Diskussion: Die Schnaps – Destillation

If you read English ( a má facon)I can tell you how completely impossible it is to answer this question in a simple way -- .
Pro primo: methanol is practically only present in fruit-based washes ("Obst-maische"). It is there prior to fermentation as it is produced from the pectin in the fruits. The commercial pectinase-preparations contains several enzymes (as do grapes) and one of them will split the esters in pectin, liberating methanol from the metylesters of glucuronic acid.
Thus, real grappa contains significant amounts of methanol-- but still not dangerous.
Methanol is more volatile that ethanol and it can be expected to be more concentrated in Vorlauf. However, the volatility of the "congeners" (other alcohols than ethanol)is very dependent on the background concentration of ethanol and you will have to read physical chemistry and use Raoult´s law + a number of empirical constants to figure out just how the concentration of the "other alcohols" will change through the distillation process.
The short version is: yes, there is methanol in good fruit-based Eau de Vie´s, especially when based on pectin-rich material, digested with pectinase/pectolase and when they are distilled, as they should be, twice in a pot still.
I believe that there are some EU-guidelines just on this and grappa is controlled for two reasons:
not too high methanol (the customers can not see their way to the shop next morning)and not too low: than the grappa is falsified with "too pure alcohol".
The Gert Strand plastic-bucket aquarium heater outfit is not attractive to a copper-smithing doctor as me. I think it has been tested on fruit-mashes with bad results (try www.homedistiller.org) -- the less volatile fruit esters which are responsible for the good taste are so un-volatile that they do not pass into the
"distillate" in the necessary amount.
But how toxic is this damned methanol they write so much about? Before I became blind I was very careful to purify my alcohol--
No, tasteless jokes apart: methanol in itself is not toxic. But it is metabolized to formaldehyde in the body and this component reacts with enzymes and proteins, especially in the retina, and destroys sight. The enzyme resposible for formaldehyde production will also metabolize ethanol and actually prefers ethanol. The treatment for methanol-intoxication is therefore intravenous ethanol to a blood concentration of 1-2 pro mille -- that is quite a heavy dose. This gives the enzyme more than enough to do with real ethanol and methanol passes out in the urine un-metabolized.
This should not be taken to imply that methanol in ethanol is un-problematical-- but keep a level head, shoot straight and speak the Truth.