Meat substitutes using twin-screw extrusion

Texturising plant proteins to make meat substitutes using twin-screw extrusion has advanced rapidly in recent years and enabled food manufacturers to capitalise on the surge of interest in plant-based eating.

Until recently, meat alternatives made from texturised vegetable proteins (TVP) were aimed squarely at vegetarian and vegan consumers who avoid meat for ethical reasons. Shifting perceptions mean that these products now appeal to meat-eaters who are adopting plant-based eating for environmental and health reasons. This has not only expanded the size of the market but also driven the development of much more realistic meat analogues: although this new generation of customers want to reduce their consumption they are not willing to give up on the experience of eating meat.

Dry TVP produced by low-moisture extrusion cooking (LMEC) has been used as a meat substitute or extender for many years but does not offer meat eaters the firm, fibrous texture they are looking for.

Development of high moisture extrusion cooking (HMEC) has addressed this. It offers a much improved fibrous consistency reproducing both the texture and appearance of meat. These high moisture meat analogues (HMMA) make plant-based products such as burgers, sausages and curries more convincing while also enabling meat-free alternatives to fresh meat such as chicken strips or beef chunks to be developed.

HIGH MOISTURE MEAT ANALOGUES

The key characteristic of HMMA is the fibrous structure, which is achieved by developing the proteins in a twin-screw extruder then stretching and aligning them in an extended cooling die. Moisture content is in the region of 60% to 70% by weight of the final product.

A range of protein ingredients may be used, typically pea, soy and wheat gluten, but there is a lot of interest in other bean and pulse sources. Downstream processing such as mincing, mixing, and forming can be done on standard meat processing equipment.

HMMA is widely used to make both ingredients and finished products. Ingredients for prepared dishes include mince, chunks and strips, typically for curries, pizza toppings, pasta dishes and soups. Completely meat-free products using HMMAinclude burgers, sausages, and meatballs.

LOW MOISTURE MEAT SUBSTITUTES

Dry TVP uses similar protein sources to MMA but in the form of lower-cost defatted flours, rather than isolates or concentrates. The process is less intensive so outputs from a given size of the extruder are much higher.

The Baker Perkins SBXMaster twin-screw cooker extruder is used to form a melt that is extruded through a die and formed/cut into flakes, pellets or chunks before being dried.

These are normally supplied as bulk dry ingredients to manufacturers who rehydrate them before incorporating into meat-free products such as burgers, sausages, meatballs and prepared dishes. They are also often used as extenders for real meat

Baker Perkins is working to develop dry TVP with a more fibrated structure and an improved texture, but still at a lower production cost than HMMA.

RECIPE AND PROTEIN CHOICES

For both processes, Baker Perkins offers standard recipes utilizing a variety of different proteins including soy, pea, wheat, beans, lentils, and other pulses. They also develop recipes for customers’ own chosen protein, with full support including initial trials in the Baker Perkins Innovation

Centre at Peterborough in the UK, process development, manufacture and equipment commissioning. They take into account taste and flavour profile preferences as well as local ingredient availability.

Baker Perkins anticipates continuous improvements in the appearance, taste and texture of TVP from a range of different protein sources. Any protein source – seaweed, algae or insects for example - can potentially be turned into a meat analogue and this is the focus for future development.

Baker Perkins has marketed twin-screw extruders to produce a wide range of foods and ingredients for over 50 years. Today's range of versatile SBX Master extruder provides continuous production at outputs from 250 to 2,300kg/hour, depending on the product.

Many dietary trends in recent years have been based on fashion rather than substantiated science or a real shift in consumer behaviour. However, the move to plant-based eating shows every sign of accelerating as awareness of the environmental impact of meat production grows. Where once increasing disposable income in developing countries inevitably led to higher meat consumption this is no longer the case, for younger consumers in particular. Improving the quality, and variety of plant-based meat alternatives will be an ongoing challenge and one that Baker Perkins is gearing up to meet. •

Courlanders – www.courlanders.co.za