Lycopene, a kind of carotenoid found in plant foods, is also a red pigment. It is dark red needle like crystals, soluble in chloroform, benzene and oil but not in water. It is unstable to light and oxygen, and turns brown in the presence of iron. There is no physiological activity of vitamin A, but it has a strong antioxidant function. The content of mature red plant fruits is higher, especially in tomato, carrot, watermelon, papaya and guava. It can be used as a pigment in food processing, and is also commonly used as a raw material for antioxidant health food.