Why add Vodka to Stock?

Question

The recipe for brown veal stock in Modernist Cuisine (Volume 2, page 300) lists Vodka as an ingredient. Why?

I have never seen Vodka as an ingredient before for stock, in no professional cooking literature. No alcohol other than wine. Do you think it makes a positive difference, taste-wise?

Would an author of a cookbook add ingredients to a recipe not for taste but to appear clever? (I could imagine it with this book)

Addition 1: Very good answers so far, thank you! So far I learned that theoretically it could make a difference. But in practice? Can anyone testify to having personally, clearly tasted a positive difference in taste due to the addition of Vodka?

Answer 1

Pure alcohol is a solvent: that is: it will dissolve other chemicals more easily than water. If you put vodka in oak barrels for long enough, it'll turn into bourbon as it will dissolve and concentrate the taste of the oak.

The same thing is happening while you're making stock:

• The oils in whatever the recipe of your stock calls for will dissolve more easily in alcohol than water.
• It speeds up the creation of the stock
• You could use any alcohol, but if you would use Bourbon the stock would get a smoky oak taste, so by using vodka (which is 40 Vol% of alcohol in water) no extra taste gets added except what's in your stock recipe.
• As alcohol has a much lower boiling point than water, the vodka will extract the oils and mostly evaporate so depending on the amount used it might be safe for children too if you follow the Halal rules but you should know a water-ethanol mixture forms an azeotrope.

Answer 2

Would a cookbook or recipe author add ingredients to a recipe to be clever rather than taste? Absolutely some would. Also, they might to make the recipe different and unique, claim it as their own rather than a copied, traditional recipe.

That said, I would doubt that is the case in your stock recommendation, rather it is more in line with @Fabby's suggestion looking for specific reactions from the alcohol. In the case of wine or stronger flavored spirits are called for, the intent usually is to retain those flavors, and potentially also have the chemical reactions which might bring out other flavors. With Vodka, it is a relatively neutral base flavor other than alcohol, so to goal would normally be just the reaction flavors, not to get the flavor of the spirits coming through. Most vodka sauce recipes I have used call for cooking long enough, and diluting enough that the alcohol in the final product would be very low by serving.

For many, any intentional use of alcohol is not acceptable, and for those, flavored spirits have a number of known substitutes such as apple juice for apple cider, almond extract for amaretto, etc. As Vodka itself is usually not intended to be tasted, I do not know of a substitute for it. So, if a person wants to exclude added alcohol in their cooking, vodka sauces and stocks are likely off the table, You certainly can make fine sauces and stocks without them, they simply will not duplicate that given dish.

If interested, USDA chart is a USDA, State of NY chart of tested alcohol cook off rates so you could estimate how much alcohol would remain depending on how much you initially added and how long you continued to cook it. Also included is a chart of non-alcoholic substitutes for many common spirits. Again, given its more neutral flavor, vodka is omitted in that table.