In my quest to discover which things are and are not gluten free, caramel coloring often comes up in conversation. Is there gluten in caramel coloring? Well, it depends. The short answer is, if you are an American, caramel coloring is almost certainly gluten free. But unless the label specifically says "gluten free," then you cannot really be 100 percent sure.
Short answer: Probably (in America); probably not (elsewhere).
Caramel coloring is in almost every food which is tan colored or darker. It can be found in products as diverse as ham, soda (75 percent of the caramel coloring on the market is found in soda), artificial vanilla extract, and brown sugar. Caramel color looks delicious, basically, so manufacturers use it a LOT.
There are a lot of potential sources for caramel coloring, including wheat and barley. Any kind of carbohydrate can be used to create caramel coloring, although some (like corn) work better than others (like potatoes). To make caramel coloring, the manufacturers simply heat the carbs until they scorch. It's the same way - and the same chemical reaction - that happens when you brown potatoes or toast bread at home.
Thus, the ingredients in caramel coloring come down to a matter of local economics. In America, corn is the clear choice. Between government subsidies and the sheer volume of corn which is grown here, combined with corn's natural suitability for being cooked into caramel color, there is no need to look farther than corn.
However, there is no labeling requirement for caramel color. Thus, it really could be made of anything. This is apparently more common in smaller, oddball brands. Most of your major manufacturers will be using the standard stuff made of corn, so there is no need to worry about caramel coloring: in America, it is pretty much guaranteed to be gluten free.
In the rest of the world, the situation is different. In Europe in particular, most caramel color is made from wheat. Although the manufacturers say that the caramel color has been so highly processed that no gluten remains. Many gluten free people in Europe still make a habit of avoiding foods with caramel color, just to be on the safe side.
Then again, if you are going gluten free for nutritional reasons, you may want to avoid the caramel coloring regardless! Much like high fructose corn syrup, caramel color is one of those indicators that the food you're looking at is highly processed - and probably not very healthy for you in general, even if it IS gluten free.