Coca-Cola contains a number of essential oils and it is the precise way that these are blended together that is responsible for the drink’s unique flavour.

This blend makes up the secret ingredient, known as Merchandise 7X, which comprises less than one per cent of the formula.

In 1993, author Mark Pendergrast published an exposé of the cola industry, For God, Country & Coca-Cola, and included what he said was the original formula.