Fig. 2: With the Ystral Conti-TDS powder wetting and dispersing machine, even hard-to-wet, dusty or sticky powders containing protein can be dispersed agglomerate-free. The particles can be broken down in cold or warm liquid.

The new types of food require new technologies

The new types of food require new technologiesThe alternative proteins used in the new food segment have one thing in common: they are difficult to process and have extremely different characteristics: Wheat protein, for example, is extremely cohesive, while soya protein is extremely adhesive. If protein powders from seeds, grains, nuts or pulses are incorporated into water, they tend to gelatinise, stick together and foam. On the one hand, the proteins are sensitive to shear, but at the same time require high shear when dispersing into the liquid. Shearing is therefore necessary under controlled conditions over a very short period of time. For optimum product quality, it is crucial that agglomerates present in the powder are completely broken up as soon as they enter the liquid and that the formation of new agglomerates is avoided. Otherwise, these agglomerates have to be subsequently broken down by prolonged stirring and time-consuming post-dispersion - with negative consequences for the product quality: dispersing the agglomerates damages the quaternary and tertiary structure of the hydrated protein and uncontrollably impairs viscosity and texture. Avoiding agglomerates is also very important with regard to the starch contained in the powder. Starch is usually broken down by enzymes, occasionally also by acids. If the powder particles are separated before the liquid is added and strongly dispersed during the powder application, the enzymatic degradation of the starch is accelerated. With conventional agitators, injectors or in-line blenders, however, the particles always come into contact with the liquid as a compact bulk. This leads to stable, partially wetted agglomerates that are difficult to break down. Post-dispersion then not only costs an enormous amount of time and energy - the air contained in the protein powder is also dispersed into unwanted microfoam in this way. If protein powder is introduced into the liquid in conventional processing methods, it either flocculates completely or sticks to the machine parts. This leads to local overheating, discolouration or even burns on rotating parts and a slightly burnt taste of the end products. A large proportion of the insufficiently digested proteins are ultimately filtered out unused.

Separation of the powder particles by vacuum expansion

These problems of conventional process engineering solutions are avoided when using the vacuum expansion method from mixing and dispersion technology specialist Ystral: The air contained in the powder is expanded many times over, which increases the distances between the particles enormously. The primary protein particles are separated by the suction vacuum, completely wetted on first contact with the liquid, dispersed in situ under vacuum and then hydrated under pressure without agglomerates. The entire process takes two to three hundredths of a second and the heat input is minimal. Each individual powder particle is wetted and dispersed in this way. The texture of the protein remains undamaged and the process time is enormously reduced compared to conventional technologies. Due to the intensive dispersion, significantly fewer enzymes are required to break down the starch compared to conventional processes. The air contained in the powder is separated from the much heavier dispersion by the centrifugal effect of the high-speed rotor and coalesces into large air bubbles that can easily escape from the process vessel. In this way, the foam that occurs during protein processing is almost completely avoided.