Course:FNH200/Projects/2022/Processing and Packaging of Mezcal

Bottles of Mezcal manufactured in Teotitlán del Valle, Oaxaca.

Introduction

Mezcal is a traditional alcoholic beverage originating from Mexico. Made from agave and maguey plants, the distilled spirit is known for its traditional production, cultural and historical significance.

In general, the production of mezcal is a long and incredibly specific one: including the cooking and crushing of the agave plant, extraction, fermentation, distillation, bottling, and aging . Due to its cultural impact, information regarding the production process is often kept local, and passed down through generations. Because of this exclusivity, only 5 companies have legal permits in producing mezcal .

The Role of Agave

12 different species of maguey used for making mezcal.

Mezcal is made from the maguey plant of the agave family, but there are more than 14 different species of the plant . The main species used in the production of mezcal are Agave salmiana, Agave angustifolia, Agave cupreata, Agave esperrimia Jacobi, Agave webericela, Agave durangensis, and Agave potatorum . These plants grow in most states in Mexico, however only certain states are legalized to produce mezcal including Oaxaca, Guerrero, Durango, Guanajuato, Michoacan, Puebla, San Luis Potosi, Tamaulipas, and Zacatecas . Most of these plants grow in the wild, but to produce mezcal many Agave plants are farmed as well .

Harvesting & Cutting Agave

For most types of the Agave plant are determined to be harvested when they reach about 10 to 15 feet and the flower has sprouted . The maturity of the Agave plant has a large variety, between 6 and 70 years and the plant grows from the inside out . The leaves of the plants have thorns and are removed by using machetes before transporting the pina, the long bulb-like shape in the center of the plant to the distillery . Removing the leaves makes it safer to carry and reduces the weight as some of the plants can weigh up to 80 to 200 pounds .

Cooking

Raw agave is cooked in the Earth oven - a hot, large hole in the ground.

There are 5 main steps: cooking, milling/extracting, fermenting, distilling, and aging . The cooking process of mezcal is very similar to that of tequila, however, on a much smaller scale. 

Initially, the raw agave gets cooked in large holes or ovens in the ground.  These are heated by hot stones and burning oak or mesquite wood .  Once the cooking process starts, the hole/oven is covered and left for a predetermined time based on the producer.  The burning wood used to heat the ovens are the main contributors to mezcal's distinct flavour and aroma.  This cooking also induces a Maillard reaction which aids with the flavour and smell .  By cooking the agave, it helps convert naturally occurring fructo-oligosaccharides to monosaccharides like fructose and glucose which will then ferment into ethanol .  This also helps prep the agave for the next step, extraction.

Chemistry of Cooking

Agave plants are unique in their carbohydrates composition. In particular, Agave species contain fructan, a fructopolysaccharides with varying degrees of polymerization. Fructans are long chains of fructose connected via beta 2-1or beta 2-6 bonds .

Studies proposed that fructopolysaccharides naturally function as an energy reserve for the agave plants and osmoprotectants in dry environments where agave species thrive.  During the cooking step, steam extracts sugars and other compounds from the agave heads (piña) by diffusion, generating a sweet juice known as ‘‘cooking honey” that is collected during this step . As a result, long chains of fructose are broken into fermentable carbohydrates including free fructose or short chain fructosaccharides. In addition, oxidation and dehydration products of sugars that play an important role on the flavour of the final product are also generated during this step. Some independent food experts suggest that ester compounds are also important for the unique flavour of each although no consensus has been reached .

On the other hand, initial cooking contributes to the flavour of Mezcal by catalyzing Maillard reactions involving inulin and amino acids . Studies done in certain species of Agave have shown that increase in cooking time directly lowers pH value, increases concentration of reducing sugar, and is proportional to concentration of Maillard products such as furan, aldehydes, terpene . Traditional earthen pit cooking requires longer time, which perhaps contributed to enhanced flavour as more Maillard products will be generated. For this reason, Mexican government regulation permits only earthen Pit and brick oven cooking for traditional and artisan Mezcal .

List of Maillard Reaction Products Found in Mezcal

Processing the Agave

Cooked agave is crushed and its juice is extracted in a mill. A horse is used to help with the process.

Concentration of fructose, reducing sugar and Brix plotted against time.

After cooking, the agave is crushed, washed in hot water to extract the sugar-rich juice from the fibrous material, and transferred to fermentation vessels, along with its juice and some remaining pulp and fibre. In traditional mezcal production, fermentation often begins naturally. Microorganisms may come from the agave itself, the equipment, wooden vats, and the surrounding environment, although some producers use a prepared starter culture . Once fermentation begins, yeasts consume glucose and fructose, producing ethanol, carbon dioxide, and compounds that shape the final flavour.

This process is commonly performed in a mill , done to extract fermentable sugars for fermentation. Difference in methods of milling contributes to difference in quality as hand milling and tahona (milling with a stone wheel) preserves insoluble fibre including pectin. Pectin under fermentation is converted to methanol, an undesirable substance, instead of ethanol. As a result, artisan and traditional grade Mezcal, which only permits the aforementioned two methods of milling, contains lower methanol levels .

The aforementioned microorganisms present can vary considerably among mezcal producers. Yeasts commonly found in artisanal fermentations include Pichia kudriavzevii, Saccharomyces cerevisiae, and Kluyveromyces marxianus . Lactic acid bacteria and Zymomonas mobilis, an ethanol-producing bacterium, have also been identified . Together, these microorganisms produce alcohol, organic acids, and volatile compounds. The particular mixture found in each fermentation helps give mezcal its distinctive aroma and taste.

The distillation of alcohol directly contributes to the mezcal's higher alcohol percentage compared to non-distilled alcohol. Ethanol’s boiling point is lower than that of water, implying that ethanol evaporates first while leaving water behind. The vapour of ethanol can then be collected on other side of distillation apparatus .

Since cooking is a necessary step for fructan hydrolysis and flavour development, raw juice obtained by diffusers is cooked afterwards in retorts or heated tanks before fermentation, which is the next step in the process .

Fermenting

Fermentation of mezcal is done using the whole mash and put into special vessels .  These are usually made of leather or wood, but other materials are used depending on the region.  A yeast starter is required and the type of yeast used in the fermentation depends on the producer.  Different types of yeast contribute to different types of volatile compounds which contribute to the smell, while other yeasts are involved with ethanol production .  After some time, the alcohol content of the mezcal will inactivate the yeast, halting fermentation and allowing it to move on to the next step, distillation .

Fermentation also depends on the agave species, yeast strain, temperature, and available nutrients. A yeast that grows well in one type of agave juice may perform poorly in another . Natural fermentation can take approximately 8 to 30 days, with the timing and outcome varying from batch to batch. Research suggests that adding a locally selected yeast starter and an appropriate nitrogen source can improve sugar use and fermentation efficiency . As discussed in Lesson 9, starter cultures give producers greater control and consistency. Open fermentation is less predictable, but its diverse microorganisms can create more varied flavours.

Distillation

Copper still pots used for mezcal distillation.

Two distillation steps are carried out in the production of mezcal. Only a few more technified factories achieve the desired alcohol content in one step by using distillation columns or through a special still design . The first distillation is called "ordinary" where the still is filled with equal parts of the liquid and fiber component from the fermentation tanks, obtaining 15-25% of ethanol . The second step is called "rectification" and it is achieved by distilling the obtained liquid again in either copper or clay pot stills, increasing the alcohol concentration to 45-50% of ethanol . During the entire process, the pot stills are frequently heated with wood, and some other ingredients can be added to the marcerate or extract to obtain flavoured mezcal . The clay pot stills are smaller than the copper stills, which hold about 100 litres, and are more common for use in rural areas. Mezcals from clay pot stills usually have an earthy character .

A special form of mezcal is called “Pechuga”, in which mezcal is usually distilled a third time, whereby fruits or nuts are added to the still or a raw, cleaned and skinned chicken breast is hung into it. Instead of a chicken breast, turkey breast, rabbit breast, venison and others can be used (“Pechuga” is derived after the Spanish name for “breast”). Some pechugas are made after the first distillation to increase the presence of the agave aromas in the distillate .

After distillations, mezcal can either be bottled or undergo aging process.

Food Safety & Regulations

Regulation

Mezcal production and labelling in Mexico is governed by the Norma Oficial Mexicana: (NOM) NOM-070-SCFI-2016, ALCOHOLIC BEVERAGES-MEZCAL-SPECIFICATIONS , which was developed by the National Advisory Committee for Standardization of the Secretariat of Economy (CCONNSE). The NOM determines: what qualifies as mezcal (1), labelling requirements (2), safety (3), additives (4) .

1. What Qualifies as Mezcal

According to the NOM, mezcal is defined as :

• A Mexican distilled alcoholic beverage, of 100% maguey or agave, obtained by the distillation of juices fermented with spontaneous or cultivated microorganisms, extracted from mature heads of cooked magueys or agaves, harvested in the territory covered by the Resolución. It is a liquid with an aroma and flavour derived from the species of maguey or agave used, as well as the production process; diversifying its qualities by the type of soil, topography, climate, water, authorized producer, master mezcalero, alcoholic content, microorganisms, among other factors that define the character and organoleptic sensations produced by each Mezcal.
  • The territory is comprised of municipalities within the states of Oaxaca, Guerrero, Durango, San Luis Potosí, Zacatecas, Tamaulipas, Michoacán, Puebla, Guanajuato, Aguascalientes, Morelos and State of Mexico

2. Labelling Requirements

Mexican Labelling Requirements

Section 6.2. of NOM indicates required labelling for export, which includes :

• Brand name
• Designation of “Mezcal”
• Aging class and period
• Designation of “100% Maguey” or “100% Agave”
• Scientific or commonly used name of agave used, listed in decreasing order of quantity used if two or more species of maguey or agave have been used
• The designation “PROTECTED DESIGNATION OF ORIGIN”
• The name of the state of the United Mexican States (Mexico) where the Mezcal was produced.
• The name or corporate name, tax address, and Federal Taxpayer Registry number of the authorized producer, bottler/packer, or registered commercial holder.
• An engraved or marked lot identification for traceability
• The designation “Made in Mexico” or “Product of Mexico”

Canadian Labelling Requirements

Labelling requirements for alcoholic beverages are governed by the Canadian Food Inspection Agency (CFIA), which includes :

• The Spirit Drinks Trade Act (S.C. 2005, c. 39) indicates the use of Spirit Drink Names, and is administered by Agriculture and Agri-Food Canada (AAFC).
  • Section 13 indicates that “Mezcal may be sold under that name if it has been manufactured in Mexico in accordance with the laws and regulations of Mexico governing the manufacture of Mezcal”
• “Alcoholic beverages with prescribed standards in volume 2 of the Canadian Food Compositional Standards (CFCS) document, incorporated by reference into the FDR include [...] some requirements are set up for tequila and mezcal in the FDR [B.02.090, B.02.091, FDR]”
  • Section B.02.091 indicates that “No person shall modify Mezcal that is imported for the purpose of bottling and sale in Canada as Mezcal except by the addition of distilled or otherwise purified water to adjust the Mezcal to a required strength.”

Alcoholic beverages sold in Canada are also subject to the provisions of the Food and Drug Regulations (FDR). Mezcal is an unstandardized alcoholic beverage (for which there is no standard in volume 2 of the CFCS document) and is exempt from declaring a list of ingredients [B.01.008 (2)(f.1), FDR] .

Nutrition Facts Table

Beverages with an alcohol content of more than 0.5% are usually exempt from carrying a Nutrition Facts table [B.01.401(2)(b)(i), FDR] .

Front-of-Package (FOP) Nutrition Symbol

Alcoholic beverages with an alcohol content greater than 0.5% are conditionally exempt from the FOP nutrition symbol requirements, when not required to declare an NFt [B.01.350(13)(a), FDR]. The product will be subject to the nutrition symbol labelling requirements if required to carry an NFt, for example, when a nutrient content claim is made .

Alcohol by Volume Declaration

All alcoholic beverages containing 1.1% or more alcohol by volume must declare the percentage by volume of alcohol contained in the product [B.02.003, FDR] .

Manner of Declaring

The percentage by volume of alcohol must be shown as "X % alcohol by volume" or be abbreviated "X % alc./vol." or "X% alc/vol". Alternatively, the percentage may be in the middle of the declaration and shown preceded by the abbreviation "alc." or "alc" and followed by the abbreviation "vol." or "vol" (for example: "alc X% vol" or "alc. X% vol.") [B.02.003, FDR] .

Location

The alcohol by volume declaration must be shown on the principal display panel [B.02.003, FDR]. For wine containers, the principal display surface includes any area, excluding its top and bottom, that can be seen without having to turn the container, as per paragraph (g) of the principal display surface definition [B.01.001(1), FDR; 1, SFCR] .

Language

The alcohol by volume declaration must be shown in both English and French [B.01.012(2), FDR]. The French translation is "X % d'alcool par volume". When abbreviated, the statements "X % alc./vol.", "X% alc/vol", "alc X% vol" and "alc. X% vol." are fully bilingual .

3. Safety

The NOM outlines the following ranges of substances :

Specs	Units	Minimum	Maximum	Applicable Standard
Alcohol by Volume at 20 °C	% Alcohol by Volume	35	55	NMX-V-013-NORMEX-2013 (See 2.6)
Dry Extract	g/L of Mezcal	0	10	NMX-V-017-NORMEX-2014 (See 2.7)
Fusel Alcohols	mg/100 mL of anhydrous alcohol	100	500	NMX-V-005-NORMEX-2013 (Version 2.5)
Methanol	mg/100 mL of anhydrous alcohol	30	300	NMX-V-005-NORMEX-2013 (Version 2.5)
Furfural	mg/100 mL of anhydrous alcohol	0	5	NMX-V-004-NORMEX-2013 (Ver 2.4)
Aldehydes	mg/100 mL of anhydrous alcohol	0	40	NMX-V-005-NORMEX-2013 (Version 2.5)
Lead (Pb)	mg/L	-	0.5	NMX-050-NORMEX- 2010 (Version 2.8)
Arsenic (As)	mg/L	-	0.5	NMX-050-NORMEX- 2010 (Version 2.8)

Notably, Methanol (formula CH3OH) formerly known as “wood alcohol”, has physical and sensorial properties like ethanol . However, methanol is more toxic than ethanol and its content in beverages is heavily restricted in all countries through quality and public health standards.

Methanol is a serious food safety concern in agave spirits as it forms during the fermentation of pectin rich plant material. The ingestion of larger amounts of methanol (for example 2 ml for an adult) causes damage to the organism . Other contaminants, such as lead and arsenic, are also closely monitored.

4. Additives

According to the NOM , Mezcal may contain sweeteners, colorings, flavorings and/or aromas as additives. When additives are included, the mezcal becomes a type indicated as abocado con: a type of mezcal to which ingredients such as maguey worm, damiana, lemon, honey, orange, mango, etc. (with the inclusions of sugar, sugar cane, honey, worms, and scorpions as well) are added , provided that they are authorized by the corresponding Agreement of the Ministry of Health . However, under the Canadian definition, spices, seasonings, flavouring preparations, essential oils, oleoresins and natural extractives are NOT considered to be additives.

Different aging methods and times leads to variation in colour. Reposado (left), Anejo 1 year (middle), Anejo 6 years (right)

Production & Packaging

Ageing

There are no real ageing requirements for mezcal . However, aged products typically fall into three categories:

• Reposado ("rested"): Mezcal that is aged for 2-12 months in wooden barrels which have no restrictions on their size, shape, or capacity .

• Madurado en vidrio ("matured in glass"): Mezcal that is aged for more than 12 months in a buried glass container .
• Añejo ("aged"): Mezcal that is stored at least 12 months in wooden barrels with a maximum capacity of less than 1000 litres .

A common feature among the three aging methods is the requirement of minimal variations in light, temperature, and humidity. This requirement is critical to better control the colour, texture, and flavour of the mezcal.

Bottling

After distillation, the spirit product is cut to bottling proof–almost always using the weakened alcohol by-product left over from the distillation process . While other spirits and their producers may/are required to use water to distill the alcohol content within their product, it is a traditional practice of those producing mezcal (e.g., the Del Maguey Single Village company) to instead use a bottling proof made from the body of the spirit (cuerpo) and the tails (colas) . This by-product is rife with furfural and methanol–a naturally occurring chemical compound generated by the cooked agave . Before the bottling itself, mezcal is often stored and sealed in plastic containers to be tested for quality in the laboratory . However, the final product is distributed and stored in glass bottles because it is non-reactive and is the universal packaging for liquor . Any other storage containers have the ability to destroy liquor aroma and flavour . Most mezcal products, aside from reposado, madurado envidrio, and añejo, are bottled within weeks of distillation to preserve the pure agave flavours. Un-aged mezcal products (joven) make up about 95% of all mezcal sold , and are often seen as a more traditional preference.

Storage Instructions

The shelf life of mezcal is indefinite due to its high alcohol content and it should be stored properly to maximize the shelf life . Unopened bottles of mezcal should be stored upright in a cool, dry place away from direct sunlight . Once a bottle of mezcal is opened, the contents may begin to slowly evaporate and may lose some of its flavours, but it still remains safe to consume if it’s stored in a cool, dry, dark place with the lid on tightly .

Although it has indefinite shelf life, it should be discarded if it develops an off odour, flavour, and/or appearance .

Mezcal v. Tequila: A Comparison

Mezcal and tequila come from the same plant family, and tequila is technically a type of mezcal restricted by law to a single agave species and region . What separates the two products is not the plant genus but the processing choices made at nearly every stage: which agave species is used, how the piñas are cooked, how the sugars are extracted, how fermentation is carried out, and how the spirit is distilled. Each of these choices leaves a measurable trace in the final product's chemistry and sensory profile .

Agave Species

Tequila must be made from Agave tequilana Weber, commonly called Blue Weber agave, grown within five designated Mexican states [2]. Mezcal has no such restriction and can legally be produced from more than 30 agave species, with Espadín being the most common . Because different agave species vary in sugar content, fiber structure, and native microbial populations, this single regulatory difference is one of the largest drivers of flavour variability between the two spirits.

Cooking

Tequila producers typically cook piñas in steam ovens or autoclaves, a process that takes a matter of hours and allows tight control over temperature . This controlled, largely steam-based cooking produces minimal smoke character. Mezcal, in contrast, is traditionally cooked in wood-fired earthen pits lined with hot stones, a process that can take three to five days . This slow, direct-contact cooking with burning wood is the primary source of mezcal's characteristic smoky aroma, since combustion byproducts are absorbed directly into the agave as it cooks.

Milling & Extraction

Industrial tequila production mostly relies on mechanical roller mills to extract juice from the cooked piñas . Many artisanal mezcal producers still use a tahona, a large volcanic stone wheel traditionally pulled by a horse or mule, to crush the cooked agave . The tahona method is slower and less efficient than mechanical milling, but producers argue it extracts juice alongside more fibrous material, which can add texture and complexity to the final fermentation.

Fermentation

Tequila fermentation commonly takes place in stainless steel tanks using a single cultivated yeast strain (most often Saccharomyces cerevisiae) over a short, controlled period of two to four days . Mezcal fermentation is more often carried out in open wooden vats using wild, airborne yeasts, with fermentation stretching anywhere from five to fifteen days or longer . This open, uncontrolled fermentation allows for a broader and less predictable microbial community to develop.

Distillation

Tequila is typically double-distilled in stainless steel column stills, a method that produces a clean, consistent, high-purity spirit . Mezcal is more commonly distilled in copper or clay pot stills, a less efficient method that retains more of the volatile compounds carried over from cooking and fermentation .

Why the Differences Matter

Each processing choice tequila makes trades character for consistency: standardized cooking, a single agave species, cultivated yeast, and column distillation together produce a clean, repeatable, agave-forward spirit that tastes broadly similar from batch to batch. Each choice mezcal makes trades consistency for character: pit cooking, wide species selection, wild fermentation, and pot distillation together produce a spirit that is inherently more variable, smokier, and more terroir-driven, with flavour shifting noticeably between regions, producers, and even individual batches. Neither approach is more or less "correct" from a food science standpoint. They represent two different sets of processing decisions optimized for two different goals, industrial consistency versus artisanal variability, and the resulting chemistry and sensory profile of each spirit reflects that .

Final Product: Colour & Taste

The final taste and colour profiles of mezcal vary, depending greatly on the agave plant itself, and whether the product was aged and for how long. In all, consumers can choose from a variety of flavour profiles, from sour and peppery, to fresh and even fruity . However, in its purest form, mezcal is often described as having a smoky taste. As some consumers don't prefer the smokiness, alternatives in which this flavour is removed via steam cooking the agave on purpose, are also sold .

If the mezcal is aged using wood, it then ends up adding a more oaky and vanilla taste to it . The overall taste of mezcal is influenced by the type of agave species used, the region it’s cultivated in and when the plant is used during the production process .

The concluding colour of mezcal ranges from colourless/clear, to a light yellow or a dark amber . This spectrum of colours is largely caused by the tannins present in the spirit, which ultimately depends on the place of manufacture and the way it was aged, either with or without using oak wood . Whether it's produced in Durango or Oaxaca, both final drinks will exhibit colours which slightly contrast one another, even if they are both aged the same way .

Fun Facts

1. Mezcal originates 3000 years ago from the Aztecs .
2. The oldest liquor in Latin America is considered Mezcal .
3. Throughout generations, families of experts control the harvesting and production of mezcal who then pass that knowledge down through others .
4. There aren’t many approved companies that are authorized in Mezcal production; about 5 companies in 9 states in Mexico .

Exam Questions

How does mezcal get its alcohol content?

a. Maillard reaction

b. Fermentation of glucose into ethanol with the addition of a yeast starter

c. Fermentation of glucose into ethanol without the addition of a yeast starter

d. Ageing in wooden barrels

This question is relevant to Lesson 9 as part of microbial changes in fermentation. This question has a very clear, correct answer and is not too tricky. We feel like it’s on par with some of the other exam questions we have encountered. Both options A and D are processes that mezcal goes through; however, they do not produce alcohol. Option C is the opposite of the correct answer, but the reader needs to know that a yeast starter is required for alcohol in mezcal.

The process of fermenting glucose into ethanol with the addition of a yeast starter is a method of preservation that helps extend the shelf life of mezcal. Due to its high alcohol content, it is a shelf-stable product; it can be stored and consumed almost forever if storage instructions are properly followed.

It's also important for students to apply the concepts learned from Lesson 9 on how alcohol production occurs to that of mezcal and observe the similarities and differences, since we only learned the common alcohol drinks such as apple cider.

Which agency below is responsible for labelling requirements for alcoholic beverages?

a. CFIA

b. Industry Canada

c. City of Vancouver

d. Health Canada: HPFB

e. BC Ministry of Health

Labelling requirements for alcoholic beverages are governed by the Canadian Food Inspection Agency (CFIA). This question should be on the final exam as it is related to Module 4 as part of Mandatory Labelling. The format is similar to quiz and midterm exam questions, and the difficulty level feels appropriate for the course. It is a good measure of basic Canadian food regulation and labelling knowledge.