Transcript Impact of Winemaking Decisions on White Wine Mouthfeel

Impact of Winemaking Decisions
on White Wine Mouthfeel
Linda F Bisson
Department of Viticulture and Enology,
UCD
May 9, 2013
Physiology of Mouthfeel
• Binding to salivary proteins
• Interference in binding of components to
salivary proteins
• Binding to other proteinaceous surfaces in the
mouth
Factors Impacting White Wine
Mouthfeel
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Polyphenolic content/Astringency
Glycerol/Sugar alcohols
Residual sugar
Acidity
Ethanol
pH
Astringency in White Wines: Phenolic
Content
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Skin contact
Skin and seed damage during processing
Varietal
Growing region
Impacted by aging
Aging and aging in barrel
Oak amendments
Ethanol
• Ethanol has an impact
• Direct effects
– Heat
– Tactile irritation
• Indirect effects
– Interference in binding reactions
– Enhances perceptions of sweetness
Acidity
• Direct effect in being detected by sensors:
astringent like sensations elicited
• Indirect effect in altering binding of other
components
pH
• Final pH adjustment of wine has an impact:
Altering binding of components to sensory
receptors
• Inverse relationship: Decreasing pH leads to
increased astringency
Factors Are Interacting
• pH and acidity can interfere in binding of
astringent compounds to salivary proteins
• Polysaccharides and small peptides:
competition for binding
• Ethanol can impact perception of other
characters: change in binding kinetics
• Factors can generate competing signals or
enhance the same signal (tone down or
increase astringency
Practices Impacting White Wine
Mouthfeel
• Native fermentation
• Direct inoculation with non-Saccharomyces
yeast
• Sur lie aging
• ML Fermentation
• pH adjustments
Native Fermentation
• Contributions from bacterial flora:
– Wild Lactic acid bacteria:
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Change in acidity/pH
Production of polysaccharides
Production of small peptides and lipids
Production of proteases and other hydrolases
– Non- Saccharomyces yeast:
• Production of polysaccharides
• Production of small peptides and lipids
• Production of proteases and hydrolases
Direct Inoculation with NonSaccharomyces Yeast
• Polysaccharide production
Sur Lie Aging
• Release of cell components
• Hydrolases
• Release of:
– Lipid
– Mannoprotien
– Polysaccharide release
– Peptides
• Stimulation of growth of other microbes
Malolactic Fermentation
• Changes in acidity/pH
• Polysaccharide release
pH Adjustments
• pH adjustment of juice complicated: multiple
possible impacts on mouth feel
• Organisms present
• Extractability and stability of macromolecular
components
• Impact on polymerization reactions
pH During Fermentation Trial
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Chardonnay
Yeast strain: EC1118
pH of juice: 3.65
Fermentation temperature: 68 F
50 ppm SO2
23 Brix
Adjusted with potassium bicarbonate or
tartaric acid to +0.2, -0.2 and -0.4 pH units
Final Values of Wine
Wine
Alcohol (%) Residual
TA
Sugar (g/L)
pH
Control
+0.2
-0.2
-0.4
14.23
14.17
14.1
14.47
3.59
3.77
3.35
3.11
0.23
0.23
0.32
0.54
6.46
6.02
7.1
8.1
Tastings
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Glass 1: Control, pH 3.59
Glass 2: +0.2, pH 3.77
Glass 3: -0.2, pH 3.35
Glass 4: -0.4, pH 3.11