Wine Filtration
(book excerpts)Various winemaking practices allow one to minimize filtration. Natural gravity is an age-old tradition but requires time and patience. Racking dislodges the carbon dioxide produced in the fermentation process. This carbon dioxide often holds certain particulate matter in suspension, when dislodged the particulate matter is allowed to settle. Fining and cold stabilization are often used to speed up clarification. Although these practices are useful, producers often choose to filter wines during their preparation for bottling. The key role of filtration in winemaking is to provide stabilization. Physical stabilization prevents the formation of hazes and deposits after packaging, while microbiological stabilization eliminates yeasts and bacteria that can destroy a wine's taste. Many types of filtration systems are available to the winemaker, each with its own advantages or disadvantages, and these can include pressure leaf filters, plate and frame filters, lenticular disc filters, membrane filters, and tangential flow (cross-flow) filters. These systems use different filter media including diatomaceous earth, cellulose pads, lenticular discs, membranes with calibrated pores, and tangential filtration through inorganic or organic membranes. Important characteristics of filtration media are the porosity, which is the percentage of empty space in a porous structure in relation to total volume, and their permeability, which represents the ability of a medium to transmit fluids through at more or less at high rates. Depending on the initial state of the wine clarity (quantity and type of solids in suspension) the wine may undergo a series of filtration steps - rough, polish, and sterile. Today, some winemakers choose to use minimum filtration to avoid what they see as stripping the body away from the wines.
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Topics Within This Chapter:
- Direct-End versus Cross-Flow Filtration
- Direct-End Filtration
- Depth Filtration
- Surface Filtration
- Cross-Flow Filtration
- Filter Performance
- Nominal
- Absolute
- Beta Ratio
- Log Reduction Value
- The Right Filter for Each Application
- Turbidity and Filterability
- Turbidity
- Filterability Index
- Depth Filters
- Pressure Leaf Filters
- Diatomaceous Earth
- Filter Operation
- Lenticular Disc Filters
- Plate and Frame Filters
- Plates
- Pads
- Filter Operation
- Membrane Filters
- Membrane Materials
- Membrane Pore Sizes
- Bubble Point Test
- Working Pressure
- Regeneration of Membrane Filter Cartridges
- Water Regeneration
- Chemical Regeneration
- Cross-Flow Filtration
- Benefits in Cross-Flow Filtration
- Membrane Types
- Ceramic
- Polymeric
- Membrane Geometries
- Choosing a Cross-Flow Microfiltration System
- Sizing the Unit
