Food Science and Technology - Thermal Processing

Thermal Processing – achieving production, quality and sustainability objectives 

A report by Holmach Ltd, December 2021

COP26 has seen world’s leaders come together to make commitments to tackle climate change and with the food and drink sector reportedly being responsible for approximately 17% of the UK’s carbon footprint, the smallest of changes that we make as an industry will have a significant impact.

It’s not as easy as asking manufacturers to just invest in expensive technology, allowing them to build a sustainable journey from field to fork. As with any business, manufacturing costs have a huge impact on RRPs, which in turn can affect sales figures and profitability, potentially having a negative effect on employment levels. These compromises just aren’t acceptable, particularly as we remain in the shadow of the covid pandemic.

As a specialist Thermal Processing Technology business at Holmach Ltd, we have been looking at some of the ways that food manufacturers can play their part in reducing emissions and minimising waste, without having to make these unacceptable compromises. In fact, our solutions have a positive impact on costs, through notable increases in production levels, reductions in waste, reductions in the use of natural resources and significant extensions to shelf-life.


Thermal Processing is a term that’s regularly bandied around technical meetings, but it hasn’t necessarily made it into the vocabulary of marketers and consumers. This is set to change as the importance of manufacturing processes within the field to fork sustainability journey come to the fore. For many years, retailers have used raw ingredient quality as a key marketing message, but with new DEFRA supported thermal processing guidelines being worked on by Campden BRI and the pressure for sustainability and nutrition in processed foods, we’re anticipating a change in narrative.

In a nutshell Thermal processing is defined as the application of heat or cold to achieve property change in a consumable product. This may be an enzymatic reaction, a gelling or crystallisation effect or more commonly a time/temperature equation to apply a log reduction to the Microbial flora. The reduction of TVC (Total Viable Count) coupled with the elimination of entero or spore forming bacteria is key to food safety and for extending shelf-life whether in chilled, frozen or ambient distribution.

The words that people more commonly understand are sterilisation and pasteurisation, but thermal processing is so much more than that.


Producing safe food and achieving an extended shelf life are key objectives for manufacturers to use thermal processing techniques but in real terms, thermal processing is the solution to processed foods biggest problem.

Even today - due to misconceptions, the words ‘processed foods’ can bring up thoughts of poor quality, tasteless food with too much sugar and salt and no nutritional benefits.

Well considered thermal processing solutions combined with innovative thermal processing technology actually enable manufacturers to reduce salt and sugar content which has historically been used as a preservation technique; retain the nutrients within natural ingredients and can actually enhance colours and flavours.

Ethnic Foods have long been associated with the “double cook” phenomenon. Simply put when you re-heat casseroles or curries they often taste better second time around. Thermal processing can intensify characteristics such as Umami whilst smoothing harsh top notes in herbs and spices. Traditionally these types have foods have needed high levels of salt or sugar to achieve flavour during short heating, such as a microwave in the home. Whilst delivering hot food, it does not heighten the cook in flavour needed to make dishes truly authentic.

A secondary thermal process, for instance in a steam-cooker/cooler when the tray is sealed, cooks in and intensifies depth of flavour. This can reduce the levels of expensive flavouring ingredients needed to achieve the same result. More importantly a small gain by 10 -14 days in shelf life is obtained without preservatives.

Over 500,000 meals per week never leave distribution and are simply dumped due to running up against use by dates and around 4% of recipe dish products are wasted in-store. Coupled with around 1/3rd of all purchased food going to the rubbish tip, a short shelf-life extension could dramatically change the waste landscape – given the environmental cost of both manufacture and disposal. Something has to change!

Below is an introduction to some of our technology partners and how their thermal processing solutions have revolutionised food and beverage manufacturing:


As one of the largest malt producers globally and with demand set to increase, it’s the responsibility of the UKs maltsters to lead the way with sustainable production processes.

With malt’s property as a natural sweetener, consumers are turning to malt-based snacks. These health-conscious individuals share a passion for supporting climate change and if they understood the environmental impact of the traditional fossil fuel powered roasters that are dominating the sector, they may think twice. Powered with gas, that’s both expensive and unsustainable, these solutions can’t possibly be defined as state-of-the-art

Revtech’s Clean Pasteurising and Roasting Solutions

Our partner Revtech Process Systems are committed to leading the charge for green powered solutions with their electrically powered continuous pasteuriser and/or roaster that roasts, puffs, steams and flavours all types of grain, making it ideal for food manufacturing and the brewing and distilling industries.

Revtech’s patented spiral technology allows the continuous flow of product into what is a heated vertical elevator. Simple to run with little maintenance and eliminating the risk of fire due to the confined product path, the technology is disrupting formed opinion on how to deliver great tasting flavours with defined colour from Lager to Black Malt.

As well as operating with sustainable power, the Revtech also significantly reduces timings to turn green malt into black malt, from the traditional 4 hours to as little as 50 minutes.


Too Good to Go report that almost half of all fruits and vegetables produced, are wasted along the supply chain. This is not an acceptable statistic and thermal processing can support the reduction in these terrifying figures through shelf-life extension and repurposing food waste.

Lyco Manufacturing – Continuous Cookers and Coolers

Our technology partner Lyco have a worldwide reputation for their continuous cookers and coolers for products including vegetables, pasta, pulses and grains. Sustainability is high on their agenda, with their Clean-Flow technology minimising water usage and reports of significant energy savings plus a 10-15% in yield from perfect hydration. Their encapsulated technology minimises heat emissions and stops water vapour affecting factory structures whilst eliminating the need for complicated and hygiene challenging air extraction.

Whether a manufacturer is looking to cook chickpeas for hummus production; scrub, cut, cook and peel potatoes for secondary processing within ready meals or par cook carrots for a frozen vegetable range, Lyco’s technology provides a gentler solution than equivalent cook-quench-chill systems, retaining the natural sensory properties of the raw ingredients.

Perfinox – Cooking Vessels and Surface Heat Exchangers

For further processing of fruit, vegetables and other raw ingredients for packaged products such as soups, sauces, creams, pates and ready meal components, Perfinox of Porto’s high quality cooking vessels and scraped surface heat exchangers allow for repeatable high-quality production processes.

Designed for CIP, with gentle product handling, variable batch sizes and short process times, the technology is designed to minimise downtime and wastage and maximise production.

Lagarde Autoclaves

Manufacturers are now taking responsibility for the challenges of products with short shelf lives and retorting plays a huge part in this mission.

At Holmach Ltd we’ve installed over 500 autoclaves into the UK and Ireland during our long-standing relationship with Lagarde and many of them have been used for the retorting of ready meals and components to maximise their shelf life and reduce unnecessary wastage.

Lagarde offer steam/air, raining water, steam spray and full water immersion retorts of all sizes.


With almost 50 years of heritage within thermal processing, we hope this article has given you an insight into the importance of thermal processing for ensuring that products not only taste and look great but are safe and have been responsibly manufactured in terms of minimising waste, maximising production and reducing the impact on our natural resources.

From small batch / high quality artisanal chocolates through to dog food, seafood, plant-based products and sauces…we support manufacturers and food innovators with their process optimisation, new product development and technology requirements. To arrange a meeting with one of our team or to find out how we can help with your next food manufacturing project, call us on 01780 749097 or email

Published 21.01.2022

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