Ch. 15 Finishing & Packaging Flashcards
Define clarification and list the main methods.
Clarification- all the processes, physical and chemical, used to make a wine clear
- sedimentation
- centrifugation
- fining
- filtering
Describe the process of sedimentation. What are the benefits and drawbacks of this method?
- Wine is stored in cool conditions, and the solid matter in wine starts sinking naturally to bottom of vessel. Wine is then racked off, leaving sediment behind.
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Some winemakers think this method avoids potential loss of texture and flavor
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Takes time - wine can’t be sold until clarified - cost
**best for premium to super premium wines - too slow for high-volume, bulk production (time is money)
Describe the process of centrifugation. What are the benefits and drawbacks of this method?
A process that clarifies wine by spinning it at a high speed.
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helpful for wines with a lot of matter in suspension
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cost of buying machine
** best for high-volume production that can spread cost of machinery, and needs to clarify quickly
Describe the process of fining and its aims.
Fining is when a fining agent is added to speed up the process of the precipitation of suspended material in the wine.
AIIMS
- catch unstable colloids (microscopic particles too small to be removed by filtering) –> colloid and fining agent bind, form a solid large enough to then be removed by racking or filtration
- helps stabilize against formation of hazes later in bottle
- solve other problems, like removing harsh tannins or browning in white wines
What are the three categories of common fining agents?
- Those that remove unstable proteins
- Those that remove phenolics that contribute undesirable color and bitterness
- Those that remove color and off-odors
What is bentonite and why would a winemaker use it?
Bentonite is a form of clay that is used as a fining agent to remove unstable proteins.
These proteins are removed in red wine when wine is racked (bc they bind w tannins), but can become a visible haze in whites and roses when wine is warmed up. Fined with bentonite to clarify.
It has minimal effect on flavor and texture of wine, but can lead to color loss in reds.
It remove large amount of sediment so wine is lost when racked off.
Which fining agents are used to remove phenolics that contribute undesirable color and bitterness?
- used in conjunction w bentonite for own properties, avoid risk of over-fining
- *if animal origin, have to be declared on label, may not be suitable for vegetarians/vegans
- egg white- ** high quality red wine bc can remove harsh tannins, clarify wine, is gentle (Napa Cab, Spanish Priorat)
- gelatine- ** PORK, clarification, bitterness, astringency, browning in whites // OJO easy to over-fine, removing flavors, risk of protein haze
- casein - **MILK, removes browning in whites
- isinglass- **FISH, clarifies white, gives them bright appearance // OJO can smell fishy, risk of protein haze forming
- vegetable protein products - **POTATO/LEGUMES suitable for vegetarian/vegan,
- PVPP - **PLASTIC removes browning and astringency from oxidised white wine
Why would a winemaker use charcoal?
Charcoal is used as a fining agent to remove color and off odors.
OJO- can easily over-fine, removing desirable aromas + flavors
SOLUTION- treat only one batch of affected wine, then blend with rest
Define filtration and describe the two main types
Filtration - a physical separation technique used to eliminate solids from a suspension by passing it through a filter that traps solid particles.
The most common way of clarifying wine
Can be:
- Depth filtration - traps particles in thickness of material that forms filter; can cope with large sediments (just pressed wine, gross lees), not absolute filter since some particles can make way through
- Surface filtration - blocks particles bigger than pore size of filter from passing; absolute filters
What are two examples/forms of depth filtration? List important considerations for each
- Diatomaceous earth (DE)- most common form of depth filtration
- DE is processed into pure silica, inert, wetted and used as filter medium. Wine is sucked from outside of rotary drum, through DE, to inside of drum
- Used for thick + cloudy wine (lees)
- Oxidative - drum exposed to air; can also be enclosed and flushed w inert gas
- can remove large or very small particles
- high cost up front, after that cost is small
- DE needs to be disposed of responsibly which adds cost - Sheet filters- plate and frame or pad filters
- Wine is passed through sheet of filtering material - more sheets, quicker wine is filtered
- High initial investment (robust frame required to withstand pressure)
- Trained personnel required to operate
What are the two types of surface filters? Describe important considerations for each.
- Membrane filters - known as cartridge filters
- Not very suitable for cloudy wines or w/ thick deposits = pores get blocked, needs pre-filtering
- smaller pores, slower process
- usually used as final step before bottling to make sure wine is clear and stable, yeasts and bacteria are gone (called sterile filtering)
- initial investment is small but cartridges are expensive - COMMON DURING BOTTLING/PACKAGING - Cross-flow filters - known as tangential filters
- Wines pass through filter while cleaning surface of filter as it works
- Quick filtering of high load of particles or lees
- Expensive to buy, but no need for continued purchase of materials - good for large/well funded wineries
What does stabilisation refer to? What are its principal aims?
Stabilisation - several winemaking interventions that need to be carried out to avoid undesired effects in finished wine
AIMS Remove - unwanted hazes - deposits in bottle - rapid changes in wine
What are the main types of stability?
Protein stability - fining w bentonite
Tartrate stability - tartrates are harmless deposits of crystals that can form in finished wine, harmless but still seen as fault by consumer
Microbiological stability
What are the main types of stability?
Protein stability - fining w bentonite
Tartrate stability - tartrates are harmless deposits of crystals that can form in finished wine, harmless but still seen as fault by consumer
Microbiological stability
What options does a winemaker have for tartrate stability?
- Cold stabilisation - 25F for 8 days- tartrates form before bottling and then are filtered out; colloids removed by fining first, needs equipment/cost of energy, only works for potassium bitartrate
- Contact Process- quicker, continuous, more reliable, cheaper; potassium bitartrate added, cooled, then crystals filtered out
- Electrodialysis - charged membrane removes selected ions; less energy, espensive at first then cheaper
- Ion Exchange - switch out potassium and calcium ions for hydrogen and sodium ions, which won’t crystallize; legal considerations, health
- CMC - cellulose that is extracted from wood and prevents tartrates from developing to visible size; used for inexpensive white wines, interacts w tannins so can’t be used for reds, cheaper than chilling
- ## Metatartaric acid - adding this to wine prevents formation of potassium bitartrate and calcium tartrate crystals; compound is unstable, effect is lost esp at higher temps - best for early consumption wines, more reds than whites
What is the importance of microbiological stability? how is it achieved?
- Avoid 2nd fermentation in bottle
- Remove bacteria that can spoil wine
HOW
- remove yeast thru sterile filtration
- add sorbic acid and SO2
Which microbes can live in wine despite its low pH and high alc levels? What are solutions?
- lactic acid
- acetic acid
- Brettanomyces (spoilage yeast)
Solve by
- ensure malo has been completed
- filter wine to remove bacteria
- if Brett is prob, filter or treat with DMDC before bottling
What final adjustments can be made as finishing options?
- Adjust SO2
- make sure within legal limits
- free SO2 contains molecular SO2 which is effective one
- Reduce dissolved oxygen
- sparging - remove dissolved O2 by flushing wine with inert gas
- dissolved O2 can accelerate speed of aging.in wine, reduce shelf life
- Adding CO2
- depending on style of wine (cheap, youthful white/rose), winemaker might add some CO2 for spritz effect, freshness - like VV, Txakolina, Cali rosé
What steps are taken throughout the production process to avoid wine faults?
- Sorting to exclude damaged or moldy fruit
- Exclusion of oxygen at key points in process
- Temperature control
- Scrupulous hygiene in wineries
- Stabilisation
- Final adjustment of SO2
- Fining and filtering
- Care over bottling
What are common wine faults found in wine?
- Cloudiness and hazes
- Tartrates
- Re-fermentation in bottle
- Cork taint
- Oxidation
- Volatile acidity
- Reduction
- Light strike
- Brettanomyces
What are the main reasons for wine cloudiness/hazes and how can they be remedied?
REASONS
- growth of yeast/bacteria + failure to filter adequately
- too high-pressure pumping through depth filter, some molecules make it through
- protein haze - fining not effective, use of wrong kind of fining agent or over-fining
SOLUTION
- better hygiene in winery
- pre-bottling chemical analysis
- filter wine
- fine correctly, conduct fining analysis
What are tartrates, how are they caused and how can they be prevented?
- Colorless or white crystals in the bottom of bottle that can be mistaken for fragments of glass
- Triggered by low temps - harmless but can be seen as fault by average consumer
- Stabilization helps prevent
