Ch. 0 – Vinification Flashcards
Name wine components
\Water Alcohol Acids Wine aromatics Residual sugar Glycerol Phenolics
Alcohol formed during fermentation
Ethanol
Gives sense of sweetness and bitterness
Contributes to the fullness of the body
Principal acids in wine
Tartaric acid and malic acid (come from the grape)
Lactic acid and acetic acid (produced acids)
Contribute on balance of sugar and fruit concentration
High acidity wines appear leaner on palate
Acetic acid expression
Volatile acidity
Vinegar smell
Generally in small concentration, if high it is fault
Reacts with alcohol and form ethyl actate (nail varnish remover smell)
Acidity and pH
Measuring acidity and pH
Linked but not correlated
high acidity usully means low pH and vice versa
grams per litre (g/l) in tartaric acid. Typical range of 5.5-8.5 g/l
pH range typically 3-4. Inverse scale, lower the number the more concentrated the acidity. And logaritmic (pH of 3 is ten times more acidic than pH of 4)
Low pH increases microbial stability of wine and effectiveness of SO2, gives red wine bright colour and enhances ability to age
Wine aromatics kinds
From the grapes
Created by fermentation due to presence of aroma precursors in grape must
Originating from fermentation and its by-products
Aromas from other sources
Aromas from grapes
Methoxyparazines (grassy, green pepper aromas in Sauvignon Blanc)
Rotundone (Pepper aroma in Syrah)
Aromas from fermentation (based on presence of aroma precursors)
Thiols (box tree aroma of Sauvignon Blanc)
Terpenes (linalool and geraniol - grapey aromas in Muscat)
Aromas from fermentation and its by-products
Esters (formed by reaction of acids and alcohol)
Fresh and fruity aroma essential for young wines
Isoamyl acetate (banana - Beaujolais Nouveau)
Unstable and will breakdown few months after
fermentation
Acetaldehyde (due to oxidation of ethanol)
Masks fruit aromas
Distictive smell of Fino sherry
Diacetyl (during fementation, especially malolactic)
Buttery aromas
Aroma of reductive sulfur from yeast during fementation and lees ageing (stuck match up to rotten egg)
Aromas from other sources
Vanilin
Eucalyptol
Residual sugar classification levels (EU)
Residual sugar contributes on body
Dry/sec/trocken
up to 4 g/l
not exceeding 9 g/l provided acidity is not more than
2g below RS content
(wine with 9 g/l RS can be SEC if it has 7g total acidity)
Medium dry/Demi-sec/Halbtrocken
more than 4 g/l no more than 12 g/l
up to 18 g/l provided acidity is not more than 10 g
below RS content
Medium or medium sweet/Moelleux/Lieblich
more than 12 g/l not exceeding 45 g/l
Sweet/Doux/Suss
at lease 45 g/l
Glycerol
Derived from sugar in grapes
In higher level in wines from botrytis and carbonic maceration
Contributes with smoothness to the texture and perception of fullness of the body.
Slightly sweet body
Phenolics
Group of compounds from skins, stems and seeds
Anthocyanins and tannins
Tannins bind with proteins in the mouth giving drying sensation on the palate.
Residual sugar can make tannins to seem softer
High acidity, dry wine - astringent tannins
Tannins react with other compounds during fermentation and maturation and change composition and their final feel
Important for structure and balance of wine
Who identified yeast and bacteria and when?
Luis Pasteur iìn the 1860s
Conventional winemaking
Temperature control
Use of additives and processing aids of many kinds
adding sugar, use of cultured yeast, fining agents etc
Manipulations (high technology such as reverse osmosis)
Aim is to produce stable wine
Organic winemaking
Wine from certified organically grown grapes
Allow many common additives and process from conventional winemaking (adding tannins, cultured yeast etc.)
Certifying body - ECOCERT
EU - allows regulated use of SO2
USA - excludes any SO2 use and require naturally occuring SO2 to be bellow 10 mg/l
(another category in USA - “wine made from organic grapes” allow SO2)
Biodynamic winemaking
DEMETER certifying body
wine from certified biodynamic grown grapes
Natural winemaking
Rejects many modern interventions in favour of artisan practises from the past.
Nothing added nothing removed
Fewest possible manipulations, fermentation by ambient yeast, absolte minimum of SO2 added
No certifying body
Reductive (protective) winemaking
Minimising contact with oxigen
Ullage
Headspace between wine and top of the container
2 important gases in winemaking
Oxygen and sulfur dioxide
Effect of oxygen in must and wine
Timing and amount of oxygen is the key
Phenolic compounds in red wine have anti-oxidative effect therefore red wine is more resistant
Advantages:
Oxygen is needed in the beginning of fermentation to
promote yeast growth and prevent reductive off
flavours
Increases oxidative stability of wine (increased ageing potential) In red wine, essential in reaction between anthocyanins and tannins to lead to greater colour stability
Disadvantages:
Threatening for production of fruity wines
Oxidative reactions such as forming acetyldehyde gives nutty, apple aroma Can favour growth of spoilage microbes such as acetic acid bacteria and Brettanomyces
Exposure to oxygen can be limited by
Avoiding ullage in vessels
Use of inert gases (nitrogen, carbon dioxide, argon)
Addition of sulfur dioxide
Use of impermeable containers (steel, concrete)
Cool, constant temperatures
Exposure to oxygen can be increased by:
Use of cap management techniques
Use of small wooden barrels
Increasing the number of racklings or lees stirring
Allowing ullage
Hyperoxydation (must) or micro-oxygenation (wine)
Sulfur Dioxide in winemaking
Preservative
Anti-oxydant
Anti-microbial - protects from yeast and bacteria
Forms - gas (sulfur dioxide), liquid (potassium
metabisulfite) or solid (potassium bisulfite)
10 mg/l naturally created by fermentation (more than this the label has to state that the wine contains sulfites)
EU max. permitted 160 mg/l for red wines
210 mg/l for white wines
Bound SO2 - SO2 which reacts with compounds in wine
or must, Ineffective against oxidation
Free SO2 - molecular form effective against oxidation
Greater amount of SO2 has to be added to wines with high pH
High levels of SO2 can dull wine aroma and flavours, eventually make the wine taste harsh
Transportation to the winery
In small crates - minimal crushing, limited oxidation
Large crates - some crushing (oxidation) adding SO2
Minimising oxidation and microbial spoilage:
Harvesting at night or sunrise
Addition of SO2
Cold storage
Sanitizing harvesting equipment
Grape reception
Sorting on conveyor belt or srew conveyor
Chilling
Preserving fruit aroma, reducing microbial spoilage
Slows down processing (higher cost)
Possibility of heat exchanger
Cost of energy and equipment
Sorting (triage)
Better the sorting, higher the cost
Labour requirement, lowering yield
Sometimes MOG only (material other than grapes)
Quality wine sorting:
Removing unwanted grapes before picking or
during hand harvesting
Sorting by hand before and/or after destemming
Optical sorting (expensive equipment)
Destemming
If stems are not ripe, they can convey green flavours
and bitter tannins into wine
Grapes not destemmed for:
Red wine fermentation with whole bunches
(Burgundy Pinot Noir)
Carbonic maceration (Gamay in Beaujolais)
Whole bunch pressing for some white wines
(common for high quality sparkling wine)
Crushing
Gentle enough not to break seeds
Combined crusher-destemmer machimes
Grapes turn into must
Must
Mixture of grape juice, pulp, skins and seeds
Pressing options
Pneumatic press (“air bag press”)
Cylindrical cage with bladder that inflates
Can be programmed to different pressures
Can be flushed with inert gas
Basket press (“vertical or champagne press”)
Pressure applied from above, juice runs through holes
on the sides of press, collected by tray on the bottom
Not sealed vessel, cannot be flushed with inert gas
Holds small loads
Labour intensive
Horizontal screw press
Mounted horizontally, above rectangular draining tray
Less gentle
Requires batch processing
Continuous press
Allows grapes to be continuously loaded
Less gentle
Pomace
Solid remains of grapes left after pressing
Must adjustments
Generally after must clarification for white wines
Enrichment
Usually before or during fermentation to raise alcohol
Adding dry sugar, grape must, grape concentrate or
rectified concentrated grape must (RCGM)
OR concentration process - reverse osmosis, vacuum
evaporation, cryoextraction (least expensive)
EU is split into zone to indicate permited enrichment
Reducing alcohol
Adding water
Only allowed in some regions
! also dillutes aroma, flavours, acids
Acidification
also used to lower pH
Usually addition of tartaric acid
Citric acid (not permitted in EU)
Malic acid and lactic acid (used after malo)
Before, during or after fermentation
EU split into zones to indicate permitted acidification
EU do not permit to both acidify and chaptalize
Deacidification
Adding calcium carbonate (chalk) or potassium
carbonate
Or using Ion exchange (expensive investment)
Chaptalization
after Jean-Antoine Chaptal
Adding dry sugar in form of beet or cane sugar
Cryoextraction
Freezing must (or even the final wine) and removing ice from it
Enrichment
Usually before or during fermentation to raise alcohol
Adding dry sugar, grape must, grape concentrate or rectified concentrated grape must (RCGM)
OR: concentration process - reverse osmosis, vacuum
evaporation, cryoextraction (least expensive)
EU is split into zone to indicate permited enrichment
Reducing alcohol
Adding water
Only allowed in some regions
! also dillutes aroma, flavours, acids
Acidification
Also used to lower pH
Usually addition of tartaric acid
Citric acid (not permitted in EU)
Malic acid and lactic acid (used after malo)
Before, during or after fermentation
EU split into zones to indicate permitted acidification
EU do not permit to both acidify and chaptalize
Deacidification
Adding calcium carbonate (chalk) or potassium carbonate
Or using Ion exchange (expensive investment)
Alcoholic fermentation definition
Conversion of sugar into ethanol and carbon dioxide carried by yeast in the absence of oxygen (anaerobically)
Also produces heat
Yeast
Needs and what they produce
Group of microscopic fungi that convert sugar into alcohol
Initially they need oxygen to multiply quickly, but once oxygen is used they switch to fermentation
They need: right temperatures, nutrients (nitrogen),
absence of oxygen
Fermentation produces:
Alcohol
Carbon dioxide
Heat
Volatile acidity
Small amount of SO2
Wine aromatics (from aroma precursors)
Glycerol - increasing body of wine
Most common species of yeast is:
Saccharomyces cerevisiae
Can stand high acidity and alcohol, resistant to SO2
Thiols
Aroma precursor
Gooseberry aroma in Sauvignon blanc
Terpenes
Aroma precursor
Linalool and geraniol - floral grapey aroma in Muscat
Esters
Aroma precursor
Banana flavours in Beaujolais Nouveau
Most common species of yeast
Saccharomyces cerevisiae
Can stand high acidity and alcohol, resistant to SO2
Ambient yeast
Present in the vineyard and winery
Range of species of yeast (Kloeckera, Candida) out of which most will die when alcohol reaches 5%. Saccharomyces cerevisiae will quickly become dominant
Advantages:
Add complexity by producing different aromas
No additional cost
Unique to place of origin - supporting terroir
Can be used as part of marketing
Disadvantages:
Fermentation may start slowly (danger of build up of
volatile acidity and spoilage yeast - such as Brett)
Fermentation to dryness can take more time
Increased risk of stuck fermentation
Consistent product cannot be guaranteed
Cultured yeast
Also selected or commertial yeast
Low levels of nitrogen can lead to stuck fementation and rotten egg smell from sulfur compounds
Selected in laboratory, usually single strains of Saccharomyces cerevisiae
Must has to be chilled (to surpress ambient yeast) or SO2 must be added to let cultured yeast to multiply. Started batch with cultured yeast is added to must to be fermented.
Advantages
Reliable fast, fermenting to dryness
Low levels of volatile acidity
Less risk of spoilage
Consistent product
Large selection available - can affect the style of wine
Disadvantages
Leads to certain similarity
Adds cost
Yeast nutrients
Nitrogen (prevents stuck fermentation and rotten egg smell)
Diammonium phosphate (DAP)
Thiamine (vitamin B1)
Fermentation temperatures
Cool 12-16 Fresher fruitier whites or rose
Mid range 17-25 Easy drinking fruity reds with low tannin
less fruity whites
Warm 26-32 Powerful red wines
Above 35 fermentation may slow down and stop
Options for temperature control
Temperature of the cellar
Water or glycerol jackets that surround vessels
Inserts put into vessels
Reducing temperature by pumping over which releases heat
Fermentation vessels
Stainless steel
Easy to clean
Range of sizes
High degree of control over temperature
Protection from oxygen
High level of mechanization
Initial investment
Concrete
Inexpensive
Maintain even temperature more efficiently
Eggs - expensive
set up currents which mix lees during maturation
Wood
Retain heat well
Attention to hygiene has to be paid
Bacteria and spoilage organisms risk
Small amount of oxygen
Expensive when new oak is used
Alternatives
Plastic (permeable to oxygen, difficult to control temp)
Terracotta
Malolactic conversion
Result of lactic acid bacteria converting malic acid into lactic acid and carbon dioxide and it produces heat.
During and after alcoholic fermentation
Encouraging conditions:
18-22 degrees
moderate pH (3.3-3.5)
low total SO2
Historically naturally started in spring when cellar warmed up, now lactic acid bacteria is added
Avoiding it: adding enzyeme lysozyme (kills lactic acid bacteria) or filtering, keeping temperature below 15
Routine for red wine, choic for white wine
Outcomes:
Redustion in acidity and raise in pH
Colour loss in red wine
Greater microbial stability (prevents malo
spontaineously happening later)
Modification of flavour (slight loss of fruit, adding
butterly notes)
Increasing volatile acidity
Alcohol adjustment techniques
Acidity and pH can be adjusted
Removal of alcohol
Adding water to must (if permitted)
Reverse osmosis - form of cross flow filtration which
removed flavourless permeate of alcohol and
water, which can be destilled to remove
alcohol. Permeate is then blended back to
recreate the wine.
Spinning cone - First extracts volatile aroma compounds
and then removes alcohol. Flavour components
are then blended back into wine
Maturation for young fresh wine
Young aromatic fruity
Protecting from oxygen
Blanketing with so2 or inert gas
Stainless steel
Can be stored in bulk and bottled for final customerO
Effect of oxygen in maturation
Reduction in primary aromas, development of tertiary
Influencing colour of wine
Exposing young red to oxygen stabilizes colour
Anthocyanins bind with tannins
Softening tannins
Wooden vessels and oxygen
Most exposure when doing transfers, rackling, lees stirring or topping up - when bung is removed
Some wine is lost because it impregnate the wood and alcohol evaporates - gradual concentration of the wine
Small vessels have large surface to volume ratio which encreases ageing, barrels need to be frequiently topped up (more exposure to oxygen)
Microoxygenation
Cheaper alternative without wood
Bubbling oxygen through wine
Increases colour stability and intensity, softens tannins, improve texture and reduce the presence of any unripe herbaceous flavours
More quick, cheaper and can be controlled
Oxygen in wine can provide environment for spoilage microbes such as acetic acid bacteria or Brettanomyces
Temperatures for maturation of white and red wine
White - 6-12
Red - 12-16
Effect of wood on wine
Age of the vessel
New wood contains various extractable compounds
Barrel looses about 50% of it new oak flavours during
the first year
New wood is used usually as proportion of blend
Size of the vessel
Greater extraction from wood and exposure to oxygen
in small vessels
Type of wood
European (French, Hungarian, Russian, Slavonian)
Imparts more tannin
More expensive production (must be split in staves)
American
Higher levels of lactones (cocounut aroma)
Greater aroma impart than European oak
Can be sawn, grows faster
Tightness of grain
Oak from continental climates grows slower and the
grain is tighter (slower extraction of compounds)
Production of barrels
Wood seasoning
Outside for 2-3 years.
Lowers humidity levels in wood, increases flavour
Cedar aromas
Heating staves to bend in shape
Transforms tannins and aroma compounds
Toasting
Light / medium / heavy toasted
Aromas: spice, caramel, roasted nuts, char and smoke
Price of barrel ageing and its alternatives
Barrels are expensive to buy
Minitoring costs
Performing winemaking operations such as lees ageing is labour intensive with growing number of barrels
Cleaning and sanitation (avoiding spoilage microbes such as Brett)
Maturation is slow process adding on cost, return on investment is slow
Alternatives:
Oak chips or staves
quick to have effect
can be speeded up by micro-oxygenation
Define lees
The sediment which settles on the bottom of the wine vessel (dead and dying yeast and bacteria, grape fragments, precipitated tannins, nutrients and other compounds)
Gross lees (settled in 24h) and fine lees
May be removed by racking
The role of lees in maturation
Yeast autolysis releases compounds contributing to flavours, body and texture.
Some of these compounds bind with phenolic compounds in grapes, reducing colour and softening tannins.
Also bind with wood components such as wood tannins (reducing astringency and modifying flavours from wood)
White wine - yoghurt, dough-like, biscuit, toast aromas
Helps with stabilization against unstable proteins (prevents hazes)
Protect from oxygen, helping to maintain slow, controlled oxidation during maturation and reducing need for SO2.
But if layer of lees is too thick, it can produce volatile reductive sulphur compounds.
Lees provide nutrients for microbes so can help to grow lactic acid bacteria for malolactic fementaion (but also risk of Brett)
Raised labour cost from monitoring and storing
Yeast autolysis
Dying and breaking down of yeast
Racking
Process of transfering wine from one vessel to another with aim of removing sediment
Can be oxidative process
Blending
What is blended and what are the reasons?
Can happen at any stage but most common before finishing
Combining: Different grape varieties Different locations Different grape growers or sellers Different vintages Wine which has been treated differently Wine which has been treated equally for logistical reasons
Reasons:
Balance - adjusting certain characteristics for balance
Consistency - non vintage sparkling wine, cheap wine
Style - ccertain house style, quality levels
Complexity - greater range of flavours
Minimise faults - diluting faulty batches
Volume - bought grapes, different parcels
Price - cheaper varieties
Best carried before stabilization
Post fermentation clarification options
Sedimentaton
Centrifugation
Fining
Filtration
Sedimentation
Natural clarification option
Forming sediment on the bottom of the vessel which will be racked off
The larger the vessel the greater the number of rackings needed
Sedimentation avoids the loss of texture and flavour
Long process, suitable for premium wines.
If barrel maturation takes place sedimentation is part of the ageing process
Centrifugation
Rapid spins to clarify wine.
Can replace depth filtration and allow early bottling
Only for high volume wineries
Fining
Fining agent is added to speed up the process of precipitation of suspended material in wine. The fining agent and the colloid attract each other and form a solid large enough to be removed by racking or filtration
Clarifies the wine and helps to stabilize it.
Can remove positive compounds or make the wine unstable if too much is added (over-fining)
Each fining agent has particular properties which can offer solution to problems
Protein or mineral origin
1) Agents that remove unstable proteins
Betonite - form of clay, some colour loss in red wines
Mainly used for whites (avoiding hazes)
Protein in reds binds with tannins (clear wine)
2) Agents that remove phenolics (colour and bitterness)
Egg white - fresh or powdered form
able to remove harsh tannins and clarify
Gentle, but must be declared on label
Gelatin - Removes bitterness and astringency in red
and browning in white
easy to overfine (stripping flavours)
Casein - Removes browing from whites and clarifies
to some extent. Must be declared on label
Isinglass - very effective for whites (bright appearance)
Too much - hazes and fish smell (from fish bladders)
Vegetable protein products - from potato or legumes
PVPP - insoluble plastic in powder form
Removes browning and astringency from
oxidised white. Rarely used for reds
3) Agents that remove colour and off-odours
Charcoal - removes brown colours (Pale Cream
Sherry) and some off-flavours
Overfines easily - stripping flavour
Filtration definition
Separation technique used to eliminate solids from suspension by passing it through a filter or medium consisting of porous layers taht trap solid particles, thus making the liquid clear.
The most common form of clarifying wine
Depth filtration
Traps particles in the depth of the material that forms the filter.
It can cope with fluid with many particles in it
Does not block easily, however is not absolutely reliable
Not absolute filter
Diatomaceous earth (DE or Kieselguhr) pure silica, inert
Rotary vacuum filters use it for very cloudy wine
Oxidative process
Enclosed DE filters can be flushed with inert gas
DE comes in range of particle sizes
Must be disposed responsibly (additional cost)
Sheet Filters (plate, frame, pad filters)
The more sheets, the quicker the filter
Require initial investment
Stabilization
Includes tackling the potential for unwanted hazes, deposits in the bottle and rapid chanes in wine (browning).
Protein stability
Fining with betonite
Tartare stability (potassium and calcium bitartrate)
-4 degrees crystals form, then filtered
only removes potassium bitartrate
cost of cooling and equipment
Contact process
Quicker, more reliable, cheaper
Wine cooled to 0 degrees, Potassium bitartrate is
added to form cryslals and after 2h filtered
Electrodialysis
Charged membrane to remove selected ions
High initial investment, low operation cost
Both potassium and calcium ions
Ion exchange
Does not remove tartrates but replaces potassium
and calcium ions with hydrogen or sodium ions
It is not allowed in some territories
Carboxymethylcellusose (CMS)
Cellulose extracted from wood and prevents
tartrates to develop to visible size
Cheap and used on white or rose
Not suitable for red as it reacts with tannin (hazing)
Metatartaric acid
Prevents growth of crystals
The acid is unstable and effect is lost over time
Microbiological stability
Residual sugar - risk of refermenting.
Removing yeast through sterile filtration or adding
sorbic acid or SO2
Malolactic in the bottle (filtration or making sure malo
was completed before)
Infection with Brett (treatment with DMCD dimethyl
dicarbonate - Velcorin)
Tartare stabilization options
Tartare stability (potassium and calcium bitartrate)
-4 degrees crystals form, then filtered
only removes potassium bitartrate
cost of cooling and equipment
Contact process
Quicker, more reliable, cheaper
Wine cooled to 0 degrees, Potassium bitartrate is
added to form cryslals and after 2h filtered
Electrodialysis
Charged membrane to remove selected ions
High initial investment, low operation cost
Both potassium and calcium ions
Ion exchange
Does not remove tartrates but replaces potassium
and calcium ions with hydrogen or sodium ions
It is not allowed in some territories
Carboxymethylcellusose (CMS)
Cellulose extracted from wood and prevents
tartrates to develop to visible size
Cheap and used on white or rose
Not suitable for red as it reacts with tannin (hazing)
Metatartaric acid
Prevents growth of crystals
The acid is unstable and effect is lost over time
Microbiplogical stability options
Residual sugar - risk of refermenting.
Removing yeast through sterile filtration or adding
sorbic acid or SO2
Malolactic in the bottle (filtration or making sure malo
was completed before)
Infection with Brett (treatment with DMCD dimethyl
dicarbonate - Velcorin)
Surface filtration
Surface filtration
Stops particles that are bigger than the pore size of
the filter. Absolute filter
Membrane filters (cartrige)
Slower, wine must be pre-filtered (easy to block)
Sterile filtering
Initial invetment is small, cartriges are expensive
Cross-flow filters (tangential)
Wine passes through filter while cleaning the
surface of the filter as it goes
Expensive machine, but no cartridges or sheets
Finishing options
Final full chemical analysis (at least alcohol, residual sugar and free SO2) right before bottling levels of dissolved oxygen and CO2 will be checked.
Adjusting levels of SO2
lower pH wine requires lower SO2 levels
Generally
white 25-45 mg/l
red 30-55 mg/l
sweet 30-60 mg/l
Reducing dissolved oxygen
can accelerate ageing
Sparging - flushing wine with inert gas to remove O2
Adding carbon dioxide
Added freshness (especially inexpensive white)
Sparging
Flushing wine with inert gas to remove oxygen
Cloudiness and hazes
Growth of yeast or bacteria
Failure to filter adequately (or filtereing too fast)
Wrong type of fining agent or over-fining
Remedy: Better hygiene Pre-bottling analysis Slow filtering Analysis after fining
Wine faults
Cloudiness and hazes
Tartrates
Re-fermenting in bottle
Cork taint
Oxidation
Volatile axidity
Reduction
Light strike
Brettanomyces
Volatile acidity
All wines have volatile acidity but high concentration results n smell of nail varnish or vinegar
Activity of acetic acid bacteria, inadequate levels of SO2 and excess exposure to oxygen
Remedy:
Sorting fruit to exclude damaged grapes
Hygiene in winery
Keeping vessels topped up
Careful racking
Maintaining adequate SO2 levels
Reduction
Sulfur like smell (onion or rotten egg)
Produced by yeast under stress (low nitrogen levels) or near complete oxygen exclusion during ageing in closed vessels especially when lees ageing
Remedy:
Assuring yeast have enough nutrients and oxygen
Not overloading with SO2
Light strike
Caused by UV radiation reacting with compounds in wine forming volatile sulfur compounds
Odour such as dirty drain
Wines which are left in direct sunlight or near fluorescent lightning are most in danger
Brettanomyces
Animal, spicy, famyard smell (complexity in low levels, high levels clear fault)
Difficult to eradicate once it occurs. Wood is hosting the organism
Keys to avoid Brett:
Excellent hygiene
Maintaining effective SO2 levels
Keeping pH level low
Keeping period between alcoholic fementation and
malolactic conversion as short as possible
Oxygen management when packaging
Final amount of oxygen in the container will determine the shelf life and expected development of the wine
Combination of:
Dissolved oxygen in the wine
Oxygen in the head space
Oxygen in the cork or other closure
Oxygen transmission rate (OTR) of the cork or closure
Options for packaging
Glass
No taint to wine and inpermeable to oxygen
Near sterile conditions
Inexpensive to manufacture and recyclable
Best option for ageing
High carbon footprint initially (heat for production)
Heavy to transport and fragile
Once open, subject to oxydation
Clear bottles are susceptible to spoilage by light
Plastic
Light, tought, inexpensive, recyclable
Must be lined with barrier to oxygen
Special filling equipment required
Bag-in-box
Carboard box, flexible bag, aluminium foil as barrier
Flexible pour size, range of container sizes
Good protection from oxygen once opened
Low environmental impact and easy to store
Wine must have slightly higher SO2, low dissolved
oxygen, no head space and low carbon dioxide level
Shelf life 6-9 months
Brick
Tetra Pak
Cardbord with plastic layers and aluminium foil
Filling equipment is large investment
Pouch
Similar to bags inside bag-in-boxes
Can
Light weight, robust, easy to open, impermeable to
oxygen and recyclable
Aluminium has to be lined with plastic to avoid being
attacked by the acidity of wine
Large investment for filling equipment
Ideal closure for wine has these properties:
Protect wine from rapid oxidation
Be inert so that it does not affect the quality of wine
Be easy to remove and re-insert
Cheap, recyclable and free of faults
Natural cork
Light, flexible, inert, renewable, natural resource
Positive image for consumers
Variable levels of oxygen ingress - wine ages at different rates in the medium to long term
Can house harmful fungi
Can taint wine through the creation of TCA (2,4,6-trichloroanisole) about 3-5% of bottles
Cleaning corks with stream extraction
Recomposed cork particles cleaned and reconstituted
with plastic
Rigorous quality control during production
Introducing barrier between the cork and the wine
Technical corks
Cork that has been subected to a manufacturing process
Agglomerated cork (granules glued together)
One-plus-one cork
central part is agglomerated cork and sides are
natural cork
Diam cork
Combination of cork and plastic
Available in different ingress rates
Synthetic closures
Food grade plastic with silicone coating
Difficult to re-insert in bottle
Limited protection from oxygen
Flavour scalping
Plastic absorbs some flavour molecules
Screwcap
From tin (impermeable to oxygen) or Saran (form of plastic with low permeability to oxygen)
Wines can become reductive after bottling - therefore lower SO2 levels should be used
Glass stopper
Vinolok (brand name)
Seal is formed by a plastic ring
Special bottles must be used to ensure perfect fit
As expensive as top quality corks
Post-bottling maturation
Increases cost
Oxygen transmission rate of closure, oxygen in head space of bottle and dossolved oxygen in wine play key role on ageing (small amount of oxygen is beneficial)
Low level of oxygen at bottling can result in volatile reductive sulfur compounds in wine (rotten egg)
Undisrupted, cool, dark place with consistant temperature ideally around 10-15 degrees and constatnt humidity. If sealed with cork bottles should be lying down.
HACCP
Hazard analysis of critical control points
Identification of hazards, their seriousness and how to prevent them and correct them
Tracability
Each consignment of wine will be given lot number which appears on bottle. EU requirement
The winery must keep records of its activities at every point of production
Transportation of wine
Bulk
Flexitank - single use, recyclable, polyethylene bag
that fits into standard container
ISO tank - stainless steel vessel built to ISO standards
which can be reused
Reefers - insulated tanks with temperature control
Advantages of bulk shipping
More environmentally friendly
Cheaper
Less fluctuation of temperature
Reducing loss of fruit and oxidation
Quality control can be analyzed better
Wine can be adjusted at the final market before
bottling
Shelf life is extented (later bottling)
Advantages of shipping bottles
Producer has control over the entire product
Disadvantages of shipping bottles
Smaller amount of wine in one container, higher cost
Weight of glass
Potential damage, breakage, temperature, labels
Shorter shelf life for inexpensive wine (bottled earlier)
