Separating ethanol from methanol

[RPh_Guy]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5028366/
This article describes the process quite well. "Methanol is produced during fermentation by the hydrolysis of naturally occurring pectin in the wort". Grains only contain very small amounts of pectin, so the methanol content of beer is very small (hops also have pectin which would contribute to methanol in beer). Fruits obviously have much more pectin, hence more methanol in wine/cider.

Do you have a reference showing how much pectin is in grain or hops?

 

[Gnomebrewer]

Do you have a reference showing how much pectin is in grain or hops?

Trace/small amounts in grain (the article is mostly about wheat, but also mentions barley).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3931795/
1 to 2% in hops.
https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1953.tb06212.x

 

[Gnomebrewer]

settle down now boys....

Well said. My post #26 was antagonistic and I apologise.

 

[RPh_Guy]

Trace/small amounts in grain (the article is mostly about wheat, but also mentions barley).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3931795/

I read through this article. I think it's pretty clear that even the trace amount of pectin compounds they detected are inaccessible during wort production and are therefore not extracted.

"To increase accessibility to pectic epitopes the sections were treated with lichenase (endo-1,3(4)-β-Glucanase) 40 U/ml (Megazyme International Ireland Ltd) overnight at 40°C and then with endo-1,4-β-Xylanase M6 (Megazyme International Ireland Ltd ) 50 U/ml overnight at 40°C in water."
"When the grain sections were incubated with both enzymes, LM20 epitopes were detected in the grain outer layers as well as in the starchy endosperm cell walls (Fig. 1F) whereas when only one enzyme treatment was applied (lichenase only or xylanase only), no labeling was observed in the endosperm (Fig. 1D and Fig. 1E)."

Without the use of their highly specific combined enzymatic degradation, there hasn't been any pectin detectable in grain.
"Until now, no pectin has been reported in wheat grain. In early biochemical studies, the polysaccharide composition of wheat flour, which corresponds approximately to the starchy endosperm, was characterized and did not reveal pectin [3], [5]."

1 to 2% in hops.
https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1953.tb06212.x

Man I don't like reading old articles.

The authors go through a whole litany of factors that make it difficult to extract and purify pectin from hops. In order to extract any tannins they needed to use a solution of acetone (not used in brewing, obviously). They further explain that pectin forms insoluble complexes with calcium (which serves to remove it from wort).
Then at the end of the article they conclude that their samples are impure and they did not successfully validate their method as reliable for quantitatively measuring pectin content in hops.

So, definitely neither one of these articles conclude that pectin makes its way into wort. It seems to me that they support the idea that it doesn't, although obviously not conclusively.

Thanks for the articles, interesting stuff!

 

[bracconiere]

lol, so the op needs this for his homemade methanol?


https://nuts.com/cookingbaking/leav...-xjwmR09QdT4Vgm34RKjfePEKL0ebwdsaAiGyEALw_wcB

 

[Gnomebrewer]

Here are another two articles about pectin in barley
https://www.sciencedirect.com/science/article/pii/S0144861718305952
https://www.frontiersin.org/articles/10.3389/fpls.2017.01872/full
Also worth noting is that in this article
https://www.tsi.com/getmedia/15881c...ectroscopy_App_Note_RAMAN-022_US-web?ext=.pdf
Single malt scotch whiskey is found to have a typical methanol content of 0.2 to 0.3%, with levels above that considered contaminated. The methanol in scotch whiskey must be produced during fermentation of the barley wort.

 

[doug293cz]

Here are another two articles about pectin in barley
https://www.sciencedirect.com/science/article/pii/S0144861718305952
https://www.frontiersin.org/articles/10.3389/fpls.2017.01872/full
Also worth noting is that in this article
https://www.tsi.com/getmedia/15881c...ectroscopy_App_Note_RAMAN-022_US-web?ext=.pdf
Single malt scotch whiskey is found to have a typical methanol content of 0.2 to 0.3%, with levels above that considered contaminated. The methanol in scotch whiskey must be produced during fermentation of the barley wort.

Methanol can come from charred wood. Think barrel aging, charcoal filtering, etc.

Brew on

 

[Vale71]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5028366/
This article describes the process quite well. "Methanol is produced during fermentation by the hydrolysis of naturally occurring pectin in the wort". Grains only contain very small amounts of pectin, so the methanol content of beer is very small (hops also have pectin which would contribute to methanol in beer). Fruits obviously have much more pectin, hence more methanol in wine/cider.

No it doesn't. All it does as far as proving a link between alcoholic fermentation and methanol production is to make inferences such as "S. Cerevisiae could be involved in the production of methanol" or "In spontaneous fermentation other naturally occurring bacteria might be responsible for methanol production in spontaneously fermented beverages" and so on and so forth. As of today there is zero proof that Saccharomyces could in any way be involved in the production of methanol. There is lots of speculation asbout that but without proof speculation is just worthless. As somebody else already pointed out there is also zero conclusive proof that the ingredients of beer contain pectin or even if they do that it could be in any way carried over to wort.

So to sum it up there is no proof that malt wort has any measurable pectin content and even if that were the case then there is no proof that any microorganism involved in fermentation is in any way capable of producing any amount of methanol from said pectin. If we apply Occam's razor then we have to conclude that any methanol that might be detected in beer must be exogenous as this is the simplest possible explanation.

 

[Vale71]

How is methanol produced in fermentations with pectin?

It simply isn't. Methanol is a naturally occurring constituent of pectin-rich fruits and vegetables, even of common tomatoes as you can see in this study. If fermented and possibly distilled beverages are produced from such fruits then some amount of methanol will inevitably be carried over to the beverage but that does not imply any direct link with the fermentation process.

 

[Gnomebrewer]

Methanol can come from charred wood. Think barrel aging, charcoal filtering, etc.

Brew on

Do you have a reference for that? I can't see how that can happen. Sure, fermentations with wood present produces some methanol, but there's no fermentation involved with whiskey in an oak barrel. The best information I can find (although admittedly not 100% conclusive) still says the methanol is from pectins in the ferment.

 

[Vale71]

The best information I can find (although admittedly not 100% conclusive) still says the methanol is from pectins in the ferment.

No it doesn't, at least not the information you have linked in your posts. Once again, there is zero proof of any methanol production during fermentation. Presence of methanol in the finished product alone does not prove anything other than that there is some methanol present.

 

[Gnomebrewer]

No it doesn't, at least not the information you have linked in your posts. Once again, there is zero proof of any methanol production during fermentation. Presence of methanol in the finished product alone does not prove anything other than that there is some methanol present.

But it's all circular logic anyway, because the original intention was to show that there is a trace amount of methanol in beer. I haven't seen any proof that there isn't some methanol in beer, the common wisdom is that there are trace amounts, and the onus of proof with food is to prove that the harmful chemical doesn't exist. Therefore, until I see conclusive evidence otherwise, I'll believe there is a trace amount of methanol in beer. I'll also continue to consider it highly likely that it comes from trace amounts of pectin from the grain. I've quite enjoyed reading about the subject and definitely learned more about it. I'm not suggesting the methanol is produced through the fermentation process (although I did originally think it was a byproduct in the same way as, for example, an ester, which I now know is not correct) but that it happens at the same time. That is mentioned many times in articles I've read, although it is possible that they all link back to one study.

 

[gatewood]

Just to clarify you guys, I ain't distilling beer, I used the word "homebrew" in a broader sense, not just beer... I apologize if I caused some confusion (didn't expect this would become such a heated discussion).

I have ferments (some made of plain glucose, others with fruit wort) with around 25% alcohol.

 

[Gnomebrewer]

Just to clarify you guys, I ain't distilling beer, I used the word "homebrew" in a broader sense, not just beer... I apologize if I caused some confusion (didn't expect this would become such a heated discussion).

I have ferments (some made of plain glucose, others with fruit wort) with around 25% alcohol.

Even if you could collect pure methanol, the methanol content is still very small in terms of collecting a pure sample of it (but remember it only takes a small amount to kill a person). In this study https://www.bio-conferences.org/articles/bioconf/pdf/2017/02/bioconf-oiv2017_02028.pdf, 280mg/L is listed as the upper end of the typical range for red wine. At that methanol content, 5 gallons of red wine would contain about 5.6mg, or about 7mL of methanol. Hardly worth worrying about when methanol produced from natural gas is cheap to buy.

 

[gatewood]

Even if you could collect pure methanol, the methanol content is still very small in terms of collecting a pure sample of it (but remember it only takes a small amount to kill a person). In this study https://www.bio-conferences.org/articles/bioconf/pdf/2017/02/bioconf-oiv2017_02028.pdf, 280mg/L is listed as the upper end of the typical range for red wine. At that methanol content, 5 gallons of red wine would contain about 5.6mg, or about 7mL of methanol. Hardly worth worrying about when methanol produced from natural gas is cheap to buy.

Then I guess I'll settle with just producing ethanol.

 

[Orval]

It simply isn't. Methanol is a naturally occurring constituent of pectin-rich fruits and vegetables, even of common tomatoes as you can see in this study. If fermented and possibly distilled beverages are produced from such fruits then some amount of methanol will inevitably be carried over to the beverage but that does not imply any direct link with the fermentation process.

True! There's some methanol in your favourite orange juice!
Methanol comes from the hydrolysis of pectins, nothing to do with fermentation. Depending upon your batch size, you discard the first ml. Let's take one example, - 20 litres batch low wines at 42%ABV from a stripping run; discard the first 50ml as foreshots, mainly acetone and methanol, keep the next 250ml as head and another 250ml which can or cannot be added to the final product depending upon how neutral and how "hangover free" you want it. Foreshots can go to a bottle of barbecue lighter or general purpose solvent, the heads can be added to the next spirit run.