Kraft introduced American cheese "Singles" in 1947. Their American cheese slices contain the following: Ingredients: Milk, Whey, Milkfat, Milk Protein Concentrate, Salt, Calcium Phosphate, Sodium Citrate, Whey Protein Concentrate, Sodium Phosphate, Sorbic Acid as a preservative, Apocarotenal (color), Annatto (color), Enzymes, Vitamin D3, Cheese Culture.