Waterless extrusion: Forced fusion of casein-based gel granulates into homogeneous and anisotropic, semi-solid structures

Anisotropic (fibrous) semi-solid structures are the main characteristic of protein-based, texturized foods and thus, are decisive for sensorial perception. The objective of this thesis was the design of a waterless extrusion process as platform technology to fuse casein-based gel granulates into anisotropic, semi-solid structures. The extrusion process was designed based on material properties, i.e. chemical composition and thermo-rheological properties. Numerical flow analysis was set up to unveil local temperature and shear gradients during texturization. The degree of anisotropy was determined by tensile testing and increased with increasing shear stress. Further, spatio-temporal dynamics during fermentation of semi-solid structures were investigated to develop an injection technology for homogeneous fermentation of these food products. The findings of this thesis deliver comprehensive insights into a waterless extrusion process and its feasibility to produce anisotropic, casein-based semi-solid structures being marketable as stand-alone or fermented food, or being available as basis for dairy protein hybrids.