Alcohol management in the winery David Wollan, VA Filtration/Memstar Pty Ltd (On behalf Steve Clarkson)
Options for lower wine alcohol Pick grapes earlier (Get it right in the vineyard) Wait for new yeast strains Manipulate the composition of must or wine
Reduce must sugar concentration Add water / Dilution Reduces sugar concentration But also acid, flavour, etc. Illegal in most jurisdictions Because it makes more, poorer wine? (Not USA where some dilution to 22 o Brix is permitted)
Options to reduce wine alcohol Add water / dilution Remove alcohol:- Distillation based techniques Membrane based techniques Or a combination of both
Spinning cone distillation
SP-AR vacuum distillation
Membrane options- Reverse osmosis Nanofiltration Evaporative perstraction (Osmotic distillation) (Pervaporation theoretical application only at this stage)
Membrane separation - Reverse osmosis and nanofiltration High pressure retentate (wine) Membrane Low pressure - permeate
Some wine components molecular weights Water 18 Carbon dioxide 44 Acetaldehyde 44 Ethanol 46 Acetic acid 60 Ethyl acetate 88 Lactic acid 90 tight RO Malic acid 134 Tartaric acid 150 Volatile phenols 120-150 loose RO (nanofiltration) Glucose / Fructose 180 Flavonoids >300
Reverse osmosis does not reduce alcohol! A common misunderstanding By itself, RO increases the concentration of alcohol in treated wine Some secondary treatment is essential (This also applies to nanofiltration)
Comparison of concentration effects Different membrane types Titratable Acidity (g/l as tartaric acid) Alcohol (% v/v) Control wine 5.9 14.10% 8% Concentration with loose, NF type membranes:- Permeate 2.4 13.35% Concentrate 6.2 14.15% 8% Concentration with tight, RO type membranes:- Permeate 0.9 8.00% Concentrate 6.3 14.70%
Reverse osmosis and water addition Wine treatment tank Reduced alcohol wine return Pressure pump Wine concentrate Make up water addition Wine to be treated Membrane separation Permeate to waste
Problem of water addition Water 18 Carbon dioxide 44 Acetaldehyde 44 Ethanol 46 Acetic acid 60 Ethyl acetate 88 Lactic acid 90 tight RO Malic acid 134 Tartaric acid 150 Volatile phenols 120-150 loose RO (nanofiltration) Glucose / Fructose 180 Flavonoids >300
Membrane separation, treatment and recombination Wine treatment tank Recombination and treated wine return Treated permeate Wine to be treated Pressure pump Retentate Membrane separation Permeate treatment Permeate to be treated
Membrane separation and permeate distillation Alcohol Wine treatment tank Recombination and treated wine return Dealcoholised permeate Distillation column Retentate Pressure pump Wine to be dealcoholised Membrane separation Permeate to be dealcoholised
Evaporative perstraction Alcohol rich stream (decreasing alcohol) Water vapour Alcohol vapour Hydrophobic membrane Water vapour Strip water stream (increasing alcohol)
Direct evaporative perstraction (Osmotic distillation) Strip water Wine treatment tank Reduced alcohol wine return Hydrophobic membrane Evaporative perstraction treatment Circulation pump Alcohol vapour passage Wine to be treated Strip water + alcohol
Membrane separation and evaporative perstraction* Wine treatment tank Pressure pump Recombination and treated wine return Retentate Dealcoholised Permeate Strip water Hydrophobic membrane Evaporative perstraction treatment Wine to be treated Membrane separation Alcohol vapour passage *Memstar patent application pending Permeate Strip water + alcohol
Alcohol adjustment plant
Alcohol reduction over time 16% Wine alcohol concentration [alcohol] 14% 12% 10% 8% 6% 4% [alcohol] = ce -kt 2% 0% - 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 Time (t)
Practical implications: With membrane based processes, Impossible to achieve zero alcohol concentration It is more efficient to take a little alcohol from a lot of wine than a lot of alcohol from a little wine. Distillation systems are more suitable for very low alcohol wines
You take alcohol out of wine? Why would you want to do that?!!