The company protects the secrecy of its syrup recipe by shipping ingredients to its syrup factories in the form of anonymous “merchandises”, numbered 1 through 9.
Factory managers are told the relative proportions of each numbered merchandise, and the mixing procedure, but not the ingredients in the merchandises, some of which are themselves mixtures of more basic ingredients. Merchandise no. 1 is known to be sugar, in the form of high-fructose corn syrup or sucrose (see variations, below); caramel coloring is no. 2, caffeine is no. 3, and phosphoric acid is no. 4. The identities of merchandises 5 through 9 are a matter of debate – particularly “merchandise 7X” (the “X” has never been explained), which is thought to contain a mixture of essential oils such as orange, lime, and lemon. Another ingredient is thought to be lavender.
Despite the implications of its name, there is no evidence that the current version of Coca-Cola syrup contains kola nut extract, which was originally included for its caffeine content. The modern source of that additive is probably caffeine citrate, a byproduct of the decaffeination of coffee.
The primary taste of Coca-Cola is thought to come from vanilla and cinnamon, with trace amounts of essential oils, and spices such as nutmeg. A 2015 study identified and measured 58 aroma compounds in common colas, confirming significant amounts of compounds corresponding to cinnamon, vanilla, nutmeg, orange and lemon essential oils in Coca-Cola.