Alginate-gelatin composite gels are used in a wide range of food, cosmetic, drug and medicinal applications. Depending on the application, the composite gels have to meet different requirements. Hence, it is necessary to understand the structure formation in detail in order to assess structure-function relationships and to be able to control the functionality in a targeted manner. For 3D Bioprinting alginate-gelatin systems are a promising technology as they enable the formation of living tissue and organ models for regenerative medicine, pharmaceutical applications, and other biological studies. So far, the animal component gelatin has been used for the production of organ models as it has the required material properties.
The mechanistic understanding of the structure-functionality of alginate-gelatin-systems enables the replacement of the animal component gelatin with alternative proteins, such as soy or pea protein. This approach facilitates sustainable and future-oriented applications in the field of medical and pharmaceutical research. To elucidate the structural functionalities of the composite gels the molecular interactions, the phase behavior, rheological properties as well as the stability and porosity of the hydrogels are investigated.
(DFG program SPP1934 „Dispersity, structure and phase changes of proteins and biological agglomerates in biotechnological processes; 2016-2022)
The aim of the project is to quantify the mechanical stress (stress residence time) and resulting process-induced structural changes on proteins and bio-agglomerates during premix membrane emulsification. Based hereon underlying mechanisms of stress response for proteins and bio-agglomerates are identified and concepts for process design and control are derived. It is assumed that the structural change of proteins depends on the stress residence time in the membrane. In the first part of the project, structural changes of β-lactoglobulin in the membrane as a function of the stress residence time were investigated at the process and on the structural level. In the upcoming part of the project, the intermolecular interactions of proteins and interactions within the process environment as well as sorption phenomena at the membrane will be systematically investigated. Protein structures will be varied by using structurally modified variants of β-lactoglobulin (high-pressure-modified protein, amyloid-like aggregates, recombinant proteins). The complex material properties were studied using high-resolution protein analysis such as Fourier transform infrared spectroscopy and circular dichroism. The analytical portfolio will be extended by osmometry and analytical ultracentrifugation. Simulation techniques will be completed with an extended approach of molecular dynamics. Furthermore, in the second part of the project, the enzyme lipase will be used as a model protein with complex tertiary and quaternary structure. Change in its activity will be investigated and thus knowledge about process-related stress and loss of functionality in biological systems will be generated. To fulfill the aim of the specific project, a close cooperation between the Department of Multiphase Flow of the Leibniz Institute in Bremen and the Department of Food Technology and Food Material Science of the Technical University Berlin with their competencies in analysis and modeling at the process and the structural level is required. Specific competencies on the characterization of intermolecular interactions and sorption processes are provided by the Department of Food Colloids of the Technical University Berlin. Close cooperation with other partners within the priority program will lead to a generalized understanding of process-induced stress and its impact on material properties of biological systems in a wide range of different scenarios. This understanding will allow a more targeted process engineering and adaption of biological systems to their specific process environment.
Projektbearbeiter: M.Sc. Christoph Hundschell
Polysaccharides and proteins are used individually or in combination in numerous food systems as ingredients with added value. With their help, the mouthfeel, structure, stability and storage life of the products can be positively influenced. To tailor biopolymers and their blends for these functions, the relationship on the microscopic and macroscopic level must be understood. On the microscopic level, the macromolecular structure, the affinity to the surrounding matrix and the interactions between the individual polymers are important. On the macroscopic level, these variables determine functional properties such as the increase of the viscosity or gel formation as well as the tendency to phase separate.
Mixtures of model proteins and previously unused microbial polysaccharides are analyzed, which in addition to their functional properties have a prebiotic effect and thus a nutritional-physiological added value. Different concentrations and volume fractions of the biopolymers are investigated while varying the molecular weight, the pH value, the ionic strength and the temperature. In addition to the phase behavior and the molecular interactions, the rheological properties have to be characterized in order to understand the formation of the structures on a micro and macromolecular level. This enables the characterization of the structure-functionalities and targeted application of these biopolymers.