Every year, without much publicity, certain bottles of Coca-Cola quietly appear on grocery store shelves with bright yellow caps instead of the familiar red ones. Most shoppers barely notice the change, assuming it’s a seasonal promotion or a simple packaging variation. But for those who recognize the yellow cap, it represents something much more meaningful. Hidden beneath that small piece of plastic is a special version of Coca-Cola made specifically to meet the dietary requirements of Passover, one of Judaism’s most important religious holidays.

To accommodate observant Jewish families, Coca-Cola temporarily changes one of its key ingredients before Passover begins. Instead of using the high-fructose corn syrup found in its standard U.S. formula, selected bottling plants produce a version sweetened with cane sugar. The bottles undergo special kosher-for-Passover certification before reaching stores, but over time, people from far beyond the Jewish community began searching for them for an entirely different reason…