Feeding and Extrusion of Meat Substitutes

Clextral is a French manufacturer of food extrusion equipment, who has been successfully partnered with Brabender Technologie in this market for many years.

Table of contents

  • challenge of feeding the growing world population
  • definition of meat substitutes
  • What exactly are meat substitutes?
  • Clextral: the food extrusion expert
  • What processes are available for the extrusion of plant proteins?
  • High-moisture extrusion-cooking process: What happens in the twin-screw extruder and in the die?
  • How does the cooling die affect the texture of plant proteins?
  • Interview with Clextral

One of the greatest challenges of the 21st century:
to feed the growing world population while protecting the environment and animal welfare.

  • Global meat consumption has more than doubled in the last 50 years.
  • This substantial increase in industrial livestock production has had a serious environmental impact and
  • raises ethical questions in relation to animal welfare.
  • In addition, excessive meat consumption has a negative impact on human health.

Definition of meat substitutes

These worrisome developments have given rise to a new food trend: a conscious reduction in personal meat consumption. Flexitarians regularly eat meat but are mindful of nutrition and the environment. They try to incorporate healthy, plant-based, protein-rich alternatives to traditional meat products in their diets.

What exactly are meat substitutes?

  • Plant-based meat substitutes resemble real meat in terms of flavor, appearance, and texture, but consist of plant-based proteins.
  • These meat substitutes are rich in protein, fiber and nutrients and contain highly effective essential amino acids, that are cholesterol-free, and low in fat.
  • The most important sources of plant-based proteins include wheat gluten, soya beans, peas, lentils, fava beans, chickpeas, green beans, and lupins.

Clextral: the food extrusion expert

Since the late 1990s, Clextral, a French manufacturer of food extrusion equipment, has been working together with food processors and food research centers to develop convenience foods made of fibrated protein products, which consist of extruded fibrous proteins. In the past few years, the sales figures for texturized or fibrated vegetable protein in Europe, Asia, America and Australia have increased steadily. Since 2001, Clextral has held a patent for High Moisture Extrusion Cooking (HMEC) – one of the two twin-screw extrusion processes used to manufacture meat substitute products from proteins.

What processes are available for the extrusion of plant proteins?

(1) the “dry” process: TVP and
(2) the “wet” proces: High-Moisture-Extrusion-Cooking-Verfahren (HMEC)

Differences between the extrusion processes
The two extrusion processes differ from one another in terms of

  • the configuration of the extruder and
  • the die used.

(1) In the dry extrusion process, Clextral usually feeds a premix made of soya powder or pea concentrate with a protein content of between 50 and 60 percent into the extruder. Using a simple die produces an extrudate with a spongy texture and a low moisture content of 10 to 23 percent at the exit of the extruder die and around 8 percent at the exit of the dryer post extrusion. After rehydration, the extrudate is ready for consumption at home.

(2) High Moisture Extrusion Cooking: Plant-based raw materials like peas or soya are also used in the HMEC process, although in the form of isolate or concentrate with a higher protein content of 70 to 80 percent. The difference compared to the dry process is that HMEC involves thermomechanical processing – “cooking” – the proteins at temperatures in excess of 120 degrees Celsius and at a high moisture content of 50 to 70 percent, as well as relatively long dwell times. This process enables fiber formation and takes place in a complex screw and barrel configuration within the twin-screw extruder, where the specific screw configuration features a high length to diameter ratio.

What happens in the twin screw extruder and the cooling die

a. This process enables fiber formation.
b. Fiber formation takes place in a complex screw and barrel configuration within the twin-screw extruder where the specific screw configuration features a high length to diameter ratio.
c. In their original state, proteins are like woolen threads that are interwoven.
d. During the cooking process in the extruder, they are disentangled, unfolded and cut into small pieces.
e. In the die, they are then re-crosslinked to produce even filaments of good quality.

How does the cooling die affect the texture of plant proteins?

A long cooling die is positioned behind the screw-barrel configuration, and it plays a key role in the HMEC process.

The setup of its cooling channels, the cross-sectional area and aperture dimensions all have a major impact on the texture and quality of fiber formation.

For example, both

  • rough surfaces featuring relatively short, thick, cross-sectionally oriented fibers and
  • smoother surfaces with long, thin, laminar-flow-oriented fibers are feasible.

Each of these products is used for specific food applications, for example, as analog chicken strips or analog pulled pork. HMEC creates intermediate products, the structure and texture of which closely resembles the muscles found in meat. Further processing also enables flavor, olfactory and visual features to be added.

“The end products of the High Moisture Extrusion Cooking process have the potential to help to feed the growing world population on a sustainable basis in the future.” Emmanuel Lavocat, food extrusion process engineer at Clextral

“Precision feeding is very important for the whole process.”

CITO spoke with Jérôme Mottaz (JM), Head of Engineering and R&D, and Emmanuel Lavocat (EL), food extrusion process engineer, both from Clextral, about the partnership with Brabender Technologie and future market trends.

CITO: Mr. Mottaz, what role does feeding play in the manufacturing process?
JM: Industrial food production always involves absolute precision. That is why accurate feeding is very important for the whole process. All ingredients have to be metered into the extruder in precisely measured quantities. The degree of precision applied at the start of the process ultimately influences the quality of the end product. You can always rely on Brabender Technologie’s gravimetric feeders to perform with absolute precision.

CITO: How do you find the right feeder for each of your customers’ applications?
JM: In our Technical Center in Firminy, we can test the different raw materials or dry mix recipes involved in almost all food applications. Brabender Technologie has provided us with a large number of different gravimetric feeders for our test lab. This provides us with the flexibility to test the required raw materials and specific formulations on different feeders. We can always draw on Brabender Technologie’s expertise and their technical centers around the world at anytime.

CITO: What benefits do Brabender Technologie’s feeding systems provide?
EL: Food safety plays an overriding role in food manufacturing. The special Hygienic Design concept employed in Brabender Technologie’s feeders reliably meets that requirement. What we particularly value is that Hygienic Design can be adapted to meet the specific requirements of the customer – from minimum requirements to a very high sanitary standard. In addition, the feeders feature exceptional cleanability and are easy to operate.

CITO: In which direction might the market for meat substitute products be headed in the future?
EL: Raw material diversity will increase. We are already testing new raw materials, such as chickpeas, fava beans or lentils, which are equally suitable for wet extrusion. However, given their limited availability on the world market they are still too expensive. This may change in the future as many consumers reject genetically modified products like soya, because of ethical and health concerns.

CITO: What does that mean in technology development terms?
JM: A major challenge is enhancing performance while maintaining the same level of operability. Our R&D team is already addressing this topic. Product expertise and process know-how are the key issues in creating the best analog meats from various sources of protein.

CITO: Mr. Mottaz, Mr. Lavocat, many thanks for the interesting conversation!