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Oxford Companion to Wine

Oxford Companion to Wine

By Jancis Robinson

Published 2006

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methanol, another name for methyl alcohol, also known as wood alcohol, is the member of the chemical series of common alcohols with the lowest molecular weight. Methanol is highly toxic. The immediate risk of ingesting any quantity of methanol is blindness, but consumption of between 25 and 100 ml (4 fl oz) can be fatal. As recently as the mid 1980s, some Italian wines were found to have been contaminated with methanol (see adulteration).

Wines naturally contain very small quantities of methanol: about 0.1 g/l, or less than one-hundredth of the normal concentration of ethanol. Some methanol is naturally present in grapes and further traces are formed during fermentation but most is formed by demethylating the pectin materials that are naturally present in the grape (see colloid and enzymes). Red wines, and particularly those subjected to prolonged maceration, are likely to have higher methanol concentrations than average. Brandy in general has rather higher levels of methanol than wine because the distillation process concentrates it. And wines and brandies made from fruits other than grapes tend to have higher methanol concentrations because grapes have fewer pectins than most other fruits. It would be impossible to ingest a dangerous level of methanol from such drinks, however, without ingesting a fatal amount of ethanol long beforehand.