From April 2020
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
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
- 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
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
Other rapid processes include thermal technologies such
as microwave, radio frequency and ohmic heating.
When should I optimise my thermal
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