Ricotta is an Italian whey cheese made from sheep (or cow, goat, or Italian water buffalo) milk whey left over from the production of cheese. Like other whey cheeses, it is made by coagulating the keratin proteins that remain after the casein has been used to make cheese, notably albumin and globulin. Thus, ricotta can be eaten by persons with casein intolerance. Ricotta curds are creamy white in appearance, slightly sweet in taste, and contain around 13% fat. In this form, it is somewhat similar in texture to some cottage cheese variants, though considerably lighter. It is highly perishable. However, ricotta also comes in aged varieties which are preservable for much longer.