Custards are sweet, egg-thickened preparations cooked or baked from milk, eggs and sugar, with corn starch added for extra body and stability. The heated egg proteins set the mixture into a smooth, spoonable texture, with some versions baked in the oven and others stirred on the stovetop. Because they are protein-rich and high in moisture, custards are potentially hazardous foods: they must be cooked to safe temperatures, cooled rapidly and kept refrigerated to prevent Salmonella and Staphylococcus aureus growth. Clean equipment and pasteurized eggs or milk add further protection.