Removing methanol taste (via evaporation?)

[bitterbad]

This is NOT about distilling. I do not want to distill anything.

In my previous batch of blackberry wine, I foolishly didn't add pectic enzyme, and it was also just generally unstable, and it seems that the high pectin content of the blackberries made a bit more methanol than is paletable (yet still in comfortable ranges I'm positive, just clearly tastes off and hits differently). The day before yesterday I poured out the remainder of a bottle into a glass and let it sit, just out of curiosity, to see what would happen. Today I tasted it and to my surprise, all of the methanol taste is gone, much smoother and tastes way better. Does methanol have a higher evaporation rate at room temperature than ethanol then? Is that what happened? Is there perhaps a way to take advantage of this in a more closed environment to save my failed batch? Maybe boil it just a little bit?

 

[Raptor99]

I was curious about this, so I did some searching for the relationship between pectin and methanol production. It turns out that some methanol is produced by pectic enzyme when it breaks down the pectin. See this article: Using Pectic Enzymes to Make Wine

I found an abstract for a research study on this question: Relationship of the methanol production, pectin and pectinase activity during apple wine fermentation and aging - PubMed If I understand the abstract correctly, it is saying that pectic enzyme contributes to methanol production. "Pectin methyl esterase" is pectic enzyme.

I am wondering if your problem is really methanol or something else. Not adding pectic enzyme would decrease the production of methanol.

 

[bernardsmith]

I wonder if the amount of methanol in any glass of wine is so small that it would be virtually undetectable by 99.9999% of the population. What you might be tasting is the ethanol (what was the ABV and how much fruit per gallon did you ferment?). Allowing the glass to "breath" would have allowed air to bind with the alcohol and that may have softened the taste.

 

[bitterbad]

(what was the ABV and how much fruit per gallon did you ferment?

This was an extraordinarily weird batch. the answer to your question is "no clue", i didn't bother with gravity readings, but it's definitely a lot, and it definitely feels distinctly different from normal alcohol, and also smells unlike even spirits, smells and tastes exactly like descriptions of methanol. Maybe it's like 0.5% methanol, maybe it's normal amounts of methanol and just high ethanol, maybe it's something else entirely, who knows.

 

[bernardsmith]

Gotta say that if one does not monitor what one is doing and one does not obtain key data points , it becomes impossible to know what might be happening when an outcome does not fit one's expectations. That said, gravity readings are but one way of knowing the starting gravity and the potential ABV. Knowing the total volume , the amount of sugar added, the amount of fruit being fermented etc allows a seasoned wine-maker to know both starting gravity and potential ABV... One pound of sugar dissolved in water to make 1 gallon increases the gravity of the water by 45 points. One pound of honey increases the gravity of the water by 35 points. Most fruit when juiced have a hefty pound of sugar in every gallon of juice - a gravity of about 1.050. Forty five points of gravity has a potential ABV of about 6%... Two pounds, about 12%.. But presumably, you know the "recipe" you used to make this batch...

 

[Bad DNA]

Today I tasted it and to my surprise, all of the methanol taste is gone, much smoother and tastes way better. Does methanol have a higher evaporation rate at room temperature than ethanol then?

The 'sciencey' answer is yes, but the answer here is vastly more nuanced. Methanol has a lower boiling point than ethanol, and ethanol lower than water. But it's a whole lot more complicated and I don't think it is a significant effect in your case. I'm sure you looked up the boiling point of each liquid in your solution. And you noted that you are playing at room temperature (and presumably 1 atm pressure). And that each compound is miscible (they all fully mix with each other due to hydrogen bonding). Vapor pressure is a function of T and P. And there are plenty of other compounds and components to your solution, not to mention variables such as surface area of container relative to volume of liquid.

Because of hydrogen bonding, and you are nowhere near the boiling point of methanol, the relative evaporation rate is slower than you may expect. Perhaps a combination of slightly less methanol (if that is really what you are tasting), some oxidation, and maybe loss of other volatile compounds.

Here's a study on ethanol evaporation rates in an open container over time:

https://bayblab.blogspot.com/2009/01/evaporation-rates-of-ethanol-solutions.html