Tag: oak aging

Tannins – Off Flavors in Homebrew

Astringent flavors

Off flavors in your booze no matter what that may be , wine, beer or whiskey all come from basically the same things. These off flavors usually result for the normal processes of making the alcohol and flavoring it.

I am going to focus on astringent flavors in this article. Astringency is the tart , tangy flavor that tends to make you pucker up like eating walnuts or pecans and getting a piece of shell in your mouth.

This flavor can come from several things including :



1. The grains during the mashing operation
2. The temperature of the fermentation
3. The trub in bottom of fermentation bucket
4. The wood used to age the alcohol

We will discuss all of these things and how to stop it from happening. It is mostly just a matter of keeping the operations within the norm of brewing specs. Sometimes these specs are difficult to adhere to especially temperature when homebrewing as you just do not have that high tech setup of a big brewery or distillery.
How ever there are ways around this and it is just a matter of working with what you have . It is not all that hard to get tasty drink with even the most primitive setups.

 “ A poor man has poor man ways

Astringency comes from tannins.  They will leave off flavors in your homebrew. These tannins are just a normal part of plant material and is bad and good in your booze. A little in the right booze is good. A little in the wrong booze is bad. It can bring on several different flavors like vanilla or clove and even that medicinal metallic flavor.


What is a Tannin

A tannin is an astringent, polyphenolic biomolecule that resides in plant tissue like galls and bark. It contains derivatives of gallic acid. It binds to and precipitates proteins, alkaloids and amino acids. Hence why they come out during your processes.

These tannins are quite useful and needed for wines but not so much for beer or whiskey. This is what causes the dry mouth effect when you drink wine. Why this is desirable I do not know as I am not a wine drinker. The tannins are released from grapes as they are smashed up. Grapes have a lot of tannins in them from seeds, skins and stems.
You will get this dry mouth from some liquors like whiskey and brandy. Anytime you have that dry mouth and slight bitter after taste it is tannins ( polyphenols). These flavors may come from the barrel it is aged in or from the grains and other plants it is made from.

Not only do tannins give you that bitter taste and dry mouth but also might give you a headache. Some people are sensitive to tannins. This mixed with other fusel alcohols present in booze can also leave you with a hangover.

A more scientific and complete description of a tannin from Horvath (1981) :

Any phenolic compound of sufficiently high molecular weight containing sufficient hydroxyls and other suitable groups (i.e. carboxyls) to form effectively strong complexes with protein and other macromolecules under the particular environmental conditions being studied


How is a tannin formed

I am glad you asked .

Here is how several types of tannins are formed:

  • Gallic acid is derived from quinic acid.
  • Ellagotannins are formed from hexahydroxydiphenic acid esters by the oxidative coupling of neighboring gallic acid units attached to a D-glucose core and then the real fun begins
  • Further oxidative coupling forms the hydrolyzable tannin (HT) polymers and stuff starts doing other things
  • Proanthocyanidin (PA) biosynthetic precursors are the leucocyanidins (flavan-3,4-diol and flavan-4-ol) yea , right
  • Upon autoxidation, in the absence of heat, they form anthocyanidin and 3-deoxyanthocianidin, which, in turn, polymerize to form PAs. Of course but then we all knew that alrady.

Now aren’t you feeling well informed and smart ?  I bet you don’t ask that question again.


Tannins in Beer

When dealing with beer the tannins are far less desirable than with other drinks. Some beers like brandy wines use a little tannins in them along with other fusels to lend the proper flavor. How ever in lighter beers any fusels or tannins is just going to make for a bad flavor.

When brewing beer you wan to keep tannins and other off flavors form forming. To do this you need to pay close attention to the temperature at which you mash and ferment along with the grind of your grain and how long it is mashed. the sparging operation also falls under these guides.


Your Grind

When grinding your grain bill up you need to only crack it’s hull for the operation to succeed. How ever a finer grind will allow for more flavor to come out in the mash.
The finer you grind the more tannins will be able to soak out of the hulls. This can be minimized by controlling your heat.


Mash Temp

I am not going to go all into mash temp at this time but simply put you need to mash at a temp that does not exceed 170 degrees. Not that your mash should be at or near that temp but that the water you start with should be no more than that. It is better to start with warm grain and less water temp. ( I keep my grain in freezer. This means it has to be warmed up first).
Pouring near boiling water over cold grain to make up the mash temp is a bad idea. the hot water will pull tannins from the grain before the temp goes down to mash level.

The longer your mash sets the more tannins can be extracted from the grain. Only mash as long as needed to complete they style of beer you are making.

Boiling the Wort

The boiling operation is not a big culprit of tannins but you need to make sure you do not get any grain in the boil pot. The other thing that may come into play during the boil is hops. They do contain a bit of tannins albeit not much.
Hops and tannins both bring on bitterness. The main difference is that the tannins in hops do not really come out in the beer unless you use a lot of hops or leave them in the fermenter for long periods of time. They also have a different type of bitterness and flavor. Hops get their bitterness mainly from oils and resins.


Fermenting and Tannins

When fermenting your wort or wash you must be careful that the temp does not exceed 80 degrees. This is the point at which tannins and fusels will be readily produced from the process of yeast eating sugars. Room temp and fermentation temp are different and confused by many people. The temp of your fermentation given in a recipe is the room temp not the beer temp. It is much hotter in that bucket than in the room. The yeast produce quite a few nasty things during their process and most are not good. You need to limit the bad stuff as much as possible by controlling the temp. Different yeast make different flavors in your beer. The nasty flavors and the tannins can not be stopped but can be greatly reduced.

Rack your beer as soon as possible so it is not sitting ton the trub too long. The trub is composed of all sorts of stuff that contain tannins and other flavors. If your beer sits on it too long it will start absorbing the off flavors from the trub. Using fining agents or putting in the cold for a while can drop out a lot of these flavors along with the yeast.
In whiskey fermentations the off flavors will be further processed during the distillation. The off flavors can be removed or limited either by the distillation or the cuts. Then after distillation is complete and the cuts have been made the whiskey can further be improved with the aging and/or filtering processes.
The preferred method of filtering or aging first may just depend on who is doing it. How ever the usual process would be to filter the whiskey through charcoal and then age in an oak barrel. This will remove off flavors. How ever the barrel could add some back in.


Aging in Oak

There are many flavors that can be achieved from aging in wood. Oak barrels or chips if you are a poor boy, is how whiskey gets it’s good flavor and mellows out. The way the wood is prepared, the strength of the liquor, the temp and humidity is what is going to make the flavors. Tannins are extracted during the aging process. The longer the whiskey is aged the more tannins and less other flavors it will have.
Another thing that I think may play here is the amount of time and use the wood has had. Home distillers often use oak chips that they either toast ( for things like Scotch ) or char ( for American whiskey). At least that is how it should be used. Some people like to use the Jack Daniels wood chips made from old barrels. They work well but do not last long. The barrels have already been used up for whiskey and are normally sold for use with scotch. These chips may lend more tannins into the hooch during aging since they have already been leeched of the other flavors. In the Hooch Bird’s opinion a good char will result in less tannins and a smoother drink. He also said that chips that have not been charred or toasted enough may cause more tannins and a hickory like flavor to be imparted into your sweet hooch.

To sum it up:
Tannins are astringent, nasty tasting, bitter, metallic crap from plants.
Wine drinkers have no taste buds obviously. They also most likely snack on walnut shells stored in tin cans of rubbing alcohol.

This leads to my next article : Wine – Really just made from soaking walnut shells in grape juice.