For more than 25 years, Foodwest Ltd., Seinäjoki, Finland, has provided testing and development of food products as well as manufacturing technologies and packaging solutions for production scale-up. Expertise at this facility covers all food sector categories from snack food and bakeries to one of food’s fast growing market sectors—plant-based foods. 

In order to provide the highest flexibility in extruded product development, Foodwest recently expanded its food development center with a Coperion ZSK 27 food extruder in hybrid design. Due to the system’s modular construction, Texturized Vegetable Protein (TVP), High Moisture Meat Analogues (HMMA) and numerous other extrudates such as snacks and cereals can be manufactured on the same machine. 

The extruder is particularly well suited for research and development with throughputs of up to 80 kg/h, and thanks to constant process parameters within the entire ZSK extruder series, ensures reliable scale up to higher throughput ranges. Along with the extruder, the Coperion system encompasses a highly accurate Coperion K-Tron gravimetric twin screw feeder for dry powders, a ZGF centric food pelletizer from Coperion Pelletizing Technology, and a cooling nozzle. 

Extrusion of plant protein products: TVP, HMMA processes defined

TVP is used both as a meat analogue or vegan meat and as a supplement to meat products. It can be produced in various sizes and forms, as smaller pellets or larger chunks, broken down or ground. TVP is a dry, expanded product with a long shelf life under normal ambient conditions. TVP requires rehydration in water/liquid before use.

When manufacturing TVP, the extruder’s main inlet is continually fed with bulk raw protein material using Coperion K-Tron’s high accuracy loss-in-weight feeders and material handling refill systems. Immediately thereafter, water is injected using Coperion K-Tron liquid feeders. In certain cases, direct steam injection is applied into the process section as well. Within the process section, materials are mixed, kneaded and cooked. The product then moves out of the extruder via a nozzle plate where it is processed such that it achieves a porous, foamy structure with oriented fibers. The attached Coperion ZGF pelletizer’s knife rotor then immediately cuts the product. The TVP granules are then dried to ensure long-term product stability.

Alternatively, HMMA is primarily used as a high-quality meat-analogue product in ready-to-eat meals. By adjusting recipe and process parameters, structures of different meat types can be replicated with striking similarity to the original. HMMA’s moisture content lies between approximately 50 percent and 80 percent and must therefore be refrigerated. Protein sources used to manufacture high-quality HMMA are primarily legumes such as soy, lupine or pea. In certain cases, i.e., when manufacturing meat product extenders, lesser quantities of genuine meat or fish products are added. 

For the HMMA process, the bulk raw protein material is fed into the extruder inlet. Water is then added. Within the ZSK food extruder’s process section, this mass is then fully mixed and kneaded. Discharge takes place using a cooling die that generates a meat-like texture which is “frozen in.” The result is a solid strand with fiber structure similar to meat; the strand is then conveyed to the next process step. (Watch video of how Coperion has produced HMMA on ZSK extruder in their test lab)

Twin screw feeder: Suitable for accurate feeding of ingredients direct to the extruder

Foodwest’s feeder is a Coperion twin screw gravimetric loss-in-weight unit. When designing a continuous extrusion line, accurate delivery of the individual ingredients to the extrusion process is critical to create stability and end product quality. For this reason, highly accurate gravimetric feeders are the feed method of choice, since they measure the weight of the material being fed and adjust feeder output to maintain the desired set point. Conversely, volumetric feeders do not weigh the flow; they operate by delivering a certain volume of material per unit time from which a weight-based flow rate is inferred by the process of calibration. 

The most popular type of gravimetric feeder used in continuous processes is the loss-in-weight (LIW) feeder, which consists of a hopper and feeder that are isolated from the process so the entire system can be continuously weighed. LIW feeders are typically either mounted on weigh scales or suspended on load cells. The Coperion K-Tron load cell is a highly accurate instrument, designed specifically for the rate and accuracy requirements of dynamic feeding, and features a resolution as high as 1:4,000,000 in 80 ms. As the feeder discharges material, system weight declines. The speed of the metering device is controlled to result in a per-unit-time loss of system weight equal to the desired feed rate. (Watch Loss-in-Weight Feeder Principle of Operation)

At any stage of the production process undetected feed rate and proportioning errors waste ingredients and add to overall ingredient costs. For example, within the very sensitive high-moisture extrusion process, feeding inaccuracy can easily cause shut-downs of the line, so that the extruder and special die head which creates the fibrous material characteristics need to be cleaned and restarted again.

Because many of the food ingredients used in food processing can be poor flowing and cohesive, Coperion K-Tron provides a variety of options in screw configurations, overall feeder designs and also innovative devices such as the Actiflow bulk solids activator. The Actiflow is a smart flow aid device which operates in conjunction with the LIW feeder controller and its load cells. The unit at Foodwest includes a hopper complete with the bracket for the Actiflow unit, in case there is need for it to be added in the future, thus adding to the system’s overall flexability. (Watch animation of Actiflow

ZSK food extruder in hybrid design for maximum flexibility

Foodwest’s new extruder allows them to develop and manufacture both TVP and HMMA on the same machine with only a minimum of retrofitting. The feeding and process section for both applications are nearly identical, while the discharge units differ significantly. While the aforementioned ZGF centric pelletizer is attached to the process section for manufacturing TVP in order to cut the product directly at the nozzle plate, HMMA is discharged using a specialized cooling nozzle which produces a product strand that exhibits a texture closely resembling that of genuine meat. Using an adapter solution developed by Coperion, the Foodwest’s ZSK extruder’s discharge can now be switched from a pelletizer to a cooling nozzle in no time. The same principle functions just as quickly in reverse when switching from an HMMA process to TVP.

In addition, the extruder twin screws’ combination of self-wiping and modular construction will allow Foodwest to develop and test numerous other products on the ZSK system such as snacks and cereals. For production of the latter, Foodwest individually configures the extruder as well as the extensive array of peripheral equipment available. As a result, the company profits from the extruder’s very high hygiene standards, intensive dispersion performance, gentle product handling and overall versatility.

For product development and manufacturing

Harri Latva-Mäenpää, PhD, innovation director at Foodwest, says, “Extrusion is one of the most interesting technologies and we wanted to include it in our new food development and piloting facility in Finland. The versatile package and expertise offered by Coperion convinced us to make this investment. We can use the ZSK extruder for process and product development and also combine it with other food production and packaging technologies. This enables us to create commercially ready solutions in our food approved facility together with our customers all over the world.”

In addition, Stefan Gebhardt, general manager of the Food & Pharma Business Unit at Coperion, says, “We’re very pleased to equip such a renowned company as Foodwest with a ZSK Food Extruder in Hybrid Design. We are convinced that the ZSK extruder, with its high configuration flexibility and reliable scale up to larger extruder sizes, is the optimal technology for a large bandwidth of product tests, research, and development. Moreover, we are very pleased to announce that, moving forward, Coperion customers will have a testing area for production of meat analogues and other products at their disposal at the Foodwest test center in Finland.“

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