Finishing

Question 1

Getting your wine ready for bottling day checklist

Answer 1

1) 4 months to 8 weeks ahead
- assemble final blend
- full chemical analysis (alcohol,rs,free SO2, etc)
2) 8 weeks ahead
- final adjustments (alcohol, acidity, tannins)
3) 6 weeks ahead
- protein stability trial (fine w bentonite if needed)
4) 4 to 6 weeks ahead
- test tartrate stability, treat if needed
5) 4 weeks ahead
- check protein and tartrate stability
6) 1 to 2 weeks ahead
- add sweetening agents if using
7) 72 to 48 hours ahead
- test filter ability of wine
8) 24 hours ahead
- adjust free SO2
9) bottling day
- adjust dissolved oxygen and CO2
10) during bottling
- check dissolved oxygen and SO2 levels;s regularly and keep samples for quality assurance purposes

Question 2

Clarification

Answer 2

All purposes, physical and chemical, that are used to make wine clear

Question 3

Aspects of post-fermentation clarification

Answer 3

1) sedimentation
2) centrifugation
3) fining
4) filtration

Question 4

Sedimentation

Answer 4

• the wine is allowed to stand and the particles with higher density than the wine form a sediment at the bottom, it is then racked off
• occurs naturally in cool cellars with suspended matter precipitating over time
• some premium wines are only clarified this way as it avoids the potential loss of texture and flavor that may occur with fining and filtration
• takes time thus reserved for premium and super-premium wines
• barrel aged wines do this naturally

Question 5

Centrifugation

Answer 5

• a rapid process that spins the wine at high speed to clarify it
• can replace depth filtration and allow early bottling
• only practiced in high-volume wineries to spread the considerable cost of buying the machine

Question 6

Fining

Answer 6

• a procedure in which a fining agent (of protein or mineral origin) is added to speed up the precipitation of suspended material in the wine
• it removes a small portion of unstable colloids, helping to clarify the wine and stabilize it against the formation of hazes later in the bottle
• able to offer solutions to other problems such as removing harsh tannins or browning
• the fining agent must have the opposite charge from the wine colloid to be removed, they attract each other and from a large enough solid to be removed by racking or filtration

Question 7

Three categories of common fining agents

Answer 7

1) those that remove unstable proteins
2) those that remove phenolics
3) those that remove color and off-odors

Question 8

Fining Agents that remove unstable proteins

Answer 8

• not necessary in red wines as they bind with tannins and precipitate naturally but in whites and roses the proteins can agglomerate into a visible haze if warmed up, thus they are fined with bentonite
• bentonite is a form of clay that adsorbs unstable proteins and unstable colloidal coloring matter
• leads to some color loss in red wines and produced large amounts of sediment, so wine is lost when it is racked off
• can be used on must and wine

Question 9

Fining agents that remove phenolics that contribute undesirable color and bitterness

Answer 9

May be used in conjunction with bentonite for their own properties and to avoid risk of over-fining (which makes the wine unstable)
1) egg white
2) gelatine
3) casein
4) isinglass
5) vegetable protein products
6) PVPP (polyvinylpolypyrrolidone)

Question 10

Egg white

Answer 10

• used in fresh or powdered form
• tends to be used for high quality red wines as it removes harsh tannins and clarify wine
• gentle
• allergen thus must be declared on EU labels if present above a specified limit

Question 11

Gelatine

Answer 11

• a protein collagen extracted from pork
• aids clarification
• removes bitterness and astringency in reds
• removes browning in whites
• easy to over-fine with, stripping flavor and character, and creating the risk of a protein haze forming
• can fine must and wine

Question 12

Casein

Answer 12

• a milk derived protein
• removed browning from whites and clarifies to an extent
• allergen so must be on labels in certain countries
• can be used on must and wine

Question 13

Isinglass

Answer 13

• a protein collagen derived from fish bladders
• very effectively clarifies white wines, giving them a bright appearance
• over-fining can create a protein haze and have a fishy smell

Question 14

Vegetable protein products

Answer 14

• derived from potatoes or legumes

Question 15

PVPP

Answer 15

Polyvinylpolypyrrolidone
- an insoluble plastic in powder form
- removes browning and astringency from oxidized white wines
- rarely used on reds but can reduce astringency and brighten the color
- gentler than charcoal

Question 16

Fining agent that removes color and off-odors

Answer 16

Charcoal
- removes browning and some off-odors
- can easily over-fine
- one option is to treat one batch and blend them

Question 17

Filtration

Answer 17

• a physical separation technique used to eliminate solids from a suspension by passing it through a filter medium consisting of porous layers that trap solid particles
• much less chance of wine developing faults as bacteria and yeast have been removed
• the two main types are depth filtration and surface filtration
• some believe filtering strips a wines texture and needs a few months after to recover from the shock

Question 18

Depth filtration

Answer 18

• traps particles in the depth of the material that forms the filter (gets stuck in the irregular channels)
• can cope with large amounts of particles (like wine that was just pressed or lees)
• is not absolutely reliable as too much pressure/ too long use some particles will make there way through
• diatomaceous earth and sheet filters

Question 19

Diatomaceous earth

Answer 19

• the most common form of depth filtration
• made of pure silica and inert
• the DE is wetted and the wine is sucked via vacuum from the outside of a rotary drum, through the DE, to the inside of the drum
• rotary vacuum filters use this method to filter very thick and cloudy wine (ex lees)
• can be anaerobic or oxidative and comes in a range of particle sizes
• very expensive

Question 20

Sheet filters

Answer 20

• aka ‘plate and frame’ or ‘pad’ filters
• the wine is passed through a sheet of the filtering material
• the more sheets, the quicker the filter
• the system requires investment but the cost of the filters is low, well trained personnel must operate them

Question 21

Surface filtration

Answer 21

• it stops particles that are bigger than the pore size of the filter from going through
• often called absolute filters
• two types: membrane filters and cross-flow filters

Question 22

Membrane filters

Answer 22

• also called cartridge filters or sterile filtering
• catch particles that will not go through the pore size of the filter
• slower than depth filtration as the pores are smaller, often less than one micron
• wine must be pre-filtered first as they are easily blocked
• generally used as a last precaution before bottling to ensure a microbiologically stable, clear wine
• initial investment is small but cartridges are expensive and an ongoing cost

Question 23

Cross-flow filters

Answer 23

• aka tangential filters
• they allow wine to pass through the filter while uniquely cleaning the surface of the filter as it works, solids cannot pass through the filter
• can handle a high load of particles or lees very quickly
• the machines are expensive but doesn’t need any replacement parts/sheets/filters making them more suitable to large, well-funded wineries

Question 24

Stabilization

Answer 24

• refers to several winemaking interventions which, if not carried out, could lead to undesired effects in the finished wine
• includes tackling unwanted hazes, deposits, and rapid browning
• tartrate stability, fining, and filtering contribute to clarification and stabilization

1) protein stability (fining w bentonite)
2) tartrate stability
3) microbiological stability

Question 25

Tartrate stability

Answer 25

- principally potassium bitartrate and less frequently calcium tartrate are harmless deposits of crystals that can form in finished wine - methods of prevention: 1) cold stabilization 2) contact process 3) electrodialysis 4) ion exchange 5) carboxymethlcellulose 6) metatartaric acid

Question 26

Cold stabilization

Answer 26

- wine held at -4C/ 25F for around eight days so the crystals form before bottling and can can be filtered out (because tartrates are less soluble at cold temperatures) - colloids must be removed via fining before this process as they could prevent crystal formation - requires cost of energy and equipment - only removes potassium bitartrate, not calcium tartrate

Question 27

Contact process

Answer 27

- quicker, continuous, more reliable form of cold stabilization - potassium bitartrate is added to the wine and speeds up the start of the crystallization process, cooled to 0C / 32F and after 1-2 hours is filtered out

Question 28

Electrodialysis

Answer 28

- uses a charged membrane to remove selected ions - high initial investment but total costs are lower than cold stabilization is it uses less energy and is faster - removes potassium and calcium ions and to a lesser extent tartrate ions - allowed in EU

Question 29

Ion Exchange

Answer 29

- replaces potassium and calcium ions with hydrogen and sodium ions that do not drop out of solution - not allowed in some places due to sodium content but its well within legal limits

Question 30

Carboxymethylcellulose (CMC)

Answer 30

- a cellulose extracted from wood and prevents tartrates from developing to a visible size - widely used for inexpensive whites - cannot be used on reds as it interacts with tannins and causes a haze - much cheaper than chilling - keeps wine stable for a few years

Question 31

Metatartaric acid

Answer 31

- adding this compound prevents the growth of potassium bitartrate and calcium tartrate, reducing the need for chilling - unstable compound thus loses effect over time, especially at warm temps (25-30C / 77-86F) - best for early-consumption red and white wines - CMC is more effective and long-lasting

Question 32

Microbiological Stability

Answer 32

- wines with RS are at risk of re-fermenting thus must be sterile filtered to remove yeast or add sorbic acid which inhibits yeast growth (has a smell even at low levels) - very few microbes can live in wine with low pH and high alcohol, the exceptions being: lactic acid bacteria, acetic acid bacteria, and brettanomyces (a spoilage yeast) - lactic acid bacteria will likely start MLF in bottle it it didn’t go through it during winemaking, must go through MLF or filter it out - brettanomyces must be filtered or treated with dimethyl dicarbonate before bottling, which inactivates brett

Question 33

Finishing options

Answer 33

1) full chemical analysis of at least alcohol, residual sugar, free SO2 and in the last moments before bottling dissolved oxygen and CO2 2) adjusting levels of sulphur dioxide - white 25-45 mg/L - red 30-55 mg/L - sweet 30-60 mg/L 3) reducing dissolved oxygen - via sparging or flushing with inert gas 4) adding carbon dioxide - added just before bottling if a spritz is wanted for freshness