Yeast Selection and Fermentation Kinetics

Problem Definition

Yeast selection and fermentation management directly determine wine quality, consistency, and style expression. The choice between indigenous (wild) and commercial yeast strains, the matching of yeast characteristics to grape and style requirements, and the monitoring and intervention during fermentation kinetics are fundamental enological decisions. Stuck or sluggish fermentations, off-flavor production, and failure to achieve desired aromatic profiles represent common operational problems when yeast selection or management is inadequate.

Technical Context

Saccharomyces cerevisiae Strains

Commercial wine yeasts are selected strains of Saccharomyces cerevisiae (and increasingly S. bayanus) characterized for:

Fermentation Parameters:

Alcohol tolerance (typically 12-18% ABV)
Temperature range (optimal 15-30°C)
SO₂ tolerance (25-100 mg/L)
Killer factor presence/sensitivity
Nutrient requirements
Fermentation speed

Sensory Contribution:

Ester production (fruit aromatics)
Higher alcohol production
Thiol release (tropical aromatics in Sauvignon Blanc)
Glycerol production
Volatile sulfur compound tendency

Fermentation Kinetics

Phases of Alcoholic Fermentation:

Lag Phase (0-24 hours): Cell adaptation, enzyme induction
Exponential Growth (1-3 days): Rapid cell multiplication
Stationary Phase (3-7 days): Maximum fermentation rate
Death Phase (end): Sugar depletion, cell decline

Monitoring Parameters:

Sugar consumption (°Brix/Baumé decline)
Density (g/mL)
Temperature
CO₂ evolution rate

Healthy Fermentation Indicators:

1-2 °Brix/day decline (vigorous)
Consistent temperature maintenance
Active cap (red wine)
Clear sensory development

Wild/Indigenous Fermentation

Characteristics:

Sequential species activity (non-Saccharomyces → Saccharomyces)
Higher complexity potential
Greater variability/risk
Terroir expression arguments

Species Succession:

Hanseniaspora/Kloeckera (0-3% alcohol)
Candida, Pichia (0-5% alcohol)
Saccharomyces (dominates above 4-5% alcohol)

Options and Interventions

Yeast Selection Criteria

High-Brix Musts (>25°Brix) — Zinfandel, Amarone:

High alcohol tolerance (16%+ ABV)
Examples: EC1118, BDX, Uvaferm 43

Cool Fermentation (12-18°C) — Riesling, Gewürztraminer:

Cold-tolerant strains
Aromatic ester production
Examples: QA23, VL3, W15

Thiol Release — Sauvignon Blanc, Marlborough:

High β-lyase activity
Thiols from cysteine precursors
Examples: VL3, X5, Alchemy I

Red Wine Structure — Cabernet Sauvignon, Syrah:

Polysaccharide production
Color stability
Examples: D254, BM45, RC212

Champagne/Sparkling:

Flocculation characteristics
Autolysis potential
Pressure tolerance
Examples: EC1118, IOC18-2007, Oenoferm X-treme

Rehydration Protocol

Critical for inoculated fermentation success:

Rehydration water: 35-40°C (not hotter)
Water volume: 10× yeast weight
Duration: 15-20 minutes
Acclimation: Temperature differential <10°C between rehydrated yeast and must
Protectants: GoFerm or similar rehydration nutrients recommended

Inoculation Rate:

Standard: 20-25 g/hL (200-250 ppm)
Difficult conditions: 30-40 g/hL
Restart sluggish: 40-50 g/hL

Nutrient Management

YAN (Yeast Assimilable Nitrogen) requirements:

Minimum: 150 mg/L YAN
Optimal: 200-300 mg/L YAN
High-Brix: 300-400 mg/L YAN

Nutrient timing:

DAP (diammonium phosphate): Add at 1/3 sugar depletion
Organic nutrients: Add at inoculation
Complex nutrients: Staggered additions

Low-YAN musts:

Higher H₂S risk
Supplement with organic nitrogen
Monitor fermentation closely

Temperature Management

White wines:

12-18°C optimal for aromatic preservation
Below 12°C: Risk of stuck fermentation
Above 20°C: Aromatic loss, rapid fermentation

Red wines:

25-30°C for extraction
Above 32°C: Risk of yeast death
Peak cap temperature monitoring critical

Trade-offs and Risks

Commercial vs. Wild Yeast

Factor	Commercial	Wild/Indigenous
Predictability	High	Low
Fermentation speed	Faster	Variable
Stuck risk	Low	Higher
Complexity	Strain-dependent	Potentially higher
Terroir expression	Debated	Argued
H₂S risk	Strain-dependent	Often higher

Aromatic Yeast Trade-offs

High ester-producing yeasts may mask terroir
Thiol-releasing yeasts require precursors in must
Glycerol-producing yeasts may slow fermentation
Killer yeasts may dominate indigenous flora

Fermentation Temperature Trade-offs

Cool fermentation (12-16°C):

Aromatic preservation ✓
Extended duration
Higher stuck risk

Warm fermentation (25-30°C):

Faster completion
Better extraction (reds)
Aromatic loss risk

Practical Implications

Variety-Specific Considerations

Pinot Noir:

Delicate aromatics require gentle yeasts
Moderate temperature (26-28°C peak)
Indigenous fermentation increasingly popular
Whole-cluster impacts yeast dynamics

Chardonnay:

Barrel fermentation requires robust strains
MLF compatibility important
Indigenous fermentation common in Burgundy

High-Sugar Varieties (Zinfandel, Primitivo):

Alcohol-tolerant strains essential
Higher nutrient requirements
Extended fermentation expected
Fermentation monitoring critical

Appellation Considerations

Champagne AOC:

Base wine fermentation: Neutral, complete
Secondary fermentation: Pressure-tolerant, autolytic strains
Riddling characteristics important

Natural Wine/Minimal Intervention:

Indigenous fermentation preference
Extended fermentation duration accepted
Higher risk tolerance
SO₂-free environments favor certain species

References

Ribéreau-Gayon, P., Dubourdieu, D., Donèche, B., & Lonvaud, A. (2006). “Handbook of Enology, Volume 1: The Microbiology of Wine and Vinifications.” 2nd Edition. Wiley. Publisher Link
Fugelsang, K.C. & Edwards, C.G. (2007). “Wine Microbiology: Practical Applications and Procedures.” 2nd Edition. Springer. DOI: 10.1007/978-0-387-33349-6
Lallemand Wine (2024). “Yeast Selection Guidelines and Technical Documentation.” https://www.lallemandwine.com
Pretorius, I.S. (2000). “Tailoring wine yeast for the new millennium: Novel approaches to the ancient art of winemaking.” Yeast, 16(8), 675-729. DOI: 10.1002/1097-0061(20000615)

Last Updated: January 6, 2026