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Tunnel Pasteurizers are used for heat treatment of products such as beer, soft drinks and acid preserves (fruits, acidified vegetables or pickles). etc. in closed bottles or cans. The containers are loaded at one end of the pasteurizer and passed under sprays of water as they move along the conveyor belt.

The sprays are positioned so that the containers are subjected to increasingly hot water until the pasteurization temperature is reached by the product in the bottle or can.

The containers are then gradually cooled with water until they are discharged from the end of the pasteurizer. A typical process will include most or all of the following steps:

  • Heating zone
  • Heat treatment zone
  • Cooling zone
  • Above zones can be sub-divided into more zones


The temperature range is typically 60 to 100°C and the length of the process is dependent on the container and product.

Temperature Distribution Test
The test is designed to ensure that the tunnel is at a uniform temperature and the test must be designed to locate the slowest heating area(s) of the tunnel (cold spot), especially across the conveyor belt. Once the slowest heating area is located the test sensors should be concentrated in that area to determine the parameters required bringing that area of the tunnel to a uniform temperature.

New chambers can be presumed to require temperature distribution studies and tunnels that have undergone repairs or redesign can also be presumed to require temperature distribution studies.

Temperature distribution tests should be performed in each individual tunnel.

Heat Penetration Test
The purpose of a heat penetration test is to determine the heating and cooling behavior of the product in a specific tunnel 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.

A Temperature Distribution Test should be completed before commencing the Heat Penetration Test. The goal in conducting these tests is to identify the worst case temperature response expected to occur in commercial production as influenced by the product and the process parameters.


In the food and beverage Industries many foods, beer and soft drink products are produced every day 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 tunnel affecting the safety and quality of the products

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 reproducibility for every batch.


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Before doing any measurements, it is essential  to use equipment which complies to;

  • ISO 9001 Certification
  • FDA/USDA & EEC Guidelines
  • CE & UL Approvals
  • cGMP or GAMP5
  • ISO/IEC 12207 Software life cycle processes
  • 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 Pro wireless data loggers of sufficient accuracy in sufficient quantity to adequately monitor the process water temperatures within the tunnel, and in the containers.


The TrackSense Pro data loggers/sensors should record the temperatures and pressure of each sensor at sufficient intervals, not to exceed one minute, throughout the test.

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Recommended Guidelines

  • Initial temperature should be recorded
  • A sufficient amount of temperature sensors are typically positioned over the whole width of the conveyor belt.
  • Data loggers with temperature sensors should be introduced into the carriers with intervals giving a representative mapping of the tunnel.
  • During heat penetration tests the temperature sensors are positioned in the “cold spot(s)” of the tunnel, detected by the temperature distribution tests.
  • Bring the chamber up to the same temperature as designed for the process and allow temperature to equilibrate before commencing tests.

Choosing the System
A TrackSense Pro wireless data logging system is logging the data which after the process are downloaded to the computer. For real time measurements a SKY option can be used.

One advantage using the TrackSense System is the capability of using dual sensors, so that Temperature Distribution and Heat Penetration can be performed simultaneously.

Validation of continuous tunnels can only be performed with TrackSense Pro wireless data loggers.

To validate the processes according to predefined acceptance criteria, ValSuite software is ideal.

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Documentation – Standard ValSuite Reports

  • Comments: Specifications and photos of test equipment.
  • Limit Report: Temperature, Pressure, P-Units.
  • Time Event Markers: Heating zone, Heat treatment zone, Cooling zone, (sub-zones)
  • Advanced Validation Report: Temperature, Pressure, P-Unit evaluation of the whole process criteria’s with pass/fail indication.
  • Statistic Reports: Min, Max, Average, Delta of all parameters.
  • Word Documents.

ValSuite® Software Reports

Pasteurization Tunnel

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Process Graph
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Limit Report
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P-Unit Calculations
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