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I would like to freeze distill some hard cider I've brewed to up the gravity. However, it is well known that freeze distillation concentrates the methanol present in the booze.

My question is, since methanol is the "first" thing that boils off during regular distillation; can I boil my cider for just a very short time to remove the methanol, cool it down, then proceed with freeze distillation? If so, what would be the best way to go about it without losing all of my ethanol?

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Methanol in cider can be a problem. It's much higher in apple juice than beer. The boiling point of methanol is 148°F(64.7°C) so if you want to boil it off before the Ethanol, boiling point 173°F (78.37°C) you could do that. Bring up to temperature for a few minutes should be enough to blow off the methanol leaving most of the ethanol behind. But this might cause a pectin haze problem. In the future, doing this before fermentation will significantly reduce the levels of methanol.

I'm adding this to my answer so you all can read it at the top level

Methanol is a result of pectin breaking down into galactose units. Pasteurizing the cider and not adding any pectinase enzyme generally reduces the methanol in hard cider. Here is a peer reviewed paper on the subject

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    How would boiling before fermentation reduce the methanol content?
    – Him
    Jan 22 '18 at 10:31
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    Before fermentation will have zero effect, doing this once fermentation is complete would affect the levels of methanol, but I don't think you would have to worry about it.
    – Mr_road
    Jan 24 '18 at 11:12
  • !!! "<...>doing this before fermentation will significantly reduce the levels of methanol." Really? Even trying to boil methanol off after fermentation would be a loss leader as some ethanol would certainly be removed too. Ethanol/methanol and water form azeotropic mixes so the distillation is not a "simple" temperature step process. Jan 24 '18 at 13:01
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    Methanol is a result of pectin breaking down into galactose units. Pasteurizing the cider and not adding any pectinase enzyme generally reduces the methanol in hard cider. sciencedirect.com/science/article/pii/S0960852409013194 Jan 24 '18 at 14:20
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    My thanks to @farmersteve. The polysaccharide pectin contains galacturonic acid which is usually found as the methyl ester. Hydrolysis of the ester produces methanol. If one denatures any natural fruit pectinase present by boiling then less methanol is produced. In practice there is some variation in this principle, but it does basically seem to be a natural source of methanol in many biological systems, including human digestion. This principle applies to many pectin rich fruits not just apples. Jan 25 '18 at 21:09
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I wouldn't worry about it. The methanol concentrated by freeze concentration of your cider wouldn't even be close to the acceptable amounts of methanol that's in commercial vodka.

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  • How would you measure that to be certain?
    – spoulson
    Jul 29 at 18:38
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My information has the boiling temperature at 144 degrees F. Heating your distillate to 144 will boil the methanol and tend to slow heat rise until it has finished evaporating and before the evaporating temperature of ethanal. This is basically what happens with every still run that I've watched on moonshiners. If methanal doesn't evaporate first how is it always first out of the still. This is how they removed the methanol on the only freeze distillation show moonshiners did in 2021.

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