What's that smell? A systematic identification of previouslyunknown and uncharacterized "smoky" odorants

Jiang, Clare Yu

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https://hdl.handle.net/2142/115947 Copy

Description

Title

What's that smell? A systematic identification of previouslyunknown and uncharacterized "smoky" odorants

Author(s)

Jiang, Clare Yu

Issue Date

2022-07-19

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

Cadwallader, Keith R

Committee Member(s)

• Pepino de Gruev, Marta Y
• Miller, Michael

Department of Study

Food Science & Human Nutrition

Discipline

Food Science & Human Nutrition

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• smoky
• whiskey
• oak
• smoke
• syringol
• guaiacol

Abstract

The smell of smoke is distinct and recognizable as it has been around for centuries. In the past, the smoking of foods was used as a method of preservation, but in present day it is mostly used to impart desired aromas and colors. The “smoke”-like odorants that are responsible for the aromas of smoked foods have been extensively studied. As a result, a common backbone structure, similar to that of guaiacol and syringol, has been elucidated. Additionally, while we commonly correlate the term “smoky” to foods such as barbecue, ham, bacon, there are also everyday products that we would not expect to contain these “smoky” compounds, like tomatoes and coffee. Recent research has also uncovered the importance of smoky compounds to the overall aroma of many products. While there have been considerable studies around these compounds, unknown odorants that could provide unique enhancements to the body of a smoky aroma are still unknown or unidentified. Previous research involving the use of gas chromatography olfactometry (GC-O) has indicated the presence of unknown compounds containing smoky aroma properties. Experiments were conducted to clearly identify the compounds responsible for this smoky, campfire-like aroma. Compounds were extracted using liquid-liquid continuous extraction (LLCE) from double oaked barrel finished American whiskies and oak extracts as source materials. These aroma extracts were then analyzed by gas-chromatography mass spectrometry-olfactory (GC-MS-O) to allow for molecular characterization and identification of the odorants. Unambiguous identifications were made by comparing the electron-impact mass spectrum (EI-MS) of the target compounds in the sample to authentic (synthesized) reference standards. Further characterization of the compounds was conducted with respect to their structures, chromatographic behaviors (such as retention indices on two different polarity GC columns), odor properties, and odor detection thresholds in air and concentration in several source materials, including two whiskies and an oak extract. Results of this study are the first to identify and characterize various syringyl derivatives with smoke-like aromas. Future work with these compounds should further investigate the roles that it plays in aged whiskies and other products in which they are found.

Graduation Semester

2022-08

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Clare Jiang

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