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Validation (Reel & Spiral)

Continuous rotary cookers use multiple chambers (“shells”) that are horizontal cylinders. The can transfer mechanisms for the cylinders are linked so that the system is always synchronized and the speed of the drive mechanism is the primary means of controlling the process. Sterilization is carried out in the first chamber(s) and cooling in the latter chamber(s). A feed device delivers the cans through the infeed valve to the revolving reel of the cooker. In the bottom of the shell cans spin freely causing product agitation that significantly increases the heat transfer rate.

The reel, working in conjunction with the stationary spiral, carries the can through the cooking steam. The continuous spiralling motion and the rotation of the can through the cylinder give an even and faster cook to every can.


At the end of the cook process, the cans are fed, via a transfer valve, into the cooler unit where a similar process slowly cools them. When the cans are processed they exit through the outlet valve.
Some systems achieve specific heating and cooling patterns by employing multiple sterilizing or cooling shells so the system may have as many as seven shells.
For validation of temperature, pressure and can rotations in these systems only TrackSense wireless data loggers mounted inside the cans using appropriate fixtures can be used. Typically most products will be sterilized at about 120-135 °C.

Typical products processed in rotary cooker-coolers:


  • Fruit
  • Vegetables
  • Ready meals
  • Soups
  • Infant formulas
  • Diary Products


Temperature Distribution & Heat Penetration Tests

The Temperature Distribution test is designed to ensure that the chambers are at a uniform temperature, and the purpose of a Heat Penetration test is to determine the heating and cooling behavior of the product in a specific cooker-cooler for establishment of a safe thermal process, and evaluating process deviations, to find the “cold spot” in the product, and to ensure that all products receive the heat scheduled.


New cooker-coolers can be presumed to require temperature distribution studies and machines that have undergone repairs or redesign can also be presumed to require temperature distribution studies. If the number of can rotations (RPM) is decreasing, and pressure drops in the transfer valves, this can indicate that the machinery needs maintenance.

Temperature Distribution and Heat Penetration tests should be performed in each individual cooker/cooler and for every product and container.



Many products are produced every day in Rotary Cooker-Coolers using different processing parameters, resulting in development of products with unique identities, but there are several critical factors that have to be monitored and evaluated periodically:

  • Acceptable heat in the chamber affecting the safety and quality of the products.
  • Fo-Value calculations of the product
  • Internal and external pressure measurements
  • Number of can rotations (RPM) during processing
  • Internal mounting of wireless data loggers.

Heat Penetration

Measurements in the “cold spot” of the product is a major source of errors, and therefore Ellab offers a wide range of fittings securing accuracy and reproducibility for every batch.

In Continuous Cooker-Coolers only the smallest wireless data loggers mounted inside the product container such as TrackSense Mini or TrackSense Micro can be used. Generally the smaller the logger the better, as this minimizes potential mixing effects and reduced the effect on the can headspace size. Where headspace size is highly critical some product may need to be removed to allow for the logger volume in the can.

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Internationally Recognized Guidelines

Before doing any measurements, it is a good idea to use equipment which is complying to:


  • ISO 9001 Certification
  • FDA 21 CFR 113 Thermally Processed Low-Acid Foods
  • 21 CFR part 11 Electronic Signatures
  • CE & UL Approvals
  • cGMP or GAMP5
  • ISO/IEC 12207 Software life cycle processes
  • IFTPS Guidelines
  • Guidelines issued by local authorities

Recommended Test Equipment

The calibrated system should be equipped with sufficient channels, to accurately monitor and record temperature and  pressure – within the process delivery system.
Use TrackSense wireless data loggers of sufficient accuracy and in sufficient quantity, to adequately monitor the process water and product temperatures within the retort.
The data loggers should record the temperatures and pressure at sufficient intervals, not to exceed one minute, throughout the test.

  • Initial temperature should be recorded
  • Depending on reel speed 6-20 temperature loggers are recommended
  • At least one Pressure logger
  • A sampling time of 1-15 seconds


Cooker Cooler validation


  • Normally the “cold spot” detected is in the geometric center.
  • Bring the chamber up to the same temperature and  pressure as designed for the actual processing parameters prior to the start of testing.
  • Check the accuracy of the sensors against a reference instrument (ETI).
  • Any single sensor should be within 0.3°C of the reference.
  • The maximum deviation between any of the sensors should not be more than 0.6°C.

Choosing the System

A thermocouple system has the advantage always being a real-time system, but the nature of the Cooker Cooler prevents this method of being used in production machines. They can still be used in Cooker Cooler simulators with special probes and a slipring contact being used to allow for the can rotation.
A TrackSense® wireless data logging system is logging the data which after the process are downloaded to the computer. This is easier and faster to install in the Cooker Cooler and the small size of the MINI and MICRO loggers make these ideal for the application.

Cooker cooler validation

Documentation – Standard ValSuite Reports

  • Comments: Specifications and test equipment.
  • Limit Report: Temperature, Pressure, F0-Values.
  • Time Event Markers: CUT, Equilibration, Holding, Cooling.
  • Advanced Validation Report: Temperature, Pressure, F0-Value evaluation of the whole process criteria’s with pass/fail indication.
  • Statistic Reports: Min, Max, Average, Delta of all parameters.
  • Heat Penetration: Ball Calculations.
  • Word Documents.
  • Unit: Graphics or photos showing probe position


Get more information

ValSuite® Software Reports

Cooker Cooler

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Process Graph
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Rotation Report
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