Comprehensive aroma characterization of silver (blanco) tequila

Huang, Xinhe

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https://hdl.handle.net/2142/121196 Copy

Description

Title

Comprehensive aroma characterization of silver (blanco) tequila

Author(s)

Huang, Xinhe

Issue Date

2023-05-25

Director of Research (if dissertation) or Advisor (if thesis)

Cadwallader, Keith R.

Doctoral Committee Chair(s)

Schmidt, Shelly J.

Committee Member(s)

• Miller, Michael J.
• Sarlah, David

Department of Study

Food Science & Human Nutrition

Discipline

Food Science & Human Nutrition

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Tequila, aroma, flavor, aroma extract dilution analysis, stable isotope dilution analysis, descriptive analysis

Abstract

Tequila, a traditional Mexican spirit, is created through the fermentation of at least 51% blue agave combined with other adjunct sugars, followed by distillation and an optional aging process. In contemporary drink and bar culture, tequila has gained immense popularity and is now one of the most widely consumed liquors across the globe. Its unique flavor profile makes it an integral component of numerous cocktails and beverages. However, despite its widespread appeal and commercial significance, our understanding of tequila's flavor and aroma chemistry remains limited. Although previous studies have investigated tequila aroma, they were unsuccessful in reconstructing its distinct flavor. To address this gap, a comprehensive and streamlined analysis of blanco tequila's intricate flavor chemistry was conducted. Fifteen blanco tequilas were evaluated, including Tequila 512 Triple-Distilled Blanco (512), Casamigos Tequila Blanco (CA), Casa Noble Crystal Blanco (CN), 1942 Tequila Reserva de Don Julio Blanco (DJ), Dulce Vida Organic Blanco Tequila (DV), El Jimador Hand-Harvested Tequila Silver (EJ), Espolòn Tequila Blanco (EP), Tequila Herradura Original Silver (HR), Jose Cuervo Tradicional Tequila Plata (JC), Member's Mark Silver Tequila (MM), Leyenda del Milagro Tequila Silver (ML), Olmeca Altos Plata Tequila (OA), Silver Patrón Tequila (PT), Playa Real Premium Tequila Silver (PR), and Tequila Reserva 1800 Silver (TR). The study was conducted in three stages: identification of the predominant odorants in the tequila samples, quantitation of selected odor-important compounds, and validation of the analytical results through creation and sensory evaluation of tequila aroma models. To identify the predominant odorants in the fifteen tequilas, gas chromatography-olfactometry (GCO) and GCmass spectrometry (GC-MS) analyses were conducted. These analyses revealed 76 odorants, 55 identified and 13 tentatively identified. Three tequila samples, CN, JC, and HR were chosen for aroma extraction dilution analysis (AEDA), and the flavor dilution (FD) factors of each odorant were determined on two different polarity GC columns. The most potent odorants contributing to tequila flavor included acetaldehyde, acetal, 2/3-methylbutanal, ethyl propanoate, 2,3-butanedione, ethyl butanoate, 2/3-methyl-1-butanol, 1-octen-3-one, 2-isopropyl-3-methoxypyrazine, (E)-2- nonenal, linalool, (Z)-2-nonenal, butanoic acid, β-damacenone, guaiacol, 2-phenylethanol, γnonalactone, γ-decalactone, thymol, carvacrol, rotundone, and vanillin.iii A total of 62 selected volatile compounds were chosen for quantitation based on their relatively high FD factors. The quantitation results were then converted into odor-activity values (OAVs) to gain a better understanding of each individual odorant's contribution to the overall aroma. OAVs were calculated using the odor detection threshold (ODT) values, which were obtained from previous literature and measured in either a 40% or 46% ethanol matrix. The ODTs for thymol, carvacrol, and rotundone were determined in this study using the 3-alternative forced choice (3- AFC) method. To compare the differences between samples and account for observed variations, principal component analysis was conducted on the OAV results for all 15 tequilas. This analysis revealed that samples clustered into two distinct groups, with two outliers. Three tequila samples, JC, CN, and HR, were further examined using sensory analysis to better understand their overall sensory flavors profiles. Based on the quantitation results, tequila flavor models were developed for each of these tequilas. A group of eight trained panelists evaluated both the samples and the models using descriptive aroma analysis. Nine aroma attributes were identified by the panelists, which included pungent, malty/fusel, honey/apple sauce, thyme, green/grass, buttery, citrus/lime, spicy/peppery, and vanilla. The most prominent attributes were pungent, honey/apple sauce, thyme, and citrus/lime. A comparison between each sample and its corresponding model revealed that the ratings for HR and CN were similar to their models, with only a slightly lower rating for the citrus/lime attribute. In contrast, the JC model had a relatively higher malty/fusel rating and a lower citrus/lime rating compared to its sample. This study offers an in-depth exploration of the flavor chemistry of 100% blue agave blanco tequila. The identification of key odor-active compounds holds promise for the development of strategies aimed at producing high-quality tequila products. Furthermore, accurate tequila aroma models were successfully constructed for CN and HR, with their flavor attributes closely aligning with the corresponding authentic tequilas.

Graduation Semester

2023-08

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Xinhe Huang

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