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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 “Canadian Muscats Muscat” Traminer Fruity (Terpenes) Rieslings Chenin blanc Chardonnay Fr. Columbard Vegetal Sauvignon blanc Classes of Flavor/Aroma Compounds • Pyrazines Pyrazines R= N N R O-CH3 CH3 -CH2-CH-CH3 Bell pepper -CH2-CH3 Potato -CH3 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 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 1 2 C C C 3 4 5 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 4 3 CH3 5 2 1 1 2 3 C CH3 CH2 Limonene 4 5 Monoterpene Alcohols CH3 CH3 CH2OH OH H C CH3 CH3 Geraniol CH2 C CH3 CH3 Linalool Monoterpene Aldehydes CH3 CH3 H CHO H C CHO CH3 CH3 C CH3 CH3 Geranial Neral Higher Terpenes • • • • Includes napthalene derivatives From plants Fruit characters Fuel characters Higher Terpenes O C CH2 CH3 Grapefruit Higher Terpenes CH3 CH3 CH3 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 O C H OCH3 OH Vanillin Classes of Flavor/Aroma Compounds • • • • Pyrazines Terpenes Shikimic acid derivatives Lactones Lactones • Oxygen-containing 5-member ring compound • From grapes, microbes, oak extraction • Typical characters: cotton candy, generic candy, generic fruit, coconut, buttery Lactones O CH2OH O O C4H9 CH3 Furfuryl Alcohol Methyl Lactone Classes of Flavor/Aroma Compounds • • • • • Pyrazines Terpenes Shikimic acid derivatives Lactones Esters Esters • From reaction of an alcohol and an acylCoA molecule • Formed mainly by microbes, but can come from plant • Readily hydrolyzed at wine pH Esters R1-OH O R2-CCoA O R1-O-C-R2 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 Acids • From plant or microbes • Sourness • Other characters: – Rancid (butyric acid) – Pungent (acetic acid) Acids Least Most Sour Sour Citrate Fumarate Malate Succinate Tartrate Lactate Acetic Acid Legal Limits: US White: 1.2 g/L Red: 1.4 g/L Threshold of Detection: 1 g/L CA OIV 1.1g/L 0.98g/L 1.2g/L 0.98g/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 OH HO O OH OH Catechin Astringency Flavanols and Non-flavinoids OH OH HO OH OH CH COOH Gallic acid Caftaric acid HC C=O O OH HOOC-CH-CH-COOH 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 microbiallyderived sulfides Sulfur-Containing Compounds • Sulfides • Thiols • Sulfoxides Sulfides • H2S (hydrogen sulfide): rotten egg • CH3-S-CH3 (dimethyl sulfide): cabbage, canned corn • CH3-S-S-CH3 (dimethyl disulfide): clam Sulfur-Containing Compounds • Sulfides • Thiols • Sulfoxides Thiols • CH3-SH (methanethiol): rubber • CH3-CH2-SH (ethanethiol): onion, rubber, skunk Sulfur-Containing Compounds • Sulfides • Thiols • Sulfoxides Sulfoxides • CH3-SO-CH3 (dimethyl sulfoxide): plastic, rubber hose Sulfur-Containing Compounds • • • • Sulfides Thiols Sulfoxides Thio alcohols Thio Alcohols • HS-CH2-CH2-OH (mercaptoethanol): barnyard • CH3-S-(CH2)4-OH (thiomethylbutanol): garlic, chive • CH3-S-(CH2)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 O N H C-CH3 O N C-CH3 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” NH2 O C-O-CH3
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