sign in sign up
<<
Home , Canopy (grape), Grape, Muscat (grape), Muscat of Alexandria, Rose, Viticulture

5/17/2017

UC DAVIS AND ENOLOGY

FLORAL AND FRUITY TAINTS

ANITA OBERHOLSTER

MAY 18, 2017

Wine 101: Recognizing Non-Microbial Taints

UC DAVIS VITICULTURE AND ENOLOGY

Outline • Origin • Formation • Characteristics • Influences

1 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Introduction

• Floral/Fruity taints • Responsible compounds present in many • Become a taint/problem when: • Too dominant in the aroma profile: loss of complexity • Present in high enough concentration to obtain a different negative aroma characteristic • Expressed in where normally below threshold of detection/not acceptable to consumer

UC DAVIS VITICULTURE AND ENOLOGY

Origin • -derived – can provide varietal distinction • Monoterpenes • Phenylpropanoids

2 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Monoterpenes • Formed through 2 potential biochemical pathways (MVA or MEP) • Important contributors to aroma of varieties • Muscat of , Muscat de Frontignan • Aromatic non-Muscat varieties • Gewürztraminer, • High corr floral aroma and high [linalool] and [-terpineol]

UC DAVIS VITICULTURE AND ENOLOGY

Monoterpenes • High conc of linalool and -terpineol = floral, citrus, , lilac aromas • Odor thresholds (μg/L) is 50 for linalool and 78 for -terpineol

linalool -terpineol

3 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Monoterpenes • (Z)-rose-oxide important aroma in Gewürztraminer = lychee aroma, although generally described as green vegetable, floral, geranium, camphoreous with spicy nuance • Odor threshold (μg/L) is 0.2

(Z)-rose oxide

UC DAVIS VITICULTURE AND ENOLOGY

Monoterpenoid • Citronellol = floral, leathery, waxy, rose citrus • Odor thresholds (μg/L) is 18

Citronellol

4 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Monoterpenoid • = sweet, floral, fruity, rose , waxy, citrus • Odor thresholds (μg/L) is 130

Geraniol

UC DAVIS VITICULTURE AND ENOLOGY

Monoterpenes in white

5 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Monoterpenes • Red varieties not phenotypically characterised by high levels of • Low levels of linalool, citronellol, neorl and geranyl/neryl acetone in Cab Sauv (<1.5 ug/kg)

UC DAVIS VITICULTURE AND ENOLOGY

Formation of terpenes • Grape Biosynthesise through isoprene/ metabolism • Monoterpenes also subject to pH and temp transformation in and • For ex. under acidic conditions geraniol and linalool degrade to linalool oxides and - terpineol • More prevalent at high temp as during storage and transport – result in aged characters

6 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Formation of terpenes • Monoterpenes can also result from non- grape materials • E.g., 1,8-cineole (eucalyptol) • Synthesize in Cab Sauv after set • Also originate from eucalyptus in and around • Eucalyptus and minty aromas • Consumer rejection threshold 27.2 μg/L

UC DAVIS VITICULTURE AND ENOLOGY

Formation of terpenes • 1,8-cineole (eucalyptol) • Synthesize in Cab Sauv berries after set

7 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Environmental influences • Exposure to sunlight favors accumulation of monoterpenes • Can be factor of temp and light exposure on enzyme activity within the • Both management and stress can manipulate fruit light interception • thinning has shown to ↑glycosylated terpenes

UC DAVIS VITICULTURE AND ENOLOGY

Environmental influences • Grape maturity • Increase in monoterpenes with accumulation • Consistent with up-regulation of genes involved in early stages of terpene synthesis during maturation

8 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Environmental influences • Fungal infections • E.g. B. cinerea causing gray bunch rot can transform monoterpenes • Novel polyfunctional cysteine conjugates were identified in botrytis-infected Sauv blanc, Semillon – contribute to unique flavour of botrytized sweet wines

UC DAVIS VITICULTURE AND ENOLOGY

Sesquiterpenes • Rotundone • Characteristic pepper aroma in vinifera cv.

9 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Phenylpropanoids • Not much known about biosynthetic pathways leading to formation in grapes • Methyl anthranilate • Responsible for ‘foxy’ aroma and flavor in Concord grapes () • May also contribute to aroma • Used as main grape flavor compound in food • May also be present in wine through external sources • (Quercus sp.) barrels used for fermentation and aging • Smoke event in the

UC DAVIS VITICULTURE AND ENOLOGY

Phenylpropanoids • Methyl anthranilate is also an • Few formed in grapes • Esters characteristic of fruity floral aromas • Enzymatic esterification in the grape • Esters in wine have mainly two origins • Enzymatic esterification during fermentation • Chemical esterification during long-term storage • Some esters are synthesized by yeast from grape precursors • Can be variety depended

10 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Phenylpropanoids - esters • For example in Pinot noir characteristic aromas • Plum, , raspberry, and blackberry influenced by 4 esters

Ethyl anthranilate Methyl anthranilate (sweet‐fruity, grape‐like odor)

UC DAVIS VITICULTURE AND ENOLOGY

Phenylpropanoids - esters • For example in Pinot noir characteristic aromas • Plum, strawberry, raspberry, blackcurrant and blackberry influenced by 4 esters

Ethyl cinnamate 2,3‐dihydrocinnamate (cinnamonlike, sweet‐balsamic, sweet‐fruity, plum, cherry)

11 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

Phenylpropanoids - esters • Another related compound is Ethyl Phenylpropionate • Hyacinth, rose, honey, fruit rum aroma

Ethyl Phenylpropionate (ethyl 2,3-dihydrocinnamate)

UC DAVIS VITICULTURE AND ENOLOGY

Ester • Methyl Benzoate • , floral, chemical with a phenolic and cherry pit note

Methyl benzoate

12 5/17/2017

UC DAVIS VITICULTURE AND ENOLOGY

To conclude • Floral and fruity taints • Floral and fruity aromas mostly increase with ripeness and sun exposure • Mostly present in grape skins • At low conc contribute positively to wine aroma • High conc can make wine one-dimensional • Very high conc seen as a taint by some • If vineyard block known to be problematic • Adjust canopy management and picking time • Adjust skin contact time and fermentation temp during

13