation is typical and expected but should be reasonably consistent frankfurters22-26 mm bratwurst28-32 mm ring bologna ~ 40 mm –breakage and weak spots (parasites) can be problems –microbial load –a problem which sometimes develops is pink color development (fat soluble pigment) –produced by a very salt tolerant bacteria that grows at relatively warm temperature (over 40 o F) –indicative of questionable storage

– non uniformity problems –do not “machine handle” well –not geometric in shape and coldest spot may be hard to find for temperature monitoring –residual fat if present may be/become rancid and may transfer radicals to product –significantly more expensive than manufactured casings –may add $.25/lb for frankfurters –need to flush, wash prior to use and soak in water for ~ 30 min.

Sheep casings are small diameter (16-30 mm) and most tender –used for products where casing is consumed

Hog casings usually are larger mm and still tender enough to be consumed in most cases –though hog bungs and stomachs usually are not

Beef casings (rounds, middles) are likely to be removed form products because of toughness

Laminated Casings

terms for casings “hanks” or “bundles” –group of hog or sheep casings of ~ 100 yards (91 meters) –160 ft for manufactured casings –“green weights” –stuffing capacity of casings per hank before cooking/smoking –“shorts” –3 - 6 foot lengths –“whiskers” –remnants of blood capillary on casing surface with hair-like appearance “shirred” –manufactured casings compressed into inch lengths “prestuck” –manufactured casings with pinholes “drilled” –addition of 1/8” holes on casing end

2. Manufactured casings a. reformed collagen –extract collagen form corium of beef hides, solubilize, shape into tube, treat to crosslink collagen and form casing –usually small diameter, tender –need to be careful - as with naturals for moisture (tenderizing, softening) and drying (hardening, impermeability) effects on collagen b. co-extrusion –Collagen or alginate dough can be extruded over a meat mixture as it is “stuffed”-becoming a major means of sausage production –combination passes through salt baths which crosslink the collagen or alginate and form a casing over the product Kontura - Townsend Engineering

c. cellulose –processed (solubilized, shaped, reprecipitated) from wood pulp –typically inedible (too tough) but work well for machine stuffing (frankfurters) and handling –highly permeable to moisture and smoke - largely impermeable to fat

d. fibrous –large diameter cellulose with fibers added for extra strength –often “prestuck” or “drilled” to help removal of air/water during stuffing –soaking in warm water prior to use is recommended to increase “expansion” flexibility for stuffing e. moisture-proof casings –for water-cooked products such as braunschweiger –include plastic coating inside or outside fibrous-type casing

Specialized casings 1. pre-smoked –for smoke transfer to product after stuffing 2. dry sausage –interior protein coating so casing adheres and shrinks with product during drying 3. non-stick coatings –for sliced products (large bologna) or skinless frankfurters, casings must peel easily 4. antimicrobials –interior coatings (diacetate, etc.) to suppress post-cooking contamination

For all casings: –manufacturers provide recommended storage conditions and stuffing diameters to allow appropriate casing performance (breakage, peelability, etc.)

Stuffing equipment considerations 1. piston stuffers –hydraulically driven piston –simple, inexpensive –batch operation 2. continuous, flow-through stuffers –auger or screw-type –rotating vanes (less severe pressure) –multiple-piston (Marlen)

Percentage of Defective Slices From Hams and Shoulders Stuffed with Different Stuffers Stuffer % Defective Slices in: Hams Shoulders 1. Multiple vanes with open air hopper - 60 mm horn Double auger with open air hopper - 60 mm horn Single vane with vacuum hopper - 80 mm horn Multiple piston with vacuum hopper mm horn Products cooked in 74 o C water to reach internal temperature of 69 o C. Chilling was to -1 o C prior to slicing.

– most include vacuum, linking, twisting attachments, portion control –stuffing horns designed to minimize product smearing with end projections 3. protein orientation –corkscrewing of frankfurters –surface rearrangement of proteins may modify finished product shape during reheating