Processing considerations key to poultry meat quality

Taking proper care of broilers from capture to bleed out will help to maximize carcass quality and yield at the processing plant.

A failure to keep wing flapping to a minimum will have implications for the quality of the processed carcass. (Eduardo Cervantes Lopez)
A failure to keep wing flapping to a minimum will have implications for the quality of the processed carcass. (Eduardo Cervantes Lopez)

To ensure high yield and quality levels during poultry processing, key factors need to be kept in mind from capture to bleed out. Operations may need to be adjusted accordingly.

Broiler harvesting is usually carried out at night when birds are the calmest, and when the house lighting is normally turned off. However, blue lighting, with special filters to protect workers' eyes, should be used.

To help ensure that birds are in a relaxed state, these blue lights should be lit an hour before harvesting starts. The lights allow for easier handling during capture, therefore reducing time spent, and helping to keep bruises, bleeds and bone dislocation to a minimum.

If birds’ stress levels increase, production of cortisol will also increase. This results in greater production of glycogen, which will eventually be broken down to form lactic acid resulting in the meat having a higher pH level. Instances of pale, soft, exudative meat syndrome increase, and this quality issue can lead to greater levels of meat being rejected.

Atmospheric conditions

Birds will respond to the temperature of the environment, including when they are inside cages or containers. If the temperature is too cold, they will huddle together to conserve body heat; if too hot, they will move toward the edges of containers to be exposed to as much air as possible. Under comfortable conditions, broilers will be as evenly spaced as possible within the transport containers.

Broilers will give off heat and moisture when caged and, if not comfortable, they will become stressed. To minimize this, there must be a constant air flow that is directed toward the cages and containers to help dissipate evaporative heat from the head and neck.

Cages and containers must be in a good state to help keep stress levels low. For example, ill-fitting lids may fall into containers, reducing available space and affecting welfare. Aggression between birds will increase, leading to wounds, such as scratches, and a deterioration of their wings.

Transportation to the processing plant

If the temperature during transport from farm to the processing plant is expected to be high, then vitamin C can be added to birds’ drinking water.

In hot conditions, the circulation of free radicals in birds’ bodies increases. Under normal conditions, birds will produce enough antioxidants to eliminate these free radicals. However, when temperatures become very high, their reserves of antioxidants become depleted and vitamin C can address this deficiency.

A good supply of air must be ensured in the middle of the loaded truck. This will stop birds from becoming overheated and ensure that there is a good exchange of gasses.

At the plant

Upon arrival, broilers should be allowed a rest period to alleviate stress and allow heart and breathing rates to return to normal. This period can last from 30 to 60 minutes.

The rest area should be lit with blue lights and be as quiet as possible because excess noise increases blood flow toward wings and legs. In many plants, the excess blood in the extremities will not be drained during bleed out. This can lead to the wings and legs having a pink tinge when the carcasses exit the last plucker and, depending on the intensity of this color, carcasses may be rejected.  

Overhead conveyor

The overhead conveyor should have as few bends and curves as possible. Turns may result in contact being lost with the breast comforter, causing stress to the birds. Any rises or falls in the trajectory will also agitate the birds.

Electric stunning, bleed out and plucking

If flapping wings come into contact with hard surfaces, there is the risk that they may be damaged. This may happen when birds are being hung on the shackles, or if they suffer pre-shock on the way to the stun bath or bleed tunnel. Similarly, flapping may take place above the bleed trough, resulting in bruises, bleeds and dislocated bones.

Should birds still be conscious after exiting the stun bath and during bleeding, wing flapping will force blood into the wings and be impossible to drain once they hang limp.

A lot of blood can remain in the carcass even after bleed, especially in the extremities. Blood accounts for about 7% of a bird's live weight and, during commercial bleeding, only about 45% to 50% of the blood is drained.

The rubber fingers used to pluck birds have a massaging effect on the carcass. If a bird has not been well bled prior to plucking, this massaging action will force remaining blood into the extremities, and this pressure can lead to vessels breaking, particularly in the wing and tail areas.

Red Tinged Broiler Wings 2

If blood is forced into a bird’s extremities, it may not drain, leading to quality issues. (Eduardo Cervantes Lopez)

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