# Spiral Pre-cooler & Spiral Defroster: The “Temperature Guardians” of the Food Processing Cold Chain

In the intricate chain of food processing and cold-chain logistics, the spiral pre-cooler and the spiral defroster act like two crucial gears. The former rapidly cools food products to lock in their freshness, while the latter precisely controls temperature to reawaken the vitality of frozen ingredients. Although these two types of equipment have opposite functions, they work together to create a “temperature safety net” that spans from farm to table, playing an irreplaceable role in ensuring food safety, extending shelf life, and enhancing processing efficiency.

## Spiral Pre-Cooler: The “Cooling Expert” for Food Processing

The core function of the spiral pre-cooler is to rapidly reduce the temperature of freshly slaughtered poultry, freshly caught seafood, or freshly harvested fruits and vegetables—high-temperature ingredients—to a temperature range suitable for storage or processing by means of forced circulation of a cooling medium. Its operating principle can be broken down into three key stages:

First, the equipment precisely controls the pool water temperature between 0 and 4℃ using an flake ice machine or a chiller unit; some high-end models can even achieve segmented temperature control, with the front section at 16℃ and the rear section at 4℃. Second, a spiral propeller rotates at a speed of 5 to 10 revolutions per minute, gently propelling the ingredients forward in a spiral motion through the chilled water, ensuring that each piece of meat or fruit comes into full contact with the cooling medium. Finally, a blower system creates a stream of microbubbles within the pool, causing the ingredients to tumble continuously and eliminating any localized hot spots or dead zones. Taking broiler chicken processing as an example, a pre-cooling process lasting 30 to 45 minutes can rapidly reduce the core temperature of the carcass from 38℃ to below 10℃, effectively inhibiting microbial growth while simultaneously completing the acid removal process and enhancing the tenderness and freshness of the meat.

## Spiral Thawing Machine: The “Awakener” of Frozen Ingredients

When frozen ingredients enter the processing stage, the spiral defrosting machine uses a reverse operation to restore their temperature. The technological core of this machine lies in its high-speed water circulation system: a power unit drives the spiral blades to rotate at speeds ranging from 300 to 500 revolutions per minute, generating three-dimensional turbulent flow in the tank water and causing ice crystals to melt rapidly within 15 to 30 minutes. Taking shrimp processing as an example, traditional static-water defrosting typically takes 2 to 3 hours and is prone to localized overheating, which can lead to protein denaturation. In contrast, the spiral defrosting machine, with its continuous water flow, not only reduces the defrosting time to under 40 minutes but also lowers the defrosting loss rate from 8% to below 3%, significantly improving the yield of finished products.

The ingenious design of the equipment is evident in its meticulous attention to detail: The support rack features a food-grade 316 stainless steel mesh belt with a mesh aperture spacing of only 2 mm, effectively preventing small particles of ingredients from falling off. The drain pipe is equipped with an automatic filtration device that can trap crushed ice and impurities, thus avoiding pipe blockages. Some models even integrate an ozone generator that performs simultaneous sterilization during the thawing process, keeping the microbial count below 10 CFU/g. Practical data from a seafood processing company show that after adopting the spiral thawing machine, the uniformity of thawing for hairtail fillets improved by 40%, and the oil absorption rate in the subsequent frying process decreased by 15%. As a result, the company achieves annual savings in raw material costs exceeding 2 million yuan.

## The Double Helix Structure: A Revolutionary Breakthrough in Spatial Efficiency

Whether in pre-cooling or thawing applications, the dual-spiral design is becoming the benchmark for technological upgrades in the industry. Compared to conventional single-spiral models, dual-spiral equipment doubles or triples production capacity by stacking two spiral tracks on the same footprint. Take the dual-spiral quick-freezer as an example: its drum system features independent variable-frequency drives, allowing the upper and lower mesh belts to operate at different speeds independently. This enables gradient temperature control—freezing the surface rapidly in the upper layer while deeply freezing the center in the lower layer—making it particularly suitable for composite ingredients with significant thickness variations, such as stuffed fish balls. The dual-spiral water-cooled pre-cooler introduced by Germany’s Bitzer, through optimized screw pitch angles and air duct designs, achieves a pre-cooling uniformity rate of 98% for meat products, representing a 12-percentage-point improvement over single-spiral models.

## Diversified Expansion of Application Scenarios

The boundary between these two types of equipment is becoming increasingly blurred. At cold-chain logistics centers, combined spiral chillers can switch between pre-cooling and defrosting modes: in the morning, when receiving fresh seafood, they activate water-cooled pre-cooling; in the afternoon, when processing frozen imported beef, they switch to defrosting mode—thus enabling a single machine to serve multiple purposes. In the pharmaceutical sector, purified spiral pre-coolers, equipped with HEPA filtration and UV sterilization, provide a sterile cooling environment for vaccine raw materials. In the chemical industry, rapid-cooling spiral chillers, featuring corrosion-resistant titanium alloy pipelines, can handle special chemicals even in environments as low as -50°C. A case study from a biopharmaceutical company demonstrates that a customized spiral pre-cooling system has boosted the retention rate of active ingredients in raw pharmaceutical materials from 82% to 95%, reducing annual quality losses by more than ten million yuan.