vodka lab analysis results : I'm pissed

[wineo]

I dont know what you mean by neutralise?

[schnell]

don't neutralize anything that has not been distilled at least once. base treatment should be reserved for low wines, feints, etc.

the presence of yeast and other biological leftovers will give you ammonia when distilled in base. this will lead to a host of other troubles, such as blue distlllate from a copper still.

As far as I am aware, most esterification is enzyme-catalysed by the yeast.

read up on fisher esterification. acid catalysis occurs is the low pH wash. this causes fatty acids to esterify with an alcohol. the most abundant alcohol present (ie ethanol) dictates that these are mostly ethyl esters. the most common short chain fatty acid is acetic acid, produced through both metabolic means, as well as, air oxidation of ethanol. we see the resulting ester, ethyl acetate, as a major heads component. longer chain fatty acids that esterify can end up in the tails, if they come over at all. (volatility is related to chain length, branching, etc) unesterified fatty acids aren't very volatile and will not be a significant component of the vapor phase, meaning they don't distill over.

remember that esters almost always exist in equilibrium with their alcohol and carboxylic acid.
base hydrolysis of the ester, combined with pairing of the acid with sodium ion which salts it out, dramatically reduces the ester concentration and shifts the equilibrium by removing a reactant (the carboxylic fatty acid). this favors hydrolysis of the ester.

[Farley]

Strewth!
If I'd known it was that tricky
I wouldn't have been getting meself skulled on it for 20 years.

[manu de hanoi]

don't neutralize anything that has not been distilled at least once. base treatment should be reserved for low wines, feints, etc.

the presence of yeast and other biological leftovers will give you ammonia when distilled in base. this will lead to a host of other troubles, such as blue distlllate from a copper still.

I am now aerating a fish smellin distillate from the neutralised wash, anyone knows how to get rid of that smell (without redistilling) ? Because apart from that smell I believe that vodka is the smothest thing I've ever done.

I also believe that the hydrolysis occured because i poured the milk of lime too fast.

[manu de hanoi]

new results after double distill and pH tinkering:

acid (acid acetic equivalent ) :6 mg/L 0
Ester: 220 mg/L 14,5 (Max limit allowed : 200)
Ethanol: 38,2 %ABV 39
Aldehydes: 188 mg/L 9,7 (Max allowed : 50)
Methanol :0,03 mg/L 0,03 (Max allowed : 0,1)
Propanol:204 mg/L 183
isobutanol: 481 mg/L 640
isoamylic: 1154 mg/L 797
furfurol: 5 mg/L traces (Max allowed: "traces" )

Conclusion : Does pass

The taste is a bit more neutral

[Dnderhead]

so the conclusion is? keep everything as PH neutral as possible (from wash to still) and run twice threw reflex?

[manu de hanoi]

so the conclusion is? keep everything as PH neutral as possible (from wash to still) and run twice threw reflex?

-Breaking what I think was esters with a basic pH is not instantaneous , something really happens if the low wines are left 1 to 3 days at pH 11 at 30C . So (for the wash I use) neutralisation for one hour is far from enough.
- yes distill twince at 95 abv but dilute in between in order to dilute the tails in water.
- it is possible to set a basic pH directly in the wash because the ammonia smell disappears during the 2nd run but it does corrode the copper condenser and I fear a basic ph in the wash for 3 days will help bacteria too much

anyone tried steam injection instead of direct heating who could comment on the flavor evolution ?

[muckanic]

Breaking what I think was esters with a basic pH is not instantaneous , something really happens if the low wines are left 1 to 3 days at pH 11 at 30C . So (for the wash I use) neutralisation for one hour is far from enough.

Just to check: did you reflux for at least 15 mins before collecting any product, with the wash saturated with alkali (allowing for the fact that solubility increases with temperature)? This is a process of hydrolysis, not neutralisation.

it is possible to set a basic pH directly in the wash because the ammonia smell disappears during the 2nd run but it does corrode the copper condenser and I fear a basic ph in the wash for 3 days will help bacteria too much

I wouldn't count on that smell going away by itself. Ammonia is fairly soluble in both water and booze. I guess you could try to cut it out like a type of head, but why make things hard for yourself ... Bacteria generally don't like pH extremes in either direction.

[manu de hanoi]

Just to check: did you reflux for at least 15 mins before collecting any product, with the wash saturated with alkali (allowing for the fact that solubility increases with temperature)? This is a process of hydrolysis, not neutralisation.

I didnt, I use a continuous still

[muckanic]

I didnt, I use a continuous still

I have just realised we went round in circles on this issue of what a continuous still actually means three months ago. Is there anything to stop you fitting a couple of valves - one to halt the inflow and one to halt the outflow? That would permit 100% reflux, although you are then effectively performing a series of batch distillations. Failing that, strip the wash, alkalise it, and cook it in a pot still with an inverted Liebig condenser (ie, with the outlet pointing upwards).

[Nykter]

Even a continuous still needs stabilisation, unless its a stripper. Its usually done by letting it run as usual, but discarding (pour back to the wash container) the output for half an hour or so.

[billy_bob_95]

If I was going to get a sample to send to a lab I would not put it in a plastic bottle. Where I work we make the plastic that those water bottles are made from. It is unreal what that plastic bottle is made from. I ask myself all the time is it really safe to even drink water from them. I would think that the alcohol would attack the plastic bottle. A lot of those chemicals you listed are used in the production of those very plastic bottles.

[manu de hanoi]

the winning samples were sent in glass bottle as recommended by the lab.
@muk: the valve thing would be very unconvenient. I could do a 100% reflux session @ ph7 with another still, no prob, but I think 3 days @ ph11 gave me the same result and is less trouble given my equipment now.

btw have you guys also noticed the awful flavor when the esters are hydrolised ?