ZSK Food Extruder in Hybrid Version – For TVP and HMMA

TVP Extrusion

TVP is used both as a meat substitute 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.

Several actions take place within the ZSK Food Extruder for TVP production. First, the raw materials are mixed to form a homogenous melt. Then there is the kneading or plasticizing step and finally, denaturation, where the protein molecules unfold and reform in the required structure for the specific product design.

The melt is heated by dissipation. This means that the mechanical energy introduced by the rotation of the extruder screws is converted to thermal energy. Additional thermal energy required can be brought in via heated barrels.

The TVP product exits the ZSK Food Extruder through a die plate which aligns the product fibers. The die plate provides back pressure on the extruder, which is necessary for the energy transfer within the extruder itself. When the material passes through the holes of the die plate, the pressure drop results in a release of water vapor, causing the material's expansion into a porous, foamy structure. The product then passes the ZGF centric pelletizer which cuts the melt strands into granules. These granules then finally to be dried for stable long-term storage.

HMMA Extrusion

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 50-80% 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 HMMA extrusion similar actions take place within the ZSK Food Extruder as for the extrusion of TVP. However, water content necessary for HMMA products is higher than for TVP. Protein molecules denature and unfold. Protein agglomerates are separated.

At the end of the extrusion process, a cooling die cools the product down and forces it into a laminar flow. The product exits the cooling die as a rubbery strand or ribbon, which is conveyed to further processing. Transformation to solid-phase happens as fibers are built through freezing the laminar flow profile into meat-like structures.