Extruders Tackle New Food Formulations

There is a noticeable trend toward healthier foods, as consumers show increasing awareness about the health impact of their diets. They want more information about what’s in their processed foods, and they’re looking for cleaner labels.

Many food manufacturers are answering that call, and they’re experimenting with their recipe formulations to provide healthier options. All of this, in turn, affects what goes on in the extrusion process—used as a key processing step for a wide range of foods, including snacks, cereals, plant-based meat alternatives, pet food and snacks, and more.

“People are looking for as few additives as possible,” notes Davide Di Nunno, head of process technology for pasta and snacks at GEA, pointing to a clean label approach that aims for shorter ingredient lists.

Consumers are looking for low-fat or even fat-free versions of their favorite foods as well. “We are suggesting alternatives to make fat-free products, so not fried snacks and not fried noodles,” Di Nunno says, pointing to other trends such as lower amounts of salt, higher protein, and plant-based products.

These changes in consumer products have their effects on the extrusion process and technology. For example, shear—the force that creates high temperatures and makes extrusion work—must be evaluated for any new material being used in a recipe.

“The shear is affected by several things, from raw material characteristics to the machine design and of course the settings that we use on that machine—temperature, screw speed, die design, screw design, barrel design—everything is affecting the process,” Di Nunno says.

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But the first consideration is that raw material and how it will affect the shear of the extrusion step. At GEA’s technology center in Galliera Veneta, Italy, which runs trials for customers, a laboratory first analyzes the raw material. “These analyses are particle size, fiber content, fiber length or solubility, protein content, protein solubility, fat content, ash content… All these characteristics affect the extrusion,” Di Nunno explains. “So at the moment that we are going to use a lower amount of fat or a higher amount of protein, this for sure will affect the final texture.”

Some materials might require a change in the process, but other materials might not be acceptable at all. “For instance, a corn flour for a gluten-free pasta cannot be acceptable to make snacks,” Di Nunno says. “In pasta, we prefer to have a higher amount of fat because the reaction of this fat is emulsifying and making the final texture of the product more similar to a traditional pasta texture.”

A GEA customer based in South Korea is using extrusion to make pellets, which are later expanded to create a new breakfast cereal for the Korean market.GEA

On the other hand, this amount of fat is not wanted in higher-energy extrusion because the fat will be damaged and will develop an acidity that will decrease the shelf life of the final product. This is a factor that makes it difficult to extrude pasta from a chickpea protein, Di Nunno explains. “Chickpea becomes an issue because chickpeas have a higher amount of fat from the crops,” he says. “This higher amount will not allow us to properly gelatinize, to properly shape the product, and then the final product becomes more of a fluffy pasta.”

Some of GEA’s extrusion customers have moved to a new toaster technology—an industrial oven akin to an air fryer—instead of frying to make cereals and snacks fat-free.

One customer based in South Korea is using extrusion to make pellets, which are later expanded with this toaster technology to create a new breakfast cereal for the Korean market. It’s a three-layer, chocolate-based cereal made on perforated sheets. “Usually, the breakfast cereals are directly puffed and not indirectly puffed from a pellet,” Di Nunno says. “They can store it and they can expand it by hot air whenever they like, even after a month, to set the baking. It’s good because they can better manage the warehouse in terms of density of the product because the pellet is smaller.”

Alternative proteins and new ingredients

One sector seeing a lot of experimentation with ingredients is plant-based meat alternatives, where several manufacturers have moved beyond the more typical soy or pea proteins into a range of other proteins such as chickpeas, fava beans, mung beans, and more.

Start-up food producer Vemiwa Foods in Königsbrunn, Germany, makes a range of plant-based meat, fish, and dairy alternatives with a focus on additive-free recipes. The company uses a wet extrusion process to achieve a fibrous texture for its meat analogues by combining plant proteins with water and oil.

Although Vemiwa typically uses legumes such as peas and fava beans as protein sources, it is also experimenting with other sources and their compositions. The flexibility of the Coperion ZSK twin screw extrusion system that the food producer is using gives them the ability to research, develop, and produce new and innovative plant-based products with different types of protein bases.

In high-moisture meat analogue (HMMA) production, the ZSK extruder achieves throughputs of up to 250 kg/h. The energy input of the extruder’s twin screws makes breakdown of the proteins in the process easier, providing greater product design flexibility. The process section’s modular design results in the greatest possible flexibility, so that recipe changes and modifications can be implemented quickly by simply changing the screw configurations and the process configuration.

“With this system, we are very flexible, and we can easily try out new recipes or products,” says Michael Walk Jr., Vemiwa’s founder. “This means we can expand our selection further, as well as how we offer extrusion on commission.”

With high-moisture extrusion cooking technology for novel proteins, the twin-screw extruder mixes and cooks ingredients, then pushes the mixture through a long temperature-controlled die that enhances cross-linkage of proteins and formation of fiber-like texture.Clextral

As food developers understand more about digestibility of various proteins, more research will be required to understand how new ingredients will react in extrusion recipes. “What we’re seeing is more R&D going on in that space with these alternative proteins and ingredients beyond the pea and the soy that’s impacting future formulations and recipes,” says John Barber, regional sales manager for Clextral. “We do a lot of R&D at our facility in Tampa, Fla., which is our corporate North American pilot plant.” Clextral works with customers on new ingredients, as well as with the ingredient suppliers themselves, he adds.

There’s a rise in inquiries from the cultivated meat sector as the industry struggles to scale up with bioreactors alone. Plant-based recipes—and extrusion—might be able to help out. “What they’re trying to do is to increase the taste and structure and texture of cultivated meat using extrusion,” says John Sheehy, global business development manager for alternative proteins at Coperion. “How can extrusion with blended plant proteins—whether that be pea, fava, mung, lentil, pumpkin, etc.—help increase the texture and taste and increase the throughput of cultivated meat?”

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Extrusion has some promise to give the cultivated meat the fibrous structure they don’t get from a bioreactor, Sheehy adds. “How are you going to get that flavor from meat that’s grown in a bioreactor the same way as you get structure from chickens or pigs that walk around? Those fibrous muscle tissues, they get fibrous because of the animal exercise. If the cells are grown inside a bioreactor, how is that fibrous texture going to transfer out? Is extrusion technology the way we can help cultivated meat get the product out the door?”

Two types of fibration for plant-based proteins include continued/longitudinal fibration (left) and discontinued fibration (right).Clextral

Another movement growing in popularity among alternative proteins, especially as it relates to sustainability, is insect protein. “You’re seeing black fly larvae, crickets, mealworms—and those are being used to produce animal feed and aqua feed,” Sheehy says. “It’s all being used to produce animal feed with zero farmland and zero water.”

Not just animal feed—insect proteins are being used in some baked products for human consumption, such as cricket flours used to make chips or crackers, adds Katie Winkle, sales director for baked products and extrusion for Baker Perkins. Coperion acquired the Baker Perkins brand last year within the portfolio of Schenck Process Food and Performance Materials.

Technology upgrades

On the alternative protein side, Coperion is seeing a need to modify the die technology following the extrusion process to get the desired results. “As far as alternative proteins are concerned, the biggest development Coperion has engineered in the last six months to a year has been better cooling die technology,” Sheehy says.

More cutting features have been added to the cooling dies as well, Sheehy comments, allowing customers to chop, grate, or shape products as they leave the cooling die.

The modular design of twin screw extruders provides flexibility for recipe changes and modifications to be made quickly.Coperion

HMMAs—which have 60 to 70% moisture, more akin to real meat—have called for a longer die. Texturized vegetable protein (TVP), which has been done for a longer time, requires a very short die, notes Ed Beecher, sales engineer for food and pharma extrusion, North America, at Coperion. “For the more recent high-moisture meat analogues, there’s intensive mixing and some texturizing that goes on in the extruder, and then you have an elongated cooling die, sometimes up to 10 ft long,” he says. “There’s laminar flow in that die, and it’s also cooling the extrudate. That creates the meat-like texture—like when you cook a chicken breast, you can peel the fibers apart.”

Along with that improved fibrous texture, equipment manufacturers are also working to improve the throughput. “You’re approaching 1,000 kilos an hour, where previously we were lucky to do 300 or 400 kilos an hour,” Sheehy says.

The Baker Perkins division has put much of its throughput focus on the feed system, and a few years ago developed its MAX3 feed system for industrial applications that increased throughputs by as much as 34% across all formulations. Winkle notes: “It was really with a redesign of the feed throat and some of the initial feed screws in the machine that helped us in some cases double what we were able to get through the machine,” she says. “We’re really trying to just take what we’re already doing and help our customer do it better, at a better scale, and with greater throughput to help them see that ROI.”Twin screws have become more common in extruders, providing more mixing and volatilization capabilities for more specialized food formulations.GEA

Much of Clextral’s development in more recent years has been with respect to controls and automation, Barber says, pointing to the company’s Fitsys+ V3 control system. The software manages tasks throughout the extrusion process, including automatic startup and shutdown.

Building on Big Data and self-learning, the system monitors process conditions and can alert customers to potential issues with the equipment. “As time goes on, it will be used even more efficiently and will learn new ways to be used for preventative maintenance, for troubleshooting, and for increased productivity and automation,” Barber says.

Extrusion technology provides a versatile platform for an array of applications, and that flexibility figures prominently in many of the new product launches. Clextral has been working with a customer recently that is making both sweet and savory products on the same extrusion line—something not typically done. It’s a matter of having the right configuration and engineering of the line layout, and having the appropriate auxiliary equipment, Barber says.

Clextral’s Fitsys automation is also a factor, he adds. “When you sugarcoat something, you coat and then you dry. But it’s just the opposite for a savory snack like a cheese puff—you dry and then you coat,” Barber explains. “So when you’re coming out of the extruder with your extrudate, it has to know: Do I go get coated now and then dry, or do I dry and then go get coated?”

The modular design of Coperion’s ZSK extruder allows for a considerable amount of flexibility in the line, Beecher notes. Users can replace various segments of the process section or modify peripheral equipment at a much lower cost than buying a new system. “It could be a million-dollar machine, but it might cost you $30,000 or $40,000 to modify the setup and boost your throughput. So being a modular design makes it adaptable,” he says.

“Extruders are some of the most versatile pieces of equipment, in my opinion,” Winkle says. “You can be making anything from alternative proteins to snacks. You could even be making ingredients, trying to extrude some type of flour that’s going to be used in an alternative application. The machine itself is so versatile.”