By Danny Bayliss - 14 March 2019

Unlike the thermal processing industry, new food processing technologies, by their very nature, will not have a long history of data and experience to back up general assumptions. In the absence of such data it is therefore important to validate products on a case-by-case basis and this may even mean that their effectiveness on individual products has to be re-evaluated.

Process validation is the collection and evaluation of data to establish that a process is capable of consistently delivering a safe product. If a product or process is not properly validated, it could lead to unsafe products and potential financial losses.

When validating new processing technologies, key issues to consider are: target microorganisms and resistance to the lethal factor, process conditions, product characteristics and chemical changes.

Target microorganisms and resistance to the lethal factor

The worst-case organism must be tested and the correct strains selected for trials relevant for the product. When using a surrogate, ensure that it behaves the same as the pathogen being targeted. Campden BRI has a class II microbiology process hall where we can challenge pathogens and surrogates for various processing technologies.

Process conditions

Making the correct assumptions for validation is important:

• what are the worst-case conditions for the product and process?
• what are the critical parameters of the process important for inactivation?
• what is the variability of these parameters?
• how consistent and representative are the conditions?
• how long does the product need to be held at these conditions?

These areas should be determined as part of the validation trials. The answers to these questions will impact on how you effectively monitor the process to ensure that it meets your critical control points (CCP).

Example 1: Effective ultraviolet-C (UV-C) inactivation relies on the dosage delivered to the surface of the product. This can be influenced by the conveyor belt and support structures blocking light to the product or the positioning of the lamps. The process would need to be mapped out to know where the lowest dose is delivered to ensure it achieves the target dose set out in the CCP.

Example 2: High pressure processing (HPP) allows pressure to be transmitted instantaneously throughout a vessel. For this process you would need to monitor the hold time and pressure achieved and, depending on the product, you may also need to monitor time to pressure and the temperature of the process.

Product characteristics

The product itself may influence the process lethality, so understanding the variability in the product characteristics is important for new technologies.

Example 1: HPP lethality has been shown to be impacted by the pH, aw, salt concentration and fat composition of a product. This differs to thermal processing which mainly considers the pH of a product when determining the process to use. Recipe changes or formulation changes can have an impact on the process lethality, so it is important that this is recognised and tested to ensure you are still able to achieve your target log reductions. It is also important that you consider the worst-case parameters of the product when validating, to ensure the new processing technology can produce a safe product within the agreed product specifications.

Example 2: UV-C can be influenced by the surface topography of a product, which can shield and protect microorganisms from the light. The way a product is exposed to the light also needs to be considered as too much product on a conveyor belt will create areas on the product which could be shadowed by the light, impacting on the effectiveness of UV-C inactivation.

Chemical changes

When validating a new process with a new product it is important that potential impacts on chemical changes, which may occur to the product during the process, are considered. This will help to ensure the product is safe for consumers.

Example 1: UV-C shelf-life extension of milk boosts vitamin D3. Whilst this is a positive effect, it illustrates the need to understand if the nutritional quality of a product is affected or compromised by the treatment used to make it safe.

Example 2: The impact of HPP on enzymes can be variable. Some enzymes are inactivated or reduced which can improve product quality such as retaining the green colour with avocado, whereas other enzymes are not affected, such as Pectyl Methyl Esterase (PME) in juices which results in cloud loss and sedimentation.

Get in touch to find out more about how we can help you validate emerging processes.

Support Team
+44(0)1386 842291
support@campdenbri.co.uk