Each spring, shoppers across the United States begin noticing something unusual in the soda aisle. Among the familiar Coca-Cola bottles with classic red caps, a few bottles appear with bright yellow caps instead. For many people, the first reaction is confusion. Some wonder if Coca-Cola has released a limited-edition flavor. Others assume the company changed the packaging for marketing reasons. A few even worry that the recipe inside the bottle may be different.

The truth is far more interesting.

Those yellow caps are not random. They are connected to Passover, one of the most important holidays in the Jewish calendar. During this season, Coca-Cola produces a special version of its drink that is certified kosher for Passover. The yellow cap helps shoppers quickly identify which bottles meet those specific dietary requirements.

At first, it may seem surprising that a soda bottle cap could carry such meaning. But for many Jewish families, Passover comes with careful food traditions. During the holiday, many people avoid certain grains and ingredients known as kitniyot, depending on their community’s customs. In the United States, regular Coca-Cola is commonly made with high-fructose corn syrup, which is avoided by many during Passover. To make a version suitable for those customers, Coca-Cola produces certain bottles with cane sugar instead.

That small change matters.

The yellow cap is used as a clear visual signal. Instead of forcing shoppers to study every label closely, the bright cap makes the Passover-friendly version easier to spot. For families preparing for the holiday, this simple packaging detail can save time and confusion.

However, the yellow-cap Coca-Cola has become popular far beyond religious observance. Many people who do not celebrate Passover also look for these bottles because they prefer the taste. Since the seasonal version is made with cane sugar instead of high-fructose corn syrup, some fans describe it as smoother, cleaner, or closer to the classic Coca-Cola flavor they remember from years ago.

For these shoppers, yellow-cap Coca-Cola has become a yearly treasure hunt.