Processing Plant-Based Flours

The latest developments in the production and processing of plant proteins were presented at Anuga FoodTec. They play a central role as an alternative to animal protein. Possible sources include wheat, rye, oats, barley, soya, peas, lentils or other cereals and pulses. "Ultra-fine grinding and subsequent sifting produce special flours with a significantly higher protein content than the starting material," emphasises Alexander Langer, Deputy Head of Sales at Hosokawa Alpine. These are then used as the basis for vegan burger patties, lupin schnitzel and many other plant-based foods. Hosokawa Alpine offers two processes for the production of speciality flours rich in protein and starch: the precision process and the standard process. "Our speciality is the precision process in which the smaller protein particles and the larger starch particles are deagglomerated and then the finer protein particles and the coarser starch particles are fractionated," says Langer. The dry fractionation of proteins consists of efficient fine grinding with the Zirkoplex ZPS classifier mill and high-performance classification of the finely ground product with the Turboplex ATP classifier. This results in two products: a fine protein concentrate and a coarse starch concentrate.

The standard process for dry fractionation involves efficient fine grinding with the Contraplex CW II pin mill and high-performance classification of the finely ground product with the ATP air classifier. "For some products with a high fibre and/or oil content, the mill is recommended for efficiently deagglomerating these components," explains Langer. In addition to the extraction of proteins from cereals or pulses, other valuable protein sources such as sunflower extraction meal, pseudo-cereals, guar gum powder, locust bean grit and food by-products from brewery and oil extraction processes can also be processed. This enables not only the extraction of valuable proteins, but also the fractionation of other valuable ingredients, such as fibre.

Cereals and pulses are not the only suitable alternative sources of protein. Insects such as black soldier fly larvae, mealworms and fruit flies are also interesting alternatives for high-quality animal protein. "Larvae are very efficient due to their high feed utilisation and only need a small amount of feed to produce large quantities of nutritious animal proteins and oil extracts," says Daan Goris. "As larvae are sensitive to heat and processing in moist feed is problematic, our Drymeister Flash drying system DMR is the ideal solution," says the Food & Feed Team Leader at Hosokawa Micron. The system combines drying, grinding and separating in a single unit. The desired properties of the insect protein powder can be achieved by adjusting the particle size and shearing force.

The upgrading of residual streams is another topic for Goris where drying processes play an important role. The residual streams are usually liquids, pastes or wet powders that contain proteins or have other positive, functional properties. "Just think of the residues from the processing of meat or fish, vegetables or fruit peelings and the side streams from bakeries, breweries and biorefineries," says Goris. For him, a typical system for utilising residual streams includes the following components: a mill to grind the residues, a cooker to generate heat for preventing microbial problems, a screw press to press out the liquid, a decanter to separate it, an evaporator to increase the dry substance content and a grinding dryer to dry the wet press cake in order to obtain the high-quality, nutritious powder. Whether the recovery of raw materials is possible and profitable can usually be estimated on the basis of Hosokawa Micron's experience. "Many natural waste streams typically contain 15 to 40 per cent solids. Our database is an excellent source of information for the analysis," concludes Goris. In addition, both Hosokawa Alpine in Augsburg, Germany and Hosokawa Micron in the Netherlands have test centres where customers can test their own products in order to find the optimum solution for their processes.

The sensory and technofunctional properties of plant proteins change depending on how they're treated. Comprehensive technological expertise is required for manufacturing convincing plant-based products. With modern twin-screw extruders in hybrid design, both texturised plant protein and meat analogues with a high water content can be produced with minimal changeover effort. The extrudates form the basis for a variety of reformulated burger patties, nuggets or sausages with significantly less fat and a favourable fatty acid profile. These are free from cholesterol as well as nitrites and phosphates. Vemiwa Foods, for example, based in Königsbrunn, Germany, produces plant-based foods according to these quality parameters and relies on technology from Coperion. Using the hybrid version of the ZSK 43 Mv PLUS Food Extruder and K-Tron feeders, the company produces vegan meat substitute products like sliced meat, pulled meat and minced meat using the wet extrusion process. Vemiwa currently uses pulses like peas and field beans as a source of protein and is also experimenting with other protein sources and their composition.

During production, the extruder achieves throughputs of up to 250 kilograms per hour and speeds of up to 1,800 revolutions per minute. The resulting increased energy input facilitates the breakdown of the proteins in the process and therefore greater flexibility in terms of product design. The deep-cut screw flights with a diameter ratio Do/Di of 1.8 also create a large free volume, which significantly improves the intake of protein powders that are often difficult to flow. The modular structure of the process section also allows a great deal of freedom: Recipe changes can be carried out quickly by changing the screw configurations and the process set-up.