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High Alcohol Wines: How to Manage Primary and Secondary Fermentation Presented by: Jessica Just of Scott Laboratories and Sigrid Gertsen-Briand of Lallemand
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Winemaking Goals in a High Sugar Ferment Convert all sugar to alcohol Minimize the production of volatile acidity Minimize volatile sulfur off-aromas Balance % alcohol with phenolic maturity Complete the malo-lactic conversion in a timely manner Minimize microbial deviations
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Glucose Ethanol Glycerol Higher Alcohols CO 2 Biomass (≈ 2% glucose) Organic Acids Esters H+H+ H+H+ Internal pH is 5-6 External pH is 3-4 H+H+ H+H+ Yeast
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Normal Fermentation Curve 2-4 million CFU/mL >100-150 million CFU/mL 2-4 million CFU/mL Time Population Survival factors are important to ensuring the proper working of the cellular membrane: poly-unsaturated fatty acids and sterols 4-8 million CFU/mL Higher yeast inoculation rate lowers dilution of the initial yeast cells survival factors Brix
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Key Interrelationships of Factors Affecting Fermentation SUGAR CONTENT TEMPERATURE CELL NUMBERS & HEALTH TOXIC FACTORS COMPETITIVE FACTORS NUTRIENTS and OXYGEN STRAIN SELECTION MAXIMUMFERMENTATIONMANAGEMENT
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Cap Temperature Control in Red Must 20 Brix 21 Brix 22 Brix 23 Brix >24 Brix 95°F 90°F 85°F 80°F 76°F Max. Temperature
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What to Know Before Restarting a Stuck Alcoholic Fermentation Total residual sugar Glucose:Fructose ratio What caused the stuck fermentation Which yeast strain was used for the initial fermentation Temperature control
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Dealing with a Stuck Alcoholic Fermentation Refer to websites for actual protocols Blend Sterile Filter Long acclimatization, build-up with sugar Short acclimatization with high inoculation rate How many times should you try to restart a stuck ferment? When can you start tasting the yeast? Use of yeast hulls Addition of nutrients?
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Alcohol content (% v/v) reached after fermentation in white wines with 56 selected Saccharomyces cerevisiae yeasts that were able to ferment all sugars.
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Alcohol content (% v/v) reached after red vinifications with 35 selected Saccharomyces cerevisiae yeasts that were able to ferment all sugars.
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WINE BACTERIA Phenols (gallic acid & anthocyananins) Growth & stimulation of MLF Biogenic amine production histamine & tyramine Oak products furfural Mannoprotein More efficient malic acid degradation L-lactate L-Malate 0.1-0.2 units increase in pH (palate) Acetate Diacetyl Citrate Pyruvate OxaloacetateAspartate Buttery, nutty aroma/flavour Fatty acids & Lipids Pentoses Lactate & acetate pentose phosphate pathway Hexoses Fructose Pyruvate D-lactate Glucose phosphoketoslase pathway (Heterofermentative) Embden-Meyerhof- Parnas pathway (Homofermentative) Trehalose disaccharide Monosaccharides Polysaccharides Sucrose, trehalose phenolic glucosides Mouthfeel contribution (1->3) glucanse Polyols Glycerol & erythritol Glucose Mannitol Fructose Mouthfeel & body contribution SO 2 -acetaldehyde Acetate & ethanol & free SO 2 Bruised apple (green, vegetative) Colour reduction Adsorption by cells Cell growth Sugar- anthocyanin glycosidase (anthocyanase) Sugar + anthocyanidin Glycoside (flavour) Sugar + flavour-aglycon -glucosidase Increase in aroma Cell growth p-coumaric acid 4-ethyl guaiacol 4-ethyl phenol Phenolic acids Spicy, clove sweaty, bandaid Esters synthesis & hydrolysis Ethylesters esterase ethyl lactate, ethyl acetate, ethyl hexanoate, ethyl octanate Fruity aroma Hydrolase ? Lipids Volatile fatty acids lipase Protein Peptides protease Bitterness ? flavour Ethanol Mousy compounds Ethyl lactate Ethyl carbamate Off-flavour carcinogen Citrulline, urea Copper ions Inhibitory to growth Eveline Bartowski, AWRI, 2004
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Key Interrelationships of Factors Affecting ML Fermentation ALCOHOL CONTENT TEMPERATURE CELL NUMBERS & HEALTH TOXIC FACTORS COMPETITIVE FACTORS NUTRITIONAL FACTORS STRAIN SELECTION
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INTERACTION OF PARAMETERS
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10x volume of water bacteria + 10x volume of wine pH > 3.5 20 MINUTES After 18 – 24 h Final wine volume
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Conclusion Proper inoculation rate Strain selection Proper Rehydration Temperature Control Balanced nutrient (and oxygen) additions Timing of additions
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Thank you! For more information on any of these HUGE topics… please contact: –Jessica Just (jessicaj@scottlab.com)jessicaj@scottlab.com –Sigrid G-B (sigrid@lallemand.com)
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