What is curdle?

Curdle refers to a process where milk or milk-based food products coagulate or thicken and form lumps or clumps. This process occurs due to the acidic reaction between the proteins in the milk and its enzymes, or due to the addition of acidic substances like lemon juice, vinegar, or rennet. Curdling is a common process in cheesemaking, yogurt production, and the preparation of certain sauces and desserts. However, curdling can also be an undesirable outcome in cooking, such as when milk curdles in soups or sauces, giving them an unappetizing appearance and texture. To prevent curdling, one can control the heat, use stabilizers like cornstarch or flour, or add acidic ingredients gradually and with caution.