This one-valued alcohol (also carbinol, methyl alcohol, wood alcohol, wood spirit) is a colorless, burning-tasting liquid with a distinctive, sweet smell. Although he is very different from ethanol (Drinking alcohol) differs, it can be overlaid with others flavorings barely recognizable in taste in alcoholic beverages. Even the ancient Egyptians made methanol from wood by pyrolysis (splitting of organic compounds by high temperatures from 200 ° C) and embalmed their dead with a mixture of substances. It received the name “methylene” in 1834 from the French chemists Jean-Baptiste Dumas and Eugène-Melchior Péligot, it is composed of “méthy” for wine and “hylé” for wood. Methanol itself is of low toxicity, but its metabolites, especially formaldehyde, are toxic.
Even the smallest amounts of 0.1 g methanol per kg body weight are hazardous to health, from 5 times the amount of life-threatening. From there it comes to cramps, vomiting, difficulty breathing, blindness and, in extreme cases, death. Natural levels are included White wine between 17 and 100 mg / l and at red wine about twice as high between 60 and 230 mg / l. These amounts are sanitary harmless. The former Austrian specialty Uhudler Incidentally, high methanol values have long been found to be wrong. There are legally defined limit values within the EU, which are at spirits 200 g / hl, with ethanol 30 mg / l, with fruit brandy 1,000 g / hl and with brandy 200 g / hl (see also under ADI ).
The chemical difference between the two types of alcohol, ethanol and methanol, is actually very small. Simply put, ethanol has only one atom longer carbon chain than methanol. Both alcohols are not toxic (in correspondingly small amounts), but they have completely different breakdown rates after consumption. Are involved in this process in the human body ADH (Alcohol dehydrogenases) involved. While ethanol first too acetaldehyde and then very quickly acetic acid is converted, the already highly toxic formaldehyde (methanal) is formed from methanol and then from it formic acid, The latter is ten times stronger than acetic acid and can only be broken down very slowly, which can lead to dangerous to life-threatening acidification of the blood.
The smallest amounts of methanol are produced as a by-product of alcoholic fermentation through enzymatic degradation of the pectins, which are mainly contained in the cell substances of the berry shells and stems (i.e. not from sugars like ethanol). It is one of the fusel alcohols that result from the fusel oils form. Through intensive and long mash contact at the maceration or at higher fermentation temperatures, larger quantities are produced. Therefore, the proportion of red wines (with berry contact) is usually much higher than that of white wines (without). Especially the solid components of the grapevine like leaves and stems (from improper vintage ) and to a small extent also the pulp lead to increased methanol formation.
Likewise in the manufacture of spirits the methanol content higher. This is especially true in the manufacture of vodka the case because potatoes contain high amounts of pectin. Therefore at distillation the methanol fraction separated. This is relatively easy because methanol at 65 ° Celsius has an even lower boiling point than ethanol (the drinking alcohol) with 78 ° Celsius. If this separation is not carried out carefully, the distillate would contain dangerous amounts. Detachment used to be the case with products from questionable producers, such as in the American era prohibition (1920-1933) because it was much easier and larger quantities of cheap fuzz could be produced and sold. But even today such illegally produced products still come into circulation.
An interesting piece of information comes from the website www.chemie-im-alltag.de (Oliver Reiser): Since methanol is oxidized by alcohol dehydrogenase much more slowly than ethanol, the best antidote for methanol poisoning is the patient for several days under an alcohol concentration to keep from 1 per mille. Ethanol acts as a competitive inhibitor for methanol, which means that ethanol binds preferentially to the ADH (about 8,000 times better), making it dangerous for the body oxidation from methanol to formaldehyde and finally to formic acid is prevented. Methanol is then excreted unchanged in the urine as a water-soluble substance over several days. See a list of all wine ingredients below total extract,