LPT 312: Abattoir Practices and Animal Products Technology (1+1)

SLAUGHTER AND DRESSING OF POULTRY

Slaughtering involves stunning and bleeding

Stunning

• Stunning prevents struggling and relaxes the muscles holding the feathers.
• However, it is generally not practiced in case of chicken.
• A low voltage electric stunning of 50 volts AC for 1 minute has been found to be satisfactory. 

Bleeding

• This process is carried out in an inverted cone shaped equipment to rest the body of the bird and keep the head out and down.
• There are several techniques of slaughtering poultry in order to seek proper bleeding.
• The technique most commonly used these days is “modified Kosher Method” in which jugular vein is severed just below the jowl taking care not to cut trachea and oesophagus.
• Another technique for slaughtering the birds is decapitation, which is not so common.
• Still another method, which involves piercing knife through the brain, has become obsolete.
• In general, a bleeding time of 1.5 to 2.0 minutes is allowed. Incomplete bleeding

Scalding

• Scalding refers to immersion of birds in hot water for loosening the feathers. It should be done when all reflexes have ceased.
• The birds are transferred into scalding tank.
• Broiler and young birds are scalded at 55°C for 15 minutes whereas culled birds and spent hens are scalded at 60°C for 2 minutes.

Defeathering

• The process is carried out in a feather plucker consisting of two drums with rubber fingers, which revolve in opposite directions pulling of feathers from the carcass. Any remaining feathers are picked up manually.

Singeing

• The carcasses are now singed over a blue flame for 5 to 10 seconds to remove hair like appendages called filoplumes.

Washing

• The singed carcasses are washed with spray water to remove dirt and reduce the microbial load.

Removal of feet and oil gland

• The next step involves cutting of feet from tarso-metatarsal joint with a sharp knife and removal of oil gland.

Evisceration

• The carcasses are hung by hooks to the shackles for evisceration.
• By a slit opening from the tip of breastbone, abdominal cavity is opened by means of a transverse cut.
• A circular cut is made around the vent.
• The viscera is drawn outside but allowed to remain attached to the carcass for postmortem inspection.
• Meanwhile, a slit is made in the skin of the neck for easy removal of crop and neck.
• After postmortem inspection, inedible offals, including trachea, lungs, oesophagus, crop, intestines, gall bladder and kidneys are removed whereas giblet consisting of heart, liver and gizzard should be collected, cleaned and packed in a wrapper.

Chilling and draining

• After washing, the dressed birds are chilled in a chilling tank containing slush ice or crushed ice for 30-45 minutes in order to cool the carcasses to an internal temperature of about 4°C.
• The chilled birds are kept on the draining rack for 10 minutes to remove the excess water.

Washing

• Dressed birds are thoroughly washed again with clean spray water preferably maintained at 15±5°C.
• Special care should be taken to wash the interior and sides.

Grading

• Dressed chickens are graded on the basis of conformation, degree of fleshing, bruises, cuts and other quality attributes.
• Indian Standards for dressed chicken are given in the table below.

Packaging

• Before packaging, dressed chickens having gizzard without mucosal layer, heart without pericardium and liver without gall bladder are placed in the abdominal cavity of the carcass and packed in polyethylene bags (200 gauge).
• Shrink packaging may be adopted if dressed chickens are to be stored in a frozen condition.

Storage

• Dressed chicken can be stored in a refrigerator at 2°C for 7 days and deep freezer at –18 to –20°C for a period of 4-6 months.

Indian standards for dressed chicken

Sl. No.	Quality attributes	Grade 1	Grade 2
1.	Conformation	Free of deformities that detract from its appearance or that affect the normal distribution of flesh. Slight deformities such as slightly curved or dented breast bones and slightly curved backs may be present.	Slight abnormalities such as dented, curved or crooked back or mis-shapen legs or wings which do not materially affect the distribution of flesh or the appearance of the carcass or part.
2.	Fleshing	The breast is moderately long and deep and has sufficient flesh to give it a round appearance with the flesh carrying well upto the crest of the breast bone along with its entire length.	The breast has a substantial covering of flesh with the carrying upto the crest of the breast bone sufficiently to prevent a thin appearance.
3.	Fat covering	The fat is well distributed so that there is a noticeable amount of fat in the skin in the areas between the heavy feathers tracts.	The fat under the skin is sufficient to prevent a distinct appearance of the flesh through the skin, especially on the breast and legs.
4.	Defeathering	Free of pin feathers, diminutive feathers and hair which are visible to the inspector or grader.	Not more than an occasiona protruding pin feather or diminutive feathers shall be in evidence under a careful examination.
5.	Cuts and tears	Free of cuts and tears on the breast and legs.	The carcass may have very few cuts and tears.
6.	Discoloration	Free from discoloration due to bruising, free of clots; flesh bruises and discoloration of the skin such as “blue back” are not permitted on the breast or legs.	Discoloration due to bruising; free of clots; moderate areas of discoloration due bruising in the skin or flesh.
7.	Freezer burn	May have an occasional pock marks due to drying of the inner layer of skin (derma), provided that none exceeded the area of a circle 0.5 cm in diameter on chickens.	May have a few pock marks due to drying of the inner layer of skin (derma), provided that no single area exceeds that of a circle 1.5 cm in diameter.