During the 1980s, in order to compete with Pepsi as well as cut production costs, the then president of Coke, replaced cane sugar with HFCS, as corn received a bunch of subsidies by the US government, which made HFCS a super cheap alternative.
Those subsidies aren’t available in Mexico, and despite corn being abundant in MX, it’s still cheap to use sugar in Mexico, so that’s why Coke’s HQ in Mexico still uses cane sugar.
As well as why people in the US will state that Mexican Coke tastes better because it’s mostly the original recipe.
Latest Answers