In automated poultry (chicken, duck, goose, etc.) slaughter lines, the spiral cooler is the critical cooling step following scalding, defeathering, evisceration, and washing. It is used to rapidly reduce carcass temperature, inhibit microbial growth, and extend shelf life.
Preparations Before Entering the Spiral Cooler:
- Carcass Condition: The carcasses have completed scalding, defeathering, evisceration (removal of internal organs), and internal/external washing. The carcass surface is clean, but the temperature remains high (approximately 30-40°C), requiring rapid cooling.
- Transfer and Feeding: Carcasses are uniformly fed into the inlet of the spiral cooler via an overhead conveyor chain or belt conveyor. The inlet often features deflector plates or distributors to prevent carcass pile-up.
Poultry spiral coolers are typically designed as horizontal or vertical continuous conveying structures, where carcasses advance spirally within a flow of chilled water:
- Carcasses enter the cooler through the inlet and are gently propelled forward by spiral blades. The blade design must be gentle to prevent damage, especially to wings and leg joints.
- Carcasses are fully immersed in low-temperature recirculating chilled water, potentially supplemented by overhead spray, achieving full-contact cooling.
- Water Temperature: 0-4°C (adjustable).
- Water Flow Direction: Counter-current flow is often used (chilled water flows from the discharge end towards the inlet end) to enhance heat exchange efficiency.
- The carcasses slowly tumble and advance due to the spiral action, ensuring all parts make uniform contact with the cold water and avoiding cooling dead spots.
- Adjustable Speed: Cooling time typically ranges from 30 to 90 minutes, adjusted based on poultry type and size.
- Flexible Spiral Design: Minimizes mechanical damage.
- The cooled poultry carcasses are discharged from the outlet and enter a vibratory dewatering unit or air blow-off line to remove excess surface moisture.
- After dewatering, they can proceed directly to the cutting line, packaging line, or freezer tunnel.