Why does soy milk curdle and what factors contribute to this process?

Soy milk curdles because of its high protein content, specifically the presence of a protein called soy protein. When soy milk is exposed to acidic substances like lemon juice or vinegar, the proteins in the soy milk can coagulate and form curds. Factors that contribute to this process include the acidity of the substance added to the soy milk, the temperature of the soy milk, and the presence of other ingredients that may interact with the proteins.