The casein in fermented milk is coagulated (curdled) by lactic acid. Whey is the liquid remaining after milk has been curdled and strained. Among their delicacies was the curdled milk from the stomachs of suckling buffalo calves. Some fresh cheeses are curdled only by acidity, but most cheeses also use rennet. Laban rayeb is a type of curdled skim milk made in Lower Egypt. In Mexico, chongos zamoranos is a dessert prepared with milk curdled with sugar and cinnamon. Chongos zamoranos is a dessert of Mexican cuisine made of curdled milk. The milk will then be curdled, and may be eaten with a spoon. The skin that forms on curdled milk is another common example of denatured protein. The whey is further curdled at and separated. For these simplest cheeses, milk is curdled and drained, with little other processing. The Batussi people are livestock raisers who consume large amounts of curdled milk. For preservation purposes, cheese-making may have begun by the pressing and salting of curdled milk. El gives them curdled milk, apparently a mark of esteem. These areas of pseudomembrane are sometimes described as "curdled milk", or "cottage cheese".