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By Eduardo Cervantes Lopez, International Processing Consultant, Barranquilla, Colombia
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The time between the hanging and the entrance to the stunner must not be longer than 20 seconds.
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1 Hanging on the conveyor
The reception zone in the plant must be dark, in order to keep the birds calm. However, in order to prevent eye fatigue of operators, special 5-filter blue lamps may be used instead of regular lighting. Since chickens are blind to ultraviolet light, they will not be affected by this type of illumination in the area, thus preventing them from flapping as they are hung onto the shackles by the operators.
The reception zone in the plant must be dark, in order to keep the birds calm. However, in order to prevent eye fatigue of operators, special 5-filter blue lamps may be used instead of regular lighting. Since chickens are blind to ultraviolet light, they will not be affected by this type of illumination in the area, thus preventing them from flapping as they are hung onto the shackles by the operators.
If this area does not meet the above important specifications, chickens flap excessively during the transportation to the stunner. Flapping demands higher effort, as the heart has to pump more blood to the muscles of the breast and the wings. Depending on how strong the flapping is, the amount of blood that accumulates in the wings varies. When flapping is too strong during the bleeding, there is not enough time to evacuate the blood: some of it remains in the joint between the humerus and the radius/ulna, as well as at the tip of the wings. This undesirable quality condition becomes evident when the birds leave the last plucker.
2 Hanging to stunning
When the time between the last hanger operator and the entrance to the stunner is longer than 20 seconds, blood starts to accumulate in the neck and the wings due to gravity. If during the bleeding, the blood is not evacuated, some amount will remain in the wings. As the heart loses pumping efficiency, only gravity is there to help. For this reason, it is impossible to move the blood through the V-shaped elbow joint, so it will accumulate in this area. In order to reduce this problem, it is necessary to monitor the flapping and the darkness in the hanging zone.
When the time between the last hanger operator and the entrance to the stunner is longer than 20 seconds, blood starts to accumulate in the neck and the wings due to gravity. If during the bleeding, the blood is not evacuated, some amount will remain in the wings. As the heart loses pumping efficiency, only gravity is there to help. For this reason, it is impossible to move the blood through the V-shaped elbow joint, so it will accumulate in this area. In order to reduce this problem, it is necessary to monitor the flapping and the darkness in the hanging zone.
3 Good stunning
One of the conditions that confirm a good stunning is that the birds exit the stunner with the neck a little bent. This particular position of the neck is not an issue for a manual slaughtering operation. However, if an automatic slaughter machine is on service, then the neck needs to be extended before the chicken enters the slaughtering machine. Failure to do the above will result in some necks not passing through the machine; personnel checking for proper slaughter after the equipment will have additional workload. This situation increases the risk of some birds entering the scalder alive and drowning.
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Chickens are blind to ultraviolet light and this will keep them quiet in the arrival area of the plant.
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Some plants with automatic slaughter equipment have installed a piece of stainless steel sheet at the exit on the bottom of the stunner. The sheet is connected with the same power supply of the stunner. As the neck slides over this sheet, the electricity helps to extend it. This is the proper condition for automatic slaughter.
4 Rinsing before scalding
Before the birds are hung on the slaughter overhead conveyor, their feathers and skin have residues of dry faeces. If hanging, stunning and bleeding are not proper, the chickens evacuate faeces again as a physiological reaction due to the trauma they suffer during these three operations. In consequence, when they enter the scalder the amount of organic load of the water increases.
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Rinsing the birds before scalding will minimise cross contamination.
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This circumstance increases the risk of cross contamination: during scalding, some pathogen bacteria like E. coli and Salmonella can enter through the beak and the cut on the neck, affecting the shelf life of the processed chickens.
This special high risk condition can be mitigated if the birds are washed and brushed using an antimicrobial product before entering the scalder.
This special high risk condition can be mitigated if the birds are washed and brushed using an antimicrobial product before entering the scalder.
5 Air water agitation of the scalder
In the past, scalders used mechanical agitation and some scalders with this technology are still in operation. New scalders use air injection through the bottom of the machine. Air injection reduces water density, which keeps birds submerged during scalding. Furthermore, the water agitation is constant during the chickens’ transit through the scalder. Proper agitation facilitates feather removal, because it opens the follicles completely, helping proper denaturation of the feather protein released. In addition, there are savings in energy and maintenance that represent a reduction of the operational costs.
In the past, scalders used mechanical agitation and some scalders with this technology are still in operation. New scalders use air injection through the bottom of the machine. Air injection reduces water density, which keeps birds submerged during scalding. Furthermore, the water agitation is constant during the chickens’ transit through the scalder. Proper agitation facilitates feather removal, because it opens the follicles completely, helping proper denaturation of the feather protein released. In addition, there are savings in energy and maintenance that represent a reduction of the operational costs.
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Source: World Poultry, Vol. 27, No. 10, 2011
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