Improving product quality with thermal process optimisation

What is thermal processing?

Thermal processing is an important method of food preservation, controlling the presence of microbial spoilage organisms in foodstuffs to ensure that products are safe. There is an ever-growing range of food products preserved by thermal technologies ranging from sterilisation (such as canning) to milder pasteurisation heat treatments (such as cook-chill and cook-freeze).

Finding the right balance

When undertaking validation work on behalf of manufacturers, our focus is on ensuring the process subjects the product to a minimum level of heat. A specific time/temperature combination is targeted to ensure a minimum level of lethality is achieved. However, it’s all too easy to get it wrong, without considering the impact on products’ nutritional and sensory attributes.

Process optimisation (i.e. a reduction in over-processing) sounds simple: it’s just a case of not processing a product for too long, right? Wrong. In reality, a lot more thought and (more importantly) data analysis is required.

When our experts validate thermal processes during trials, they often find data that shows some degree of over-processing - that is additional heating of the product which is not necessary for food safety. To us, this common occurrence highlights that some food manufacturers are missing out on the benefits of optimising their thermal processes.

Why optimise?

Minimising the amount of heat delivered to the product by reducing temperature and/or process time can have some real advantages, including:

• improved product quality and sensory perception. For example, preservation of colour, textures and specific flavours
• retained nutritional attributes of a product. Vitamins such as A, B1 and C can be broken down with heat
• higher throughput: shorter cook times lead to overall efficiencies in production
• greater energy saving with a process that requires less heating

How can thermal processing be optimised for quality?

Thermal processes are primarily applied to ensure product safety. The time and temperature of the treatment can be tailored to optimise quality without compromising safety. This can be achieved by analysing thermal validation results to understand when, during a cook, the minimum thermal target is reached.

Maximising the efficiency of the heat transfer is also crucial. Several factors affect the rate of heat transfer, including heating method, packaging type and product composition. Adjusting any of these factors to improve the rate of heat transfer can aid quality retention - and sometimes a small adjustment can have a large impact.

Rapid advances are also being made in process technologies and with equipment used for thermal processing to aid heat transfer. We trialled one of these as part of a member-funded project that investigates new technologies. We found continuous microwave processing to be an effective method of preserving the vibrant green colour of pea and ham soup. Find out more about this study by reading our blog CMP benefits.

Other rapid processes include thermal technologies such as microwave, radio frequency and ohmic heating.

When should I optimise my thermal process?

Quality optimisation work can be a simple add-on to a thermal process validation project. If you’re looking to improve existing processes, or to explore the potential of new products and process equipment, we can help you optimise your existing processes using calculations, modelling or with on-site trial work.

Contact: David Whittaker
+44(0)1386 842031
david.whittaker@campdenbri.co.uk