Chapter 15 - Finishing & Packing P1 Flashcards
(35 cards)
Clarification Methods:
Sedimentation
Centrifugation
Fining
Filtering
What are Colloids?
Microscopic particles too small to be removed by filtering
What are the 3 categories that Fining Agents remove?
- Remove unstable proteins
- Remove phenolics with undesirable color and bitterness
- Remove color and odors
How do you fine unstable proteins?
Unstable proteins from must & wine (not necessary in red wines bc they bind to tannins and precipite out naturally)
Bentonite - fining agent to use. A form of clay
Fining agents for phenolics to remove unwanted color & bitterness
For reds (harsh tannins, clarify, remove bitterness) and whites:
- Egg whites
- Gelatine
For whites for color and to clarify:
- Casein
- Isinglass
- Vegetable Protein Product
- PVPP
Fining Agent for Color & Odors
Charcoal
Levels of removing sediments
Sedimentation –> Depth Filtration –> Fining AND/OR Surface Filtration
Depth Filtration
Examples?
Wine is passed through a filter with many irregular channels.
Good for wine when it has a lot of particles (ie after pressing or still has lees)
1. Distomaceous Earth (DE) w/ rotary vacuum filter (wine starts on outside of vacuum and move inside as it goes thru the filter. Can be flushed with inert gas. Can remove particles as small as yeast
2. Sheet filters - liquid flows thru individual sheets (the more, the quicker the process). Can remove yeast as well
Surface Filtration
AKA absolute filters. Stops particles bigger than the pore size
- Membrane filters - slower and must be pre-filtered first or membrane would get blocked. Usully used as a final precaution immediately before the wine is bottled to make sure wine is clear and microbiologically stable (sterile filtered). Removes yeast and bacteria
- Cross-flow filter - aka tangential filters. Wine flows thru machine while surface of filter is cleaned. Solid particles cannot pass thru filter. Quicker method but very expensive
Sterile filtration
Filtering out a wine so that it is clear and microbiologically stable (no yeast or bacteria)
Types of Stability
- Protein Stability (w/ bentonite. Same as Clarification)
- Tartrate Stability
- Microbiological stability
Tartrate Stability methods:
Crystal deposits of potassium bitartrate and calcium tartrate
- Cold Stabilization - freeze to -4C for 8 days to cause the tartrates to precipitate out and then filter the wine. *Colloids must be fined first or tartrates won’t precipitate. Only removes potassium bitartrate
- Contact Press - Potassium bitartrate is added to the wine to induce the rest to precipitate out. Occurs at 0C and takes 1-2hrs
- Electrodialysis - Uses a charged membrane to remove potassium bitartrate and calcium tartrate
- Ion Exchange - use Hydrogen and Sodium ions to replace the potassium and calcium, causing the tartrates to not be able to drop out of solution
- Carboxymethylcellulose (CMC) - wood cellulosethat prevents tartrates fromd eveloping to a visible size. Popular for cheap whites
- Metatartaric Acid - Prevents potassium bitartrate and calcium tartrate crystals to grow. Usually used for early drinking reds
Microbiological Stability Methods (post fermentation)
- Removing yeast via sterile filtration
- Add sorbic acid and SO2, which inhibits yeast from growing
- Filter out lactic bacteria if malo hasn’t occurred yet
- Filter or use DMDC to remove Brettanomyces risk
Things to test for before bottling:
Levels of alcohol, RS, free SO2, dissolved O2 and CO2
How do you reduce dissolved O2 in wine?
Sparging - flushing the wine w/ an inert gas to remove the O2
What are the steps winemakers take to prevent faults in their wines? Starting from when the grapes first arrive at the winery
- Sorting out damaged, moldy, diseased fruit
- Making sure the grapes and must have limited O2 at all times
- Temperature control - constant, cool temp
- Scrupulous hygiene in the winery
- Appropriate use of SO2
- Clarification and Stabilization - esp fining and filtering
- Pre-bottling chemical analysis
- Making sure bottles are sterile
- Making sure the closure is sterile
Most common faults
- Tartrates
- Re-fermentation in bottle - effervescent and cloudy. yeast still present. Sterile fertilize
- Cork Taint
- Oxidation - brown, loss of primary fruit, vinegar aroma
- Volatile Acidity - nail polish remover and vinegar. Caused by acetic acid bacteria, not enough SO2, excess O2 exposure. Can be avoided by proper grape sorting, winery hygiene, limiting O2 contact (topping off, careful racking), appropriate SO2 levels
- Reduction - rotten eggs, Caused by stressed yeast and not enough Nitrogen or too little O2 during aging esp w/ lees aging
- Light Strike - UV radiation reacting with wine compounds forming volatile sulfur compounds that smell like dirty drains. Use dark glass bottles
8, Brettanomyces - Causes animal, barnyard smell, strong tannins, loss of fruity aromas. Limit bacteria by limitign O2 exposure, having adequate SO2 levels, sterile filtration, hygiene, low pH, no stuck fermentation. Can also treat with DMDC before bottling
What fining agent is good for high quality reds because it can remove harsh tannins as is gentle on the wine?
Egg White
What is a fining agent good for removing bitterness and astringency in red wines and browning in white wine? It is not allowed in vegan wines
Gelatine
What is a fining agent good for removing browning from white wines?
Casein
Gelatin
What fining agent gives white wines a bright appearance?
Isinglass
What fining agent is good for vegan wines because they are derived from potato or legumes?
Vegetable protein products
What fining agent removes browning and astringency from oxidized white wine?
PVPP
What fining agent removes brown colors and off odors. This agent can easily over-fine wines
Charcoal
