The Science of Wine Aroma Kits

Wine Aroma Kits

At the National Wine School, wine aroma kits are indispensable tools in both educational and professional wine tastings. Our kits are composed of vials containing scent compounds. They are designed to help sommeliers and students identify and understand the complex aromatic profiles of different wines. The ability to discern and describe these aromas is crucial for sommeliers, winemakers, and wine enthusiasts alike.

I would like to delve into the chemical compositions of these aromas, examining both common and obscure scents. My goal is to outline our scientifically-grounded approach to creating wine aroma kits for a range of wine types and sommelier courses.

Aromas and Flavors in Wine

One important details is that scents contribute to the perception of flavor in wine. In fact, it’s estimated that aerosolized scents are about 80% of a wine’s flavor. These aromas are incredibly diverse and are categorized into primary, secondary, and tertiary groups.

Primary Aromas: These originate from the grape itself. Common primary aromas include:

  • Fruity: Compounds like esters (e.g., ethyl acetate) give wines apple, pear, and tropical fruit notes.
  • Floral: Terpenes such as linalool and geraniol impart floral scents like rose and lavender.

Secondary Aromas: These arise from the fermentation process. Notable secondary aromas include:

  • Yeasty/Bready: Produced by compounds like ethyl lactate and 4-vinyl guaiacol.
  • Buttery: Diacetyl is responsible for buttery aromas, especially in Chardonnay.

Tertiary Aromas: These develop during the aging process. Examples include:

  • Nutty: Acetaldehyde can give a wine nutty characteristics.
  • Spicy: Compounds such as eugenol contribute to clove and spice aromas.

Obscure Aromas: While less common, these add to the complexity of a wine’s profile:

  • Petrol: Found in aged Riesling, often attributed to TDN (1,1,6-trimethyl-1,2-dihydronaphthalene).
  • Barnyard: Brettanomyces yeast can produce 4-ethylphenol and 4-ethylguaiacol, leading to barnyard aromas.
  • Wet Dog/Wet Wool: Usually caused by geosmin, a compound produced by certain bacteria.

Chemical Composition of Wine Aromas

Understanding the chemical underpinnings of wine aromas involves identifying specific volatile organic compounds (VOCs) that contribute to each scent. Here are some key compounds:

  • Esters: Ethyl acetate (fruity, apple), isoamyl acetate (banana), and ethyl hexanoate (pineapple).
  • Terpenes: Linalool (floral, lavender), geraniol (rose), and limonene (citrus).
  • Thiols: 3-mercaptohexanol (grapefruit), 4-mercapto-4-methylpentan-2-one (boxwood).
  • Pyrazines: 2-methoxy-3-isobutylpyrazine (green bell pepper).
  • Phenols: Guaiacol (smoky), eugenol (clove), and vanillin (vanilla).
  • Alcohols: 1-hexanol (green, grassy), phenylethyl alcohol (rose).

Designing the NWS Wine Aroma Kits

To effectively teach the chemistry behind wine aromas, a comprehensive aroma kit should include vials representing a broad spectrum of scents. Here are suggested components for kits tailored to different types of wine. The schools and colleges who utilize our educational platform have access to multiple types of wine aroma kits. The kit most commonly used is our varietal fingerprint kit, which is used in conjunction with our L2 Sommelier program.

Red Wine Aroma Kit

  • Primary Aromas: Blackberry (ethyl butyrate), cherry (benzaldehyde), plum (damascenone).
  • Secondary Aromas: Vanilla (vanillin), clove (eugenol), smoke (guaiacol).
  • Tertiary Aromas: Leather (ethyl isobutyrate), tobacco (nicotinamide), forest floor (humulene).

White Wine Aroma Kit

  • Primary Aromas: Citrus (limonene), green apple (hexyl acetate), pear (isoamyl acetate).
  • Secondary Aromas: Butter (diacetyl), honey (phenylacetaldehyde), yeast (ethyl lactate).
  • Tertiary Aromas: Petrol (TDN), nutty (acetaldehyde), brioche (furaneol).

Sparkling Wine Aroma Kit

  • Primary Aromas: Apple (ethyl acetate), lemon (citral), almond (benzaldehyde).
  • Secondary Aromas: Toast (furfural), cream (butyric acid), biscuit (acetoin).
  • Tertiary Aromas: Hazelnut (pyrazine), caramel (maltol), dried fruit (sotolon).

Each vial in these kits contains a diluted solution of the relevant compound in a neutral medium, allowing users to experience the pure aroma. Proper labeling and educational materials accompany the kit to explain the chemical source and significance of each aroma.

We believe that wine aroma kits are valuable educational tools that bridge the sensory and scientific aspects of wine appreciation. By understanding the chemical basis of wine aromas, sommeliers quickly learn that ideas such as “terroir” are outdated. Our sommelier programs –like our scent kits– are designed to offer a full and unbiased wine education.

Our kits were originally designed by the brilliant Keith Wallace, the founder of the Wine School of Philadelphia. For more information, we recommend checking out his article on the subject: Wine Aroma Kits for Sommeliers.

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