The Effects of TemperatureLinda F. Bisson

Department of Viticulture and Enology University of California, Davis, CA

Outline of PresentationOutline of Presentation

Impacts of Fermentation Impacts of Fermentation Temperature on Wine Temperature on Wine CompositionComposition

Control of TemperatureControl of Temperature Temperature OptimizationTemperature Optimization

Impacts of Fermentation Impacts of Fermentation Temperature in Red Temperature in Red

FermentationsFermentations

Impacts of Fermentation Impacts of Fermentation TemperatureTemperature

ExtractionExtraction VolatilizationVolatilization Chemical ReactionsChemical Reactions Enzymatic ReactionsEnzymatic Reactions Microbial Growth and Microbial Growth and

Persistence Persistence

Extraction: Skin, Seeds, Extraction: Skin, Seeds, StemsStems

Extract anthocyanins from skin cellsExtract anthocyanins from skin cells Extract phenolic participants in co-Extract phenolic participants in co-

pigmentationpigmentation Extract phenolic compounds that Extract phenolic compounds that

participate in stable pigment and tannin participate in stable pigment and tannin formationformation

Extraction of flavor componentsExtraction of flavor components Does seed extraction occur?Does seed extraction occur? Impact of stem extraction (whole cluster Impact of stem extraction (whole cluster

ferments)? ferments)?

AJEV (1987) 38(2):120-7

Location of Compounds in BerryLocation of Compounds in Berry

Sucrose Glucose

Location of Compounds in BerryLocation of Compounds in Berry

Malate Tartrate

Location of Compounds in BerryLocation of Compounds in Berry

PhenolsPhenolic

compounds

Location of Compounds in BerryLocation of Compounds in Berry

Potassium

Location of Compounds in BerryLocation of Compounds in Berry

Inorganic

anions

Factors Affecting Extraction: Cap Factors Affecting Extraction: Cap ManagementManagement

TEMPERATURETEMPERATURE TIMETIME MIXINGMIXING MACERATIONMACERATION USE OF ENZYMESUSE OF ENZYMES

VolatilizationVolatilization

Higher temperature = greater loss of Higher temperature = greater loss of volatilesvolatiles

Impact depends upon reservoir of Impact depends upon reservoir of volatile compoundsvolatile compounds

Also impacted by vigor of yeast Also impacted by vigor of yeast fermentationfermentation

Fermentation rates faster at higher Fermentation rates faster at higher temperaturestemperatures

Chemical ReactionsChemical Reactions

Endothermic (heat absorbing) Endothermic (heat absorbing) reactions go faster at higher reactions go faster at higher temperaturetemperature

Exothermic (heat releasing) reactions Exothermic (heat releasing) reactions go slower at higher temperaturego slower at higher temperature

Some hydrolytic reactions stimulated Some hydrolytic reactions stimulated by heatby heat

Enzymatic ReactionsEnzymatic Reactions

Some enzymatic reactions are Some enzymatic reactions are endothermic, some exothermicendothermic, some exothermic

Heat can speed up or slow down Heat can speed up or slow down enzymatic reactionsenzymatic reactions

If too hot, enzymes lose structure and If too hot, enzymes lose structure and become inactivatedbecome inactivated

Hot Fermentations:Hot Fermentations:

Trade off between extraction of Trade off between extraction of color and phenolic compounds color and phenolic compounds and loss of aromatic and loss of aromatic componentscomponents

Temperature and MicrobesTemperature and Microbes

Microbes have optimal temperatures Microbes have optimal temperatures for growthfor growth

Warmer favors bacteriaWarmer favors bacteria Warmer favors Warmer favors SaccharomycesSaccharomyces over over non-Saccharomycesnon-Saccharomyces wine yeasts wine yeasts

Warmer impacts ethanol toleranceWarmer impacts ethanol tolerance

Temperature and MicrobesTemperature and Microbes Temperature impacts: Temperature impacts:

– Metabolic ratesMetabolic rates– Metabolite profilesMetabolite profiles– Cell leakinessCell leakiness– Tolerance to other stressesTolerance to other stresses– Higher temperatures: higher ester Higher temperatures: higher ester

formation but higher retention of off-esters formation but higher retention of off-esters (longer chain)(longer chain)

Control of TemperatureControl of Temperature

Control of TemperatureControl of Temperature

Fermentation is exothermic: rate of heat Fermentation is exothermic: rate of heat release directly proportional to rate of release directly proportional to rate of fermentationfermentation

If too hot, thermal death may occur and If too hot, thermal death may occur and such fermentations are difficult to restartsuch fermentations are difficult to restart

ΔΔT (ºF) = 1.17 x Brix value, depends upon T (ºF) = 1.17 x Brix value, depends upon ambient temperature, vessel ambient temperature, vessel characteristics, surface to volume ratio, characteristics, surface to volume ratio, thermal conductivity of wallthermal conductivity of wall

Type of Cooling SystemType of Cooling System

Tank type and size of jacketTank type and size of jacket Internal coolingInternal cooling Coolant heat transfer coefficientCoolant heat transfer coefficient Coolant temperatureCoolant temperature

Tank TemperatureTank Temperature

Temporal fluctuation: due to changes in Temporal fluctuation: due to changes in metabolic activitymetabolic activity

Fluctuation within tankFluctuation within tank– Cooler nearest the jacket, warmer in centerCooler nearest the jacket, warmer in center– Warmer nearest the cap (enhanced metabolic activity)Warmer nearest the cap (enhanced metabolic activity)– Dependent upon mixing, cap management practices Dependent upon mixing, cap management practices

and temperature equilibrationand temperature equilibration

Optimization of Optimization of Fermentation TemperatureFermentation Temperature

Optimization of Fermentation Optimization of Fermentation TemperatureTemperature

Depends upon varietalDepends upon varietal Depends upon styleDepends upon style

– Reliance on volatile compoundsReliance on volatile compounds– Strength of reservoir of volatilesStrength of reservoir of volatiles

Optimization of TemperatureOptimization of Temperature

To achieve optimal pigment extractionTo achieve optimal pigment extraction To minimize loss of aromatic volatilesTo minimize loss of aromatic volatiles To avoid spoilage organismsTo avoid spoilage organisms To prevent arrest of fermentationTo prevent arrest of fermentation

Optimization of Temperature Optimization of Temperature Influenced by:Influenced by:

Sulfite useSulfite use Vineyard floraVineyard flora Winery floraWinery flora Site characteristicsSite characteristics Presence of rot/cluster damagePresence of rot/cluster damage

The Experiment:The Experiment:

Ferment Cabernet Sauvignon at four Ferment Cabernet Sauvignon at four different temperatures: 60, 70, 80 different temperatures: 60, 70, 80 9090ºFºF

Examine color and sensory differencesExamine color and sensory differences Using TJ fermentersUsing TJ fermenters

Fermentation Curves of Cabernet Sauvignon

Temperature FlightTemperature Flight

Glass 1: 60°Glass 1: 60° Glass 2: 70°Glass 2: 70° Glass 3: 80°Glass 3: 80° Glass 4: 90°Glass 4: 90° Glass 5: Mixture of all 4Glass 5: Mixture of all 4