Methanol in distilled beverages.
Methanol is an alcohol that is found in all distilled beverages (such as tequila, whiskey, mezcal, etc.) in different proportions. This alcohol is considered an unavoidable compound in distilled beverages, since it is formed from the fermentation of pectins originating from the raw material with which the distillate is produced.
In more detail, methanol is generated by the demethylation (removal of a methyl group) of the pectins present in the raw material of the distilled beverage. Excessive hydrolysis (breakdown of molecules in aqueous solution) can cause problems with methanol, increasing its amount in the product; otherwise, poor hydrolysis prevents the production of methanol, but causes a loss of sugar from carbohydrates (1).
What is the maximum methanol limit allowed by the Ministry of Health in the distilled beverage industry?
The amounts of methanol in distillates are of utmost importance for the alcoholic industry, because this compound can be dangerous for its consumers if its ratio indices are not adequate. For this reason, there are established standards for controlling the levels of methanol that a distilled beverage can contain. In Mexico, there is the standard “NOM-142-SSA1 / SCFI-2014, Alcoholic beverages. Sanitary specifications. Sanitary and commercial labeling. " (2), issued by the Ministry of Health, which establishes the permissible limits of methanol content for different distilled beverages.
The standard establishes a maximum methanol content of 300 mg per 100 ml of anhydrous alcohol. It only presents an exception for whiskey and cognac drinks where the maximum allowable limit is 1000 mg of methanol per 100 ml of anhydrous alcohol.
The highest concentration of methanol is found in the tops and bottoms of the distillate. That is, the first and last collection fraction of the distillate after condensing. Producers of distilled beverages cut through the distillation process to collect only the heart, and discard the heads and tails. The cuts is the key operation where the distillate is collected with less amount of methanol, which is why this stage of the production process is very important for producers of distilled beverages, where knowledge and experience are necessary when making cuts .
Regarding the toxicity levels of methanol, it has been established that the potentially lethal dose of methanol is approximately 30 to 240 ml or 1 g per kilogram. Methanol has a reputation for being linked to visual damage, which is a reality. Permanent visual damage can occur from a minimum intake of 30 ml of methanol (3)What it does is destroy the optic nerve by concentrating on that area. For these reasons, consumers are recommended to pay attention to the distilled beverage products they consume, to check that the bottles are certified and that they contain their respective quality hologram. If a distilled product does not contain these parameters that ensure quality, it is very likely that it contains high levels of methanol (higher than those established by the standard).
It can be concluded that methanol is an important factor to consider so that a distilled beverage can be sold to the public, as well as, as a fundamental part so that this drink can be considered alcoholic (which is why it cannot be less than 30 mg of methanol per 100 ml of anhydrous alcohol).
When methanol levels need to be corrected, once the final product is in place, activated carbon will be the best option for methanol reduction. By maintaining the profile of the distilled beverage and reducing the methanol levels, activated carbon is able to perform this operation.
- Tequila Regulatory Council. Tequila Production Process. CRT. [Online] CRT, 2019. https://www.crt.org.mx/index.php/es/el-tequila-3/elaboracion-normativa/63-proceso-de-elaboracion-de-tequila.
- Official Mexican STANDARD NOM-142-SSA1 / SCFI-2014, Alcoholic beverages. Sanitary specifications. Sanitary and commercial labeling. Health, Secretary of. sl: Official Gazette of the Federation, 2015.
- Ashurst, John V. and Nappe, Thomas M. National Institutes of Health (NIH). Methanol Toxicity. [Online] NCBI, November 2019. https://www.ncbi.nlm.nih.gov/books/NBK482121/