If the caramel is present at an insignificant level and does not have any technical or functional effect in the food, it is considered an incidental additive and would not have to be declared on the label. (Of course, the label would have to note the addition of natural or artificial flavors, whichever the case may be.) The regulation on this exemption can be found in Title 21 of the Code of Federal Regulations (C.F.R.) part 101.100(a)(3). The regulation provides specific examples of incidental additives, including "substances that have no technical or functional effect but are present in a food by reason of having been incorporated into the food as an ingredient of another food, in which the substance did have a functional or technical effect" (21 C.F.R. 101.100(a)(3)(i)). However, sulfites are only considered to be incidental if they are present at less than 10 parts per million (ppm). For more information, see the Ingredients Lists section of the U.S. Food and Drug Administration's guidance on food labeling.