Thank you for your recent inquiry.
There may be some confusion in terminology based upon your inquiry. Actually, carmine is not "Dye #40".
There are two coloring agents for foods allowed by the FDA. These are called "certifiable color additives" which are synthetic products derived mostly from petroleum distillates. They are synthetic chemicals created in laboratories.
The other substances that are used to color foods are known as "exempt color additives." They are from plant, animal, or mineral sources.
Carmine is a "wine red" coloring agent that is extracted from an insect (cochineal). It is used on cake icings, hard candy, bakery products, yogurt, ice cream, gelatin desserts, fruit syrups, pet foods, jams, and preserves.
Red #40 is actually "orange-red" or "Allura red". This is a petroleum distillate and is also found in similar products including gelatins, puddings, dairy products, confections, beverages, and condiments.
If a true dye such as Red Dye #40 is used, the food must list it explicitly in the product ingredient list. It would therefore be listed such as "FD&C Red Dye #40" or "Red 40". If you are reading a product ingredient list and all you see is the nonspecific listing of "Artificial Color", then you can be certain that it is not a petrolatum chemical dye. It would be an organic substance such as, for example, beet juice. Carmine is actually an "Exempt Color" and can be listed simply as "Artificial Color", "Artificial Color Added", or "Color Added".
Since you specifically mentioned "Dye #40", I assumed that you are speaking of the petrolatum derived chemical and not carmine per se. However, since I am not sure if this assumption is correct, I will mention both in terms of possible tests for detection of specific IgE against such agents.
I am not aware of any test that would detect specific IgE to the Red Dye #40, but there is an in vitro test offered by IBT-Viracor Laboratories for carmine. It is: Carmine/Red Dye-Cochineal (Dactylopius coccus) IgE (Red #4)
I must mention parenthetically that I am not sure that the Red #4 labeling attached to this laboratory request site is correct. In fact, I think it is probably incorrect. On the FDA website listing approved agents (link noted below), carmine does not have a number by it. However, there is another FD&C synthetic dye which is separate from carmine, and called FD&C Red #4. Thus I believe the proper terminology is "Carmine only" without the number.
Regardless, you can, as mentioned above, order an in vitro specific IgE to carmine at IBT-Viracor. The Test Code is 184110E.
There is, to my knowledge, no such in vitro test for Red Dye #40, however.
Thank you again for your inquiry and we hope this response is helpful to you.
FDA website link:
http://www.fda.gov/forindustry/coloradditives/coloradditiveinventories/ucm115641.htm
Sincerely,
Phil Lieberman, M.D.