Poultry slaughtering and defeathering consist of hanging, stunning, bleeding,
scalding, picking, and washing.
Birds generally are not fed for 12 hours before slaughter to ensure that their crops are empty, which makes for cleaner operations. Bleeding may take anywhere from 1 to 3 minutes, but must be complete to produce the desirable white or yellow skin color in the final dressed bird.
After bleeding, the birds are conveyed through a scalding tank. Scalding loosens the feathers and makes for easier plucking and pinfeather removal. Carcasses scalded in water of 138 to 140°F for 30 to 75 seconds are generally considered to be sub-scalded. Semi-scalding, often called soft- or slack-scalding, is carried out at 123 to 130°F for 90 to 120 seconds. Scalding temperature is of greater importance than scalding time. The higher the temperature, the shorter the time required, but careful time and temperature control is important because at higher temperatures there is a greater danger of removal of portions of skin in the defeathering machines. Optimum conditions must be established for the kind of bird being dressed. The FDA requires using a minimum of 1 quart of hot water per bird. Many plants use much more.
Defeathering is performed mechanically by a device with many rotating rubber fingers, which beat and rub the feathers from the carcass. A steady stream of water washes the feathers away and acts as a lubricant. Feathers are sold as a byproduct. Carcasses are then singed to remove hair-like appendages, called filoplumes. Each carcass passes through a sheet of flame as it moves along the conveyor line. Finally, the carcasses are washed with a stream of water and scrubbed with rubber fingers at the same time.
Evisceration and inspection are generally accomplished in a conditioned room. Usually, an air handling unit with cooling and heating coils is used to provide the required conditioning and ventilation.
Birds passing inspection are thoroughly washed and then rapidly chilled with chilled water or ice slush from about 30 to 35°F to preserve quality and to prevent spoilage. The birds absorb a small amount of moisture from the slush. After chilling, the birds are drained of excess moisture and are sized and graded for quality. The FDA requires a chilled water flow rate of about 2 gallons per bird.
"Drag" chillers are most commonly used for this final step. They consist of two vats in which carcasses, suspended on shackles, are dragged through the cooling medium.
The graded poultry is packaged fresh in boxes surrounded by crushed ice. Birds must be kept below 40°F and rapidly moved to retail distributors since shelf-life may be only a few days. To prolong storage life, poultry is often frozen. The birds are vacuum packed in low-moisture and low oxygen transmission bags or films, since the fat of chicken is highly susceptible to microorganism growth.
