The physical phenomena called “Ostwald ripening” and “disproportionation” are often discussed in molecular gastronomy circles, because dispersed systems such as foams or emulsions are frequently part of dishes. This chapter provides elementary data about what was made about the theory of these mechanisms, and provides some comments about how the theory can be applied. Sauces have complex structures, comprising emulsions, foams, suspensions and more complex structures based on the elementary dispersed systems. Regarding food emulsions, one the simplest is mayonnaise. One important question about culinary foams and emulsions concerns their stability, because, if it is recognized that energy is needed to make them, this means that there is a possibility of destabilization, lowering their energy. As a result of their thermodynamic instability, emulsions and foams will generally tend to reduce their total free energy through an increase in droplet or bubble diameter, thereby reducing their total interfacial area.