Herbal ingredients for use in the food, cosmetic and pharmaceutical industry are mainly gained from plant extracts. The challenge of producing these ingredients is the economic optimization of the design for the corresponding technical processes. To achieve this goal, a systematic, model-based approach is necessary, which is not yet available for complex mixtures (Bart and Pilz, 2010 [11]). The general basis for modeling and simulation of industrial processes is the knowledge of the physical properties of the system. A cost-effective option to get hold of separation factors of mixtures is the direct characterization of the multicomponent system, which has been the subject of earlier publications (Josch et al., 2012 [2]; Josch and Strube, 2012 [3]; Bart and Pilz, 2010 [11]). In this work, a systematic approach is illustrated on how to effectively characterize complex mixtures for a first process design. In addition, physical properties for individual plant components can be determined for modeling to optimize industrial processes. For this purpose, those processes which are well established in the chemical industry, including the use of substance databases and calculation of properties by means of thermodynamic theories, will be discussed. In addition, limitations of these approaches and resulting research requirements are shown.