MEZCAL: EVERY SIP BEGINS WITH A

MEZCAL

Written by GARY SPEDDING, PH.D. An Eighty-Plus Named Family of Agave-based Distilled Spirits

EVERY SIP BEGINS with A.

There are more than two hundred species of the plant genus Agave, making it one of the most interesting and complex groups of plants in the world, filled with great diversity and adaptations. One such adaptation includes the production of a single massive inflorescence (group or cluster-of-flowers — the largest here among plants) where after growing for sometimes more than 30 years, the rosette of leaves (pencas) and plant body die shortly after the flowering (1).

So, what has all this got to do with mezcal? Without the agave plant there would be no mezcal. As will be shown, agave plants store their energy reserves in the form of carbohydrates that are different from starchy raw materials found in cereal grains or the free sugars as with fruits, used as the source of fermentable sugars for other classic spirit styles. Commonly referred to as inulin, their story is more complex and they will be referred to as fructans and agavins more so than inulins. Distinct species and varieties of agave (wild harvested or cultivated stocks) used for mezcal production will present a vast array of nuanced flavor profiles, especially based on variations in processing conditions. Typically for mezcal production, the agave plants need to grow for about 8-12 years, and they will have their flowering stage terminated to ensure the stored energy reserves — fructans — are not consumed but remain stored in the stem, heart, or pineapple (píña) of the plant, thus making them ready for the distiller to make the most efficient use of the subsequently hydrolytically released, and, therefore, fructose-enriched fermentable sugars. Table 1 provides brief details regarding the agave plant family.

FROM AGAVE THEN ON to MEZCAL

The word mezcal (mescal or mexcal) translates from cooked or baked maguey, deriving from the Nahuatl words metl (maguey) and ixcalli (baked). Agaves (magueyes in Spanish) being the most important aboriginal food in arid and semiarid Mexico prior to the emergence of agricultural practices.(2, 3). Mezcal then is a generic name designated to all Mexican-produced agave spirits and includes products called mezcal, tequila, bacanora, raicilla, and sisal, along with effectively up to eighty total, regionally named types (1-4). The baked core or hearts of certain agave species, as noted above, being used for the various “family member” mezcals. Figure 1 shows a general map of the main production regions for the mezcal, tequila, bacanora, raicilla and sisal distillates. Table 2 illustrates the main mezcal types covered here, along with agave species often used for each type and the denominations of production origin/regions. Sidebar One presents more details on known key species of agave used for mezcal production with specific flavor profiles delivered to the final distillates via the use of such species.

The use of agave plants for beverage production had a rich cultural history prior to the introduction of distillation techniques to make mezcal spirits (2-5). That complex history can be recounted via referral to the previously noted citations. What is clear is that an amalgamation of pre- and post-Columbian techniques through American, European (Arab-Spanish culture), and Asian influence, along with developments of the Mexican peoples, most certainly did take place early in the 16th century, along with the evolution of regionally dependent techniques and processes (6). Current production methods and techniques (as noted below) are based on those used during the colonial period, with minor variations/differences and improvements applying to mezcal as the “original” main type of agave-based spirit. In comparison, the type of mezcal we have come to know as tequila is made today with ever im-

proving technology. [Note — confusion arises here as mezcal is the general class of agave-based distilled beverages but is also a distinct type of mezcal as defined historically. The other mezcals are often named after the local regions where they originated or after the agave species used for their production.]

TABLE 1 — General taxonomic details and characteristics of agave species

CHARACTERISTICS OF AGAVE

Family: Asparagaceae A large family with a complex and changing taxonomic categorization. Agave and eight related genera fall within the subfamily Agavoideae and under family Asparagaceae: 143 genera with Subfamily: Agavoideae over 3500 species. Over two hundred species of the Agave plant (formerly known as family Agavaceae) alone being noted.

Agaves: Perennial plants found widely in Mexico especially scrub and forested regions. Growing better in mountainous regions between 1000–2000 meters elevation. Plants exhibit succulent leaves, a system of superficial roots, thick cuticles in the epidermidis of the leaf and with waxy surfaces. These latter features, coupled with specific metabolic systems, allow them to grow under environmentally challenging geographies and climates. Agave plants are comprised of two main parts: (1) large leaves with spines, (penca = leaf; from some agaves the source of a strong/tough type of fiber — sisal fibers with that name also given to a lesser-known type of mescal — Sisal mezcal), and (2) the píña or pineapple which is the primary location of the agave fructans; the source for the fermentable carbohydrates for mezcal production (píña or cabeza = stem and leaf bases). Being well-adapted to several types of habitats, agave plants can grow to 1.8 meters tall with their succulent rosetta of leaves and largely buried or “hidden” stem and can weigh up to 250 Kg wet weight. The thick fibrous stem forms along with a flower and carbohydrates are laid down as an energy storage source over a life-span range of from 8 to 20+ years.

FIGURE 1 — Mezcal producing regions of Mexico

Sonora

Mezcal A. angustifolia, durangensis, potatorum, salmiana

Bacanora A. angustifolia

Tequila A. tequilana Weber var. azul

Raicilla A. maximiliana

Sisal A. fourcroydes (A. sisalana)

Durango

Zacatecas

Narayit

Jalisco

Michoacán

Guerrero

Oaxaca Tamaulipas

San Luis Potosi

Guanajuato

Mexico Yucatan

Mezcal producing regions (color coordinated) deduced from key references cited in the text (most notably, 7 and 8). Mezcal, bacanora, raicilla and tequila being the main named mezcal family types considered herein.

TABLE 2 — A summary of the main types of mezcal described in this article, common agave species utilized and designations of origin/regions of production

MEZCAL TYPE AGAVE SOURCES DESIGNATED REGION OF PRODUCTION

MEZCAL

TEQUILA

Agave angustifolia, A. asperrima, A. weberi, A. potatorum, A. salmiana var crassispina, et al. Many species depending upon State — local flora. A. cupreata, A. inaequidens, A. americana var. oaxacensis, A. karwinskii, A.marmorata. A. rhodocantha, A. durangensis — also a named species for mezcal. A. fourcroydes (Henequen A. fourcroydes Lem) in Yucatan?

Agave tequilana blue variety [Agave tequilana var Azul]

BACANORA Agave angustifolia Haw.

RAICILLA

Agave defined only by its common name: Raicilla. Though others quote: A. angustifolia, A. inaequidens and A. maximiliana. Six districts of Oaxaca (see Figure 1). All of Guerrero, Zacatecas, San Luis Potosi, and Durango, one municipality of Guanajuato, and eleven of Tamaulipas. A large area not connected tightly with natural agave species distribution or “Mezcal” regions.

181 municipalities of Jalisco, Nayarit, Michoácan, Guanajuato, and Tamaulipas. Region associated with the natural distribution of the agave species and a long history of tequila production. Thirty-five municipalities of Sonora. Associated with a long-established production of bacanora Seven municipalities of Jalisco. Coincides with the raicilla process. The agave species not so well characterized (but see left).

SISAL

Agave sisalana [May be related to A. fourcroydes] Southern Mexico — Yucatan [Regarded as a variant of Tequila, though not produced in Tequila DO territories.]

Main references drawn upon (10-12) and unpublished charts created by G. Spedding. See Sidebar One for more detail on agave species The text and Table 4 covers some more detailed notes on the flavors and flavor profiles of mezcals. See Sidebar Two for information on regulatory bodies and agencies.

HARVESTING the AGAVES

In general, agaves will have reached at least eight years of age and exhibit the right signs of maturity prior to harvesting. In readiness for mezcal production the leaves (pencas) are removed from the plant and the heart (corazón, mezonte) is cut just above the ground, the shape resembling the pineapple or pinecone (píña), except for A. karwinskii, which forms a strongly woody stem which more resembles a yucca plant than a pineapple. Harvesting is known as jima and is done manually by jimadores with special cutting tools, machetes or circular sharp blades on a long stem called coas. Careful harvesting to remove the green parts of the leaves is important to prevent the development of unwanted bitter substances during cooking. The growth, harvesting, and preparation of the agaves are succinctly described, along with the names of all the workers involved in the process, by Tello-Balderas and Garcia-Moya (13). As noted earlier, the fermentation substrate sugars arise from a different type of storage carbohydrate than found within the raw materials used for most other classic spirits. After harvesting, the agave hearts are transported to the distillery (14).

Fructans, classified according to the type of chemical bonds present and the degree of branching of their chemical structures, exist in the form of large-molecular-weight polysaccharides and short-chain-length oligosaccharides. These are built up of glycosidically linked “fruit sugar” fructose molecules (the monosaccharide building block). As glucose molecules can also be involved in bonding with fructose, a great diversity of fructans exist and, due to two configurational bonding patterns, the fructans are highly branched molecules. These carbohydrates are known as inulins, agavins, graminans, and branched neo-fructans and, due to their branching patterns and sizes, the overall spectrum of such molecules differ between different Agave species. Furthermore, the concentration of these carbohydrates increases with the age of the plant. Moreover, agricultural conditions, climate, and species can all ultimately impact the efficiency of sugar utilization for mezcal production and potential flavor profiles.

In addition to the fructans, mezcal producers must pay attention to another class of heterogeneous structural polysaccharides called pectins. Like the agavins — having varying degrees of polymerization and branching — these carbohydrates exist in the cell walls of higher plants. Cooking the agave píñas leads to the generation of methanol and this is a compound subject to regulations as to final amounts allowed in any spirit beverage. As for the fructans/agavins, the methanol content in mezcal varies and is dependent upon the species of agave, maturity of the plant, geographical origin, harvesting system (and making a clean harvest of the píña without leaf tissues), cooking temperature, grinding, shape of the still, and management of the distilled fractions.

The PRODUCTION of MEZCALS

The denomination of origin was granted for mezcal in 1994. Originally limited to five states, it included Oaxaca, Guerrero, Durango, San Luis Potosí, and Zacatecas. Subsequently, municipalities from the states of Guanajuato, Tamaulipas, and Michoacán were added in 2001, 2003, 2012, respectively, with Puebla added in 2015. This persists today, despite the knowledge that mezcal is in fact touted as produced in at least twenty-six of the thirty-two states of the country. The main regions producing the various mezcals are shown in Figure 1 and noted in Table 2 — The Types of Mezcal. Sidebar Two presents a brief outline of the denominations of origin and rules and regulations pertaining to mezcal production, safety for consumption purposes, and overall product quality. A guide to agave species used in the production of mezcals.

Notes include common names/aroma and flavor descriptors.

A. americana cv. subtilis Also known as chato, sahuayo. Maguey ash or white.

A. angustifolia Haw. The most widely distributed maguey — good yield and mild flavor. Widely cultivated in Oaxaca and Guerrero. Many subspecies/varieties. Other names: doba-yej, maguey de flor, mezcal del monte, bacanora, sprat, espadilla and espadin. Common names for several varietals of A. angustifolia used for coastal raicilla: Cenizo (literally “ashy”), Chico Aguiar, and Pencundo (literally “spiky”).

The aromas of mezcal made with this species noted as orange peel and wet woods. Flavor: slightly smoky and follows with a fruity aftertaste.

A. cupreata Sweet and “bronco” like as described for the mezcal and peoples/cultures of the Balsa basin region of Mexico. A. cupreata (Berger) aka. papalote/papalometl maguey, ancho, chino (kite or Chinese), cimarron, tuchi. Used in Guerrero.

In Nahuatl Papalometl means maguey butterfly so named due to the shape of its leaves, wide, like the wings of a butterfly. Its scientific name A. cupreata means coppery agave, due to the color of its thorns. It is distributed throughout the Sierra Madre del Sur from the state of Guerrero to the eastern part of Oaxaca. It is a mezcal with lactic aromas and mineral characteristics.

A. durangensis Exclusive to Durango (municipalities of Tamazula, Mezquital, Nombre de Dios and Durango) and Zacatecas — used for pulque and mezcal beverage production. A wild agave of variable size of broadleaf that might also be semi-cultured. Also called cenizo.

A. fourcroydes Lem. The leaves of A. fourcroydes yield a fiber also called henequen, which is suitable for rope and twine but not of as high a quality as sisal (see A. sisalana below). It is the major plantation fiber agave of eastern Mexico, being grown extensively in Yucatán, Veracruz, and Tamaulipas. It is also used to make licor del henequén, a traditional Mexican alcoholic drink.

A. karwinskii From arid areas of southern Mexico (Tehuacán Valley/central valley of Oaxaca). Has many variants to its name. Agave karwinskii (Zucc) maguey cirial or cuishe, bicuixe, tobasiche, barril — herbal and intense flavor — usually mixed with other agaves to soften the result.

Tobaziche, sub-species of Agave karwinskii commonly cultivated. The aromas of the mezcal of maguey tobaziche are described as reminiscent of the scent of chamomile and piloncillo along with predominant mineral notes. Following the initial taste of mineral and herbal flavors, the aftertastes are described as fruity and with slightly toasted qualities.

Mothercuish, like a tobaziche, but with the most abundant leaves. One of the most voluminous varieties of A. karwinskii. Its rosette detaches itself from the ground because it grows on a trunk that rises high from the ground. It is an endemic maguey of the Sierra Sur de Oaxaca and the Central Valleys. Its aromas are always mineral like the smell of sand. It is a mezcal with a smoky taste and very mineral notes.

Cuish, another member of the agave species karwinskii family, characterized as looking like a “maguey tree.” It has green-yellow leaves with black spines. In the valleys of Oaxaca, it takes between 9–11 years to mature. It is an agave that has much morphological diversity, so different names have been given to the same species such as madrecuish, barrel, or cirial. Aromatic notes, with a slight smell of pennyroyal. Taste: smoky and mineral-like.

A. marmorata Roezl Known also as variety maguey tepeztate (or tepextate). Arid regions southern Mexico. With “beautiful inflorescences” also has ornamental and ceremonial uses. Tepeztate with life cycle commonly noted as 16–18 years. The scientific name A. marmorata means maguey marmoreado (marbled) due to specific white colorations to the plant. Its striking inflorescence has important ceremonial uses. Commonly one of the magueys with the most complex aromas and flavors that range from mineral and lactic, to herbal and fruity. A. maximiliana Mezcals made using this plant were banned for a period in Sinaloa (18th century) A common species used for raicilla mezcal is A. maximiliana (Baker). Also known as lechuguilla, manso, tecolote.

A. oaxacensis Domesticated variety aka. dulce arroqueño with a long-life span. Arroqueno Agave americana var. oaxacensis. One of the largest known magueys. It is a sub-species that grows naturally only in the central valleys and southern highlands of Oaxaca. Taking 16–18 years to mature. Arroqueno de Santa Catarina Minas, distilled in a clay pot, is noted as a very fruity mezcal on the nose and on the palate with notes reminiscent of plum and melon.

A. potatorum Known as the tobalá, a wild, highly prized maguey species for mezcal production in Oaxaca. Said to carry complex and sweet flavor. AKA Tobala agave with wide leaves and red spines. Its scientific name can translate to “drinkers maguey.” One of the most recognized magueys and resultant mezcal names in Oaxaca. The tobala mezcal from San Baltazar Chichicapam is said to present sweet aromatic notes and intense notes of cooked maguey. Taste: herbal, and with fruity aftertaste.

While tobalá has commonly been classified as Agave potatorum or Agave seemanniana, studies from the last decade have confirmed that these plants are more than often hybrids between the two species, resulting in infinite morphological expressions. This shows the complexity of understanding the overall taxonomy of this vastly numbered species.

A. rhodacantha Qualities and its isolated growth in the highlands (Sonora to Oaxaca) led to the name “Mexican” for this species. The yellow Ixtlero and gives rise to the name called “creole mezcal.” One of the largest magueys — taking between 8–10 years to grow. The aromas of the distillate from the central valleys of Oaxaca are described as sweet pumpkin and ocote (resinous pine). Taste: intense smoky flavor and green leaves.

A. salmiana Broadleaf species from the highland’s region of Potosino-Zacatecano. Naturally and culturally integrated. The main wild agave species is sometimes considered to be A. salmiana subsp. salmiana crassispina (Trel) (sometimes called verde/ green, bronco/rough, manso/meek or cimarrón/maroon).

A. seemanniana Jacobi Known as maguey chato. (See A. potatorum above)

A. sisalana Possibly related to henequen A. fourcroydes with that plant’s arrival in Yucatan via the port of Sisal (see A. fourcroydes above). A rarer and little discussed mezcal class is Sisal.

A. tequilana Weber, Var azul The Tequila mezcal species (named after the town in Jalisco). Located in the states that have the denomination of origin of tequila: Jalisco, Nayarit, Michoácan, Guanajuato and Tamaulipas.

The plants are like those of the species A. angustifolia, varying in its characteristic blue color and softness of its leaves and lower regions. A. tequilana (blue Agave) is a medium-sized species that forms a spreading succulent rosette with thin, rigid blue green leaves. The high production of sugars, mostly in the form of fructose, in the core of the plant is its most important characteristic, making it suitable for the preparation of alcoholic beverages. The varietals and traditional cultivars lost over time leaving behind only the blue variety.

A total of fifty-three agave species, thirty-seven of which are wild collected from forests, with twenty incipiently managed and/ or cultivated recently are used for spirit production as noted and cross-referenced elsewhere (9). Details drawn upon from cited references, with the caveat that data will be incomplete and, especially, in view of the complexity of taxonomic relationships could be subject to revisions as more insights and studies become available. Owing to a range of factors affecting the characteristics of the harvested agave plants, including temperature, humidity, natural cycles, and average yearly rainfall during the extended growth periods, the spirit products obtained in each region are often completely different from that found in any other region. As such, cultivation, selection and harvesting, climate and geography, the species present or adopted from any one region (wild or cultivated) and how the agaves are processed contributing to a diversity of favor profiles for the mezcals.

A Quick Word about GI’s, DO’s, NOMs and NORMAs.

Geographic Indications (GI), Denominations of Origins (DO), Official Mexican Standards

(NOM/NORMA, NMX)

Mezcal and Tequila have existed under protected Geographical Indications (GI) for several decades. The Designation of Origin Tequila (DOT, 46 years old) and Designation of Origin Mezcal (DOM, 26 years) are noted here as to their development as legal documents. The rules, suggestions and regulations presented in these documents helping ensure the quality of mezcal and promoting the integrity of the industry.

The Norma Oficial Mexicana (Official Mexican Standard), abbreviated NOM, is the name of each of a series of official, compulsory standards and regulations for diverse activities in Mexico. They are more commonly referred to as NOMs or NORMA’s. These documents, prepared following the guidelines of the International Organization of Standardization (ISO), are set to regulate products, processes, and services when these may constitute a risk to people, animals, vegetables, and the environment in general. The NMX (Normas Mexicanas) form other guidelines. NMX's are voluntary standards and reference guides, and they are obligatory when a Law, Regulation or NOM obligates their use. Mezcal producers apply for a NOM and their assigned 4-digit number is representative of the distillery where the tequila is made for example and denotes that the bottle is authentic tequila produced in Mexico. Mezcal and Tequila fall under the following Official Mexican Standard classification/NOM status: NOM-070-SCFI-1994/NOM-070SCFI-2016, Alcoholic Beverages – Mezcal-Specifications/NOM006-SCFI-2005/ NOM_006_ SCFI_2012, Alcoholic BeveragesTequila – Specifications, and Bacanora: NOM-168-SCFI-2004 Alcoholic Beverages-BacanoraPreparation-SpecificationsPackaging and Labeling. Details presented here were in part drawn upon from such documents and can be found on the worldwide web.

Mezcal is now defined as a 100 percent maguey or agave Mexican-distilled alcoholic beverage. Earlier regulations allowed two types of mezcal production based on sugars derived from agaves and/or supplemented with up to 20 percent other sources. It is also further noted as an alcoholic beverage produced from one or more agaves, of which 14-20 species are often listed as most common, with Agave angustifolia, A. cupreata, A. salmiana, A. potatorum, A. pacifica (maguey), A. palmeri (Lechuguilla), and A. inaequidens the most notable (2, see Table 2 and Sidebar One). Mezcal is obtained through the fermentation, via the spontaneous inoculation or addition of cultured microorganisms, of extracted juices from the matured heads (píñas) of cooked maguey or agaves. This is then followed by the distillation of the fermented musts (or worts). The agave plants must have been harvested in the territory covered by the November 1994 resolution and as provided in subsequent modifications. Mezcal distillates are also classified into various categories, including white, matured in glass, rested, aged, “abocado con” and “distilled with.” See Figure 2 and Tables 3 and 5 for classifications and terminology.

SPECIFICALLY, TEQUILA! An INTRODUCTION and DEFINITION

Between the 18th and 19th centuries, the mezcal produced in a small town called Tequila located in the northeast of the state of Jalisco “began to acquire fame for its extraordinary quality.” The word tequila, under one interpretation, derives from the Nahuatl word tequillan, tequitl relating to tribute, tequitl meaning work or employment, and tlan meaning place (15). There are other explanations and word origins not covered here. Tequila is produced exclusively in the territory of its appellation of origin and regulated under the ruling of the latest implementation of its norma: NOM-006-SCFI-2012. See Figure 1 for a map of the territories of production and Table 2. Produced now exclusively from Agave tequilana Weber, which has been considered as the king of the agaves (16, 17),it was originally produced in the valleys of Tequila and Atotonilco in the state of Jalisco, and in adjoining areas of the states of Michoacán, Nayarit, and Guanajuato. In recent times, its cultivation has been introduced in the state of Tamaulipas. Again, further detail may be found in Table 2, Types of Mezcal, agave species utilized, and designations of origin (18-22).

The two categories of tequila are 100 percent agave tequila and tequila, sometimes called “mixto,” which has the allowable addition of up to 49 percent of other fermentable sugars, e.g., from cane, molasses, corn, or other sources, during fermentation. Following this classification, three types of tequila exist, derived from either 100 percent agave or mixto tequilas: blanco (white), reposado (rested) and añejo (aged). The NOM regulations also specify the maximum permissible levels of ethanol, higher alcohols, methanol, aldehydes, esters, and furfural — all compounds arising from the process. See Tables 2 and 3, and Sidebar Two.

MEZCAL, ARTISANAL, and ANCESTRAL MEZCAL

The goal of mezcal distillers (mezcaleros) is to efficiently recover the hydrolysable and fermentable carbohydrates from the agave plant píñas, along with other key compounds. Those components will impinge on flavor and provide nutrients for the microorganisms involved in converting the subsequently liberated sugars into, primarily, ethanol and other important flavors. Then recovering those desirable components, eliminating others, and, finally, refining the product — via dilution to appropriate alcoholic strength and, optionally, by flavor addition or by maturation in contact with wood — finishes the process.

Certified mezcals are classified by local regulations (currently NOM-070-SCFI-2016) in three general classes — industrial, artisanal, and ancestral mezcal — in accordance with the allowed procedures used. To affect the conditions as outlined above, the preparation of mezcal must comply with the following four stages utilizing the appropriate equipment: > Cooking: Cooking/baking piñas or the juices of maguey/agave in earthen pits, brick ovens, or autoclaves. This stage hydrolyzes the complex carbohydrates, liberating fermentable sugars and nutrients from the agave. > Milling: Tahona, Chilean or Egyptian mill Trapiche, or other mechanical mills. Squeezes the fermentable juice out of the agave fibers (bagasse). > Fermentation: wooden containers, animal skins, masonry basins (concrete or earthen

tanks) or stainless-steel tanks (sometimes even plastic tubs today).

Sugars are converted to alcohol and congeneric flavor molecules produced through the metabolic activities of microorganisms. > Distillation: alembic pot still made of copper or stainless steel, continuous/column stills made of copper or stainless steel. Separation and concentration of alcohol and flavor volatiles from solids and undesirable congeners happens. The success for this stage of operations is part art and science, as well as the unique experience of each distiller.

A summary of the processes involved in the production of each class — mezcal, artisanal and ancestral — is presented in Figure 2. See Figure 3, Table 5, the glossary of important terms pertaining to mescal production to get a full grasp of the various certified classifications and the tools and implements of the trade used for processing the raw materials into finished mezcals. Ancestral mezcal is defined as the spirit manufactured by exclusively pit-cooking and mallet or stone-milling the maguey (agave) with a final distillation comprising a direct heating of the raw fermented material in clay pots sealed with clay or wooden jackets. Thermal regulation is ensured in part through the presence of the agave fibers (bagasse). The use of stainless steel in ancestral mezcal production is not allowed. Artisanal mezcal distillers may use mechanical shredders for milling, and either copper alembics or stainless-steel vessels for distillation. The use of autoclaves for cooking or diffusers (see below) to extract juices from cooked agave or column stills for distillation are, as of now, prohibited for artisanal mezcal. Each of these three categories of mezcal can be made with any agave and bottled between 35-55 percent ABV.

Mezcal COOKING: Cooking of maguey or agave heads or juices in pit, elevated stone ovens, masonry or autoclaves. AGAVE: Cultivated vs. wild maguey (agaves) most likely used. Espadin! GRINDING: Tahona (rotary stone), Chilean or Egyptian mill, trapiche (drawn by mule/horses), harrowing machine, mill train/heartbreaking/shredder mills. FERMENTATION: Wooden containers, masonry basins or stainless steel tanks. Sometimes plastic tubs/vats used today. Cultured yeasts likely used — more flavor control. DISTILLATION: Alembic stills — continuous or columns — copper or stainless steel columns. Most modern part used — Firewood or gas heat. Less smoke/flavor with gas heat. More consistent flavor possible. Artisanal Mezcal COOKING: Cooking of maguey or agave heads in pit (earth) or elevated masonry ovens. Based on: Cooking, Grinding, Fermentation, Distillation specifications MEZCAL CLASSIFICATIONS AGAVE: Use of wild or locally grown agaves. GRINDING (manual): With mallet/canoe, tahona, Chilean or Egyptian mill, trapiche (wooden roller mill) or harrowing machine. Maybe today shredder/electric mills. FERMENTATION: cavities in stone, soil or trunk, masonry basins, wooden or clay containers, animal hides/skins, whose process may include the fiber of the maguey or agave (bagasse). Fermentation may be spontaneous — wild yeasts/bacteria giving rise to flavors based on their metabolic actions. DISTILLATION: Direct fire in copper boiler stills or clay pot and clay, wood, copper or stainless steel cap/montera, whose process can include the fiber of the maguey or agave (bagasse). Retains smoky flavor — mainly made in micro-distilleries. Ancestral Mezcal COOKING: Cooking of maguey or agave heads in pit ovens. Well furnaces — stone or earth pit. AGAVE: A. angustifolia Haw (Sprat) GRINDING: Mallets (mazo), Stone wheel (tahona), Chilean or Egyptian mill. FERMENTATION: Cavities in stones, soil or trunks, masonry basins, wooden or clay containers/ barrels, animal skins/leather. Process may include the fiber of the maguey or agave (bagasse). Spontaneous inoculations of local microbes. DISTILLATION: Direct fire in a clay pot and a clay or wooden hat/cap (coils). Process can include the fiber of the maguey or agave (bagasse). Retains smoky flavors (pine/mesquite woods used for fires). Flavors from earth/stone/mud contact (local microbes impact). Agaves covered with stones, palms, agave leaves (pencas), etc., during cooking/baking. NOM-070-SCFI-2016 a) White or Young : Colorless and translucent mezcal that is not subject to any type of subsequent process after distillation other than proofing down. b) Matured in Glass : Mezcal stabilized in a glass container for more than 12 months, underground or in a space with minimal variations in light, temperature and humidity. c) Rested : Mezcal that must remain between 2 and 12 months in wooden containers that guarantee its innocuousness, without restriction of size, shape, and capacity in L, in a space MEZCAL CLASSES with minimal variations in brightness, temperature and humidity. d) Aged — Reposado : Mezcal that must remain more than 12 months in wooden containers that guarantee its innocuousness of capacities less than 1000 L, in a space with minimal variations in brightness, temperature and humidity. Containers of white oak or with oak wood. Aging not as common for mezcal as for the tequila class. e) Focused or Flavored (“Infused”) with Abocado Con : Mezcal to which ingredients must be directly incorporated to add flavors, such as the maguey worm (larvae), damiana (shrub with aromatic flowers), lemon, honey, orange, mango, among others, as long as they are authorized by the corresponding Agreement of the Ministry of Health and other NOM regulations. f) Distilled with (Destilado con) : Mezcal that must be distilled with ingredients to incorporate flavors, such as turkey or chicken breast, rabbit, mole (the condiment), plums, among others, in terms of this Official Mexican Standard. Other ingredients used locally — iguana/cooked pork. Pechuga the most well known. Only mixing mezcal of the same category and class is allowed.

CLASSICAL MEZCAL METHODS

AGAVE

(1) COOKING

Earth/ Stone Pit or

Oven

(2) MILLING

Egyptian or Chillean Mill/Tahona or

Canoe (canoa) + Mallet (mazo)

Juices +/- Bagasse on to FERMENTATION, then DISTILLATION AGAVE Autoclave

Raw Materials Oven

(1) Cooking/ Baking

(2) Milling Shredding

Extraction by diffuser Bagasse

Hydrolysis (boiling) Fermentation

Roller Mill

Bagasse

TEQUILA PRODUCTION

Dilution

(5) Resting/ Maturation

Dilution

Bottling 2nd Distillation Rectification

(4) Distillation

Pot Stills

(3) Fermentation Yeast

Addition of other sugars for Mixto Tequila

1st Distillation Ordinary (ordinario)

Culture Propagation

Stillage Stillage

Vinasses

MORE MODERN TEQUILA PROCESS

This figure is based on several works of Miguel Cedeño (19, 20), lecture notes taken by the author from presentations made by the esteemed Mr. Cedeño and several other works. Brief details about the Diffuser technology found in the text and the Manual Del Técnico Tequilero (24).

NOTES on the COOKING of AGAVE – MEZCALS

Agave is cooked in ancestral pits/stone furnaces using volcanic rocks heated red hot with firewood and then covered to protect the loaded agave pineapples. Whole or split agaves are then manually placed inside and covered with branches, sheets, or other lightweight material (Figure 3). Cooking time lasts between 48 to 72 hours. The surface layer of the oven may then be allowed to cool down after cooking, or the cooked agave píñas can be removed while still hot prior to the next stage — grinding (molienda). Overall, this is quite an inefficient process due to the loss of honeys (the resulting sugar syrups) partially due to caramelization and poor management of the cooked agave. Stone furnace surfaces also harbor microorganisms and, as the agave is exposed to the environment, this can also impact yield of alcohol during fermentation. The flavor characteristics of the mezcals obtained in this process include smoky aromatics and a strong flavor of cooked agave. They may also carry notes of hay or palm — as palm leaves may be used as coverings in the pit ovens. In addition to pit ovens, tall kilns with back-flues and rear pit ovens, fueled by firewood, have and may still serve the same purpose for cooking.

Again, it is noted that the descriptions of the milling methods and the designs of the mills used for the extraction of the agave sugar juices or honeys, are outlined in Figure 2, with such tools of the trade showing the ingenuity of early cultures in the manner of food and beverage preparation. Descriptions of the terms are presented in Table 5. Juices, now as musts or worts with or without attendant agave fibers (bagasse), will then be readied for fermentation.

Fermentation – Mezcals

Traditionally, spontaneous fermentation would have been used as there was little understanding of the indigenous microorganisms involved in the then-mysterious conversion of the sweet honeys into alcohol and other flavorful ferments. A complex interplay of microorganisms is involved and has been extensively studied but is not further discussed here. The metabolic activities of yeasts and bacteria contribute to the flavor profiles of the resultant mezcals.

Distillation Processes in Mezcal Production

Alembic and column stills have been traditionally manufactured with copper. Stainless steel sees more use today. The role of copper in the removal of unpleasant aromatic sulfur compounds such as thiols present in distillates exerts a favorable effect on the sensory character of tequila and mezcal. Two stages are involved in substitution of the earlier used one-stage distillation system to meet official regulations. For the record, distillation in Oaxaca is sometimes accomplished using stacked clay pots (23). Some mezcal distillation operations are conducted with agave bagasse and firewood as a heat source with the traditional mezcal classification seeing more use of gas heat today. Distinctive sensory notes in mezcal include soil, smoke, and acidity. The compounds conveying these qualities are clearly all collected during the distillation.

The PRODUCTION of TEQUILA

As noted above for other mezcals, the sugars for tequila fermentation need to be liberated from the agave fructans (inulin/agavins) by the process of hydrolysis (splitting in the presence of water), and this may be achieved via chemical, thermal, or enzymatic mechanisms or a combination of these methods. In the case of tequila, 100 percent of all the sugars must come from the agave plant. In mixto tequila a maximum 49 percent of total sugars may be derived from processed cane sugar (glucose and fructose), from corn, or molasses (therefore largely sucrose) (24). Important organoleptic volatiles are also produced from the manipulation of sugars during cooking and later the fermentation processes that add to the character of the finished tequila. Overcooking of sugars can lead to caramelization and methanol production. The conversion of too much sugar also leads to reduced ethanol yield. These are not as much of an overarching concern today as will be shown below.

While stone ovens were originally used, and still are in rural locations, today three different processes and equipment types are used to conduct the hydrolysis of agave polysaccharides: (1) Masonry ovens: The agave is cooked with direct steam from boilers. Such masonry furnaces saw widespread use until the 1970s; (2) Stainless steel autoclaves with agave cooked using straight steam from boilers; (3) A newer method involves the mechanically efficient extraction of the raw agave juices with the hydrolysis of the extracted polysaccharides conducted in stainless steel cooking tanks, provided with heat exchange system steam derived from boilers and delivered by means of a stainless steel or copper metal coil or a plaster to a unit called a diffuser. See Figure 3, Stages 1 and 2, and the diffuser. The main characteristics of today’s tequilas, in comparison to the classic mezcal methods, is a strong smell of cooked agave, caramelized sugar, and a sweet taste.

If diffuser technologies are not used, once cooked and then cooled down, the agaves are conveyed to a mill — shredded with rotary knives and washed under pressure to dissolve the resultant sugars from the hydrolysis (Figure 3, Step 2). The material is then pressed in a mashing unit, extracting the syrup and leaving behind the fiber known as bagazo or bagasse. The extracted juice or maguey honey is mixed with that collected from the ovens (minus the so-named first running’s of “bitter honeys”).

Fermentation – Tequila

For tequila 100 percent (100% agave sugars), fermentation will utilize only the agave-derived juices. If mixed (mixto) tequila is to be made, then 49 percent of other fermentable sugars are added in the tanks. Various sugar sources are permitted (Figure 3, step 3). The classic fermentative yeast Saccharomyces cerevisiae is the main workhorse organism used today. However, and not detailed here, the evolution of understanding of the microbiology of tequila must fermentation has led to a more careful use of selected yeast species — Saccharomyces and various non-Saccharomyces yeast species involved.

Distillation – Tequila

Fermented musts (or worts in brewing parlance) form the starting raw material for distillation in most standard or conventional operations. These contain solid particles consisting of agave fibers (cellulose, pectin), yeasts, proteins, mineral salts, and organic acids, with an alcohol content between four and up to 10 percent by volume. Distillation of tequila can be conducted by using differential and/or continuous fractionation with different conditions such as reflux, heads and tails cuts, utilization of equipment manufactured with copper or stainless steel, and heat supply rates. Pot stills and rectification columns are used today by distillers, but the pot still is the most common with two copper pots in tandem (Figure 3, Step 4).

Figure 3, Step 4 shows a more classic twostage still system — a stripping or ordinary still followed by the rectification or enriching still used for separation of the more volatile compounds. The first — a “breaking” or ordinario still — distilling the fermented must or mash to remove those solids noted above including yeast, proteins, and salts. Tequila ordinario, 2530 percent alcohol by volume, and vinaza (vinasse) are the major products. Vinasses are deep brown liquid residues generated during distilling and remain in the bottom of the still, the equivalent of stillage in other spirits’ production processes. Other volatiles will still be present and include heads (acetaldehyde, methanol, and ethyl acetate) and tails (amyl alcohol, other fusel oils, other ethyl esters, other higher alcohol esters, furfural, and sometimes acetic acid). Some distillers will separate the first volume of distillate (the heads) and this cutoff is recycled to fermented must or pumped to a heads and tails storage tank.

The second-stage distillation, rectification (rectificación), takes the heart cut (the tequila ordinario) from the first still to obtain tequila rectificado, which is purer and higher in alcohol content, up to 55 percent v/v, and containing desired congeners, the flavorful molecules. Heads and tails fractions constitute further waste product. Distillation continues until runoff distillate has an ethanol content around 25 percent ethanol v/v. The distillate obtained after this cutoff is called tails. How the distiller makes the cuts will vary from distillery to distillery. Separating the heart fraction from the head and tail fractions allows the still operator to attain a spirit cut or fraction, with the appropriate concentration levels of congeners conveying the desired organoleptic characteristics, while also avoiding undesirable components such as methanol and the earlier generated furfural and related Maillard compounds. This stage of the operation provides another variable leading to nuanced differences between brands. The primary product of this second distillation may be sold as tequila blanco (if bottled: diluted to 30–42 percent ABV) or rested or aged (see Table 3).

As to continuous distillation systems, these are described in detail elsewhere (25). It is noted here, however, that the quality of the distillates produced using only pot, pot and column, or simply modern column stills will be quite different. This also applies to the amount of copper that the spirit is exposed to during distillation.

Maturation of Tequila

As noted, especially in Table 3, there are officially noted and classified process types or classes of matured-in-wood mezcals. Full details of resting and maturation, which is common for tequilas though recently more mezcals have been subjected to it, of mezcals are briefly outlined in Figure 2 and Table 3.

OTHER MEZCALS

Bacanora

Bacanora is a variety of 100 percent agave mezcal with classification under NOM-168SCFI-2004, made using Agave angustifolia Haw., in the mountainous regions of the eastern part of the State of Sonora (2). The name is derived from the town’s name of Bacanora and produced in an artisanal way. This mezcal is distinguished from other mezcals due to adoption of a procedure known in Sonora by the term “resaque” (26). This involves, during the rectification stage operation, the mixing of the first distillate heads components (a carefully collected fraction of high alcohol content) arising out of the alembic into the second stage rectified spirit to adjust the alcohol content in a process to “compose” it. This ends up conveying a different palate profile to such mezcals, giving them distinguishing flavor characteristics with descriptors including smoke/smoky, citric, leather, and straw (27). Bacanora has white, rested, or aged types (see Table 3). In October 2000, a declaration of protection for a denomination of origin for Bacanora, which confined it to thirty-five municipalities in the east and to the state of Sonora, was issued and presented a month later in the Official Gazette of the Federation representing this spirit.

Raicilla

The cultural heritage of the west coast mountain region Costa-Sierra Occidental of

TABLE 3 — Summary of all mezcals classes including bacanora, raicilla and tequila MEZCAL CLASS TYPE AGING PERIOD (See footnotes) CONTAINER TYPES

White or Young (Blanco or Joven) Not Aged NA

Matured in glass (Madurado en Vidrio) At least 12 months Glass containers

Rested (Reposado) 2-12 months Wood containers

Aged (Añejo)

At least 12 months Max. 1000 L wood containers Silver (Blanco) Not Aged NA Gold (Joven or Oro) Not Aged (See far right column) NA

Aged (Reposado) A mellowing period of at least 2 months

Extra Aged (Añejo) At least 1 year

Ultra-aged (Extra Añejo) At least 3 years White oak (Quercus alba) or holm oak (Q. ilex) barrels or tanks

Max. 600 L wood containers

White (Blanco) Not Aged NA Gold (Joven o Oro) Not Aged NA Aged (Reposado) At least 2 months White oak or holm oak barrels or tanks

Aged (Añejo)

At least 1 year Max. 200 L white oak or holm oak barrels Young, White, or Silver Not Aged NA Golden (Dorado) At least 2 months to 1 year White oak or holm oak barrels or tanks

Aged (Añejo)

Grand Aged More than 1 year, and less than 2 years

White oak or holm oak barrels or tanks At least two years White oak or holm oak barrels or tanks

The Tequila category Silver (Blanco) is transparent though not necessarily colorless and understood to be without additives and with distillates diluted with water. However, certain regulated amounts of sweeteners, coloring agents and flavorings may be added post-distillation and resting for less than 2 months in oak or Encino oak containers is permitted. Blanco bottles labeled “joven” thus typically contain a small amount of aged tequila blended with unaged tequila. Tequila añejo is tequila aged in American or European oak barrels for at least a year. Barrels made of other wood species may also be used by some distillers for aging and blending. Caution: Joven — young or gold tequilas — amber color can indicate the age of a tequila, however, the class of oro or gold tequila may simply be tequila plus caramel coloring and/or artificial flavoring as noted above.

The result of blending aged tequila with extra-aged tequila is considered aged tequila. The result of blending extra-aged tequila with ultra-aged tequila is considered extra-aged tequila. The result of the blends of white bacanora with rested and / or aged bacanora is considered as young or gold bacanora. In mixtures of different bacanoras reposados, the age for the resulting bacanora is the weighted average of the ages and volumes of its components. In mixtures of different aged bacanoras, the age for the resulting bacanora is the weighted average of the ages and volumes of its components. Such is the same for the other classes of mezcals — the respective and most current NOMs always carry the full details.

NOMor Reference to Classification and Notes NOM-070-SCFI-2016 NOM-006-SCFI-2012 Joven or Oro: a product of the mixing of white tequila with aged, extra aged, or ultra-aged tequilas. May also be a product resulting from the blending of silver tequila with caramel coloring, natural oak or oak extracts, glycerol, or sugar- based syrup to soften or mellow the flavor of the spirit. NOM-168-SCFI-2004 (CMPR 2018) DOF: 06/28/2019 No NOM in place yet. Under development/ consideration. Aged in glass and flavored with and distilled with categories also in place. (See Figure 2) Jalisco is associated with the production of another 100 percent agave artisanal mezcal style/type known as raicilla. As of June 2019, it is produced (under degree of a denomination of origin in both the mountain and coastal areas of Jalisco and Nayarit, seventeen municipalities between both states (see the map in Figure 1). Raicilla is made with distinct types of agaves: rhodacantha and angustifolia along the coastline, and with maximiliana, inaequidens and the “giant mezcal agave” valenciana included in the mountain regions. Made in the artisanal way, with wooden and copper utensils, with the sensory characteristics of the raicilla arising from the properties of the medium in which the agave grows, as processed from the natural elements such as earth and water, along with oak firewood to cook the pineapples (28). A specific NOM does not yet exist for raicilla, though it is covered under the DO, General Declaration of Protection of the Racilla Designation of Origin (DOF: 06/28/20129). The classes of raicilla spirits are noted in Table 3. In addition, as for other mezcals, raicilla may be aged or matured in glass over twelve months, underground or somewhere with minimal variation in light, temperature, and humidity. Storing in glass (especially buried underground) is a traditional practice that is stated to soften the raicilla over time without lowering the alcohol content. It may also be made “abocado con” — “flavored or infused with” ingredients noted elsewhere in the text and “destilado con” — “distilled with,” a pechuga process, in which fruit, meat, or other ingredients are present in the still during a distillation (29, see Tables 3 and 5). This is only permitted in artisanal and “ancestral tradition” categories.

Mezcal aromas and tastes (flavor)

Mezcals have distinctive and unique aromas and flavors with regional and brand differences inherent in their make-up. Moreover, they convey quite different flavor profiles compared to most other distilled beverages, while still harboring the more common distilled spirit volatiles. From raw materials,through all stages of production, flavor molecules or precursors to flavor volatiles arise or are extracted or chemically manipulated to collectively yield an ultimate flavor profile. All classes of chemical components are present in the final spirits, and a very brief outline only could be presented here (see Table 4). Differences between mezcals and the tequila class type will be apparent in the richness of Maillard compounds for example, presence or absence of smoky notes (from the use of wood, with mesquite sometimes used for mezcal baking operations) and nuances of the earth — soil, mud, plus acidity from bacterial activities (12). Less smoky character in tequila in general and an even cleaner profile for tequilas is made via the implementation of diffuser technology (see Figure 3).

SENSORY EVALUATIONS and EXPECTATION of CONSUMERS

Trained sensory teams will use technically correct terms and chemical names to describe products being assessed. A review of the literature, both scientific and promotional in nature, reveals the descriptors that sensory panelists in training or those workers looking at consumer opinions will use to describe mezcals. Generic flavor wheels may be found in the open environment — the worldwide web. These are tools to guide the evaluator to look for specific flavor nuances (memory joggers) to seek out the keys to defining the profile of the spirit under the nose and as it tastes. However, with a suggested eighty or so named mezcals in the entirety of Mexico, only selected basic information could be illustrated here (and that for the more common classes). To assist, a figure has been provided illustrating key terms applicable to mezcals and to the tequila class specifically and the differences and similarities in flavor descriptors to look for when assessing future mezcal taste experiences. See Figure 4 and refer also to Table 4 for specific flavor descriptor information and to see how, why, and when these flavors might arise (23, 27, 28, 30-33).

With a high degree of training and an overall understanding of the flavor profiles and origins, it is

Raw material or process stages associated with the origin and formation of the flavors associated with mezcals, along with some chemical species and common names. Plus, notes of general flavor descriptors ascribed to the sensory perceptions of the listed volatiles.

AGAVE RAW MATERIAL

Components: Plant — carbohydrates (sugars), organic acids, amino acids, lipids, terpenes derived from metabolic activities of the plant. Specific chemical compounds: Lipids including fatty acids, glycerol, and sterols. Many flavorful terpenes. Flavor descriptors or notes of sensory characteristics: Those free fatty acids passing through to finished product providing some oily notes and dairy/musty flavor characteristics. Cooked agave has odor-flavor notes of browning reactions as noted below. Agaves also donate spice flavors, due to the presence of eugenol and wood related compounds (vanillin and syringaldehyde), as well as terpenes with floral and herbal notes. Volatile acids can donate sour attributes and vanilla and other woody notes may appear in white/silver tequilas as derived from the agave plants. Agave flavor, and the fruitiness and vinous character are provided by fermentation (more on this below).

COOKING

Components: Important organoleptic volatiles are also produced from the manipulation of sugars during the cooking and later fermentation processes that add to the character of the finished spirits. Overcooking of sugars can lead to their caramelization. Via the complex Maillard reaction combinations of amino acids and sugars lead to flavorful products. Cooked agave thus has odor-flavor notes of browning reactions that are reminiscent of caramel, molasses, or raw brown sugar. They are also similar to cooked pumpkin and overripe or fermented fruits. If mud/earth pits used for cooking — microbes present can add acidic contributions to flavor. Mud and earthy notes and specific firewood and plant materials used as coverings also provide smoky and other notes. Specific chemical compounds: Important Maillard chemistry by products include, furfural, acetyl furan, 5-methylfurfural (5-MHF) and derivatives of pectins (heteropolysaccharides which are mixed sugar polymers). An issue with respect to pectins is the release of methoxy groups responsible for methanol production. Firewood and charring of agave pineapples produce some phenols like guaiacols. Flavor descriptors (general for the Maillard compounds) or notes of sensory characteristics: Toasted, burnt, nutty, caramel, candy-like, meaty, astringent. Phenols convey smoky, burnt, and spicy notes. Acids from bacterial action: acetic and lactic — vinegar and dairy notes. Three major furans of note and that have been used to discriminate mezcal brands are: • Furfural (brown, sweet, woody, bready, nutty, almond, caramellic with a burnt astringent nuance) • 5-Methyl Furfural (sweet, brown, caramellic, grain, maple syrup-like) • 2-Acetyl Furan (sweet, nutty, almond, cocoa, caramel, coffee, roasted and with a sweet, baked-goods like characteristic)

MILLING

Continued Maillard reactions. Bitter substances from residual leaves/tissues possible. Mud and dirt from pit coverings may convey earthy, musty notes etc. FERMENTATION

Components: Esters, alcohols, acids, terpene manipulation and many other metabolites — sulfur compounds, ketones. Specific chemical compounds: Ethanol the key desired alcohol. Ethyl acetate — main ester produced. Isoamyl acetate and other ethyl esters. Ketones include diacetyl (2,3-butanedione). Aldehydes and acetals possible. Flavor descriptors or notes of sensory characteristics: Esters are solventy, fruity and floral. Ethyl acetate — solventy and fruity nuances. Iso-amylacetate — fruity, banana, pear nuances. Diacetyl — buttery, dairy-like yogurt notes. Aldehydes — green/fresh green floral and woody notes. Fermentation provides a vinous character due to the production of higher alcohols Terpene transformation and release, carried out by yeast, also contribute to herbal-floral characteristics. Among impact compounds, phenylethanol has been reported as odor-active, with a floral odor, with β-damascenone contributing to a fruity-winey aroma. These compounds reported as odor-active components with indications that 3-methyl butanol and phenylethyl acetate generate a fermented fruit note.

DISTILLATION

Distillation — second or rectification stage. Alembics and columns have been traditionally manufactured with copper — today stainless steel gained higher relevance. Copper is noted as exerting a favorable effect on the sensory character of tequila and mezcal due to its role in removing unpleasant aromatic sulfur compounds such as thiols present in distillates.

Specific chemical compounds: Leads to 45-50% ABV, ethanol and methanol plus the higher carbon length alcohols — more than three carbon atoms. The alcohols 2-butanol, 3-methyl-1-butanol, 2-methyl-1-butanol (active and isoamyl alcohol isomers) and 1-pentanol form the bulk of the fusel oils. Flavor descriptors or notes of sensory characteristics: High concentrations of phenylethanol (floral, honey, roses) and the amyl alcohols (banana, pear) add some of the leading floral and fruity aromatic and flavor characteristics to mezcal. Other higher alcohols can lend harsh solventy, rubbing alcohol-like and bitter flavor impressions.

MATURATION

Components: Estery congeners, higher alcohols, and acids plus many other metabolic compounds from the raw white or flavored spirit. Plus, lignin-, hemicellulose-, tannin-derived wood components, lipids, oils, terpenes, lactones, furfural, and related compounds plus phenolics derived from the wood. Specific chemical compounds: As a major class of compounds found in spirit beverages, key esters are of note in mezcals. (Most flavor studies to date made on tequila samples). Certain terpenes, higher alcohols and fresh/green earthy acetals also show increased aroma-flavor intensity in mature versus non-mature spirit. The source material, the size of the barrels used in maturation (surface contact), as well as the duration of spirit contact, generate different volatile profiles in tequila and can offer a variety of sensory nuances. Oaky, nutty, and spiced flavors, as well as enhanced vanilla and caramel notes, are found in the rested and aged tequilas. With prolonged aging, the woody bouquet may override the agave notes.

Mineral Earthy/ Land (tierra) Fermented Chemical Wood (madera), Smoke (humo), Ash (olor ceniza) Alcohol Spices (especias), Herbal (hierba) Candy (caramelo) Fruity (frutal) Floral Citric (citrico) Agave — cooked (maguey cocido — olor a maguey cocido), burnt (olor a maguey quemado) notes Tastes: Sweet (sabor dulce), sour (sabo agrio), salty, bitter (aftertaste sabor residual amargo) Sensations: spicy (picante), hot (calor), unctuous (untuoso), rough (aspero), cool (fresco) General Similarities

Lemon Fruity Agave Caramel Woody Guaiacol Vanilla

Other terms: fruity — strawberry, jelly (gelatin), green grass, cedar wood, petroleum, vitamins, musty, menthol, plastic, wet earth and leather. Solvent Straw Burnt Smoky Mud Generally Different Attributes of Mezcals in comparison to Tequilas Rancid

Stronger Alcohol Piquant Acetic Herbs

TEQUILA

Smoked Piquant Almond Anise Varnish Citric Rancid coconut Fermented Fruity, Dried Fruit Flowery Resinous wood Wet straw Vanilla

Three month old Gold (Oro) Tequilas:

Smoke Almond/cherry Caramel Cork Citrus Mint Plastic/cherry Vanilla Vinegar/ fermented

Based merely on few studies, the figure shows notable descriptors to evaluate mezcals and tequila styles and brands (29-34). Mezcal and tequila are essentially represented here, however, with notes drawn from bacanora and raicilla sensory research. The key terms covered here but recalling that there may be eighty different regionally named mezcals further work is needed in this arena. This table should provide a good starting point. suggested that an assessor might be able to pinpoint the place of production of these agave-based spirits. A tall order maybe, but as mezcals gain in worldwide popularity it may be a worthy challenge to sample glasses of a selection of spirits to see what you can learn. Sensory characteristics of a product are considered today a key quality factor, often adding a sense of place, and so sensory programs and the understanding of flavor profiles are becoming of evermore importance to the modern

TABLE 5 — Glossary of a few important terms pertaining to mescal production.

Abocado Flavored or infused mezcal. Mezcal that has been “softened” by the addition of one or more natural products, flavorings or colors allowed within the legal and health/sanitary regulations. This category includes all mezcals that have an insect, fruit, or herb included the bottle. Agavina A specific name given to agave fructans. Alambic/Alembic A copper-pot still used to make artesanal mezcal. Its evaporation chamber is separated from its condensation chamber by a gooseneck. There are four parts that make up the alembic still system: Pot: Contains the mixture of substances to be separated – buried within a cubic structure under which logs are placed that generate heat required for the separation of alcohol from the fermented must. Montera: Captures vapors generated after heating the mixture and leads them to the condensation/recovery stage. Based on its shape it is also often known as a bell. Turban: An elongated tube responsible for conducting the vapors towards the cooling section. Serpentine: Typical of distillation systems this is a spiral-shaped tube, immersed in a tank with water. The purpose being to cool and, therefore, to condense the vapors coming from the pot. Ancestral mezcal Applied to mezcals made from maguey heads cooked in conical floor ovens, ground using a tahona or manually using mallets, fermented with maguey fiber, and distilled with direct fire in pots of mud and with wooden hats. Artesanal mezcal Artisan mezcal. Type of mezcal obtained through a production process based on in traditional techniques. It is considered as a product of good complexity where the congeners produced during fermentation are present at a medium level, giving rise to the notes of cooked agave and the “green” notes of the plant. Cabezas de mezcal Heads of mezcal. First fractional part of the distillation that is separated and sometimes discarded. Also called “tips.” Also known as Puntas de mezcal – “points or heads of distillation.” Flavorful and high in alcohol, they are sometimes used to adjust the final alcohol content of mezcal. Campana An internal part of an alembic where certain items (fruits, chicken breasts, etc.) are placed/suspended with the objective of producing distillates with certain characteristics (fruity mezcal, mezcal de breast – pechuga, etc.) Canoa Canoe. Lined concave bowl or cavity or made of wood (e.g., hollow tree trunk) that is used for manually mashing the cooked agave. The agave is pounded and ground up via the use of wooden mallets. Larger canoas may also be used for fermenting cooked agave. Colas de mezcal Tails of the mezcal. “Queues” or cuts. Tails of the distillation – the last running’s. The tails are separated as are the heads. Cuerpo de mezcal Body of mezcal. The desirable spirit fraction resulting from mezcal distillation – the heart – collected in between the tips (heads) and the tails Difusor Diffuser. Machinery for industrial production of mezcal – mainly tequila (or mezcal in Oaxaca). Allowing for the efficient extraction of the carbohydrates from raw agave by means of diffusion. Such equipment replacing the traditional cooking and grinding stages of mezcal production. Hydrolysis of the fructans to fermentable sugars then achieved by means of an autoclave. May also be used to extract juice from cooked maguey. Ensamble Mezcal made from two or more types of agaves to obtain a mezcal with particular and desired characteristics. Example in the state of Puebla the species combined are A. angustifolia (Espadín or Espadilla), and A. potatorum (Papalometl). Fructano Fructans. The class of polysaccharides formed as straight or branched chains of fructose, with a terminal glucose unit. Found in all species of agaves. Their synthesis is carried out in the leaves but is transported to the plant stems to serve as an energy store. When suitably hydrolyzed it provides the fermentable sugars for mezcal production. Furfural A notable chemical compound from within the class of compounds known as furans. An aldehyde derived via cooking reactions – Maillard reactions and caramelization of sugars. Conveying nutty, burnt, and almond aromas to mezcals its concentration is regulated based on health reasons. This compound is limited to a maximum of just 4 mg/100 mL of absolute ethanol in all classes of tequila. Also derived from agave lignocellulosic components. Gusano blanco White (maguey) worm. Acentrocneme hesperiaris, is the larva of a butterfly, which grows in the leaves, stalks, and roots of the maguey. It is white (except brown head and limbs), and in Mexico it is eaten fried. Is related with the chinicuil, which is also a red colored edible worm, yet parasitic to the maguey plants, but red. The worm is added to certain brands of mezcal during the bottling process. It is suggested that this tradition began around the year 1940. See Mezcal con gusano below, and the text. Gusano rojo Red (maguey) worm. Hypopta agavis, also called “chinicuil” or “tecol” – more correctly known as Comadia redtenbacheri Hammerschmidt, Of the order Lepidoptera (a moth though some might call it a colored night butterfly) and native to North America. The name derived from chinicuil or chilocuil – Nahuatl chilocuilin, “chili worm.” These larvae/caterpillars are of a reddish in color and up to 5 cm long. This species attacks the maguey plant and causes damage but are also edible and has by custom been included as a “flavoring” ingredient in mezcal. Belatobes is a Zapotec word that applies to maguey worms (H. agavis), which are added to some mezcals in the state From Oaxaca. See Mezcal con gusano. Heartbreaking mill Mechanical or electrically driven implement used to tear the heads or pineapples of cooked agave. Varied types and sizes. Workings through the application of rotary discs and hammers. Horno Kiln. The Space where cooking of the heads of agave (pineapples) takes place. There are several types of ovens, which vary by region based on variables such as shape, capacity and the materials used for their construction. Industrial mezcal Type of mezcal obtained through a process characterized by use of semi-automated equipment such as diffuser or distillation columns. It is cataloged as a product with truly little expressiveness and poor congenerics. Commonly made with added flavorings and sugars sourced from commodities other than agave. Note: Since the latest NOM for the mezcal category (i.e., not Tequila) the diffuser in not allowed for use. Maguey Common name for agave. The preferred term for agave in Oaxaca. The Spanish conquistadores brought the word with them from Hispaniola. One type of agave can have different names depending on the region. Therefore, the name is given by the producers of mezcal. Etymologically, the word maguey, is derived from the Greek meaning “admirable.” in Nahuatl it is called “Metl.” Maillard reaction When amino acids and sugars react under heat conditions a rich reaction cascade known as the Maillard reaction takes place – much like the toasting of bread, to yield many flavorful compounds, with rich, sweet, caramel, toasted, nutty and burnt nuances. Under extremely high heat conditions sugars react together to create similar components and other complex sugar derivatives with similar flavors. One compound, furfural (2-furaldehde) is of note and concern as it is carcinogenic. See Furfural. Methanol A compound which needs to be regulated in amount for human consumption purposes. Mezcal abocado This type of mezcal is usually infused with herbs, plants, fruits, insects, or animals. The intention being to modify flavor. Flavors such as caramel or colorants are also included under this term. See Abocado. Mezcal añejo Aged mezcal. According to the NOM-070, this type of mezcal is aged in wooden barrels for more than one year. Mezcal blanco White mezcal it is the same as mezcal joven. Mezcal de pechuga Mezcal of breast. Meaning (poultry) breast. In this type of mezcal a fully defatted turkey or chicken breast is placed inside the alembic still during (typically a third) distillation. Other ingredients such as the breast of a rabbit or iguana (the latter in the mountainous regions of Guerrero and Michoacán), fruits (pineapples, bananas, apples guava, raisins), almonds mole (the Mexican condiment), cinnamon, white sugar etc., may be incorporated. In the state from Puebla, the breast is hung inside the alembic with a net or with a thread and at the steam distilled from the fermented wort passes through the breast and the mezcal acquires that characteristic aroma and flavor. Defined as the Destilado con class in the Norm.

The Ejutla District of Oaxaca is known for “Mezcal of fruits” – when distilling in an alembic includes a puree made with various fruits (banana, apple, pineapple, etc.), and mezcal that is obtained acquires a taste and aroma of the fruits used. Mezcal joven In English means 'young mezcal'. According to the NOM-070, this type of mezcal is unaged. Therefore, it is transparent, and the flavors and aromas are those from the agave and derived from components generated during the production process. Mazo Large wooden mallet used for hand-mashing cooked maguey in ancestral processes. Mezcal raicillero Raicilleros typically

day mezcalero and tequilero. It is important for the producer to highlight the sensory characteristics of each product within the brand, and to know, or to show, how that profile derived from its traditional manufacturing method (now including diffuser technology for tequilas), as well as the relationship to its geographical origin (33).

Gary Spedding, Ph.D. is a brewing, distilling, and sensory analytical chemist, and owner of Brewing and Distilling Analytical Services, LLC — with two facilities (Lexington, KY and Denver, CO). Acknowledgments. I would like to thank Dr. Ana G. Valenzuela-Zapata for the useful comments she made over the past two years in response to questions I posed to her regarding agave and mezcal. Any errors or omissions here remain my responsibility. This brief review has arisen out a major work submitted by me for a book chapter to appear in a new Distilled Spirits volume in 2022. Knowledge and information was gained from hundreds of documents represented in the statements both here and in that book chapter manuscript. Overall, I hope that I have done justice to this vast topic. Finally, I note a good many new papers have been published, or are due out soon, in 2021 and beyond which are, and will, help us to further unravel the details of the vast richness of beverages and flavor enjoyment that agave plants, the fermentation of their hydrolyzed juices, and their subsequent distillation have provided us for hundreds of years.

call agaves by their older names of “mezcales.” A mezcal raicillero is any agave varietal used to make raicilla. Madurado en vidrio “Matured in glass.” One of the categories of mezcal as defined by the Norm or NOM. Mezcal reposado Rested mezcal'. According to the NOM-070, this type of mezcal is aged in wooden barrels for two months to one year. Metl Nahuátl word for “agave.” The word “mezcal” is derived from metl ixcalli – “cooked agave.” Mezcaleros Name given to a person who has some relation with mezcal through its production or distribution. Mezcal afrutado Fruity mezcal. Mezcal to which fresh or dried fruits were added at the time of distillation. Providing components lending certain visual or organoleptic characteristics such as distinguishing colors, aromas, or tastes. Ordinario Liquid condensed from the first distillation of maguey juice. When re-distilled (rectified), it becomes mezcal. Palenque Oaxaca term for a traditional mezcal distillery. Often part of the mezcalero’s home or property. It is characterized using family labor, traditional technology and local materials (including cultivated or wild agaves). The term also applies to a shallow round hole, built with stones, in which the agave pineapples art cooked. Palm leaf Plant leaves used to cover the heads of agave during cooking, especially in the states of Michoacán and Guerrero, where the species Brahea dulcis (Soyate palm) exists. Such trees are common on cliffs in rough terrain and dry woodlands. Penca Spiky and fleshy leaf of the maguey. Píñas Name given to the heart of the maguey. Is the part used for mezcal production. Raicilleros Producers of raicilla in the state of Jalisco, Mexico. Also called Taberneros. Rectificación Second-stage distillation. Process used after the first stage mezcal distillation to achieve the desirable alcoholic level (greater than 40% ethanol by volume), and flavor and taste. Refinado is also a similar term for final adjustments of spirit qualities. Shredder mill Machine used for shredding agave into a fibrous mass by means of rotors, hammers or strings with variable capacities. Tahona Tahona Chilena: circular stone pool or cement grinding in which another circular stone*, of approximately five hundred kilograms turns, that being pulled around by a pack animal (horse or mule). This type of mill is called Chilean mill, Chilean tahona, Egipcio o chileno, or Egyptian mill. In some mezcal regions it is also called trapiche or tahona. Of Egyptian origin, it was the main piece for the crushing of minerals given its efficiency in the Chilean region, hence also came to be referred to as an Egyptian mill. *(Molino) The large stone wheel used to crush the baked/roasted hearts of agave rendering them into a fermentable mash. It is typically pulled by a donkey or a mule. Taverna A traditional raicilla distillery. Tepache In this context, fermented maguey juice ready to be distilled. Tequila A regional alcoholic beverage obtained by the fermentation and distillation of musts derived from cooked agave heads or hydrolyzed juices of the species A. tequilana Weber (azul = blue variety) and produced in territory covered by a denomination of origin. Musts – derived from the agave plants may be supplemented or enriched and mixed with other sugars up to a proportion of no more than 49%. Tequila is a liquid that can be colored, when has matured, or has added coloring ingredients. Approved sweeteners, coloring agents and flavoring as allowed by the Ministry of Health are used to provide or intensify color, aroma and/or flavor. Tequila should taste of the materials from which it has been produced Tequileros Name given to a person who has some relation with tequila through its production or distribution. Vinasses Liquid waste resulting from the production of mezcal. It is an acidic liquid extremely aggressive to the environment. Vinatero Person (in Sonora) in charge of supervising the production of bacanora – equivalent of the master mezcalero.

Terms derived from many references cited in the text and with special acknowledgement to the author of the Mezcalero Breviary for a complete dictionary of terms (35). Some of the detail here is repeated in the text and the other tables. Terms only covered by their definition here will assist understanding of mezcal types, production and flavors etc., as introduced in the main body text. 1. Eguiarte, L. E.; Jiménez Barrón, O. A.; Aguirre-Planter, E.; Scheinvar, E.; Gámez, N.; GascaPineda, J.; Castellanos-Morales, G.; Moreno-Letelier, A.; Souza, V. Evolutionary ecology of Agave: distribution patterns, phylogeny, and coevolution (an homage to Howard S. Gentry). Am J Bot. 2021, 108 (2), 216-235. doi: 10.1002/ajb2.1609. 2. Bahre, C.J.; Bradbury, D.E. Manufacture of mescal in Sonora, Mexico. Economic Botany. 1980, 34(4), 391-400. doi: 10.1007/ BF02858316.

3. Zizumbo-Villarreal, D.; Colunga-GarcíaMarín, P. Early coconut distillation and the origins of mezcal and tequila spirits in west-central Mexico. Genetic Resources and Crop Evolution. 2008, 55(4), 493-510. doi: 10.1007/s10722-007-9255-0.

4. Bruman, H.J. Alcohol in Ancient Mexico. The University of Utah Press. 2000.

5. Valenzuela-Zapata, A.G; Buell, P.D; Solano-Pérez, M.D.; Park, H. ‘Huichol’ stills : a century of anthropology - technology transfer and innovation. ACM Crossroads Student Magazine. 2013, 8, 157-191.

6. Jiménez, E.S.; Oregón, F.T.; Nonato, J.C. Conocimiento y empleo de destiladores de mezcal en el siglo XVI. Influencia y continuidad en tres experiencias de fábricas mezcaleras de México (Knowledge and use of mezcal distillers in the 16th century. Influence and continuity in three experiences of mezcal factories in Mexico.). Universidad Autónoma de Guerrero (UAGro) ca. 2017, (article undated). 23 pages. 7. Lopez Romero, J.; AyalaZavala, J.F.; Aguilar, G.; PeñaRamos, E.; Ríos, H. Biological activities of Agave by-products and their possible applications in food and pharmaceuticals: Biological activities of Agave extracts. Journal of the Science of Food and Agriculture. 2017, 98. doi: 10.1002/jsfa.8738. 8. Bowen, S. Divided Spirits Tequila, Mezcal, and the Politics of Production. Berkeley: University of California Press. 2015. 9. Figueredo-Urbina, C.J.; Casas, A.; Torres-García, I. Morphological and genetic divergence between Agave inaequidens, A. cupreata and the domesticated A. hookeri. Analysis of their evolutionary relationships. PLoS One. 2017, 12(11), e0187260. doi: 10.1371/journal. pone.0187260. 10. Renard, M-C.; Arista, D.R.D. 10 The geographical indication of mezcal in Mexico. In, Geographical Indication and Global Agri-Food: Development and Democratization (1st ed.). Bonanno, A., Sekine, K., & Feuer, H.N. (Eds.). Routledge. 2019, 173-186. doi. org/10.4324/9780429470905. 11. Granich, C.I. The Case of Mezcal, Mexico. Guide to Geographical Indications. International Trade Center. 2010. doi.org/10.18356/dfcbaa39-en. 12. Vera-Guzmán, A.M.; GuzmánGerónimo, R.I.; López, M.G.; Chávez-Servia, J.L. Volatile Compound Profiles in Mezcal Spirits as Influenced by Agave Species and Production Processes. Beverages. 2018, 4 (1), 9. doi:10.3390/beverages4010009. 13. Tello-Balderas, J.J.; GarcíaMoya, E. The Mezcal Industry in the Altiplano PotosinoZacatecano of North-Central Mexico. Desert Plants. 1985, 7(2); 81-86.

14. Martínez, S.; Nuñez-Guerrero, M.; Gurrola-Reyes, J.N.; RutiagaQuiñones.; Paredes-Ortíz, A.; Soto, O.N.; Flores-Gallegos, A.C.; Rodriguez-Herrera, R. 4. Mescal An Alcoholic Beverage From Agave Spp. With Great Commercial Potential. In Alcoholic Beverages, Volume 7: The Science of Beverages. Edited by A.M. Grumezescu and A.M. Holban. Woodhead Publishing. 2019, 113-140.

15. Lappe-Oliveras, P.; MorenoTerrazas, R.; Arrizón-Gaviño, J.; Herrera-Suárez, T.; GarcíaMendoza, A.; Gschaedler-Mathis, A. Yeasts associated with the production of Mexican alcoholic nondistilled and distilled Agave beverages. FEMS Yeast Res 2008, 8 (7), 1037-52. doi: 10.1111/j.15671364.2008.00430.x.

16. Prado-Ramírez, R. Tequila and mezcal distillation technology : Similarities and differences. In Sustainable and Integral Exploitation of Agave. Antonia Gutiérrez-Mora (Ed). CIATEJ. 2014; pp 72-76. 17. Gentry, H.S. Agaves of Continental North America. University of Arizona Press. 2004. 18. Gaytán, M.S. The perils of protection and the promise of authenticity: Tequila, mezcal, and the case of NOM 186. Journal of Rural Studies. 2018, 58, 103-111. doi: 10.1016/j. jrurstud.2017.12.017. 19. Cedeño, M. Tequila production. Crit Rev Biotechnol 1995, 15 (1), 1-11. doi: 10.3109/07388559509150529.

20. Cedeño Cruz, M., 15 - Tequila production from agave: historical influences and contemporary processes. The Alcohol Textbook (4th Edition). Edited by K.A. Jacques, T.P. Lyons, and D.R Kelsall. Nottingham University Press. 2003; pp 223-245. 21. Lopez, M.G. Tequila from Mexico. Brewer & Distiller International. Dec. 2013, 58-59. 22. López, M. G., Authenticity: The Case of Tequila. In Authentication of Food and Wine, American Chemical Society. 2006, Vol. 952, pp 273-287. doi:10.1021/bk-2007-0952.ch018 10.1021/bk-2007-0952.ch018.

23. Medina, M.G. Rethinking Mezcal: A New Materialist Approach. MSc. Thesis. Wageningen University & Research. 2018.

24. Manual Del Técnico Tequilero (Tequila Technician Manual) Consejo Regulador del Tequila (Tequila Regulatory Council). 2019.

25. Cedeño Cruz, M.; AlvarezJacobs, J. 15 - Production of tequila from agave: historical influences and contemporary processes. The Alcohol Textbook (3rd Edition). A reference for the beverage, fuel and industrial alcohol industries. Edited by K.A. Jacques, T.P. Lyons, and D.R 27. Álvarez-Ainza, M.L.; GarcíaGalaz, A.: González-Rios, H.; Prado-Jaramillo, N.; AcedoFélix, E. Análisis Sensorial y de Compuestos Volátiles Minoritarios en Destilados de Agave angustifolia Haw (Bacanora). (Sensory Analysis and Minority Volatile Compounds in Distillates of Agave angustifolia Haw (Bacanora)). Biotecnia. 2015, Vol. XVII (3); 22-29. 28. Gutiérrez-Coronado, M.L.; Acedo-Félix, E.; ValenzuelaQuintanar, A.I. INDUSTRIA DEL BACANORA Y SU PROCESO DE ELABORACIÓN BACANORA INDUSTRY AND ITS PROCESS OF PRODUCTION. Ciencia y Tecnologia Alimentaria (Food Science and Technology) 2007, 5 (5), 394-404. doi: 10.1080/11358120709487718.

29. Arrizón, J.; Arizaga, J.J.; Hernandez, R.E.; Estarrón, M.; Gschaedler, A. Production of Volatile Compounds in Tequila and Raicilla Musts by Different Yeasts Isolated from Mexican Agave Beverages. In Hispanic Foods, American Chemical Society: 2006, Vol. 946, pp 167177. doi:10.1021/bk-2007-0946. ch014/10.1021/bk-2007-0946. ch014.

30. Mozqueda-Balderas, R.; Delgado-Alvarado, A.; HerreraCabrera, B.E.; López-Vargas, S. Evaluacion sensorial del mezcal de la localidad de Totomochapa, Tlapa de comonfort, Guerrero, Mexico (Sensory evaluation of mezcal from the town of Totomochapa, Tlapa de comonfort, Guerrero, Mexico). AGROProductividad. 2018, 11, 81.

31. Villanueva-Rodriguez, S.J.; Escalona-Buendia, H.B., 18 Tequila and mezcal: sensory attributes and sensory evaluation. In Alcoholic Beverages, Edited by J. Piggott. Woodhead Publishing. 2012; 359-378. doi.org/10.1533/ 9780857095176.3.359.

32. Villanueva-Rodríguez, S.J.; Rodríguez-Garay, B.; PradoRamírez, R.; Gschaedler, A. Tequila: Raw Material, Classification, Process, and Quality Parameters. In Encyclopedia of Food and Health, Caballero, B.; Finglas, P. M.; Toldrá, F., Eds. Academic Press: Oxford. 2016; pp 283-289. doi.org/10.1016/ B978-0-12-384947-2.00688-7.

33. García-Barrón, S.E.; Guerrero, L.; Vázquez-Elorza, A.; Lazo, O. What Turns a Product into a Traditional One? Foods. 2021, 10 (6), 1284. doi:10.3390/ foods10061284.

34. Carador-Martínez, A.; Estarrón-Espinosa, M.; GonzálesRobles, I.W.; Martín-del-Campo, S.T. 4 Fermented Products Produced from Agave. In Agave: Characterization, Analysis and Uses. Edited by Eilish Engman. Nova Science Publishers. 2018.