If you go to the TTB website (http://www.ttb.gov/spirits/bam/chapter4.pdf ) you will see a chart describing all the Spirit categories. At the top of this chart is the Class category for NGS (neutral grain spirit) and a definition:
Spirits distilled from any material at or above 95% alcohol by volume (190 proof), and if bottled, bottled at not less than 40% alcohol by volume (80 proof)
Next comes the Type of Spirit, Vodka, and a definition:
Neutral spirits distilled or treated after distillation with charcoal or other materials so as to be without distinctive character, aroma, taste or color
Although the definition states, “…without distinctive character, aroma, taste or color”, I believe that to be, mostly, an erroneous statement. I will grant you the no color. Vodka is a clear Spirit (although I did see a barrel aged Vodka the other day). As for taste, character and aroma; Vodkas have always had their specific tastes, characters and aromas. If you pay attention you can smell and taste the difference in Vodkas made from various ingredients (i.e.: Wheat, Rye, Corn, Grape, Potato, Rice or even plain sugar).
I, personally, classify being smooth as a character trait. If all the Vodkas in the world met the TTB’s criteria they would all taste and drink exactly the same. Yet they don’t.
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WHAT'S INSIDE: VODKA
Ethanol
Vodka, by definition, is ethanol cut with water to at least 80 proof (40 percent purity). Despite its common sobriquet of "potato juice," it's actually pretty hard to make it from spuds—the tuber tends to produce more methanol (poison) than grain feedstocks, requiring additional distillation. More often, commercial vodkas are fermented and distilled from wheat, rye, or corn.
Water
According to the US government, vodka is ethyl alcohol "without distinctive character, aroma, taste, or color," yet each brand insists it's unique. That may be: Water as a diluent leads to the formation of ethanol-water hydrates, in which an alcohol molecule is "trapped" in a cage of water molecules. Scientists speculate that these hydrates stimulate the palate differently than pure alcohol or pure water do. Different brands of vodka, using different sources of water, can vary in hydrate concentration, which may result in distinctive character.
Citric acid
Permissible in vodka at up to 1,000 parts per million (0.1 percent). Federal regulations call this "a smoothing agent to correct objectionable tastes" that may arise from using, say, mineral-heavy water. But some distillers (disdainfully) call it a tax dodge: Adding acidified ethanol lets producers avoid some federal excise taxes.
3-Hexanone
Do you drink to get numb? Was this inhalational anesthetic put in vodka to help you feel no pain? No such luck: The ketone is deployed as a flavorant in specialty vodkas, since its smell is described as grape- and wine-like while also earthy and ethereal.
Sugar
People on low-carb diets maintain that they can drink all the vodka they want because alcohol is not a carbohydrate. That's true: Vodka's maximum allowable 2,000 ppm of sugar may seem like a lot, but it's only 0.2 percent—a bottle of a fully sweetened vodka would provide only 5.5 calories from carbs. But a 750-ml bottle still provides you and your liver with more than 1,600 nonnutritive calories. Compared to that, sugar is a piker. (By the way, there's no gluten in here, despite what you may have read on the Internet, so celiac sufferers can drink with abandon.)
Methanol
Found only in the cheap, poisonous stuff, this short-chain alcohol is metabolized into a substance called formic acid, which does a real number on the eyes, blocking mitochondrial pathways in the optic nerve and retina. Incredibly lucky methanol guzzlers might start to get their vision back within a week; unlucky ones face optic atrophy and total, permanent blindness.
Propanol
A component of fusel oil, this alcohol lends some flavor to products like whiskey but can also be a sign of poorly distilled vodka. It's not very good for you: It seems to affect the central nervous system more strongly than ethanol, and one form of it can metabolize into liver-harming chemicals like acetone. You could try the James Bond method of detoxifying Iron Curtain vodka: In the book Moonraker, he claims that a few grains of black pepper will drag the nasty stuff to the bottom of the glass. Like the novel itself, this is fiction.
Learn more about Vodka
VODKA
C.F. Hayman, in Encyclopedia of Food Sciences and Nutrition (Second Edition), 2003
Characteristics of Production
Vodka is a fairly tasteless and neutral spirit product which is mainly derived from the fermentation and distillation of grain. However, some producers will use other raw materials such as potatoes, sugarbeet, grapes, or cassava instead of grain, depending on the local availability and cost. Once the grain or similar has been converted into neutral alcohol by fermentation and distillation, the vodka producer will start the process. Different producers have developed their own methods of production.
Some distillers will further distil or rectify the spirit, retaining only the middle part of the distillation for additional processing. The foreshot and feints are disregarded. The spirit will be passed through charcoal or carbon filters which remove the remaining flavors and odors to give vodka its clean and smooth character.
The various producers have developed their own, often secret, ways of filtering but are very concerned about the contact time of the spirit with the charcoal. Some distillers have a single filter (Figure 1) while others require the spirit to pass through a series of filters. The choice of charcoal varies as it affects the final product. One producer uses charcoal specially made from Sussex oak trees; another uses carbon derived from peat found in the Dutch polders. After filtration, some distilleries will regenerate the charcoal using steam whilst others discard the spent charcoal.
Figure 1. A typical vodka filter. Reproduced from Vodka, Encyclopaedia of Food Science, Food Technology and Nutrition, Macrae R, Robinson RK and Sadler MJ (eds), 1993, Academic Press.
The character of the water added to the finished vodka to reduce it to the required bottling strength is very important. The increased technology of water demineralization plants allows a greater consistency in quality than ever before. Water quality is of a vital significance in the final taste of the product.
In the European Community, the minimum level of alcohol acceptable for vodka is 37.5% (v/v), but often higher-strength vodkas are available, particularly coming from eastern Europe, e.g., 45–55%.
Many vodkas are flavored and this again originated from both Poland and Russia. One Polish vodka is flavoured by steeping buffalo grass (Hierochloe odorata) in the product to give it an additional aromatic flavor, and it also takes on some of the green color from the grass. An old Russian vodka is prepared with an infusion of leaves from apple and pear trees, to which is added brandy and port-type wine. This vodka is mellow in taste and pleasing to drink. Some high-strength vodkas are aged in wood, often giving them a brown color derived from the cask. In more recent times, Pepper vodka has been produced, the pepper enhancing its aroma and giving it a slight burning sensation on consumption. Other vodkas flavored with the addition of lemon, peach, and other fruit flavors are now appearing. (See BARRELS | Wines, Spirits, and other Beverages; FLAVOR (FLAVOUR) COMPOUNDS | Structures and Characteristics.)
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