PORTFOLIO

The increasing demand for meat analogues asks for alternative production technology of plant-based food sources. Current extrusion-based structuring of plant proteins is energy-intensive and limited in material selection, structuring ability, and food design. As an alternative pathway, we propose to grow fungi, i.e. it’s root (mycelium), directly in pre-designed food substrates and thus mimic the fiber-like structure and taste of meat. Guidance for the directed growth of fungi is provided by the templated anisotropic 3D host substrate, which provides beneficial mechanical properties, nutrients, and architecture for fungal growth. By designing a 3D matrix to direct mycelium growth, we aim to achieve anisotropy spanning over several length scales, crafting a meat analogue with unprecedented micro and macroscopic fibers that interconnect the entire food product. This approach will demonstrate how biological structuring through growth can be used as a structuring tool while providing general design concepts for plant-based foods.

Meat analogues are already widely produced via various extrusion and shearing methods. The taste and texture demand of consumers are often not met by current analogues or products like tofu and seitan. While textured plant proteins produced via extrusion are nicely structured, they require costly and high pre-processing of the raw material. This project intends to address this gap by providing a foundation for the production of meat-like structures from fungal mycelium. The mycelium is grown into pre-designed two- or three-dimensional templates, which provide nutrients and direct the growth towards a meat-like three-dimensional structures.
The project started out by screening potential fungal species as well as examination of various substrate and nutrient conditions to promote fungal growth. Even though fungi generally grow on everything within days, the screening procedure yielded two fast-growing fungi (Ganoderma lucidum, Ganoderma sessile), which were used for all further experiments. To achieve meat-like structures, both the nutrient composition and the three-dimensional template must stimulate the mycelium growth. In the first step, a method was developed to process substrate material to printable inks that can be extruded to design a three-dimensional matrix of desired shape and size for fungal proliferation. Having both boundary conditions, nutrient availability and templated structure linked, a clear distinction of the influencing factors and, thus, design guidelines were hard to define. As a consequence, by only focusing on the biochemical toolbox of fungal mycelium – substrate relationship it was possible to link the mycelia formation to the growth conditions given by the nutrients. By fine-tuning the substrate’s mechanical properties such as viscosity and viscoelasticity as well as its nutrient content and nutrient gradient it was possible to control and direct fungal growth. In the following step, towards heterogeneous food products, three dimensional structures with different porosity, directionality and oxygen availability were designed from the most promising growth media and colonized by the mycelium. In agar-based porous template, i.e. agar foams it could be shown that the filamentous fungus Ganoderma sessile can enhance mechanical properties, including stiffness and elastic recovery of the hydrogel template.
Following this two-step approach, i.e. by first optimizing the nutrient profile and second templating of the growth media, it is now possible to provide a ‘home and garden’ for fungi proliferation suitable for the manufacturing of new food products.