Jacqui M. writes in to ask:
I have recently developed a severe allergy to corn and yeast. Can you imagine how difficult it is to find something to drink for a cocktail? Help would be greatly appreciated. I love vodka. Can you recommend a brand that would be safe for me?
I'm not qualified to give medical advice and you'd be crazy to take it. But I can comment on the booze.
One thing I can say for certain is that all alcohol is made using yeast. It is the key ingredient in transforming sugar (glucose) into alcohol (ethanol). Once the process of fermentation and distillation is finished, however, I do not believe there is any yeast left in the final product. But whether or not it is safe for you to consume is a question for your doctor
Vodka is distilled from starch/sugar of one kind of another. It can be made from corn, other grains (like wheat or rye), potatoes, grapes, sugar beets and God knows what else. The same goes for gin (which is basically vodka that is infused with various botanicals like juniper).
In the United States, all vodka and gin must be labeled with the commodity from which it was produced. However, the statements don't have to be terribly specific. So if you have a vodka "distilled from grain," you wouldn't necessarily know if it was made from corn or wheat.
If you stick to potato vodka (e.g., Chopin or Luksusowa) or grape vodka (e.g., Cîroc), you can be sure it won't have any corn in it. Some other vodkas trumpet their source ingredient -- wheat with Grey Goose, rye with Belvedere -- so those would presumably be safe as well.
As for other spirits...
Bourbon and corn whiskey are, by law, made from corn. Rye whiskey often has corn in it, although there are some 95% rye whiskeys out there (the other 5% is malted barley) and even a few 100% ryes.
Single malt Scotch is made from malted barley. But other whiskeys -- blended Scotch, Irish or Canadian -- could potentially contain corn.
Brandy (and Cognac) is made from grapes.
Tequila is distilled from the agave plant. However, unless the label states "100% agave," it can include other substances and spirits, including vodka. (This is the case with the basic Jose Cuervo expression, for example.) So if you want tequila that you're sure isn't made from corn, look for the 100% agave label. (You should do this anyway, as mixto tequila is vile.)
Rum is distilled from sugar cane or sugar cane byproducts like molasses. So in generaly it doesn't contain any corn. You should be aware, though, that rum can legally have a small amount of additives in it. So I suppose they could slip some corn syrup in there, although it's unlikely.
Most liqueurs and cordials -- the fruity, spicy, nutty, sweet stuff that goes into cocktails -- are made from a vodka base, so they could contain corn.
I hope that helps!