If you regularly make soy coffees for your customers, you have probably noticed that soy milk is often harder to work with than dairy milk – it tends to curdle more in coffee, especially when steaming hot. With some coffees it behaves well, with some it doesn’t. The delicate protein structures in milk are to blame for the curdling effect. Proteins are long, folded chains of amino acids. Humans only use about 20 different amino acids, and they can be linked after one another in any order. Most proteins contain hundreds of them.