Natural casings are obtained from animal intestines and are used to contain sausage mixes. They are derived mainly from sheep, goats and pigs but also from cattle and horses. Natural casings are strong enough to withstand pressure from filling and allow moisture and gases to pass through, absorbing smoke flavor. They are processed by removing the intestines from slaughtered animals and stripping them through various steps to remove contents and tissue layers, leaving the edible submucosa membrane. Processed casings are then salted and stored for use, with dry salted casings requiring soaking and ready to fill casings a brief soak before use. Storage times depend on temperature with dry salted casings lasting 6 months to 3 years at

1. Manufacturing of natural casing
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3.  Casings are soft cylindrical containers used to contain sausage
mixes
 Casings can be of natural origin or artificial.
 Natural : edible and inedible

4. Natural casings are obtained from animal intestines
derived from slaughtering.
Natural casings are mainly derived from small and
large intestines from sheep, goats and pigs, but also
from cattle and horses

5. Characteristics of natural casings:
# strong enough to resist the pressure produced by filling
them with sausage mix
# permeable to water vapour and gases, thus allowing fillings
to dry
# absorb smoke for additional flavor and preservation
# expand or shrink firmly attached to the sausage.
# can be closed at the ends by tying
or clipping.

6. Steps in the conversion of the digestive tract into sausage casing:
1-removal of the intestine from the animal .
2-running – removal of loose mesentery fat.
3-first stripping-squeezing to force out intestinal.
4-washing and cooling (10 degree Celsius)
5-mechanical or hand stripping .
6-brushing to remove fat.
7-slimming-removal of tissue layers –in revolving drums and warm
water or by hand slimming.

7. 8-stripping or hand removal appropriate tissue layers.
9-storage overnight in ice and 15-20% saturated salt solution.
10-grading-species ,size ,quality.
11-curing-rubbing with salt ;allowed to set for 1 week.
12-removal from cure, shaking free of excess salt, rubbing with
fine salt, and packing(40% salt).
13-flushing prior to use .

8. Sheep and goat casings
Processing steps for small intestines
Step 1: Separation of the small intestines from
mesenteric tissue

9. Step 2: Stripping out intestinal content
Step 3: Loosening of tissue layers using a
small-scale manual casing cleaning machine

10. Step 4: Removal of remaining parts of the serosa
membrane
Step5: Removal of "slime" by using
spoon

11. Step 6: Flushing of clean casings .
The photo shows the remaining submucosa membrane
b1/b2 ("edible" casing)
a = unprocessed casing
b1 = processed casing (slimed and cleaned)
b2 = processed casing (slimed and cleaned and being flushed (with water)
c = "slime" removed from inside of casing
d = tissue layers removed from outside

12. Step 7: Salting of clean "edible" casings for storage
Natural casings from sheep :
Sheep casing (small intestines)
Sheep fore-stomach and tripes (cleaned and scalded stomach)

13. Oesophagus and tongue (1), stomach (2),
small intestine (3), cap (4),
pig middles (chitterlings) (5), pig middles (after ends) (6),
pig bung (7), pig bladder (8)
Natural casings from pig

14. Beef gullet (1) Beef tripes (2)
Beef rounds (3) Beef caps (4)
Beef middles (5) Beef rectum (6)
Beef bladder (7)
Natural casings from cattle

15. Recommended treatment of natural casings
# Natural casings are usually available and best stored dry-
salted.
Prior to the filling of sausage mix into such kind of casings all
the adhering salt must be washed off with cold water.
Addition of lactic acid (2%) to the water can support this
process further.
# An alternative way of storing natural casings is in saturated
salt solutions
This is the ready-to-fill natural casing type, as it requires only
brief soaking periods ranging from minutes to up to one hour,
and proper rinsing. This type must always be stored chilled.

16. Recommended periods for soaking in water
Dry salted natural casings:
General : 10-12 hours
For pig large
intestines
: up to 24 hours
For cattle
intestines
: 5-10 hours
Ready-to-fill natural casings (stored in saturated salt solution)
General : maximum 10-60 min.
For large pig
intestines
: 2-3 hours

17. The storage periods for natural casings depend on the storage temperature. Dry-
salted casings in closed containers, which also protect them against light impact
causing fat-rancidity, can be stored at 6-8°C from six months to 3 years. Storage
periods are reduced with higher storage temperatures. Adhering fat reduces the
shelf-life.
The casing industry has established the following minimum requirements regarding
storage and transport:
Transport and storage of natural casings
Dry-salted maximum
+15°C
at least 3
months
Ready-to fill maximum
+10°C
at least 4 weeks

18. thank you