You might be a whiskey snob, or a whiskey lover, but are you a whiskey nerd?
Well sit back and watch because we’ve got some whiskey science for you!
All booze making starts the same way--by mixing micro-organisms (usually yeast) and sugar.
The microbes eat the sugar and makes alcohol as a byproduct of their digestion process,
which we call fermentation.
And actually, that should be alcohols.
The important one--the one that humans like so much--is ethanol.
Anyway, whiskey’s yeasts get the sugar for fermentation from grains, however, which grain
depends on what you’re drinking.
Scotch whisky mainly uses malted barley.
The malting process halts the grains’ growth so it’s only partly sprouted.
If it’s a single malt whiskey, that means it came from a single distillery with only
malted barley.
Scotch grain whiskies and American whiskeys use cereal grains like corn and wheat.
Bourbon whiskey has to be made from at least 51% corn, while rye whiskey has to be at least
51% rye.
There is all kinds of other whiskeys -- we’re looking at you Irish whiskey -- but we don’t
have enough time to cover everything.
You’ll have to ask your bartender.
What separates beer and wine from whiskey is what happens after fermentation.
At that point, they’re all about 5 to 10 percent ethanol.
But liquors routinely get up to 40 or 50 percent and even higher.
How?
Distillation.
Distillation is a way to separate different chemicals according to their boiling points.
Ethanol boils at 173.1 degrees fahrenheit.
Methanol--which is poisonous--boils at 148.5 degrees fahrenheit.
So if you pour your mash -- the fermented water-grain mixture -- into a pot and start
heating it, the methanol will boil off first, followed by ethanol.
After that, you’ll be left with mostly water.
Now onto the good stuff.
Whiskey needs to retain the flavors from the fermentation … otherwise all liquor would
taste like vodka or worse, Everclear.
Whiskey makers have ways to raise the ethanol percentage while retaining all the yummy flavors.
The mash is poured into a still and steam is pumped in at the bottom.
We should note the structure of the still depends on the spirit - scotch is made in
pots, but bourbon is made using columns which separate out even more flavors.
Inside these columns is a stack of chambers separated by perforated plates.
Ethanol-rich vapor rises from the pot.
At the highest, coldest, points of the column, the vapor condenses out and and drips back
down into the hotter zones where the flavor molecules easily dissolve in the ethanol-rich
liquid.
Flavor molecules like ethyl hexanoate, which has an apple-like aroma, or diacetyl, which
makes for a buttery taste.
Over time that concentrates the flavor and the alcohol.
Thanks column still!
But not all flavors are good flavors.
So distillers usually make their column stills from copper or give them copper linings.
The copper reacts with sulfur-containing compounds, which often have bad flavors and smells.
Hydrogen sulfide is a common one.
No one wants the smell of rotten eggs in their glass.
So distillation sends all those flavors and ethanol up the column.
Near the top, that alcoholic mixture drips out this arm.
Since most mashes start out the same, it’s the distillery’s own unique distilling process
that really makes their product stand out.
Still designs and processing methods used are carefully protected knowledge, putting
each distillery’s special note on a mash that starts pretty much the same for everyone.
The key to whiskey’s flavor is the aging process, not fermentation.
Once we put whiskey in those barrels, it does what it does best, thanks to ethanol.
Ethanol is really good about dissolving flavor molecules so once we’ve got whiskey in those
barrels it starts leeching all those delicious flavor chemicals out of the wood of the barrels.
To get even more flavor into the whiskey, the insides of the barrel are charred with
flame.
That causes chemical reactions in the wood that produce a whole range of additional flavors.
Charring is good for making more phenolic compounds, exemplified by this structure.
One of them, guaiacol, has a smokey flavor.
Meta-cresol smells a bit like bandaids and shows up in scotch, mostly thanks to the peaty
smoke that’s used in scotch distilling.
No, I don’t understand scotch drinkers either.
Changes in atmospheric pressure and temperature throughout the year force whiskey in and out
of the wood as it ages, helping it pick up more of those flavor molecules.
That’s one reason connoisseurs insist aging increases the depth of a whiskey’s taste.
Actually, some whiskey makers are trying to see if there’s a shortcut for that.
Some high-tech distillers are experimenting with using sound waves or varying pressure
to artificially speed up whiskey aging, which some traditionalists aren’t very into.
But these newcomers think they can reduce the aging process from years to mere hours.
Who’s ready for a drink?
The next time you’re enjoying whiskey with your friends, you can regale them with all
the whiskey chemistry you learned from today’s video.
A special thanks to District Distilling Company for letting us film today and thank you for
watching!