*Die Arbeit kann auf Deutsch oder Englisch geschrieben werden.
Protein is an essential nutrient for the human body. Currently, meat and dairy products are the main sources of the proteins consumed in developed countries. However, the production of these animal-based proteins on a large scale is inefficient and negatively affects the ecosystem. Considering the expected world population of 9 billion in 2050, the current production and consumption patterns will increasingly overpressure the ecosystem and endanger the future food security. An effective option to reduce the strain on environment due to intensive animal husbandry is to eat less meat and dairy products and to shift towards more sustainable protein sources such as grains, legumes, nuts or even insects. From a nutritional standpoint, sustainable proteins can supply sufficient amounts of essential amino acids and therefore give an adequate replacement for meat and dairy products in human diets. However, required changes in consumption behavior can often take long time to realize, if at all. To facilitate a quicker change, sustainable proteins can be incorporated into readily accepted and widely consumed food products.
Extruded foods, such as breakfast cereals and snacks, are good examples for such products. Fortification of starch based extruded foods with proteins is not a new idea and has already been studied for selected protein sources. It has been shown that extrusion generally improves protein quality and digestibility while retaining active nutrients which makes it principally a suitable process for the production of protein-rich foods. However, extrusion is a complex process including several process variables (e.g. screw speed, feed rate, water content) that affect the extent of thermomechanical treatment and intrinsic properties (e.g. molecular structure, viscosity, elasticity), which influence the micro and macro structure of the product determining the product quality attributes. Although there are vast numbers of studies on protein-fortified extrudates, the decisive process parameters and their correlation with the final product characteristics (e.g. texture, porosity, water solubility, protein structure and digestibility) remain unknown.
Therefore, primary focus of this study is to determine the extrusion and system parameters playing a decisive role on the final product characteristics of a starch based matrix fortified with sustainable proteins, and if possible, to develop process and property functions describing their correlations.