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 consistentfrankfurters 22-26 mmbratwurst 28-32 mmring 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 40oF)

– 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 28-48 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 12-18 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 casings1. 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 openair hopper - 60 mm horn 13.2 22.5

2. Double auger with openair hopper - 60 mm horn 8.1 11.4

3. Single vane with vacuumhopper - 80 mm horn 0.8 1.2

4. Multiple piston withvacuum hopper - 125 mm horn 0.3 0.5

Products cooked in 74oC water to reach internal temperature of 69oC. Chilling was to -1oC 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