Here’s my take on taste. And on how to distill in such a way that you get over taste. Better yet: that you get over the taste profile you are after.
Just some starting points:
1. Taste is mostly created during the fermentation process (and only partially during mashing and even less during distillation);
2. Distillation is all about harvesting the right taste molecules for your drink (and desired taste profile).
Taste formation is the creation of taste molecules. Taste molecules are called “esters”. The process of taste formation is called “esterification”. Esterification takes place where alcohol molecules meet organic compounds in a wet environment. Esterification is accelerated by two additional conditions:
More esterification takes place in a sour environment. Esterification takes place at a faster pace at higher temperatures.
But there are more variables to play with. Time is one. If you ferment for a longer time, you allow for more esterification. And in the equasion “esterification takes place where alcohol and organic compounds meet in a wet environment”, it is the organic compounds that are the bottle-neck. Stronger ABV ferments won’t do it (in fact: are counter productive), while more organics (on the grain for instance) present during fermentation does enhance esterification.
There are also limits. Dropping pH is good, but dropping it too much will cause stress to the yeast (below pH 4.0). My tests indicate to me that a pH lower than pH 4.0 seems to increase the number of Tailsy molecules. On the other hand, if you ferment very hot, this also creates yeast stress, mostly resullting in excessive Heads formation. So if you want more esterification and if you want to play with higher temperatures while fermenting, make sure you have a yeast that’s temperature resistant.
Summary: if you want more taste, ferment hotter, at lower pH, and with lots of organics present.
Distilling is about harvesting the right esters. Here’s a starting point:
1. Heads are fruity;
2. Hearts comprise the body of the product you are making (grain taste for whiskey, molasses taste for rum);
3. Tails are rooty, nutty.
And the funny thing is that the same order appears when you taste your product:
1. Heads (and fruity notes) are recognized at the front of your mouth;
2. Hearts are tasted in the middle of your mouth;
3. Tails (and rooty tastes) are tasted in the back of your mouth and throat.
Just to clarify: Heads and Tails are not a bad thing for a taste rich product. Smearing late Heads and early Tails into Hearts are essential to making a complex, taste rich product.
It becomes almost funny, but even timewise the order of Heads, Hearts, Tails is there:
1. It’s the fruitiness one tastes first;
2. The body comes right after that;
3. The rooty tastes come last.
Both locationally and time-related, the sensations of tasting a drink follow the natural order in which a distillation run goes: from Heads to Hearts to Tails.
Okay. What drinks are favoured by what esters? Not so difficult. Fruit brandy needs to be identifiable as FRUIT brandy. This explains why fruit brandy benefits from more late Heads smearing into Hearts. Rum and especially whiskey benefit from a long lasting, rooty taste. It therefore benefits from smearing some more early Tails into Hearts. Okay, it may take more aging, but it will result in a better product.
The art of distilling taste rich product is about fermenting all possible tastes to start with. And then … to be able to harvest those factions (and their associated esters) that compliment the drink you are trying to make.
Allow for a bit more Heads in your fruit brandy, but cut early, because there is nothing fruit brandy-like in Tails. Allow for a bit more Tails in your rum or whiskey.
Also see the bellow picture that depicts my Tree Metaphore on Taste and Cuts (thanks for the drawing, Nick, so much better and for sure more colorful than I do it!)