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The Proof is in the Pudding

English Christmas pudding was served flaming in Charles Dickens’ A Christmas Carol. Boz said “the pudding… blazing in half of half-a-quarter of ignited brandy”. What an image! Thank you, Mr. Dickens!

So, why do whiskey, brandy and other spirits burn? And, does it have anything to do with “proof”? What in the heck is the “proof” anyway? Why is there a proof number on the labels of bottled spirits? The answers require that we take a step back in time.

As early as the 1600s, the English based taxation of whiskey and other distilled spirts was based on the liquid’s proof. Spirits were originally tested with a basic “burn-or-no-burn” test, in which an alcohol-containing liquid that would ignite was said to be “above proof”, and one which would not burn was said to be “under proof”.

Another early method for determining proof involved applying rum to gunpowder to test its strength. When the rum-soaked gunpowder was loaded into the chamber of a rifle or pistol. If the weapon still fired, they had “proof” that the rum was strong enough.

Neither of these methods were easily reproducible due to variations in temperature, alcohol content, gunpowder granule size and a host of other factors that made it difficult to get consistent and verifiable results.

It was much later, at the end of the 17th century, England introduced tests based on specific gravity for defining proof. It wasn’t until 1816 that specific density became the legal standard. 100 proof was defined as a spirit with 12⁄13 the specific gravity of pure water at the same temperature.

The proof system in the United States established in 1848 was based on percent alcohol rather than specific gravity or specific density. Fifty percent alcohol by volume was defined as 100 proof.

Proof as a measure of alcohol content has become somewhat quaint, linguistic and historical. Today, we use the much simpler, percentage of alcohol by volume, or the ABV designation. However, distiller’s still state proof of their product because of its long use in the industry. The fact that proof is a larger number than percentage of alcohol, may be a factor spurred by ‘bigger is better’ thinking.

This raises another interesting issue. Here is a consumable that is flammable. Arguably, spirits are the only type of stuff that we humans ingest that should be kept away from open flames, unless of course, one is making Bananas Foster, Baked Alaska or even a savory dish such as Steak Diane that is finished a la flambé. Flambé, of course, is the cooking procedure in which alcohol is added to a hot pan to create a burst of flames. The word means “flamed” in French.

Why in the world do we humans like the stuff? Well, it does in fact taste good. There’s the consciousness altering effect and coming full circle, we have alcohol proof to thank for our vision of that lovely English, Christmas pudding.

Bon Appetit!