VEN124 Section VI Wine Aroma and Flavor: Putting It All Together

Lecture 19: The Flavor and Aroma Compounds of Wine

Distribution of Aroma Compounds in White Wines Vegetal Fruity (Terpenes) Muscats Chenin blanc Fr. Columbard Chardonnay Sauvignon blanc “Canadian Muscat” Rieslings Traminer

Classes of Flavor/Aroma Compounds Pyrazines

N N R O-CH 3 R = -CH 2 -CH-CH 3 -CH 2 -CH 3 -CH 3 CH 3 Bell pepper Potato Peanut

Pyrazines Derived from grape Not microbial in origin Vegetal characters –Bell pepper –Chili –Bean –Carrot –Potato –Peanut –Roasted Barley

Classes of Flavor/Aroma Compounds Pyrazines Terpenes

Fruity fruit/floral aromas from grapes Can be produced by some yeasts and molds (but not by Saccharomyces) Derived from isoprene units May be unbound or bound (as glycosides) Only unbound terpenes can be detected

Terpenes Formed from isoprene units C C C C The double bond can occur anywhere in the 5-member structure

Terpenes Monoterpenes: C10 Higher terpenes:  C10

Terpenes Can occur as: hydrocarbons alcohols aldehydes ketones esters

Monoterpene Hydrocarbons CH 3 C CH 3 CH Limonene

Monoterpene Alcohols C CH 3 CH 2 OH H CH 3 OH CH 2 C CH 3 Geraniol Linalool

Monoterpene Aldehydes CH 3 CHO H H CC CH 3 Geranial Neral

Higher Terpenes Includes napthalene derivatives From plants Fruit characters Fuel characters

Higher Terpenes C CH 3 CH 2 O Grapefruit

Higher Terpenes CH 3 Trimethyl Dihydronapthalene “Kerosene”

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives

Shikimic Acid Derivatives Derived from aromatic amino acid metabolism Produced by plants, microbes, oak extraction

Shikimic Acid Derivatives C O H OCH 3 OH Vanillin

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives Lactones

Oxygen-containing 5-member ring compound From grapes, microbes, oak extraction Typical characters: cotton candy, generic candy, generic fruit, coconut, buttery

Lactones O CH 2 OHO C4H9C4H9 O CH 3 Furfuryl Alcohol Methyl Lactone

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives Lactones Esters

From reaction of an alcohol and an acyl- CoA molecule Formed mainly by microbes, but can come from plant Readily hydrolyzed at wine pH

Esters R 1 -OH R 2 -C  CoA O R 1 -O-C-R 2 O

Esters Alcohol: ethanol or alcohol from amino acid, purine, pyrimidine degradation Acid: acetic acid or acid from amino acid degradation, fatty acid biosynthesis

Esters Ethyl acetate: nail polish remover/glue Ethyl laurate: soap Isoamyl acetate: banana Phenethyl acetate: rose oil

Esters Short chain: fruity, floral Long chain: perfume, soap Lower concentration: fruity, floral Higher concentrations: perfume

Ester Formation Influenced By: Temperature –Higher temperature: increased loss Volatilization Hydrolysis Oxygen exposure –Stimulate fatty acid biosynthesis Nitrogen source availability –Precursor availability Strain/genetic background –As much as 10-fold difference in level of production

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives Lactones Esters Higher alcohols

Higher Alcohols Made mostly by microbes, can be made by plants From amino acid degradation/ biosynthesis Fusel oils Aromatic amino acid derivatives

The Fusel Oils 3-Methylbutanol 2-Methylbutanol Isobutanol Propanol

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives Lactones Esters Higher alcohols Acids

From plant or microbes Sourness Other characters: –Rancid (butyric acid) –Pungent (acetic acid)

Acids Least Sour Most Sour Citrate Fumarate Malate Lactate Succinate Tartrate

Acetic Acid Legal Limits: US CA OIV White: 1.2 g/L 1.1g/L 0.98g/L Red: 1.4 g/L 1.2g/L 0.98g/L Threshold of Detection:  1 g/L

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives Lactones Esters Higher alcohols Acids Phenolic compounds

Phenolic Compounds Bitterness Astringency Produced by plant Can be converted into vinyl phenols by microbes (spoilage characters)

Bitterness Flavanols OH HO OH O Catechin

Astringency Flavanols and Non-flavinoids OH HO COOH OH CH HC C=O O HOOC-CH-CH-COOH OH Gallic acid Caftaric acid

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives Lactones Esters Higher alcohols Acids Phenolic compounds Sulfur-containing compounds

Sulfur-Containing Compounds Low thresholds of detection Generally produced by microbes –Degradation of sulfur containing amino acids –Spontaneous reactions from microbially- derived sulfides

Sulfur-Containing Compounds Sulfides Thiols Sulfoxides

Sulfides H 2 S (hydrogen sulfide): rotten egg CH 3 -S-CH 3 (dimethyl sulfide): cabbage, canned corn CH 3 -S-S-CH 3 (dimethyl disulfide): clam

Sulfur-Containing Compounds Sulfides Thiols Sulfoxides

Thiols CH 3 -SH (methanethiol): rubber CH 3 -CH 2 -SH (ethanethiol): onion, rubber, skunk

Sulfur-Containing Compounds Sulfides Thiols Sulfoxides

CH 3 -SO-CH 3 (dimethyl sulfoxide): plastic, rubber hose

Sulfur-Containing Compounds Sulfides Thiols Sulfoxides Thio alcohols

Thio Alcohols HS-CH 2 -CH 2 -OH (mercaptoethanol): barnyard CH 3 -S-(CH 2 ) 4 -OH (thiomethylbutanol): garlic, chive CH 3 -S-(CH 2 ) 3 -OH (methionol): raw potato, soy

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives Lactones Esters Higher alcohols Acids Phenolic compounds Sulfur-containing compounds Amino acid derivatives

Amino Acid Derivatives Several other types of compounds can be formed from amino acids by yeast and bacteria Appearance depends upon which microbes are present and what nitrogen/carbon sources are present

Amino Acid Derivatives: Mousiness N N C-CH 3 O H O 2-Acetyl-tetrahydro-pyridine Metabolite of lysine made by Lactic Acid Bacteria and Brettanomyces

Classes of Flavor/Aroma Compounds Pyrazines Terpenes Shikimic acid derivatives Lactones Esters Higher alcohols Acids Phenolic compounds Sulfur-containing compounds Amino acid derivatives Specific compounds

Specific Compounds Other plant compounds associated with aroma Not well characterized

Specific Compounds: Methyl Anthranilate Concord Grape Character: “Foxy” NH 2 C-O-CH 3 O