Focus: Exploring behind the scenes of extrusion technology for confectionery

Confectionery Production speaks to key businesses about the new flexible extrusion and co-extrusion technology helping to shape the snackification trend. Daisy Phillipson reports

Gone are the days when snacks were considered a guilty pleasure, saved for special occasions or weekend treats. Today’s consumer expects their protein bars, crisps or candy to provide nutritional value and health benefits, all the while delivering pleasurable taste and texture.

Although the food sector faced disruption due to barriers to the movement of goods and closure of retail outlets during Covid-19, people’s appetite for snacking surged. A recent survey from market research group Harris Interactive found that nearly 60 per cent of those questioned added snacks into their weekly grocery baskets.

When asked why they choose to skip meals and eat snacks instead, 30 per cent replied that it’s easier, 18 per cent said they eat-on-the-go and 10 per cent noted a lack of desire to cook. Perhaps the statistic most symptomatic of the snack segment is the 66 per cent of participants who said they tried healthier alternatives, 84 per cent of which said that they would want to try again.

Even before the pandemic, the healthy snack trend continued to surge as busier lifestyles and the rise of single households called for convenience food products that still offered nutritional value. Witnessing this, manufacturers have launched products that are enriched with protein, vitamins and functional ingredients, giving consumers on-the-go sustenance while snacking.

Extrusion is a popular process with snack manufacturers due to the capability for rapid, continuous production of numerous products. A recent report from Research and Markets showed that the global extruded snack food market reached a value of $45.42 billion in 2020.

Looking forward, the firm predicts this segment will grow at a CAGR of nearly five per cent between 2021 and 2026. The report goes on to discuss the advantages of extruder technology, such as the ability to choose the ingredients and the ways of processing them to produce healthier snacks with varied ingredients and diverse taste, texture and visual appeal.

Twin screw extrusion for healthy snacks
The growing trend for healthier snack products was highlighted by twin screw extruder specialists Clextral. As well as a heightened interest in claiming health benefits on products, Julie Prost, pilot plant manager and Process engineer at Clextral, notes the numerous diets emerging, the most significant being keto and paleo where sustainability and ethical production are also driving these choices. With these diets on the rise, suppliers must answer the needs of grain-free, gluten-free, GMO free, vegan and allergen-free trends, adding to the challenges of ingredient selection.

“The great news is that ingredient suppliers are finding many more solutions to deliver options to meet this challenge,” adds Prost. Some of the ingredients that encompass healthier snacks include protein-rich sources such as grains, pulses and animal-products including eggs and whey. For fibre rich formulations, a lot of products made with flour obtained from the whole grain are available.

“The use of these healthy ingredients can be seen as hurdles, because without the appropriate process adjustment and fine-tuning, they can lead to denser, rougher, bitter products,” notes Prost. To overcome these hurdles, Clextral highlights the benefits of twin screw extrusion technology. Using their new range of Evolum+ twin screw extruders as an example, Prost explains that a number of features have been improved, including increased OD/ID ratio and an operating speed of 800 rpm, which can reach up to 1200 rpm.

Since healthy snacks often involve finely ground flours, with small particle sizes, the use of twin screw extruders such as the Evolum+ enables the use of these raw materials by improving the feed capability, the conveying of the mix along the machine and the overall capacity of the system.

Temperature control Another critical property of extruders is temperature control, as some ingredients such as egg white or certain proteins are heat sensitive. To ensure precise temperature control throughout the extrusion process, Clextral designed its Advanced Thermal Control, a self-learning proprietary technology which continuously monitors and adjusts to changes in production parameters for process and product consistency.

Turnkey systems specialist BCH has also witnessed a growing trend towards manufacturers being able to add healthier snacks to their portfolio. Discussing the importance of temperature control, Stuart Grogan, operations director, BCH, says: “To meet these trends, BCH have continued to develop their independent cooking, extrusion and forming equipment, which provides a more controlled process at much lower pressures and temperatures than alternative methods, thus allowing the flexibility to process more sensitive products.” One of the company’s most recent projects involved the turnkey supply of a multifunctional line that was capable of producing multi-coloured extrusions of various shapes with up to two other combined masses being introduced at the extrusion head.

“The line also boasts the latest in our range of Maxivap Evaporation systems, so the client can simply switch to 100 percent fruit snacks,” adds Grogan. “This was implemented in order to fulfil their growing demand for healthier alternatives.”

Co-extrusion for high value snacks
Alongside the snackification trend, whereby consumers are choosing nutritious snacks over sit down meals, producers are seeking technologies that encompass the most flexibility, the least amount of manual intervention and improved process control, performance and hygiene.

And this is where co-extrusion technology comes in. Using protein bars as an example, equipment firm Aasted discusses how this market is becoming more dynamic: “We have noticed a clear indication from the market that there is a need for more sophisticated protein bars with fillings and inclusions.

And this goes well hand-in-hand with the scope we are offering – extruded bars and particularly co-extruded bars offer a fast and flexible method to produce these indulgent protein bars.” Aasted’s latest development for this market is the Alice S, an extruder for handling sticky, dense and stringy.medium to high viscosity masses, applying a torque above 2000 Nm.

The solution can be used for single or double-extruded products. To increase versatility, the Alice S can be adjusted with a vertical head movement and can be fitted with a number of forming and cutting tools, with Aasted adding: “The solutions can increase product variety and reduce production downtime.” In addition, co-extrusion systems are often simple to fit onto an existing extrusion line.

An example is equipment business Baker Perkins’ CoEx Master co-extrusion system, which the firm’s business development manager, Keith Graham, says is the acknowledged route to higher value snacks. “It can be added to virtually any new or existing food extrusion line to incorporate fillings with contrasting textures and colours into a cereal outer, with out-of-the-ordinary shapes that catch the eye, complemented by exotic flavours and fillings.”

The latest addition from Baker Perkins is a twin-filled bar offering two differing tastes and textures such as cream and jam. Utilising this process, it’s possible to include fillings of virtually any colour or flavour. There is also the option to include the development of surface textures such as grooves and highlights, and lighter products by either partially filling or using a special die to inject air. “Production with a co-extrusion system is versatile as key parts can be changed over quickly,” adds Graham.

“It is an affordable means of expansion – with minimal investment in R&D or equipment.” The company’s latest development utilises innovative technology to improve process control, performance and hygiene on all the units in CoEx Master co-extrusion systems. Manual intervention is also addressed by co-extrusion technology, as it reduces physical labour and allows staff to focus on more value-added tasks.

For example, BCH’s latest development in this area is a multi stream co-extrusion line for a particular range of products that has significantly reduced the amount of manual labour effort traditionally used.

This required the equipment firm to find a method of switching from what was always a semi-automatic labour intensive process to a completely continuous one.

Addressing waste and hygiene

Beyond flexibility and the healthy snack trend, the entire food industry places a significant focus on waste and hygiene.

As regulations on food safety standards tighten, BCH addressed the challenges this may present by developing its extrusion lines to be one of the few solutions where the core cooking, extrusion and extrusion dies can be truly ‘cleaned in place’.

“This meets the growing demand for more effective cleaning and due diligence protocols for confectionery manufacturers, and ultimately any standards set out by their customer base and changes in legislation,” says Grogan. Furthermore, the company claims that the completely continuous process developed for its multi stream co-extrusion line yielded a reduction in waste by at least 10 per cent. The other innovations discussed take hygienic design into consideration, including Aasted’s Alice S system. Where sanitation is of extreme



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