Syneresis is what happens when a substance — usually a gel — contracts on standing and squeezes liquid out. Managing syneresis is key to raising curd yield and improving cheese quality; it matters equally for yoghurt, where surface whey separation counts as a defect. Syneresis depends on a combination of specific and nonspecific interactions within the protein network: pH, temperature, and calcium balance all influence it. Managing it means managing the gel’s structure from formation onward. In cheese vats it is encouraged deliberately; in set yoghurt it is a defect to be minimized.