Wset Advanced: Section 1/6 Maturation And Packaging

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Constituents of Wine
Solutes

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Determine by clarity, stability and ability to benefit from maturation. Bigest components are water and ethanol (ethyl alcohol) [C2H6O]. Other components are either dissolved or suspended in the liquid mixture.
Solutes-chemical dissolved in wine (acids and sugars) Acids- tartaric, latic and malic (not finished MLF). There is a lot of tiny solutes that contribute to flavour of a wine.

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Constituents of Wine
Particles in suspension

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vary dramatically in size. Larger are death yeast cells and fragments of grape, both of them make wine cloudy.
Gross lees forms shortly after fermentation
Fine lees forms during maturation slow deposit
COLLOIDS are contributes to wine texture, they are extremely small and can't make wine cloudy, also the gravity is to week to pull them down. Most important colloids are tannins and colours compound. Amino acids and proteins are the smallest colloids presents during maturation (usually will be removed later).

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Maturation and Blending

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To survive medium or long term agening, wines need sufficient levels of tannins, acidity or alcohol and most important fruit extract that will developed in specific flavours. If winemaker want to retain as much fruit character than bottling comes after several months in inert vessel.

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Changes During Maturation

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Pre-bottling maturation vessel can give components to a wine as tannins toasty flavours. Slow oxidation can contribute to complexity, character of a aroma and soften and stabilize tannins. Some coloids and solutes can form particles that will drop down due gravity and altering the wine composition (tannins and acid can be lost this way)

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Use of Lees

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Fine lees can be used for adding extra flavour and textural roundness of the wine.

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Blending

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Every wine is blending more or less. Maturation is doing in several barrels than blending each others.
Some grape will be maturate in new oak barrels for more oak flavour, some in old barrels to avoid strong oaky flavour and use just slow oxidation, and third can be in inert vessels. Different repines, fermentation, yeast, than wine from old vintage can be refresh with newer vintage, easy change style due market demands.

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Clarification

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The vast majority of consumers expect their wines to be crystal clear, from other side they value quality by the minimum treated and unconcerned by sediments wine. Achieve the clarity the winemaker must remove large sediments (death yeast cells, gape skins) as well as any colloids that can form a haze or sediment in bottle.

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Sedimentation

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When fermentation finished most wines go to sedimentation by using process known as RACKING.
This process can repeating during maturation because wine will produce fine lees.
Sedimentation uses gravity and its slow process to accelerate need to put wine to centrifuge (risk of dissolved oxygen)

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Fining

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Colloids and smallest particles have electrostatic charge: Tannin are negatively charge and proteins have positively charge. Adding fining agent with opposite charge of unwanted colloid they clump together and became large enough for gravity do the job (egg white, bentonite)
Fining can altering flavour and character of the wine. Winemakers carefully use fining usualy to solve problems with oxydative taint, or as in Bordeaux use egg whites to remove astriggent tannins without flavour components.

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Surface Filtration (absolute)

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Works as very fine sieve, its expensive and clog up very easy, so can filtered wine they already passed depth filter. This filtration is last before bottling, because in this filtration we can remove bacteria it is refereed as sterile filtration.

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Depth Filtration

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Works by passing wine through a permeable material that traps solid particles.
Common materials are Kieselguhr (type of earth rock) and sheets made of cellulose fiber.

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Stabilisation

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is important for vintage wines because wine is slow changing in predictable manner for a consuming period. Mass market red wine which should be consumed for an year should not deposit tannins, but Vintage Port will expected to deposit tannins for a lifetime over 50 - 60 years and need removed unstable colloids. Fining can be used also to stabilise wine in predictable outcome after bottling.
There are three important areas of stability.

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Tartrate Stability

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Tartaric acid is less soluble in wine than in grape juice because of presence of alcohol. Over time can deposit lees as potassium bitartrate or calcium tartrat. This appear as white crystals in white wine and purple crystals in red wine. They form In cool environment so winemaker can force forming crystals by chilling wine below to freezing temperature and adding potassium bitartrate powder and formed crystal can removed by filtration. Some unstable colloids prevent forming crystals and they is necessary remove by fining process.

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Microbiological Stability

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Yeast, acetic and latic bacteria can spoil the wine.
Fortified wines is out of risk because contain high level of alcohol which kills all microorganisms.
Alcohol, acidity and lack of nutrients reduce chance for microorganisms to spoil wine.
Prevent from spoiling wine by microorganisms is filtration or pasteurization.
Cold bottling - filtering and bottling in cold environment.
Hot bottling - pasteurizing wine, hot temperature risk for flavours, using for inexpensive wines.

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Oxygen Stability

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Avoid exposure to oxygen when bottling wine, change fresh aroma and colour turn to brown.
Prevent of that is adding SO2 or in modern wineries anaerobically packaging and bottles are flushing with carbon dioxide or nitrogen.

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Packaging
Bottles and Alternatives

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Glass bottle-inert, impermeable, portable and cheap to produce, bottle agening negative: heavy and brittle, raise transport cost.
Plastic bottle, light but negative is not inert.
Bag-in-box inert, low cost transport negative: high quantity for consumer use, not for bottle agening.

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Closures

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Cork-most used in wine industry, risk of cork-taint (TCA Trihloroanisole) give to wine mouldy, cardboardy aroma. Effect from micro transfer of oxygen through cork is unknown, the best cork minimize oxygen transfer.
Syntetic Cork- can't ensure protection from oxygen for a long therm, can be used for wine consumption for an year. Some of them can harm flavour.
Screwcaps - thay preserve fruit flavour longer than a cork. No informations about bottle agening. Consumers from some markets are not accepted but final result is raising from year to year.

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Bottle Agening

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For a short period after wine has been bottled, it can suffer from BOTTLE SICKNESS or BOTTLE SHOCK (not smell and taste as it should) as result of SO2 or wrong handling. Disappear for a few weeks.
Majority of wines is best consumed within an year of bottling and agening them result losing fruit fresh flavour.
There is many that can mature in bottle and are not are their best in year of bottling, example Vintage Port, Finest German Riesling, Classed-Growth Bordeaux which may not rich their pick for 20 years.
Bottle agening environment will be, udisturbed laying bottle in cool dark place, constant temperature 10-15C and constant humidity.