In the 1930s, Coca-Cola began producing their signature soft drink with a different sugar substitute, sucrose, that made it kosher for Passover. Jews observing Passover cut out chametz, or any grain-based products that are capable of leavening. Some Jews also cut out kitniyot, which includes foods like rice, beans, peanuts, and corn. Regular bottles of Coke contain high-fructose corn syrup which is not kosher for Passover. Today, bottles of Coca-Cola that are kosher for Passover have yellow caps instead of the traditional red ones. In addition to the yellow cap, the bottle has a Passover certification symbol.
The Hechsher, or the Ⓤ marking on many common food items, is a signifier that the food is certified kosher. Kosher for Passover items require an additional Passover hechsher. There are various symbols that appear on food packaging. The symbols differ depending on which kosher organization has certified the food and the contents of the food. The small letters next to kosher symbols signify if the food is dairy, meat, pareve (neither dairy nor meat), or kosher for Passover. You can find the Ⓤ on Oreos, Coca-Cola, and many other items people purchase regularly.