Pasteurisation (Batch, UHT & HTST)

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Batch Pasteurisation

Does the company use batch pasteurisation as a means of heat treatment?

If so, the company will need to include:

  • How the heat treatment system is validated
  • The system is supported by an independent evaluation of the pasteuriser and its effectiveness
  • A continuous recording of temperature, using calibrated temperature probes and recording holding time
  • If there is heated head space and how this is controlled
  • If there is an ongoing phosphatase testing regime in place, how is this managed and described in procedures
  • Defining daily verification checks are in place and they are described in the procedures
  • Procedures should include training, corrective action, and notification for failed results

HTST Pasteurisation

Does the company use HTST pasteurisation as a means of heat treatment (heat treated to not less than 72 degrees for 15 seconds)?

If so, the company will need to include:

  • How the heat treatment system has been validated.
  • That temperature monitoring devices such as probes and chart records are regularly calibrated (at least annually).
  • That integrity checks of the plate packs are conducted at least annually.
  • That integrity plate checks are conducted on all cooling units that use glycol or other chemicals as their cooling medium (eg/at milk receival).
  • That the diversion valve operation is tested, recorded and signed daily.
  • That the holding tube is in a continuous upward slope in the direction of flow.
  • That the diversion valve is in the correct position (based on response time).
  • That all the thermometers are in the correct position.
  • That the sanitation of the pasteuriser is effective (how is this demonstrated).
  • That the holding tube time is calibrated every 5 years or after the system is changed.
  • Where applicable, a phosphatase test can be conducted on every batch of pasteurised milk. If not, what is the frequency of phosphatase testing.
  • A documented procedure for conducting these tests. This procedure includes training, corrective actions and notification for failed results.
  • Suitably qualified persons for all key devices (e.g. pasteurisers).

ESL/UHT Treatment

Does the company use an alternative heat treatment such as ESL/UHT processes as a means of heat treatment?

If so, the company will need to include:

  • Details of how the heat treatment has been validated.
  • That temperature monitoring devices such as probes and chart recorders are regularly calibrated (at least annually).
  • Daily monitoring checks defined and controlled.

Key instruments are calibrated and verified.

For the relevant legislative references in the Export Control (Milk and Milk Products) Rules 2021, please refer to the department’s, Approved Arrangement Checklist.

Heat treatment processes are designed to ensure sufficient heat treatment is applied to achieve a safe dairy product, with minimal effect on the quality and flavour of product. This means that the process must be tightly controlled to ensure that the equipment design and operation are working effectively.

Pasteurisation is a process that heats milk to a specific temperature for a set period of time, killing the common pathogenic microorganisms present in milk.

Processing at higher temperatures or times has a greater lethal effect and can kill a broader range of pathogenic and spoilage microorganisms, providing a safer product with a longer shelf life.

Batch Pasteurisers are a bit like cooking in a pot. You process one batch of milk at a time, using low heat with agitation, over a set period of time. High-Temperature-Short-Time (HTST) pasteurisation, ESL & UHT heat treatments are continuous flow processes which use higher temperatures or times to provide a greater lethal effect on pathogenic microorganisms, followed by cooling of the milk product. Vacreators, used for the pasteurisation of cream and deodorisation of butter products, utilise both vacuum and steam to achieve the same food safety effect. High Pressure Pasteurisation (HPP) places the product under high pressure whilst canned dairy products undergo a retort process which includes both heating and pressure to achieve the desired food safety outcome.

DFSV Technical Information note: HTST and The Food Standards Code ‘A guide to Standard 4.2.4 Primary Production and Processing Standard for Dairy Products - Part 3: Dairy Processing’, provides guidance for the dairy industry, when considering using a widely accepted alternative heat treatment process for their site, which would have an equal or greater lethal effect on microorganisms as the minimum pasteurisation requirement.

Regardless of what heat treatment system your site has, you must have supporting evidence to show that your heat treatment system is validated and compliant. Validation means to obtain evidence to show that a control measure (or measures) in place, when implemented correctly, can eliminate or reduce a hazard to an acceptable level, rendering your product safe for human consumption and extending its shelf life.

Your site procedures must describe how the heat treatment system has been designed to ensure that it is effective. They must describe how your system has been validated with supporting evidence. A key part of validation involves the commissioning of the pasteuriser equipment. Your pasteuriser can be designed to comply with the requirements set out under Australian Standard AS 3993:2003, and installed by a qualified technician. The validation will be influenced by critical design features such as the holding tube (e.g. length, diameter, gradient), and position of temperature monitoring devices and divert valves. The technicians will need to make calculations and perform tests to determine that the design allows for your product to meet the required parameters for pasteurisation. You should ensure that you have a documented executive summary describing the purpose, methodology and outcomes of the validation, supported by relevant evidence such as commissioning documents, calculations, test reports and validation certificates.

Ongoing pre-process checks, such as daily divert test as well as, post-process verification checks, such as phosphatase tests, enables you to quickly assess whether your heat treatment process was effective in meeting the minimum requirement. Records of calibration of pasteuriser temperature monitoring devices, as well as annual plate integrity tests, pump speed verifications and divert valve checks will also need to be kept and maintained. Such verification activities must be documented in your procedure and personnel carrying out these activities must be competently trained.

The ANZDAC - Australian Manual for the Validation and Verification of Heat Treatment Equipment and Processes sets out guidelines to be followed to help develop procedures so that a measure of the validation and verification can be achieved.

Prescribed milk, liquid milk products or cheese, intended for export must be pasteurised by being held at a temperature of not less than 72 °C for not less than 15 seconds, or to temperature and time combination which produces a lethal effect that is equivalent or greater. The milk must be immediately cooled to a temperature of 5 °C or cooler. This criteria must be used unless the Approved Arrangement and your production procedure specifies that the operations to prepare the milk or milk products for export requires a different time and temperature control.

Please refer to the Export Control (Milk and Milk Products) Rules 2021 (Chapter 5, Part 2, S5-17 to S5-19) for additional information.

The establishment must supply applicable evidence that the equipment used on site meets the requirements.

Examples of such evidence may include:

  1. calibration certificates for temperature monitoring probes and other sensors (with traceable matching device IDs),
  2. plate integrity checks,
  3. confirmation report of pump speed and actual product flow rates,
  4. records of product divert valve checks for functionality,
  5. confirmation of reaction/response times for valve sensors to ensure untreated product does not contaminate treated product
  6. information regarding the continuous temperature monitoring device functionality and its recording accuracy,
  7. records of pre-production hygiene checks,
  8. preventative maintenance records,
  9. records of corrective actions,
  10. records of post-production cleaning verification activities,
  11. staff training and competency assessments (pasteuriser operators require role-specific training).

Modified heat treatment equipment must be re-validated before they are put into normal production use, as a record of its process reliability in achieving the desired outcomes. You need to assess if the changes to be made could impact on the operation of the pasteuriser and influence any of the previously validated parameters.

When documenting and reviewing your procedures for your heat treatment process, you should consider the following:

  • What is your milk treatment critical limit? Is it reflective of your HACCP plan? Have you clearly defined the Time and Temperature requirements?
  • Have you validated your system based on scientific studies or regulations? Information must be available to describe how the heat treatment system has been designed and commissioned to ensure that it is effective, with appropriate calculations and certificates. If you are manufacturing a new product for example, you would need to design a study that validates a process to confirm the safety of the product.
  • Have you described how your system has been validated, with supporting evidence available?
  • Is information on the design of equipment used available? This may include any schematic diagrams or simple descriptions of the process.
  • Is there a description of the heating process (this may include plate heat exchanger, holding section, etc.)?
  • Are daily checks performed and recorded each time the process is used?
  • Have you taken into consideration the position of sensors, thermometers, divert valves, heat exchangers and CIP input valves in the design of your process?
  • Do you check the diversion valve is in the correct position, operational and effective to respond on time?
  • Is the product flow clearly identified to show how raw and pasteurised product is separated? Have you ensured no cross connections which could contaminate the product?
  • Is there continuous recording of temperature and time? Is it electronic and saved?
  • Do you compare the indicating and thermometer recording readings for proper functionality? (e.g., use of side-by-side digital and analogue temperature monitoring devices)
  • Do you have evidence of assessment of potential processing risks? (This could include any dead spots where the heat treatment has not been effective).
  • Is your holding tube in a continuous upward slope in the direction of flow to avoid entrapment of air in the tube? Is the holding tube time re-validated every 5 years? (or whenever there is a change in the system)
  • Do you conduct integrity checks on the plate packs at least annually? The integrity plate checks must be conducted on all cooling units that use glycol or other chemicals as their cooling medium (for example, at milk receival). Are these checks recorded?
  • How do you ensure sanitation of the equipment is effective and can you provide evidence for this?
  • Are calibrations conducted minimally annually for thermometers, or more frequent per you Importing country, and recording devices (is the accuracy recorded) per your procedure? Can you match each calibration record to the individual thermometer or device?
  • Is the level of tolerance (+ or – X°C) acceptable for your process and calibration frequency?
  • Does your procedure include training, corrective action, and notification for failed results?
  • Is a phosphatase test conducted on every batch of pasteurised milk? If not, what is the frequency of phosphatase testing? Is the result and any corrective actions taken recorded?
  • Have you checks in place to ensure that your product cannot be contaminated post-pasteurisation?
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Self Assessment

How much do you know about Pasteurisation (Batch, UHT & HTST)?

Take this short assessment to find out.

Question 1

Basil is a pasteuriser operator at a dairy facility. He has been trained to conduct the phosphatase testing on milk, post pasteurisation.

Phosphatase testing is used by the site to verify the milk products have been properly pasteurised. He has just conducted a phosphatase test on pasteurised product, which has failed.

As the milk pasteurisation is a CCP step and the phosphatase test is used to verify effective pasteurisation, is it important for Basil to take corrective action immediately?