Heat stability determines the selection of natural colours available for extruded pet food. To overcome grayness, food manufacturers may choose caramel colour for brown (beef) hues and turmeric for yellow hues. Turmeric helps to brighten the appearance of chicken or salmon flavored kibbles. Titanium dioxide is part of the colourings ‘kit’ that provides different hues to a kibble mix. It can highlight chicken, turkey or milk flavors. Beta-carotene and other carotenoids like lutein and lycopene are used as nutritional supplements that may impart colour.