Amino acids are widely used in food, chemical, agricultural, cosmetic, and pharmaceutical products. Crystallization is one of the key steps in their manufacturing processes. However, for a complex multicomponent system with solvates and compounds, it is not clear how to recover a specific amino acid or its salt. To address this issue, this article proposes a general framework for the conceptual design of amino acid crystallization processes. It is based on the representation and experimental determination of solid-liquid equilibrium (SLE) phase diagrams. Glutamic acid and its sodium salt, monosodium glutamate, are chosen as a model system to illustrate this framework. SLE experiments were performed to estimate the location of the boundaries between different crystallization compartments in each of which a single component can be recovered.