The Noble Art of Fermenting (1)


This Tech Talk is about fermenting. We may not be able to answer all your questions in one go, but I think this post will help you on your way. Provocative? Sure. Here we go: most distillers take a swing at fermentation from the wrong angle. Let’s amend that right away!

Wrong starting point

If we look at whiskey making, many believe that it’s made from a beer that isn’t hopped. The better the non-hopped beer is … the better the base for the whiskey is, right?

Wrong! A good drinkable beer is an end product. For the craft distiller, the distillers beer is a means to an end, not an end on itself. Great tasting distillers beer creates one dimensional whiskey. Not very interesting to drink, not very easy to sell.

Many other distillers I speak find fermenting a bore. Yeah, it takes a long time, that’s true. And distilling is much more fun. Heck, mashing is more fun than fermenting. But is that a reason to approach fermenting like many micro distillers do? By fermenting in an uncontrolled manner?

No, it isn’t. Fermenting isn’t boring, and it is actually the most important step in the spirits production process. Over 80% of taste is created during fermentation, that’s why.

Change your paradigm!

If you want your whiskey (let’s focus on whiskey in this iStill Blog post) to be tasty, to be remarkable, to be multi-dimensional in taste … you don’t want to make a perfectly drinkable distillers beer. And you don’t want to leave your fermentation unmanaged either.

For better tasting whiskey, you need as many different taste categories as you can get. Beer as an end product tries to get rid of off-tastes, whereas in distilling it’s the off-tastes (yes, associated with Heads and Tails), that create taste complexity.

Look at is as if you were a painter, trying to make your new whiskey as good as Rembrand’s famous painting “The Night Watch”. You, the craft distiller, have brushes, a rainbow of primary colors, and a pallet to mix yourself endless combinations.

A brewer paints with maybe black, white and some green, representing malt, water and hops. He doesn’t want off-tastes in his final product, so that’s the colors he works with and mixes. IPA? More green. Barley wine? More black …

If we follow the brewer, and make “perfectly drinkable” distillers beer, we have to skip the green. No hops, please. So, we are left with just black and white. Now that may become a rather one dimensional painting, right? The Night Watch in black and white … just imagine.

It may feel counter-intuitive at first, but making a good distillers beer (instead of a perfectly drinkable one) is on the one hand  related to letting go of the rules that control a brewer’s approach to fermentation, while on the other hand it’s about not letting off-tastes spin out of control. More colors, yes, to start with, to chose from, to separate while distilling. I mean: if there are more colors, there is more tastes to chose from while distilling.

How brewers ferment (and how you shouldn’t)

Brewers ferment with little yeast, at low temperatures, slow, and with relatively high pH. Oh, and they use malt, just malt. And sometimes a very little bit of other grains. And they ferment a clear beer. The grains themselves do not make it to the fermenter.

The less yeast a brewer uses, the less will end up in the beer. Yeasty beer is not so tasty. At least the yeast in it isn’t. And the low temperatures create very little chemical reactions and slow fermentation cycles. It’s like driving a car slowly. Yes, you won’t get any tickets nor injure yourself or others, but it isn’t as rewarding as driving fast, even though that may come at the “price” of higher risks and more wear on you and your car.

A relatively high pH, like pH 5.2 to pH 5.4 also creates a very neutral environment for the yeast, while malted grains are full of nutrients. To summarize, everything is done to make the beer taste like water, malt and (later) hops.

How you should ferment (and it will horrify the brewer)

Easy: with more yeast, different grains, at higher temperatures, and at lower pH. If you do so, you will create many more “colors” on your pallet.

A lower pH (like pH 4.0 to pH 4.8) has two benefits. First, taste formation while fermenting (esterification) is the result of a chemical reaction:

E = ((OxA)*pH)*T*S

Esterification is the formation of taste molecules. Taste molecules (esters) form where organics and alcohols meet in a wet, warm, and sour environment:

  • E = Esterification (taste formation);
  • O = Organics (grains);
  • A = Alcohols;
  • pH = Sourness (the less sweet, the lower the pH, the more Esterification)/
  • T = Temperature (higher temperatures create more Esterification);
  • S = Speed (longer interaction between A and O creates more taste).

So, yes we need low pH. For taste and (below pH 4.8) as a defense against bacterial infections, of which most can’t survive in below pH 4.8 environments. But, as you have guessed, there’s more!

If we want more tastes, more colors so to say, we need the grain present while fermenting.  We don’t need more alcohol. In the equation of “OxA”, it’s the organics (“O”) that are the bottle neck. For more of the chemical reactions to take place we also need higher temperatures and a longer fermentation time.

Examples of how to create more taste while fermenting

Say you are situated in the USA and make a Bourbon with the following grain bill: 80% corn, 10% wheat, 10% 8-row malted barley. You mash, you sparge, and you ferment the clear beer at 25 degrees C. This is what you could do to get more taste:

  1. Change the grain bill to a higher percentage of wheat (and/or rye, and or 2-row barley);
  2. Ferment with the grains present during fermentation;
  3. Ferment at 30 degrees C instead of 25.

Now what if you are a Scottish single malt distiller? You ferment for three days, like all the others, because after three days almost all the alcohol is converted and wash temperatures start to kill of the yeast (>35 degrees C). But you could also do this:

  1. Ferment for five days for more esterification;
  2. Ferment in a temperature controlled environment.

To be continued …

There is much, much more to fermenting. We’ll dive in deeper in another post!

Regards, Odin.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s