Wine Flavor Chemistry Flavor is the psychological interpretation of the physiological response to a physical stimulus  Milton Bailey, University of Missouri, 1986

2 -methoxy 3 isobutyl pyrazine (2 ppt) Identified in Bell Peppers (1969) Sensitive to light (1986) Method for quantifying : (2003) WHAT CAUSES VEGY FLAVOR in WINE?

SENSORY PCA – 19 wines (1986)

SOIL PCA

PLS of Soil and Vineyard factors versus Sensory Noble and Elliot-Fiske, 1990

Heymann (1986) Descriptive Analysis of Cabernet sauvignon

Sivertsen, et al.(1999). Classification of French red wines according to geographical origin by of multivariate data analyses

Fischer, et al. (1999) The impact of geographic origin, vintage and wine estate on sensory properties of Vitis vinifera cv. Riesling

Karen Hein, 2005

CANONICAL VARIATE ANALYSIS OF SPIKED WINE SAMPLES

Morrison and Noble, Am. J. Enol. Vitic.41: Cabernet sauvignon – differences too subtle to describe

Fraction Light Vigor Pyrazine Bell Pepper Aroma Vegy Saga

Evaluation of 96 Bordeaux red wines IBMP is the contributor to vegetal aroma in Cabernet sauvignon; Cabernet franc and Sauvignon blanc Compound only found in a minority of Merlot

Compounds released in white wines 4-mercapto-4-methylpentan-2-one (4MMP) (also in Scheurebe) 0.8 ng/l*; range box tree, broom flower; cat pee; conifer 4-mercapto-4-methylpentan-2-ol (4MMPOH) 55 ng/l*; range citrus zest; grapefruit 3-mercapto-3-methylbutan-1-ol (3MMB) 1,500 ng/l*; range – cooked leeks 3-mercaptohexan-1-ol (3MH) 60 ng/l*; range 200-5,000 – grapefruit; passion fruit; passion fruit skin 3-mercaptohexylacetate (3MHA) (also in Merlot, Cabernet sauvignon) 4.2 ng/l*; range – box tree; passion fruit; sweet sweaty Aqueous 12% alcohol solution with 5g/l tartaric acid; pH J, triangle; 50% correct increases during fermentation as these potent thiols released from their S-cysteine conjugate precursors Markers for great Sauvignon blanc

Thiols in other varieties 4MMP and A3MH (3-mercaptohexylacetate [box tree]): Impact on aromas of Colombard and Muscat d’Alsace wines As well as on young wines from Petit manseng* 3MH Contributes passion fruit and grapefruit to Gewurtztraminer, Riesling, Petit manseng and botrytized Semillon * White variety, South West France – may be Albarino: floral fruity flavors, a distinct lemon and fruit salad flavor & high acidity increasing popularity in Languedoc & California Tominaga et al. (2000) AJEV 51(2):

Production, location and extraction of S-Cysteine Conjugates Moderate water stress favor S-cysteine conjugate (P-thiol) formation; severe prolonged stress limits production Location of P-thiolsdiffer as f(volatile thiol) P-4MMP and P-4MMPOH -- 80% in juice P-3MH – 50:50 between juice and skin Upto 19 hours skin contact Some ↑ in P-4MMP and P-4MMPOH (20% + 30%) 50% ↑ in P-3MH (even more extracted if skin contact at 18C vs 10C) Peyrot des Gachons, Catherine: Aroma Potential of Sauvignon blanc grapes, PhD Dissertation Bordeaux

Transformation of p-thiols into varietal aromas Transformation % low (1 month after fermentation) – due to yeast lyases 1.4% for P-4MMP; 3% for P-4MMPOH; 4.2% for P-3MH Not much transformed? Or Lost? Or metabolized or unstable? – do not yet know Do know that P-thiol disappearance is correlated with thiol appearance Peyrot des Gachons, Catherine: Aroma Potential of Sauvignon blanc grapes, PhD Dissertation Bordeaux

Norisoprenoids/norterpenoids from carotenes Beta-damascenone Shiraz stalky, earthy, cigar, and tobacco aromas black pepper aroma by GCO not id’d Cabernet Sauvignon and Merlot dried fig, tobacco and chocolate aromas Zinfandel Preliminary studies: Not much contribution Glycosides in Red varieties

floral apple honey honey chocolate chocolate dried fig dried fig tobacco tobacco Base wine Napa Cabernet juice glycoside hydrolysate Juice glycoside hydrolysate n=14 judges x 2 reps

floral apple honey chocolate dried fig dried fig tobacco tobacco Base wine Napa Cabernet skin glycoside hydrolysate Skin glycoside hydrolysate

PLS of Aroma attributes versus volatiles floral apple honey dried fig chocolate tobacc o volatiles juices skin extracts Component 1 Component 2

Volatiles related to the honey attribute Norisoprenoids: damascenone hydroxydamascone dehydro ß ionone TDN vitispirane actinidol Benzene derivatives: vanillin acetovanillone cinnamic acid Monoterpenes: ocimenol furan linalool oxide an ene diol Others: acetyl furan ethyl decanoate diethyl propanedioate

PLS of Aroma attributes versus volatiles floral apple honey volatiles juices skin extracts Component 1 Component 2 dried fig chocolate tobacc o

Volatiles associated with dried fig/tobacco Benzene derivatives: syringic acid ethyl syringate a methoxy phenol Monoterpenes: trimethyl vinyltetrahydropyran furan linalool oxide Others: two unknowns heptanoic acid hexadecanoic acid 2-Et-3-Me maleic anhydride

Trellising or leaf removal increases light < 2-methoxy 3 isobutyl pyrazine > norisoprenoids Maturity How to assess pH, TA, °B? Grape Must Evaluation (evaluate in < 1 hour) Rinse and Crush grapes, add 20 ppm SO2 Homogenize skins/juice versus juice Grape Berry Evaluation Vineyard Variables:

Temperature: Cool: retain more volatiles Warmer: more esters but lose more (fruity) low MW Yeast strain:? Biggest issue is H2S production “Natural” versus inoculation Skin Contact Time/Cap Management Increase K, pH, phenols, anthocyanins Centrifuging? FERMENTATION

Terpene glycosides hydrolyze, but terpenes interconvert to less fruity forms Vitaspirane and 1,1,6 trimethyl 1,2 dihydronaphthalene  increase Esters hydrolyze slowly: Acetate esters & higher MW faster. Acids esterify; pH  ; Tannins polymerize Oxidation reactions AGING

Extraction of volatiles: vanillin, eugenol, oak lactone Extraction: phenols, acids, lignins, CHO Oak Aging

Oak aging continued VARIABLES: Source oak (Am  Vanillin; Fr  Phenols, extract) Sawn vs split Air vs kiln drying Air  Vanillin; Kiln  HMF Air drying in cool vs hot area Hot  Vanillin,Oak lactone Hot  vanilla, caramel, buttery Steamed or bent over fire Degree toasting  Furfural,  Vanillin