Coconut milk separates into a watery liquid and solid curds after refrigeration due to its natural composition and the presence of fats in the milk.
Coconut milk is made by blending grated coconut meat with water and then straining it to extract the liquid. The fats in coconut milk are primarily composed of coconut oil, which is rich in saturated fats. When the coconut milk is refrigerated, the fat content tends to solidify and rise to the top, while the water content remains at the bottom. This separation is a natural process known as "creaming."
The solid curds that form at the top of the coconut milk are the coconut cream. The watery liquid that accumulates at the bottom is referred to as coconut water or coconut milk's "lighter" part.
This separation is not a sign of spoilage or that the coconut milk has gone bad. It is merely a physical change due to the differences in density between the fats and water in the coconut milk. To restore the coconut milk to its original consistency, you can gently shake or stir the contents before use to remix the cream and water.