Wednesday, March 16, 2011

Kentucky's Bourbon Trail - Part One

Oh, whiskey you're the devil...
You're leading me astray...
Over hills and mountains...
Until I'm merry gay...

Ironically, this Clancy Brothers' song played on our car stereo as my husband navigated our little Honda through a snow storm in the West Virginia mountains.  We were on our way to Kentucky and its infamous Bourbon Trail.  Our obsession with whiskey was indeed leading us astray...and over hills and mountains...and, yeah, we were pretty merry.

Now, I promise to share the details of our trip in upcoming posts, but first I want to give you a little primer on bourbon.

What is bourbon exactly besides delicious?

All bourbon is whiskey, but not all whiskeys are bourbon.  As defined by a 1964 Congressional Resolution, bourbon is an indigenous product of the United States and it must meet certain requirements.

First, bourbon can only be made in the United States.  It does not have to be made in Kentucky, but they do make over 90% of it.

Second, bourbon's grain composition, also known as the mash bill, must contain at least 51% corn. Other grains can include malted barley, wheat, and rye.

Third, bourbon must be distilled to no more than 160 proof.

Fourth, bourbon must be aged for a minimum of two years in a never-used oak barrel that has been charred inside, and must enter the barrel for aging at no more than 125 proof.

Fifth, bourbon must have no added coloring, flavoring, or other spirits.

Finally, bourbon may not be bottled at less than 80 proof or 40% ABV.

What does all that mean and how is bourbon made?

Many of our favorite alcoholic spirits come from cooking grains.  For bourbon, the grain mixture or mash bill of at least 51% corn and possibly malted barley, wheat, and/or rye is ground to a flour-like consistency.  Mills vary between distilleries, but here is the grinder at Maker's Mark.

Some distillers will share the exact proportions of grain with visitors and others leave it a mystery.  This mash is cooked in hot water to release the natural sugars, and each grain must be introduced in a particular sequence and at a particular temperature since the grains cook differently.  This all takes place in a huge cooking vessel known as a mash tub or mash cooker.  After a couple of hours of cooking and cooling, the mash is sweet-smelling and the consistency of porridge, and is now often referred to as sweet mash.

Some distillers add backset or sour mash to this sweet mash mix.  Backset with some still active yeast is a portion of an earlier distillation that is returned to the product to add continuity of quality, think sourdough bread - you hold back some starter to create another batch.  Others wait to add sour mash to the fermenter tank which is the next step.

Yeast is then added to eat the sugars from the grain in the cooled mash.  This is called fermentation.  Each distiller uses a proprietary yeast strain and they are closed guarded secrets, and the yeast are sometimes even kept in secret locations and have been held by distilling families for generations.  Over a period of several days you can see the liquid mixture in the fermentation tub bubble and churn as the yeast does its work - releasing carbon dioxide gas and raising the alcohol content.

The length of time for fermentation can depend on the mash bill, the weather or temperature of the fermentation room, and the strain of yeast.  At the end of fermentation the mixture is referred to as disiller's beer which is about 12 to 16 proof.

The distiller's beer then gets pumped out of the fermentation tanks and heads to the stills.

Now it is ready to be distilled.  Simply, distilling is boiling the fermented distiller's beer to make alcohol vapor which is then condensed into liquid corn whiskey.

The beer is heated and enters a still.  If it is a columnar still like in the picture below, the beer enters near the top and runs down a series of perforated copper plates.  At the same time, steam is blasted up the still from the bottom, and as the steam meets the beer, the alcohol, which boils at a lower temperature, rises in vapor form to the top of the still.

If the distillery is using a pot still (as seen below) the mash is held in the wide bottom and is heated so that the alcohol vapor rises to the narrow top end where it is trapped.

Regardless of which still form is used, the alcohol vapors are re-condensed creating a spirit known as low wine.  It has not yet reached the desired alcohol level so it must be distilled again.

Spent mash or distillery slop (grain solids and water) accumulates at the bottom of a still as the alcohol vapor is removed.  Many distilleries give this to farmers as high-protein feed for cattle and/or hogs.

Nearly all bourbon is distilled at least twice, increasing the purity and potency of the spirit while removing rough or raw flavors.  This re-distillation takes place in a smaller version of the large columnar or pot still called doubler or thumper.  In this process, the spirit is again heated until it evaporates and then re-condenses, resulting in a higher proof product called high wine, white dog, or moonshine.

If you recall in order to be called bourbon, the high wine must come off the still at less than 160 proof.  This is determined by a measurement of proof known as gauging.  After coming off the thumper, the vapors are re-condensed and the white dog bubbles through a try box, an ornate copper and glass chamber where samples of new-make bourbon can be sampled and gauged for proof.

After distillation, whiskey is a clear spirit.  This spirit is poured into oak barrels that have been charred inside.  The level of char varies between distillers.  It is the char the gives bourbon its amber color.

This picture helps illustrate the difference between charred and uncharred barrels.

Another requirement for bourbon is that it must not enter the barrels at more than 125 proof.  Therefore, the spirit must be reduced using neutral de-ionized water in a reducing tank, where the new-make bourbon and pure water are combined before barreling.  In the course of the aging process, water molecules pass through the walls of the barrel, but the larger alcohol molecules do not, meaning the proof will generally rise as the bourbon ages.

The full barrels (weighing over 500 pounds) are stored in warehouses or rickhouses.  While in the rickhouses, temperature changes from hot Kentucky summers and cold winters cause the wood to expand and contract,  and the alcohol moves in and out of the charred lining of the barrels.  Soaking in the wood gives bourbon its distinctive flavor, aroma, and color.

This picture shows the soakage line - where the bourbon moved in and out of the wood.

Each distiller seems to have a different opinion about how to store its barrels.  A barrel warehouse is known as a rickhouse, and a rick is a layer of two to six barrels (depending on distiller).

Rickhouses are built of different materials (wood, metal, brick, or stone); some are painted dark colors while others are painted light colors; they are different heights with varying layers of barrels; some have windows and others do not; the barrels face different directions to or away from the sun; and some warehouses may have climate control systems and others only open doors and windows to regulate temperature.  

The philosophy is that each of these factors impact the temperature of the alcohol and therefore flow of whiskey in and out of the wooden barrels to influence the final bourbon product.

The bourbon is aged in barrels for at least two years, but some distillers have batches that are decades old.  Storage in wood is not perfect and most distillers lose about 4% of the whiskey each year to evaporation, leaks, and other problems.  This is referred to as the "angel's share."  Most distillers don't operate on a strict calendar for aging.  The bourbon is tasted at various points in the aging process to determine when it is ready to bottle.

The bottling process varies between distillers and labels, but at the minimum the bourbon is filtered to remove wood dust and other residue from the barrel.  Bourbon barrels cannot be reused for bourbon so many distilleries sell their used barrels to scotch producers and recent buyers include beer brewers who are creating bourbon barrel ales and stouts.

Why is it called bourbon?

Kentucky based farmers found that shipping corn was easier when it was distilled into alcohol.  And shipping was easiest in wooden barrels.  "Bourbon" was stenciled on the barrels as they were shipped from the Bourbon County region of eastern Kentucky to indicate port of origin.  Whiskey from this part of the country was different because it was corn-based and in time the term bourbon came to mean any corn-based whiskey.

Stay tuned for my reports from the Bourbon Trail...

No comments:

Post a Comment