Methanol concentrate in the tails according an EC study

[Edwin Croissant]

As requested by Odin
I'm exploring the feasibility to design a low power (500W electrical powered and air cooled) continuous still and was looking for a way to remove the unwanted higher alcohols like methanol as you cannot make cuts with this type of distilling. During my research I stumbled upon a 1996 study called: A study on the possibilities to lower the content of methyl-alcohol in eaux-de-vie de fruits. This is a free publication of the European Commission and can be downloaded here.

I was expecting that due to its lower boiling point methanol concentrate in the heads. Surprisingly this study found the opposite: methanol concentrate in the tails due to molecular polarity (I'm not a chemical engineer, so don't ask me what this this means ). It seems that more factors then boiling point alone determine this separation process. Sometimes one picture can say more then a thousand words so I made a graph in Veusz based on the data of distillation number 5 of the above mentioned study:

I found a similar graph on the dutch forum which I presume is from a Bosnian or Serbian report about plum brandy as I traced it origins back to a Serbian forum about distilling. The black dots are alcohol strength in ABV the bars are the methanol concentration in mg per liter absolute alcohol,
destilacija means distillation and frakcije means fractions in Bosnian according to Google translate.

Another graph surfaced on that Serbian forum showing the relative volatility of congeners and ethanol from the chapter “Chemical Aspects of Distilling Wines into Brandy” in issue 137 of “Chemistry of Winemaking”. Below 40% ABV methanol is less volatile then ethanol!

A similar graph can be found in the chapter “From pot still to continuous stills: flavor modification by distillation” in “The Alcohol Textbook”, page 263 figure 8.

Based on the data in the study I think that an economical distiller reusing the tails from the previous run in the next run will end up with a leveled out 50% higher methanol concentration compared to the initial run after three or four runs. In that case 1 liter of pear brandy (40% ABV) would contain more then 6 ml of methanol. Ingestion of 10 ml of methanol can make you blind . I think that people making pear brandy, grappa etc. should think twice about reusing their tails. Saving these tails for a separate run is, I think, a really bad idea.

Methanol can be removed with a dedicated column (30 to 50 plates) fed with at least 70% ABV. The few hobby build continuous stills I found incorporate such dedicated column.

Please note that I am not (yet?) a distiller so everything I write in this context is from a theoretical point of view only.

Happy distilling

[Usge]

Ed,
It's is a complete fallacy that everything in your mash/wash boils at frational boiling points and you get "pure" methanol, or acetone, or whatever boils at that point. Ethanol has a low(er) boiling point...and yet..you still find it throughout the run (although in varying purity/volume).

For the sake of simplicity...the boiling point of a "mixture" of "2" things...is somewhere in between the boiling point of each. So, the case of water/ethanol....they have a fairly wide difference in boiling point (172.5 vs 212F (not corrected for sea level). The boiling point of that "mixture" would be somewhere in between those two, and what would come off would be relative to that. If it was more water than ethanol (the case with a wash/mash) ..then the starting boiling point would be higher and the resulting proof would be lower. And visa versa.

Compounded with that...no pun intended....are that chemical reactions...can bond or form compounds on a molecular level with ethanol, etc.

All of this is why your fermentation is very important. Because this is where the chemical make up of your wash/mash is actually produced/made. AFAIK, fruit mash also tends to have or produce more methanol than your typical grain mash does.

[midwest shinner]

Very interesting indeed, especially considering standard practices with recycling of feints or tails. Thanks for posting EC

[Jimbo]

Ed,
It's is a complete fallacy that everything in your mash/wash boils at frational boiling points and you get "pure" methanol, or acetone, or whatever boils at that point. Ethanol has a low(er) boiling point...and yet..you still find it throughout the run (although in varying purity/volume).

To help understand what Usge is saying think about your shower, or washing dishes with hot water running. The water is far below the boiling point of 212 yet there is still a vapor cloud of water molecules that come off and steam up the windows.

[Pesty]

I've never been one to collect much tails and I've only saved them so as to do a sac run on new stills in the works.

Ed,

All of this is why your fermentation is very important. Because this is where the chemical make up of your wash/mash is actually produced/made. AFAIK, fruit mash also tends to have or produce more methanol than your typical grain mash does.

this is what everyone is going to miss so quoting it out of the body.
The methanol is made by your yeast. So picking the right yeast for the job and letting it work in the right conditions i.e. temp and quantity is just as if not more important as making cuts.

[Odin]

Thanks for sharing, Edwin! I think the notion that methanol is concentrated in the tails rather than fores or heads will shift our paradigm in the right direction.

Odin.

[lampshade]

Thanks for sharing, Edwin! I think the notion that methanol is concentrated in the tails rather than fores or heads will shift our paradigm in the right direction.

Odin.

This leads me to wonder about the underlying mechanism of making "Pure Whiskey" with a reflux still and with the recycled heads and tails from the previous generation. The paper mentions that the heads and tails components are smeared into the hearts. And that recycling heads and tails cause greater smearing. Thus, this method yields similar results as does potstilling, which also causes greater smearing than reflux stilling.

I also wonder if it is necessary to discard the fores when recycling heads and tails, as the methanol is not in the fores.

[lampshade]

To help understand what Usge is saying think about your shower, or washing dishes with hot water running. The water is far below the boiling point of 212 yet there is still a vapor cloud of water molecules that come off and steam up the windows.

I think the analogy works this way. In the wash, the BP of methanol is elevated to the tails temperature. But before the wash reaches the tails temperature, some of the methanol gets into the fores, heads and hearts by virtue of "a vapor cloud of [methanol] molecules that come off and steam up the windows."

[lampshade]

One revelation to me is the extreme shift of the methanol BP that is caused by mixing with the wash components. Until now, I assumed that the BP shift was minor (but varies enough to defeat PID controllers). After all, the ethanol BP shift does appear to be minor. Apparently this is not so with some of the other wash alcohols.

[Buccaneer Bob]

Okay, I found this in "Artisan Distilling: A Guide for Small Distilleries".

According to this chart, methanol is spread through the entire run, with a bit more in the heads and a bit more in the tails. However, I think a lot of how the methanol is distributed through the run is based on the type of still and how it's run.

If you take a look at the tables in "Increasing Direct Marketing for Fruit Farmers by Connecting Producer to Producer through Research and Development of a Value-Added Product", they are getting almost all of their methanol in the heads and almost none in their tails. Of course, they're using a rather complex still, and maybe that's why their methanol is distributed like it is.

Methanol seems to be one squirrely beast, and that makes it very difficult to draw simple conclusions on how it distills. The only way to know for sure where it ends up in a run would be to send samples from a particular still and a particular wash and a particular distilling method off for analysis.

[lampshade]

Okay, I found this in "Artisan Distilling: A Guide for Small Distilleries".

Here is an interesting quote from the referenced paper (The text highlighting is mine):

The highest quality portion of the distillate is found in the heart cut. It possesses the most fruit character and the least amount of lower and higher alcohols that mask the fruit aromas of the fruit distilled.

[Jimbo]

... the heart cut. It possesses the most fruit character

nonsense

[lampshade]

That's what I thought... but maybe there is something else at work that might lead to a "paradigm shift". Just speculating.

[Odin]

In the pure whiskey approach, it isn't smearing heads and tails into hearts. It is about compressing exccessive amounts of heads and tails so much that typical heads and tails associated congeners bleed into hearts. The taste rich components bleed into hearts, not the headsy and tailsy alcohols themselves.

Paradigm in America (originally whiskey based):
- Fores, heads, hearts tails;
- Discard fores, collect collect hearts;
- collect tails seperately;
- Re-run heads and tails on a consecutive run;
- Allow for the tiniest bit of heads into the hearts faction, allow for some tails in the hearts faction.

Paradigm in continental Europe (Eau de Vie / Fruit Brandy based):
- Fores, hearts, tails (where fores are a bit bigger than fores American style, but nowhere nearly as big as the American heads cut);
- Discard fores, collect the rest as hearts, stop when tails arrive;
- Don't re-run tails;
- Allow for quite a bit of what Americans call heads into hearts.

In general the continental European paradigm does not see 4, but only three stages. Fores (3% of boiler content), hearts, tails. The heart cut is an earlier cut, comprizing most of what the Americans call heads and non of the tails.

Now, fruit washes have more methanol. And fruit washes are more dependent for their taste profile on the early parts of hearts (that Americans call heads).

With the new methanol information here, we can look at those two different approaches and see they both make sense. Fruit washes having more methanol, may explain why re-running tails is not a European distillation tradition. Methanol (and in fruits: lots of them) are concentrated in tails. And the European paradigm to incorporate most of the heads also makes sense. Contrairy to whiskey / grain based alchohol, fruity tastes come over in the early part of the run ...

Now this paradigm may make sense to a fruit brandy maker, but it is held throughout Europe. Vodka makers do the same. Actually, makers of Dutch whiskey also see only three stages and make earlier cuts then American distillers. Re-running feints and/or tails does happen, but only two or three times.

Regards, Odin.

[lampshade]

Thanks, Odin.

Your information clears up a lot of the confusion I had regarding what I read on the Internet about European distilling versus what people on HD were telling me.

And bleeding congeners into hearts.... well, that is a lovely way to get flavor without being subjected to the nasty headsy and tailsy alcohols.

LS

[Odin]

I am thinking LS, that maybe the info on European vs American distilling paradign should be posted here. Would you do that, if you agree?

On the pure approach ... bit off topic, but I am doing a run as we speak. And I am trying to tape it. Will try to turn it into a Youtube video. Unedited, etc., but I hope it gets the message over.

Regards, Odin.

[Edwin Croissant]

Thank you all for a vivid discussion it seems that there is a paradigm shift

I like to add some comments:

USGe and Jimbo, you are absolutely right that it is a misconception that everything in your mash/wash boils at fractional boiling points and you get "pure" methanol, or acetone, or whatever boils at that point and that was not the message. It is common believe that methanol concentrate in the heads and to the surprise of the researchers that common believe is wrong. And that is what science is about, you got an assumption: lower boiling points are first to leave, you test and measure and found your assumption does not match reality. So there is more involved then boiling point alone. Methanol seems to like water so much more than its cousin ethanol that it leaves the boiler rather late.

You are also absolutely right that fruit mash also tends to have or produce more methanol than your typical grain mash does. There are some recommendations in the report how to lower methanol production during fermentation and methanol seems to be a problem only for spirits made of fruits:

Buccaneer Bob
Thank you for the mentioning the book "Artisan Distilling: A Guide for Small Distilleries". It,s a great addition to my library. Your graph shows the methanol / distillate ratio, not the methanol/ pure alcohol ratio. As the ABV is not available in this graph I plotted the methanol / distillate ratio on the raw data of the EC report and the shape of the resulting curve is the similar as in your graph for the heads and hearts. The other report you mention give for the first entry in table 3 an ethanol percentage of 154. How a sample can contain more then 100 percent of a substance is beyond my comprehension.

Regards, Edwin

[Jimbo]

Yes very thought provoking thread. I was surprised to hear about methanol higher in tails than hearts, and did some more poking around after reading your post. Low and behold, there's reports and data out there supporting that. Crazy. Interesting!

Yeast create more methanol in fruits due to yeast acting on the pectin in the skins. Pectin is hydrolyzed and the methoxyl chains blend with water to create methanol. Im not a chemist but thats what Ive read here and there. More to the point, for us, I ve also read methanol production in the ferment is significantly reduced by NOT fermenting on the pulp, and by NOT using pectic enzymes.

I been making apple brandy for a long time. There have been occasion where I killed a fifth with a friend. No terrible hangover or illness. So methanol levels must be pretty low. I squash the apples and ferment the cider, no skins, and run a potstill taking larger fores cuts than usual (double) but keeping the heads as thats where most of the apple essence seems to be.

[sounder_4]

OK, so what are the implications for this on stripping runs when making grain whiskey? Does mean that the traditional method of stripping and keeping everything down to 20% or so ABV needs to be re-thought? If the methanol is concentrated in the tails, then should a stripping run be cut off at, say, 55% ABV? It would seem so.

[Jimbo]

Na, if you stopped a stripping run at 55% you'll lose more than half your hooch. I take some fores but strip everything else right into a 5 gallon carboy. The cuts I make for AG's are about 55% by volume of the spirit run, here's a picture from recent converstaion on another thread. You can see most of the heads and tails are lopped off. http://homedistiller.org/forum/viewtopi ... 2#p7093394

Note also methanol content in AG batches is very very low to begin with.

[lampshade]

Note also methanol content in AG batches is very very low to begin with.

Let me state the obvious, to help newbs like me. Tails can be blended or re-cycled for whiskey, since the methanol content is low for whiskey. This is not true of fruit distillates, which are high in methanol, especially in the tails, as documented in the referenced study.

Also: For fruit distillates, the fruit flavor is in the heads. For whiskey, the grain flavor is in the tails.

[Buccaneer Bob]

This thread is just turning into a clusterflip of confusion.

Edwin, I just don't even know where to begin. A continuous still? What's up with that? You might as well just buy the worst store-bought liquor you can get your hands on, because that's what you're going to get from continuous distillation.

And your first chart is skewed horribly and has no relevance in the real world. To look at it, one would think that methanol radically spikes at the end of the run, and it doesn't. Your chart divides grams of methanol per 100 ml of pure ethanol, and so methanol appears to spike only because the ethanol percentage is dropping as you go along. It doesn't actually spike, certainly not as dramatically as the chart makes it look, anyway.

Next, some of you guys are talking "paradigms". There are no paradigms. There are the commercial enterprises running continuous stills and churning out crap. Then there are the artisan commercial enterprises who are doing batch distillation. Those guys are employing a system of cuts, and they're making liquor several grades above what the continuous still enterprises are doing.

And then there's all of us amateurs, and we are all over the spectrum with regard to how we make our liquor because we are all over the spectrum about what tastes good to us.

Now if some of you guys like drinking heads, good for you, have at 'em. You are not going to convince me to drink them too, because I don't like heads.

Nobody's shifting my paradigm about what tastes good to me and what doesn't.

Methanol is an important topic for us amateurs, and it's certainly worthy of discussion. But if you have some other agenda here, I'm afraid I am not interested.

[YHB]

.

Here is a document from the UK Government indicating the amount of Methanol in Orange juice.

http://archive.food.gov.uk/maff/archive ... orange.htm" onclick="window.open(this.href);return false;" rel="nofollow

A glass of orange juice has anywhere up to 150mg of methanol.

A bottle of whiskey has, I believe, 15 to 25mg of methanol. Please correct me if I am wrong.

The UK Department Of Health recommends that the maximum intake of methanol for a 60kg adult is 600mg per day, which equates to 6 glasses of Orange Juice or 24 bottles of whisky.

I stopped worrying about methanol along time ago.

[heartcut]

The cutoff for most of the GC/LC (whiskey/ brandy/ vodka/ gin) spirit assays I've seen for methanol is 10 mg/L (10ppmv) and it's rare to see anything other than <10 as a published result. The ethanol would be more of a hazard and I'm OK with that...
A continuous still with one product output would not be a good thing for one of us, but one with multiple product outputs would be a lot more effective than the stills that I use and see here. Probably just keep on with one run stills myself, but I imagine someone like OD will make a hobby size one eventually. A trayed column with a thermometer and liquid takeoff at every tray would open up a lot of possibilities. Hmmm.

[Jimbo]

This is not true of fruit distillates, which are high in methanol, especially in the tails, as documented in the referenced study.

Also: For fruit distillates, the fruit flavor is in the heads. For whiskey, the grain flavor is in the tails.

This might be semantics, but I think its important, methanol is 'higher' in fruit than grain distillates, but not 'high'. I dont want folks to be freaked out here about methanol, its very low in general and not at a level to be unheathy. You can mix up any fruit mash and drink the wash, you do it every time you crack a bottle of wine. With distillation, even very sloppy cuts of some heads and tails, will result in a beverage with less nasties than the wine you started with.

Also, 'fruit' flavors also occur in grain mashes, from yeast esters, the grain itself (especially wheat and rye) etc., and come off in the heads in AG's as well, so care should be taken not to lop off the heads carelessly in AG's as well as in fruit distillations.

[Odin]

I do think fruit brandies that were fermented both on the pulp and with stones in can get close to what is still considered healthy.

... remember a few drinks like that. One was enough to give a head ache.

Odin.

[Edwin Croissant]

I don't have a agenda Buccaneer Bob, do you? The shift in paradigm in not about taste. If what you do with your cuts is influenced by the assumption that the methanol is concentrated in the first part of the distillate you can now take that factor out of the equation. If you make pear brandy etc. play safe and discard the tails. Or buy a gas chromatograph. Or don't drink to much of your stuff, I think that the biggest trap a distiller can fall into is becoming his best customer, the tragedy of the home distiller is that he is his only customer.

The relevance of showing the methanol / pure alcohol ratio is that it removes the influence of the alcohol strength so the graph show the same outcome for a simple or a fractional distillation and thereby giving a hint about the underlying mechanism. The methanol / distillate ratio is of coarse handy to sell your product stating that it contains only half the methanol as the competition without telling that it also contains half the ethanol. But that is marketing, not science.

I am interested in continuous distillation because (if my calculations are right) 500W will produce about 0.5 liter of pure ethanol per hour. So I am envisioning an apparatus that don't stand out in my garage and can be air cooled with for instance processor coolers. Only after I saw the automated iStill 50 I realized that this idea might be feasible. I am a retired design engineer and this project combines my skills in electronic control systems, stainless steel components and sensors. This is a good exercise for my brain as I am aware that if I don't use it I will lose it.

Regards, Edwin

Edit: changed the phrase “Polish automated still” into something more searchable for those of you who where wondering what the heck he was talking about.

[goose eye]

Edwin you preachin the gospel when you warnin homedistiller to tread litely on drinkin there likker cause the likker store never closes.

enjoy readin your words


so im tole

[Jimbo]

Edwin you preachin the gospel when you warnin homedistiller to tread litely on drinkin there likker cause the likker store never closes.

.... and gallons is made fer pocket change.

[Buccaneer Bob]

I'm sorry I was so harsh on you this morning, Edwin.

If I had to guess, I would say that only about 1/3 of the guys on this forum would think in terms of units of methanol per unit of pure alcohol. That would be the 1/3 who favor neutrals over liquor with flavor and perhaps the "alcohol as fuel" crowd.

The other 2/3 of us, the ones who are after liquor with flavor, would tend to think in terms of units of methanol per unit of distillate. We are after a particular flavor profile, and we will take our flavors wherever we can get them, quite often from the tail-end of the run.

When we're collecting distillate, we aren't doing alcohol percentage math, we are just tasting and measuring the volume of the distillate into quarts or liters or whatever as we go along. It doesn't matter much to us if this liter of distillate has 600 ml of alcohol or 300 ml of alcohol, just so long as we are getting the flavor we are after.

Does that make sense?

As far as your still ideas are concerned, I'm not so sure about the "automated" thing.

You're not hoping to go away and leave your still running, are you? Because you might come home to find the fire department out in your front lawn if you do. Stuff can, and quite often does, go wrong, and you want to be there when it does.

But perhaps when you say "automated", you just mean a little less fiddly? Like maybe you don't have to sit there making constant tweaks through the course of the run. In that case, maybe "automated" may not be such a bad thing.