PROCESSING OF MEAT, FISH AND POULTRY PRODUCTS

SLAUGHTERING AND STUNNING TYPES

Slaughtering means pulling the animals to death and thereafter preparing the
carcasses for human consumption. The objective of carcass dressing is to remove
all damaged or contaminated parts and to standardize the presentation of carcasses
prior to weighing.
Basic requirements for slaughtering-
- Cleanliness of meat produced
- Hygiene of production area
- Efficiency of meat inspection
- Adequacy of meat preservation
- Need for skilled butchers and proper tools and equipment’s for slaughtering
There are two main types of slaughter methods.
- A. Scientific or Humane slaughter.
- B. Ritual slaughter
-
A. Scientific or Humane Slaughter
Stunning is a process employed to create s state of immobility or
unconsciousness at the time of slaughter to 1 minute. Immediately, the animal is
hostel and bloods the animal to death.
Stunning Techniques and Devices
They fall into three main categories
1. Mechanical stunning
2. Chemical stunning
3. Electrical stunning

1. Mechanical stunning-
As per the name physical force is used to produce unconsciousness by
damaging the brain tissues. It can be classified under two categories:
I. Non penetrative mechanical
II. Penetrative mechanical
i. Non penetrative - Non penetrative method does not make a visible
hole to damage the brain tissues. Here a small iron rod is used to
strike at head and if practiced with accuracy produces immediate

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insensibility. Since this method does not involve penetration, brain is

edible.
ii. Penetrative - Penetrative mechanical stunning as per name leads to
formation of hole. It produces immediate and permanent
insensibility by destruction of brain tissues. The brain cannot be
utilized for edible purposes because the brain is destroyed by the
penetrating bolt. The different ways of penetrative mechanical
stunning are:
a. Captive bolt pistol
b. Pneumatic bolt stunner
c. Water jet stunning
d. Free bullet pistol
a. Captive bolt pistol: Generally, Cattle and buffaloes are stunned by
captive bolt pistol which is operated by means of a blank cartridge. A
bolt attached to pistol is propelled forward on discharge of blank
cartridge and automatically recoils into the barrel. The cartridge of
correct strength should be used. Captive bolt pistol produces
immediate insensibility by destruction of the cortex and deeper part
of the brain. Captive bolt pistol is effective in cattle, buffdo, sheep
and calves but not effective in bulls, pigs in which frontal bone is
very thick.
Three types of blank cartridge are used viz.
Green topped cartridge – Larger animals (Cattle)
Black topped – medium sized animals
Red topped – small sized animals (Sheep)
b. Pneumatic bolt stunners: Here bolt is activated under high pressure
(80 to120 psi) to achieve high velocity.
c. Water jet stunning: Fine jet of water is utilized to penetrate the
skull. Usually jet of 0.5 mm at pressure of 3500 to 4000 bar is
applied.
d. Free bullet Pistol: used for horses and calves

2. Chemical method
It is well known that the chemicals can be used as an anesthetic agent before
operation. Various gases and their combination are also being used to make the
animal unconscious. The induction time and the respiratory distress are two
important factors in selecting the gas and its concentration. N 2O has a higher
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induction time while CO2 being irritant produces respiratory distress at higher
concentration. Similarly a mixture of two per cent oxygen and argon induces
unconsciousness but it is slow process to be used commercially.

Carbon dioxide anesthesia is an effective stunning method. It is suitable for pigs.

Carbon dioxide is stored in cylinders or bulk tanks or liquid under pressure. It is
also available in solid form as dry ice for refrigeration purpose. A concentration of
CO2 is 65 to 70 % is more suitable with exposure period is 45 seconds. If the
concentration is too low, animals will not be stunned properly and if too high, the
animals will become stiff and bleed poorly. The CO 2 anesthesia also can be utilized
for turkeys (73-77% CO2) and chicken (70%).
The CO2 anesthesia is advantageous because-
- Meat and offal are free from harmful residues
- Relaxed carcass allows easier deskinning and dressing
- Less noise
- Reduced labor requirements, muscular hemorrhages can be avoided due to
stimulated bleeding
- Lower pH of the meat due to application of CO2

There are three main forms of apparatus used for CO, anesthesia depending upon
the rate of slaughter-

a) Oval tunnel- A slot conveyor carries the pigs through an oval tunnel which
slopes downwards at an angle of 30' to the anaesthetizing chamber. This is
used for higher killing rate, e.g., 120- 140 pigs hour.
b) Dip lift- When animals enter the cage, it descends vertically to the CO, pit
where they remain for the pre-set time and then automatically return to the
ground level.
c) Ferris wheel- This is a horizontally revolving apparatus divided into three
compartments operating in such a way that when one section is uppermost
the other two are submerged in the gas chamber.

3. Electrical method
In this method, an alternating current is passed through the brain/heart of the
animal. Electrical stunning is being used from the year 1930. Electrical stunning
causes cerebral nerve cells incoordination resulting in unconscious state of the
brain.
The electrodes of stunners are kept moist for proper shock while head of the
animals are kept clean and dry. High voltage may result into death of animal. For

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production of genuine anesthesia by electrical method, following factors to be

considered-
- The strength of the electric shock should be of sufficient magnitude. The
strength of the current should not be less than 250 mA and the voltage
should not be less than 75 V.
- The current should be applied for a sufficient time to induce an electroleptic
shock. 10 seconds is recommended for a genuine shock.
- The electrodes should be correctly positioned so that current will pass
through the thalamus and cortex of the brain.
- The animal should be immediately bled after unconsciousness has been
produced.
As per operational voltage electrical stunning can be studied under following
headings:
a) Low voltage electrical stunning: An electrical current of low voltage i.e.,
70 to 80 volt is manually passed through the brain of an animal for about 7
to 10 seconds to produce unconsciousness. A pair of head tong is suitable for
pig and sheep. The electrode is applied with pressure. Automatic electric
stunner for pig and poultry are suitable.
b) High voltage electrical stunning: high voltage stunners using 300V are
now available but have to be used with caution both for animals and the
operator. Brain function stops within 2 to 3 seconds. After high voltage
stunning and the animal is killed before bleeding. Therefore, this method of
slaughter of dead sheep or goat or cattle would not be accepted in ritual
methods of Muslim.

B. Ritual method

The ritual slaughter of livestock is carried out as per the religious rites of the
particular community. In this method, the animals must be in a state of
consciousness at the time they are bled. The bleeding must also be complete. This
is mandatory in the best known ritualistic slaughters, Halal, Kosher and Jhatka
methods.
1. Halal Method-
It is the Muslim method of slaughter of animals. Eating of dead animals,
consumption of blood and pork is not permitted in Islamic practices. Animals are
fed and watered before slaughter. Islamic law prohibits slaughter of sick animals.
The animal must be alive, healthy and free from injuries. Therefore, prior stunning
is not permitted. The animal is cast down and laid on its back. The site of cut is the
throat. Two jugular veins and carotid arteries are cut by a sharp knife. The spinal

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cord is not cut. The head is not separated at the time of slaughter. God's name is to
be mentioned as "In the name of Allah and Allah is great'' (Bismillah Wa Allah - o
-
Akbar). Therefore, machine slaughter is not permitted. The approved Islamic
organization should certify halal slaughter. Although muslim method of slaughter
is not controlled by a central board but is overseen by local Islamic authority
known as Muftis. Better bleeding enhances the keeping quality of meat.

2. Kosher Method-
It is also known as Jewish slaughter as the jews consumes meat of only those
animals that have been slaughtered by this method. The act of killing or method of
slaughter is called shechita. The act of slaughter is being controlled by central
body-Jewish Board of shechita. The shechita (slaughter) is performed by shochet
or cutter who slaughter the fully conscious animal with a single, deliberate, swift
action of a razor sharp knife called chalef: The shochet is being assisted by shomer
who puts seal of kosher mark on the brisket and edible offal. The shochet and
shomer are being trained and then licensed to perform slaughter. The meat fit for
consumption of jews i.e. fullfilling the requirements of Jewish law is called
"kosher meat". Any disease or deformity discovered in the carcass render the meat
'terefa' (rejected) i.e., unfit for consumption by jews. Stunning of animals is not
permitted. The five rules for Jewish ritual slaughter are that the neck incision is
completed without pause, pressure, stabbing, slanting or tearing. If the knife
receives any nick during act of shechita, the meat is not permitted for Jewish food.
Spinal cord is not cut in Jewish method. Kosher meat must be consumed within
three days of slaughter if kept under chilling condition.
3. Jhatka method-
This slaughter is performed according to rites of Sikh community. The head
of the animal is chopped off at the neck with sharp sword in one stroke. The head
and rest of the body of the animals are there by separated completely. The animals
are not stunned before slaughter, since the spinal cord is totally severed, the animal
does not experience pain of slaughter. The nutritional quality of the meat is high as
the carcass contains more blood due to incomplete bleeding.

 Dressing of carcass

The objective of carcass dressing is to remove all damaged or contaminated parts

and to standardize the presentation of carcasses prior to weighing. Veterinary
inspection of carcasses and offal can only be carried out by qualified personnel.

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After stunning of the animal, bleeding and complete dressing is carried out
speedily on overhead rail. This is called as line dressing or rail dressing systems.

Dressing steps for Sheep/ Goat

a) Decapitation: removal of the head.
b) Removal of legs: fore legs are disjointed at the knee joint.
c) Skinning / Flaying: skin is also removed by putting air in between the skin
and underlying tissue. Skin is reflected on both sides by twisting and
thumbing and this process is called as Fisting.
d) Evisceration- Process of removal of visceral organs.pluck includes larynx,
trachea, heart, liver, lungs and spleen. Stomach is removed first (paunch)
then pluck is removed.
e) Carcass washing: spraying of potable water.

Dressing Steps for buffalo/ cattle

a) Dehiding: is the removal of hide or skin. The hide/ skin over the fore
limb and hind limbs is removed and followed by the skin/ hide of belly,
chest and neck.
b) Eviscreation: Process of removal of visceral organs. In case of cattle/
buffalo carcass larynx, trachea, heart, liver are collectively known as
pluck.
c) Splitting: Carcass are split vertically into two halves(Right and left) using
sterilized saw or cleavers.
d) Carcass washing- spraying of potable water to remove soil, blood, stains
etc. The carcass is dried to avoid bacterial growth.

Dressing steps for Pig-

a) Scalding- Skin of the pig is not removed during dressing instead scalding
is done by exposing to hot water treatment (62-64°c). The process
loosens the attachment of hair/ bristles by partial cooking of hair follicles.
b) Dehairing- hairs or bristles are removed either by dehairing machine
(Mechanical scrapper) or manually. All bristles are not removed, so
singeing is done. In this process skin surface is exposed to blow lamp
which chars the remaining bristles and hairs.
c) Rinsing- carcass is rinsing thoroughly with cold potable water.
d) Evisceration- almost same as followed in case of cattle.
e) Final washing- clean, cold and potable water is used.

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