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APRIL 2022 HAWAII BEVERAGE GUIDE VOLUME 73, NO. 10 APRIL 2022 PUBLISHED MONTHLY

APRIL 2022 HAWAII BEVERAGE GUIDE VOLUME 73, NO. 10 APRIL 2022 PUBLISHED MONTHLY HAWAIIBEVGUIDE.COM PHONE (808) 591-0049 BEVERAGE GUIDE THE M ISSUE The Science of Tequila In the production of a distilled spirit, the first question that needs to be answered is: What is being fermented? The answer, when it comes to alcoholic fermentation, lies on a molecular level, because it is a mo lecular process which requires glucose or sucrose to undergo alcoholic fermentation by Saccharomyces cerevisiae. However, in many fermentations, a raw material needs to be transformed into glucose or sucrose first. Metl in the Náhuatl language, or maguey (de Sahagún et al., 1970), is more recently known as “agave,” a term used by botanist Carlos Linneo in 1793, who derived the word from the Greek word “agavus,” which means admirable and illustrious. For this guide, we referenced The Alco hol Textbook Fourth Edition: The reference for the beverage, fuel ethanol industrial alcohol industries. Edited by K.A. Jacques, T.P. Lyons, D.R. Kelsall. Published October 15, 2003, by Nottingham University Press. We highly recommend purchasing a copy, as it provides technical insight from the distiller’s perspective, as to what goes into the development of a spirit. In par ticular, we used the chapter "Tequila pro duction from agave: historical influences and contemporary processes" by Miguel Cedeño Cruz. The 4th Edition: www.whitelabs.com/merchandise- detail?id=91&type=MERCHANDISE The 5th and 6th Editions: www.lallemandbds.com/en/canada/ ethanol-technology-institute/the-alcohol- textbook/ We also recommend reading hawaiibev guide.com/agave-spirits as that is the pre- cursor to this article. Plant Biology of Agave Agave are monocarpic plants which are those that flower, set seeds, and then die. This process is ultimately the way to tell the agave has reached full maturity. It is also a crassulacean acid metabolism (CAM) plant, that is, a plant that reduces the amount of water lost through respiration by open ing its stomata at night and fixating CO2 to malate to produce malic acid using PEP carboxylase, which accumulates during the night when the temperature is cooler, and closes its stomata while breaking down the malic acid to use the CO2 for photosynthe sis during the day. Though this metabolic process is similar to a cactus, the agave is in the lily and ti leaf family. To make tequila, only the agave spe cies Agave Azul, also known as Agave te quilana, Blue Weber Agave, or Blue Agave may be used. The Chemical Composition of Agave Azul Fructose is the monosaccharide that is fermented by yeast. However, fructose in agave is stored in complex chains called fructans, which must be broken down to be accessible to yeast for fermentation. Agave Sugar: Fructans and Agavins Fructans, a polymer of fructose molecules attached to one or more glucose molecules, are the primary type of sugar in agave, and the second most abundant nonstruc tural polysaccharides in nature (the most abundant being starch).1 They are primar ily stored in the agave’s rhizome (piña), the key ingredient in agave spirits. Fructooligosaccharides (FOSs): Short chains of fructose and less complex than a fructan. These are indigestible and pass through the intestinal tract before being fermented in the large intestine by bacte ria into lactate and short-chain fatty acids to yield 1–2 kcal/g rather than the 4 kcal/g of digestible carbohydrates.2 Fructans Accumulation Factors in agave: • Agave species have fructans that vary by molecular shape and the distribu tion of fructan types.3 However, we have not found any research on the organoleptic influence of the type of fructans present in agave. The pri mary fructans in Agave tequilana, for example, are branched inulin-levan type fructans which contain inulin, levan, and neo-inulin groups linked together4, rather than the previously- thought inulin type fructans.5 • Fructans are affected by agave grow ing location and conditions, in par ticular, factors like climate, rainfall, altitude, and soil. For example, Man cilla-Margalli and López (2006) noted that in 6-year-old Agave tequilana propagated asexually by rhizomes6: • Los Altos Jalisco • Temperature Range: 8-22 °C • Rainfall: 705-870 mm • Average dry weight of soluble carbohydrates (WSC): 900 mg/g Penjamo, Guanajuato • Temperature Range: 18-24 °C • Rainfall Range: 700-800 mm • Average dry weight of soluble carbohydrates: 550 mg/g • The high sea level and fresh nocturnal temperatures favor uptake of CO2 and consequently carbohydrate accumulation. An analysis of carbohydrates in Agave te quilana by Waleckx et al. 2008 found: • Fructans (93.4%) • Free disaccharides (2.0%) • Free glucose (0.8%) • Free fructose (3.8%) • Fructan bound glucose in agave as a ratio to glucose is estimated to be at least 1:15 4 For more detailed insight into Agave fructans: López, Mercedes G. & Mancilla-Margalli, N.A.. (2007). The nature of fructooligo saccharides in agave plants. Recent Adv. Fructooligosaccharides Res.. 47-67. www.researchgate.net/publica tion/286685949_The_nature_of_fruc tooligosaccharides_in_agave_plants Classes of Fructans (from Velazques-Martinez et al. 2014) Fructan Name Number of Links fructosyl linkage location Inulan 1 β-2,1-linkages Levan and Phelin 1 β-2,6-linkages Graminin 2 β-2,1-linkages and β-2,6- linkages Neo-inulin /inulin neoseries Multiple predominant β-2,1-linkages Neo-levan type/ levan neoseries Multiple predominant β-2,6-linkages HAWAIIBEVGUIDE.COM APRIL 2022 HAWAI'I BEVERAGE GUIDE 3 Fibrous solids aka bagasse (removed be fore fermentation) • Comprise approximately 40% of the total wet weight of the milled agave. • Composition (dry weight basis): 43% cellulose, 19% hemicellulose, 15% lig nin, 3% total nitrogen, 1% pectin, 10% residual sugars, and 9% other com pounds.8 • Bagasse is a byproduct of production and can be used Agave Azul Phenolics Beyond sugar, plant phenolics can provide organoleptic properties. For agave, there is limited research in regards to agave phe nolics’ impact on the organoleptic proper ties of agave distillates, however there is research related to their potential medical usages. In a study by Morales-Serna et al. (2010) of Agave tequilana grown in Jalisco, Mexico, the primary phenolics in uncooked agave were homoisoflavanones of:9 • 5,7-dihydroxy-3-(4-methoxybenzyl)- chroman-4-one • 7-hydroxy-3-(4-hydroxybenzyl)-chro man-4-one • 4-demethyl-3,9-dihydro-punctatin The study, however, did not provide any organoleptic properties, nor are there any that we were able to find. We would hy pothesize that during fermentation, these phenolics may be converted by enzymes into another aromatic molecule. The agave-derived (rather than yeast or bacterial derived) phenolics in tequila dis tillate, as found by Alcazar Magana et al (2014), were: 10 • The main source of small phenolic compounds in tequila are derived from maturation in wooden barrels. In particular these are: syringic, vanillic, protocatechuic acids. • Homovanillic acid was present in all three tequila types and in almost all samples. The authors suggest the compound may originate as-is from the A. tequilana plant, or may be formed during the tequila manufac turing process. For a literature review of agave phenolics: Almaraz, Norma & Delgado, Amanda & Ávila-Reyes, José & Uribe-Soto, José & Gonzalez, Laura. (2013). The Phenols of the Genus Agave (Agavaceae). Journal of Biomaterials and Nanobiotechnology. 04. 9-16. 10.4236/jbnb.2013.43A002. https://doi. org/10.4236/JBNB.2013.43A002 Climate (from Cedeño Cruz, 2003) • Temperature: Minimum of 3°C, an op timum of 26°C and maximum of 47°C. • Soil: • A depth of 30-40 cm. • Adequate levels of nitrogen, phos phorus, potassium, and boron are required to not impede growth.11 This can be supplemented with fertilizers, including distillery ef fluent (vinasse) which was found to increase potassium, magne sium, and calcium.12 • Good drainage is essential, as the region floods regularly, which can produce detrimental effects. • Planting season: June to September which is immediately before the rainy season. This reduces the plant’s water stress during the first year of growth. Stages of Growth (from Acosta-Salazar et al. 2021): • First stage (from 1 to 3 years): The plant generates its fundamental structure for its subsequent growth. • Second stage (from 4 to 7 years): Al most exponential increase in size as the plant begins to store water and sugars. For example, Acosta-Salazar et al. 2021 found weight increases of: • Years 4-5: Weight increase of 12.5% • Years 5-6: Weight increase of 23.18% • However, the specific amount of increase is not as important as the trend that exponential growth oc curs between years five and six. • Final stage (from the seventh year): The reproductive phase begins. This reduces the concentration of sugars and ends its life cycle. Impact of agave age on tequila Agave age is influential on the final product because of differences in the concentration of compounds, which in turn impacts fer mentation. It is confirmed however that the characterization of the final product showed the feasibility to use agaves (less than 7 years) to produce the Tequila 100% agave silver class and to comply with the quality criteria (Acosta-Salazar et al. 2021). We will be citing the following two stud ies periodically throughout this piece. • Pinal et al. 2009: The differences be tween Agave tequilana juice of differ ent ages (4 and 8 years) and of differ ent cultivation fields after cooking, and through fermentation. It should be noted that the study was to show if there were differences, but not to spe cifically define the underlying causes of the differences.13 • Acosta-Salazar et al. 2021: Agaves of 4, 5 and uploads/Ingenierie_Lourd/ hbg-the-science-of-tequila.pdf