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Jun 08, 2022 View:

Head Cut Experiment - thoughts

As a new distiller (active brewer), I am trying to wrap my head around heads cuts for various spirits.  Perhaps someone with some technical knowledge or experience can help with something I find puzzling.

I lautered about 450 gallons of malted barley mash, and brought the wort to a quick boil, so as to eliminate any competitors - so essentially I have a pretty clean beer.  I pitched a clean culture of ale yeast.

I ran 3 stripping runs thru my 200 gallon still and then combined everything into one spirit run.  The still consists of an 8 inch column with 3 plates.  I refluxed for about 1/2 hr and then started taking heads.  I separated the first six 1/2 gallon containers of heads and measured the ABV and lyne arm temps with the goal of running them through a 20 plate small reflux still to see how much methanol I would pull off. 

the 1st two 1/2 gallon containers (collected off the 3 plate still at about 170 F and 87ABV)  were refluxed in the 20 plate still  for 30 mins and I then started very slowly taking off condensate at 190 proof.

My lyne arm immediately read 170F collecting the distillate at 190 proof - (no methanol)  The first 2 pints of liquid definitely have an acetone like aroma (assumed to be ethyl acetate),   After the first two pints the 190 proof distillate cleaned up of ethyl acetate, but the aromas/flavors changed throughout the gallon collected.

Assuming I'm only getting a couple pints of Ethyl acetate, what else is in the heads that is undesirable after the ethyl acetate that shouldn't be either recycled back into the next run or saved as new make to be barreled?

To rephrase this, as a general target,  how much should I be throwing out, and how much should I be recycling back into the next spirit run -assuming about 36 proof gallons or so of product from a batch?  If I wait until the distillate has a clean "malt whisky" taste aroma, am I eliminating anything that could contribute to the product?   I figure there will be differing opinions on the subject, considering that taste is very subjective.  I will be aging in 30 gallon barrels for 2 years.

My assumption is that anything with ethyl acetate should be tossed... but what after that...

Thx!

 


Reply:

Easy answer, but not the one you want, I think.

On the initial run - you sound like you are noticing the trend where the solventy/estery aromas begin to fade to neutral, then aroma goes completely neutral/clean, and then whiskey flavor (not aroma) begins to come in, followed by aroma a bit later (at least to my own sensory experience).  That's the ballpark neighborhood on the heats cut, at least in my book.  Dirty to the left, clean to the right.  Damn those late heads are so compelling though.

Back to the first question, it's highly unlikely that you would have any material amount of methanol on a malt wash.  It's going to be a relatively small amount, roughly in-line with Ethyl Acetate or acetaldehyde.  This is on a weight/volume basis, not organoleptically, as the esters will overpower.  

Ethyl Acetate and Acetaldehyde both distill mainly in the heads.  While acetone does as well, generally it's either not found, or found in very low quantities in comparison to Ethyl Acetate and Acetaldehyde.  Worth noting though, on the GC analyses I've seen, acetaldehyde tends to smear over a broader set of fractions than ethyl acetate.

So, you are taking your whiskey heads cut (or at least a fraction of) and then running through a 20 plate to further break it down.  Almost like you are doing a GC, but using your senses as the detector?  That's a cool experiment.  What you are probably noticing, I'd guess, is that the heads cut, even early heads, are vastly comprised of ethanol, likely greater than 80-90% of the volume.  Too bad though, because what you can get in terms of clean separation on the 20 plate, isn't possible with the 3 plate, so you'll smear those esters and aldehydes across a much larger volume of fractions, hence your larger heads cut.  You may not be leaving anything on the table.

Just from my own experimenting on a 4 plate, I don't feel you generally gain a tremendous amount of heads compression by refluxing for 30 minutes, the tray volumes are just so small in the grand scheme.  I feel I can get better heads compression running at high reflux, with lower power levels through the heads.  The other issue with refluxing is that you are likely going to increase your ester composition as a result (this is my theory), which may actually be counterproductive.


Reply:

I second the sentiment about heads compression with a long reflux. I find that the best way to get the cleanest heads cut is to engage all plates and run the still as low and slow as I can stand to sit there and watch it. By refluxing for long periods of time you're also allowing some of your heads compounds to drain down towards the pot (although not much) via the tray drain tubes, which is just remixing them into the pot, where they then have to fight their way through the trays again to finally get to the dephlegmator and on to the final condenser. By letting it go in essentially one pass, just very slowly, you'll achieve a better separation and less smearing.


Reply:

Head compression during equilibrium works great, but most stills are designed by people that do not understand the interplay between vapor-liquid surface area and overall velocity. If your column plates are big diameter and the volume between plates is big, then try refluxing hot and fast. If you are small and there are a lot of plates, sloooow down, and try diluting your charge a bit. 

If your plates drain directly to the pot or plate scupper instead of to the plate below, that's just stupid design. 

Hope that helps :-)

 

Dan