Depth-Bed Filtration Diatomaceous earth; cellulose; perlite Cost effective Minimal clogging “Rough” filtration: sieving action is minimal Principle of “torturous path” for particles to travel
The “Torturous Path”
Kinds of Filter Units Depth-bed Pad
Pad Filtration Filter matrix is a preformed sheet or pad Sieving as well as adsorption Pads come in a variety of porosities, but pore size is heterogeneous Flow of wine perpendicular to pad “Dead end” filtration
Pad Filtration Wine Filtered wine
Kinds of Filter Units Depth-bed Pad Membrane
Membrane Filtration Like pad filtration, but uses a membrane Fixed pore size Sieving as well as adsorption Clog easily “Finishing” filtration
Membrane Filtration WineMembrane Filtered Wine XX XX XX XX XX
Kinds of Filter Units Depth-bed Pad Membrane Cross-flow
Cross-Flow Filtration Same porosities as membrane filtration Wine flows across matrix, not through it Wine retentate can be re-circulated Back flux can be used to clear membrane Does not clog that easily
Order of Filtration: Rough Before Finishing XXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The Question: Does filtration impact wine flavor and aroma?
The Belief: Filtration removes flavor and aroma compounds and is therefore undesirable. “Unfiltered” wines are more complex than filtered.
The Facts: Several studies have shown that expert tasters are not able to recognize filtered versus unfiltered control wine. Unfiltered wine allows continued microbial activity, which may explain differences perceived in unfiltered wines in general.
The 5 Goals of Post-Fermentation Operations: 2. COMPOSITIONAL ADJUSTMENT
Compositional Adjustment Acidity
To increase acid add: –Malate –Tartrate –Citrate To decrease acid add: –Calcium carbonate To remove volatile acidity: –Reverse osmosis
Compositional Adjustment Acidity Sugar level
Sugar Level Add juice concentrate Arrest fermentation –Addition of ethanol Fortified wine Fortified juice –Temperature shock