Curds

Curds are the solid portion of milk that forms when milk coagulates and separates from the liquid whey. They consist mainly of casein proteins that have aggregated into a gel-like network, often with some fat depending on the milk. The liquid that remains is whey, which contains water, lactose, and soluble proteins.

Coagulation can be achieved by acids (such as vinegar or lemon juice) or by lactic acid bacteria that produce acid, or by enzymatic action with rennet. The milk is encouraged to coagulate at a moderate temperature, then the curd is cut into blocks or grains to allow whey to drain. The curds may be heated, washed, pressed, or salted to influence texture and moisture. If pressed and aged, curds can become cheese; if kept moist and fresh, they form products such as cottage cheese.

Common curd-based products include cottage cheese, which is made from large, moist curds; paneer and queso fresco, which are pressed blocks; and queso blanco, which is similar. Ricotta is a separate product made from whey proteins heated and strained, not from curds.

Nutrition and storage: Curds are a good source of protein and calcium, with fat content determined by the milk used. Fresh curds should be refrigerated and consumed within a few days; signs of spoilage include sour odor, sliminess, or mold.