Impact of Winemaking Decisions on White Wine Mouthfeel

Linda F BissonDepartment of Viticulture and Enology,

UCDMay 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

• Polyphenolic content/Astringency• Glycerol/Sugar alcohols• Residual sugar • Acidity• Ethanol• pH

Astringency in White Wines: Phenolic Content

• 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: • 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 Non-Saccharomyces 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

• 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 Sugar (g/L)

TA pH

Control 14.23 0.23 6.46 3.59+0.2 14.17 0.23 6.02 3.77-0.2 14.1 0.32 7.1 3.35-0.4 14.47 0.54 8.1 3.11

Tastings

• 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