13 Responses

  1. Tyler at |

    Awesome.. should arrive in time for my bday. Do you cover the updated NOM? I was reading an article about how tequila can be 1% additives by total volume and not have to put that anywhere on the label, even 100% agave tequilas (except blancos, that rule might not apply).. are there rules about additives in mezcal? Looking forward to reading your thoughts on where mezcal is heading in a commercial sense and changes to the DO.

  2. David at |

    Yeah, your mail order PhD is not in chemistry, that much is very evident by this description of the distillation process. For starters, ethyl butyrate IS AN ESTER! It is the condensation product of butyric acid with ethyl alcohol. Esters can exchange alcohols and acids when resting so the esters you started with can be interesterified into new chemical products during a long maturation in a charred oak barrel. Yeah, I also know that most all Mezcal producers skip that step or shorten it to at most a couple of months. And methanol is never really a problem congener unless a problematic yeast strain is used that over expresses methanol production enzymatic pathways (they do exist and are used industrially in certain situations for fuel feedstock production etc).

    Mezcal producers skip the long barrel aging or age for short periods of time only compared to whiskey and brandy producers while the alcohol is resting and maturing. The most reactive species of congener is the aldehyde congener and it can pass through the micro-porous wooden barrel and escape during a several year resting period as all simple aldehydes also have pretty low boiling points so usually end up in the heads fraction. But realize the distillation technology employed for Mezcal production is very very rudimentary. Sure that contributes to it’s charm and flavor profile but the lack of aging means that many of the hangover producing congeners are still present in the product you are drinking. Also realize that aldehydes are the MOST dangerous of the congeners as they are very reactive with the proteins in your body and react to form Schiff base’s called advanced glycation end-products or what the biochemists call AGE metabolites for shorthand. These AGE products are chemically transformed proteins with the amines from the N-terminus of the protein or lysine side chain being capped off by the aldehydes and they are basically PERMANENTLY transformed metabolites (the proteins lose their function when AGED by cross reactive simple aldehydes and pre-dispose you to cancers by their production and storage inside your cells, yikes!). Want to know the name of the most dangerous aldeyde? Yup, the undertaker aldehyde called FORMALDEHYDE. It is the most reactive aldehyde (it is really a gas at room temperature and can outgas from many house construction materials causing nasty exposure related symptoms in people who do not drink alcohol at all) and it reacts and PRESERVES your proteins almost forever! Number two aldehyde nasty is called acetaldehyde and is made in appreciable quantities by many wild yeasts and bacteria. It smells fruity but can kill you! This is medical fact and it isn’t just drinking that ages your cells by the their formation. but drinking an aldehyde rich distilled product can greatly accelerate the amount of AGE metabolites inside your body.

    All of these congeners are created by the wild yeasts and bacteria during the tohona milling and fermentation processes involved in making a Mezcal worth drinking. The distillation just cleans things up by separating the organic volatiles from the water and waste solids. Because most artisan Mezcal makers do not use industrial autoclaves to high pressure steam the pinas for days like the tequila producers do, breaking down the inulins into fermentable sugars, the conversion efficiency of the fermentation is pretty damn low as the total amount of fermentable sugars is low to start with in these wild crafted pinas. And many of the fermentable sugars are not simple mono and disaccharides (fructose, sucrose etc) so the yield of ethyl alcohol to higher order fusel oils is much lower than in a typical whiskey or vodka produced from all grain mashing using saccharified worts made from malted barley for enzymatic breakdown of the starches into simple fermentable sugars, In other words a very high percentage of the plant mass is not converted into ethyl alcohol when making artisan Mezcal. The process is just a very low efficiency method and has not been modified for yield the way Tequila makers have optimized their methods over centuries of production.

    Let me describe one such trick employed by some Mezcaleros to reduce the amount of reactive simple aldehydes in the mezcal they are making. it is the “witchcraft art” of hanging a chicken breast “Pechuga” in the still right above the ascending vapors. This chicken breast is a source of protein primary amines which can and will react to with the simple reactive aldehydes produced by the bacteria and wild yeasts used to fermented to ground up cooked pinas. In other words it is a sacrificial source of animal protein to reduce the amount of aldehydes in the final mezcal product. Do this work? Probably a little but I know of no scientific study that shows it reduces the amount of aldehyde in the final distilled product in a meaningful way. You know what works better? Using a polished (that is polished on the inside not the outside where it does not matter except for visitors to be wowed) raw copper still to react with odorous sulfur containing thiols and aldehydes. Better yet, get some theoretical plates in your column still and remove these nasties by having a much tighter control of your distillation separation efficiency. And switch to modern yeasts with well controlled genetics to reduce the amount of nasty congeners. Sure that would make your Mezcal more like Tequila but I bet these small scale producers end up going that route when they are forced to scale up production without having access to increased pina harvests.

    See what knowing about yeast genetics and the biochemistry of fermentation can do to explain stuff you are mystified about? It’s better not to make stuff up when your are not sure even if it appears to be a working strategy for our not so well informed POTUS.

    For people who are sensitive to multiple congeners, Mezcal is not going to be the drink of choice. Lack of resting, maturation and methods of fermentation make it a drink that can require days to recover from, especially compared to modern mashing and fermentation methods. Thats said, much of the latest and greatest in small scale distillation artisan US distilling is going towards rough and ready high rye mash bills and they also suffer from a need for a longer maturation to reduce the greater quantity of aldehydes and reactive congeners introduced during a longer slower fermentation process with these high rye all grain mash fermentations. Chose your poison wisely and consume in moderation or pay the price.

    Good luck with the second edition it will still contains a great amount of research into small scale mezcaleros that can’t be easily located anywhere else as far as I know.

    1. Rimas at |

      WOW! That’s super informative and kind of depressing at the same time. I noticed a couple of years ago that I started developing what I thought was an intolerance to alcohol, but looking back, it started around the time I discovered Mezcal. According to you, maybe I’m sensitive to the higher quantity of congeners found in Mezcal compared to other alcohols?

      Would glass maturing of Mezcal help lower the count?

      1. David at |

        The only commercially distilled spirit matured in glass that I know of is European (mostly German, Austrian, and some French made) Eau de Vie or so called clear fruit brandy. These are not the brandies distilled from waste pomace after winemaking like the Grappa’s of Italy (although many of those are now made from pure whole grapes grown especially for distillation instead of the leftover pomace Grappa production of yesteryear. Let’s not forget about Slivovitz production but that is a story for another time….

        These clear fruit brandies are often used in desserts and fine pastry making and real Swiss fondue uses a splash of kirschwasser mixed in to help melt the rich cheese mixtures . And you can also drink them as an after dinner aperitif, if you are tough enough. Talk about an aldehyde rich fruit brandy! So the small scale clear fruit brandy makers are generally the fruit growers or located around fruit growing regions with many orchards. The fruit is picked when ripe and very fragile and so must be fermented before it becomes bruised and the skin is broken, allowing wild yeast to degrade the natural fruit flavors. The amount of fruit needed to make a fifth of clear fruit brandy is staggering as the sugar content is low compared to grape sugar (measured as degree Brix at harvest). Low sugar means the yeast have to work extra hard and will tend to make a much higher percentage of higher order alcohols and congeners that will distill over in the alcohol fraction and the total alcohol yield per 10 gallons of fermented fruit wine is very low, just like Mezcal production! I do not believe any of the major clear brandy producers in EU or USA do any significant maturation of their products as they use a higher efficiency distillation process to remove unwanted congeners during distillation rather than attempt to change the composition during resting and maturation. The goal is a product true to the fruit and not aged to make a Cognac or Armagnac or Calvados product.

        The farmhouse distillers used to collect the product in very large glass bottles and used to store them with a cloth packed in the opening up in the farmhouse attic rafters for at least one season after distilling was completed in the fall. During the attic rest, lower boiling aldehydes and esters would be partially reduced as they turned to vapor in the headspace and were pushed out of the large glass vessel while warming up during the day from sunlight heating the roof tops. At night, the glass and clear brandy contents would cool down again, allowing more air to enter and the process would repeat the next day. Over time, the continued expelling of small amounts of air from expansion of the liquid brandy would push out a greater fraction of the low boiling congeners and leave the brandy slightly enriched in the ethanol and higher boiling congeners. Given the low yields and cost of the fruit going into this product, you can see why the producers can’t afford to lose too much to the Angel’s share so aging in glass made sense. Also aldehydes have a strong fruity nose and most fruits are rich in particular aldehydes that give each fruit variety it’s distinct nose when ripe. Go ahead and price 375Ml bottle of Clear Creek Framboise to get an idea of what I am talking about, the stuff costs like a fine Mezcal.

        What this story illustrates WRT Mezcal production is that lower fermentable sugar musts from whatever source of plant material will produce a much higher amount of congener per liter of ethanol. Using wild yeasts and bacteria will also greatly contribute to the (sometimes desirable) contamination of the ethanol with higher order and more complex congener production. Plant proteins also contribute methionine and cysteine amino acids that the bacteria and yeast use to metabolize into disagreeable thiols and strong smelling sulfur compounds.

        Natural wines tend to go this route as well although modern science has shown via quantitative rt-PCR that the starting yeast that appear first in your fermentation often go away at later stages, only to be replaced by more alcohol, tolerant S. cerevisiae strains, even when they are not added to the fermentation by the people in control of the process. In other words, the wild bacteria and yeast start things off even when copious amounts of sulfur dioxide is used to suppress their growth in the case of winemaking. The low sugar in Mezcal mash means that the sugar is all fermented before the alcohol tolerant yeasts can really start to chow down. Typical Mezcal mashes only hit 6% alcohol tops so compared to 14% alcohol for brandy production, you need more than twice as much mash to make the same amount of distilled product. Mezcal is a tough road in many ways (ask the guys hauling the ripe pinas down from the steep ravines about that) but so are most of the most ancient distilled products.

        1. Rimas at |

          Again, very informative David. Thanks for the quick and thorough response.

          I’m not an expert in the exact history of glass matured Mezcal, but I just bought a bottle that was intentionally matured in glass for 10 years. My understanding is that this practice has been around and is slowly becoming more popular.

          They say that it mellows the Mezcal and allows the character to come forward as the harshness and alcohol get pushed to the background. I’m on some forums where people have been asking what the scientific explanation to that would be assuming its not just in the imaginations of those consuming glass matured Mezcal.

          You seem like you’d be qualified to answer that question…in fact, your explanation using clear brandy seems to point to some of the science behind the concept. Very interesting stuff!

          1. Rimas at |

            I look forward to reading about it in the new edition Doc!

            I’ll probably give me older copy to a friend 😉

  3. Mike Jones at |

    Can’t wait for the new edition John. Heading to Oaxaca tomorrow 🙂

    All the best,


  4. Bruce Turbeville at |

    Well… as a vodka lover… oh, who am I kidding… I’ll buy the new edition the minute it hits “the shelves”…. thanks, John, for keeping the spirit of Mezcal alive and well… I just hope there’s an expanded “review” list at the back…


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