<<Disclaimer: Verify this information before applying it to your situation.>>

I had a few questions about the source of the vanilla and coffee bean
extract in the Kahlua.  I wrote them (Allied Domecq) again and below is
there response.  If you have any more questions in regards to the
Kahlua, please visit their web-site below.  Hope this information
helps.  Sidona

"Dear Ms. Ryan:

You will be pleased to know we use only cane alcohol and vanilla
solution, which is prepared with cane alcohol as part of the Kahlua
process.  Even the caramel color is produced from cane sugar.

No grains are involved, therefore absolutely no possibility for gluten
residue in Kahlua.

Regard,
Dina Howe"

http://www.allieddomecqplc.com/flashed.htm