Aseptic processing of prepared foods

Aseptic processing permits food companies to produce products that are healthy and tasty yet infinitely shelf-stable. To achieve these goals, each component in the processing line must meet stringent standards to preserve the ingredients’ taste, color and texture as well as to make food products microbiologically stable.

DATE 2023-11-28

The Contherm Scraped-Surface Heat Exchanger is a versatile vertical heat exchanger that can handle aseptic products of varying consistencies including chunky homestyle soups, cream and cheese sauces, salsa, puddings, dips and hummus. The Contherm has been specifically designed to provide efficient and gentle treatment so that none of the flavour, nutrients or consistency is lost during processing.

Heating and cooling that maintain flavour

During aseptic processing, the Contherm can heat and cool almost any product that can be pumped, especially those that traditional heat exchangers cannot handle. The Contherm is equipped with a two-stage aseptic seal designed to provide constant flushing on the non-product side of the seal in order to minimize the risk of microbiological contamination.

The product is heated in the Contherm to cooking or sterilization temperature using steam or hot water as the heating medium. The product can then be held in an insulated tubular holding cell for the time required to achieve sterilization or the right product texture before cooling in the Contherm to the correct temperature for packaging.

The Contherm Scraped-Surface Heat Exchanger

The Contherm Scraped-Surface Heat Exchanger is vertically mounted and designed for the heating and cooling of particulate, sticky, viscous and crystallizing/phase-change processes. It is available in three sizes and can serve in a wide range of process stages including heating, cooling, slush-freezing, pasteurization, sterilization and crystallization. The Contherm can operate with either steam, water, brine ammonia, glycol, R22, R12, thermal oil or liquid gases.

During operation the product is pumped through the lower end of the heat exchanger through specially designed tangential heads that provide a gentler introduction of the product into the cylinder than the center-port high-shear head design. The heating or cooling media flows in the annular space between the cylinder and the insulated jacket. When liquid media or steam is used, a spiral coil is installed in the annulus to provide high heat transfer efficiency.

As it flows through the cylinder, scraping blades remove the product from the cylinder walls which allows fresh product to continuously be exposed to the heat transfer surface, thereby providing efficient heating or cooling without fouling.

Advantages of the Contherm in a continuous processing line

  • tangential head design provides gentle treatment in heating and cooling particle-laden, high viscosity and heat-sensitive products
  • mixing/scraping action of blades provides sufficient turbulence to assure even heat transfer and uniform consistency,
  • even heat treatment preserves the ingredients while producing a microbiologically stable final product without conventional preservation techniques closed system ensures energy and utility savings,
  • continuous system reduces labour costs compared to batch systems
  • vertical design and a hydraulic lift system provide rapid removal of the internal rotor assembly in order to facilitate easy inspection and maintenance
  • maximum process control ensures consistent quality
  • closed system maximizes product recovery, optimizes cleaning-in-place and reduces the risk of contamination
  • vertical design provides effective air purging and true plug flow which helps minimize product loss

Alfa Laval’s Unique Customer Testing Center

The Contherm Product Center for Alfa Laval Inc in the USA is located in Newburyport, Massachusetts. The Contherm Product Center staff provides design, application and service expertise for heat exchangers for the food industries including the Contherm and Convap heat exchangers as well as sanitary plate heat exchangers.

Alfa Laval’s new Customer Testing Center offers customers testing capabilities for all products from the thinnest to the most viscous, from the smooth to the most chunky. In the laboratory customers can simulate processing conditions in a full-scale processing line. The laboratory consists of mixing equipment and a battery of six Contherms for testing evaporation, heating or cooling processes. A state-of-the-art rheology laboratory offers customers food analysis with valid data on the food products processed.

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