Clarification Flashcards
What are the main types of wine filtration?
RDV (Rotary Drum Vacuum), Earth filters (pressure leaf), Depth filters (pads/cartridges), Membrane filters, Cross-flow filters.
How does an RDV filter work?
Uses a vacuum to adhere filter media (e.g., perlite) to a rotating drum; turbid wine is sucked through, solids are scraped off.
What are the advantages of RDV filters?
Effective for lees/ferments, high liquid recovery, cheaper than centrifuges. Disadvantages: Oxidative, slow, generates waste.
What is diatomaceous earth (DE)?
Fossilized diatoms used as filter media; health hazard. Alternative: Perlite (expanded volcanic glass).
How do earth (pressure leaf) filters function?
Pressure forces wine through DE/perlite-coated screens; solids trapped in media. Advantages: Fast, non-oxidative. Disadvantages: Waste slurry, media matching critical.
What are depth filters?
Pads/cartridges capturing solids via sieving, depth entanglement, or electrostatic charge (e.g., Zeta Plus™). Used for clarified wines.
What causes depth filter failure?
Type 1: Pore blockage (pressure ↑, flow ↓). Type 2: Charge loss (turbidity ↑, flow stable).
How do membrane filters ensure sterility?
Defined pore sizes (0.2–1 µm) sieve particles; require pre-filtration. Advantages: Sterile output. Disadvantages: Slow, expensive.
What is cross-flow filtration?
Tangential flow keeps membrane clear; wine flows parallel to filter, permeate passes through. Handles high turbidity, no solid waste.
Why use reverse osmosis (RO) in winemaking?
Removes water/alcohol (permeate) to concentrate flavor/tannin (retentate) or reduce faults. Pore sizes target specific MW compounds.
What are key factors in filter selection?
Turbidity level, desired clarity (sterile/polishing), waste volume, cost, organoleptic impact, and operational complexity.
How does electrostatic charge aid filtration?
Positively charged media (e.g., Zeta Plus) captures negatively charged colloids/bacteria, enhancing submicron filtration.
What are environmental concerns with filter waste?
Spent DE/perlite: High COD/BOD, landfill issues. Solutions: Distill with marc or recover tartaric acid.
What operational tips apply to earth filters?
Dose media slowly, match grade to turbidity, maximize flow rate, monitor pressure rise.
How does cross-flow differ from perpendicular filtration?
Cross-flow parallel flow reduces membrane blinding; perpendicular flow clogs faster.
