D1: finifhin and packaging Flashcards
Check list: getting your wine ready for bottling day:
1) 4months to 8 weeks ahead: assemble final blend
full chemical analysis, alc residual sugar, free so2 etc
2) 8 weeks ahead: final adjustments: alc, acidity, tannins f desired
3) 6 weeks ahead: protein stability trial and if necessary fine wine with bentonite
4) 4-6 weeks ahead: test for tartrate stability and if necessary, treat
5) 1-2 weeks ahead: add sweetenig agents eg grape concentrate, for mouthfeel and finish
6) 72- 48 hours ahead: test filterability of wine
7) 24 hrs ahead: adjust free so2
8) bottling day: adjust dissolved oxygen and co2
9) during bottling: check dissolved oxygen and so2 levels regularly and keep sample of bottle wines for quality assurance purposes
Post fermentation clarification is trem that stands for all the processes (physical and chemical) that are used to make wine clear:
1) particularly sedimentation,
2) centrifugation
3) clarify the wine
- - in addition wine ay be fined and filtered
What is sedimentation ?
1) if wine is tored in cool cellar conditions it will begin the process of clarification naturally with suspended matter precipitating over time
- - the particles with higher density than wine will form a sediment at the bottom of the container
- - the wine can be racked off
2) the number of rackings depend on size of the container: bigger, more
3) some premium wine only be clarified in this way: to ensure no loss of texture and flavour
4) it takes time so also a additional cost because the wine can only be released if clarified
- - if aged in barrel the sedimentation already takes place during this stage
in many cases the winemaker will accelerate the process of clarification in high volume production where the speed of processing wine is financially important and use the following options:
centrifiguration and fining
centrigiguration:
1) rapid process that spins the wine at high rotational speed to clarify it
2) it can replace depth filtration and allow early bottling
3) very effective with wines with a lot of matter in suspension
4) only practised in high volume wineries
fining:
1) procedure where fining agent is added to speed up the process of precipitation of suspended material in wine
2) can be of protein or mineral origin
3) they remove a small proportion of colloids (microscopic particles too small to be removed by filtering)
4) it helps to clarify and to stabilise against the formation of hazes later in the bottle
5) trials in laboratory are needed to ensure the min effective amount is used
- - because many agents can remove positive compounds from wine or unstable the wine too much if too much is added
6) in addition to clarifying the wine, each fining agent has particular properties that can offer solutions to problems such as harsh tannins or browning in white wines
7) the agent and the colloid attract each other and form a solid large enough to be removed by filtration
There are three categories of fining agents:
1) those that remove unstable proteins
2) those that remove phenolics that contribute undesirable colour and bitterness
3) Those that remove colour and off-odours
Fining agents that remove unstable proteins:
1) must and wine contain grape derived proteins
— it is not necessary to remove these in red wines as they bind with tannins, precipitate natural and are removed when the wine is racked
2) however the proteins in white and rosé can agglomerate into a visible haze if warmed up (eg in transit)
- – this would be seen as a fault
- — as a result these wines are often fined with bentonite
Fining agent bentonite:
1) a form of clay which absorbs unstable proteins and unstable colloidal colouring matter (holds moleculesof a gas, liquid or solute as a thin film on the outside surface or on internal surfaces within the material)
2) it has a minimal effect on the flavour and texture of wine
3) it does lead to colour loss in red wines and produces large amounts of sediment
- – so wines is lost when it is racked off
Fining agents that remove phenolics that contribute undesirable colour and bitterness:
The fining agents listed below, may be used in conjunction with bentonite for their own properties and to avoid the risk of over fining (which in itself could make the wine unstable)
1) egg white
2) gelatin
3) casein
4) isinglass
5) vegetable protein products
Egg white:
1) due to its protein content, egg white is often used in fresh or powdered form
2) it tends to be used for high quality red wines becauseof its abitlity to remove harsh tannins and clarify wine
3) it is gentle to the wine
4) as it is an allegen, it must be declared on the label if sold in EU
Gelatin:
1) a protein collagen (vezelvormig eiwit) extracted from pork that aids clarification
2) removes bitterness and astringency in red and browning in white wine pressings
3) small proportion becaus it has a high risk to over fine
- - stripping flavour and character
- - risk of forming a protein haze forming later
4) it is not suitable for vegetarian wine as it is derived from animals
Casein:
1) milk derived
2) removes browning from white wines and clarifies to some extend
3) must be declared as an allergen on the labels in some regions
Isinglass:
1) derived from fish bladders
2) very effectivly clarifies white wines
- - giving them a bright appereance
3) smallest effective amount must be added:
- - avoid potentiol to the formation of protein haze
- - and the creation of a fishy smell
4) not suitable for vegies
Vegetable protein products:
derived from potato or legumes and are suitable for vegan friendly wines
PVPP:
Polyvinylpolypyrrolidine is an insoluble plastic in powder form that removes browning and astringency of oxidised white wine
– gentler than charcoal
rarely used on red wines, but can reduce astringency and brighten the colour
Fining agents that removes colour and off odours: charcoal:
1) this removes brown colours (eg to create pale cream sherry) and some off odours
2) care has to be taken as charcoal over fines easily, removing desirable aromas and flavours
3) one option is to treat only one batch of the affected wine and then blend it with the rest of the wine to reduce this effect
WHat is filtration ?
1) 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, thus making the liquid clear
- – most common way to carifying wine
There are two main types of filtration:
1) Depth filtration
2) surface filtration
Depth filtration:
1) traps particles in thedepth of the material that forms the filter
2) it can cope with fluit with many particles in it
- - wine that has just been pressed or lees
3) small particles are trapped within the many irregular channels through the filter
4) this type of filter does not block eaily:
– not absolutely reliable because:
if too much pressure is applied or too long usage
—– some particles will make their way through the filter
* in other words it is notan absolute filter
what kind of depth filters are available and their products:
1) a rotary drum filter
2) a plate and frame filter
products:
1) diatomaceous earth
2) sheet filters
Diatomaceous earth:
1) most common
2) also kwown as DE and Kieselguhr
- – once processed, is pure silica and inert
- rotary vacuum filters use this method to filter very thick and cloudy wine (eg mixed with lees)
- it is an oxidative process as the drum is exposed to air
- enclosed drum filters do the same job, but can be flushed with inert gas (nitrogen) to avoid oxidation taking place
- DE comes in a range of particle sizes and thus can remove large or very small (eg yeast) particles
Sheet filters:
1) ) also known as pad, plate or frame filters
2) the wine is passed through a sheet of the filtering material
3) the more sheets there are in the filter, the quicker the wine can be filtered because any portion of wine olnly passes through one sheet
4) very fine graded sheets can be used to remove any remaining yeast at bottling
5) remains a initial cost (frame need to be strong) although cost of filter sheets is low
- - trained personnel need must operate them to work properly
Surface filter stops particles particles that are bigger than the pore size of the filter from going through, they are often termed absolute filters. there are 2 types:
1) membrane filter
2) cross flow filters
Membrane filter:
1) also called membrane cartridge filters
2) slower than using depth filters as the pores are smaller, often less than 1 micron
- - so wine need to be prefiltered (depth filtration)
- – otherwise membranes get blocked
3) usually used as a final precaution immediately before the wine is bottled to ensure that the wine is completely clear and microbiologically stable
- – called sterile filtering (yeast and bacteria are have been removed) but not entirely accurate
4) in contrast to depth filters the initial cost is low, but the cardridges are expensive
Cross flow filters:
1) known as tangential filters
2) allow wine to pass through the filter while uniquely cleaning the surface of the filter as it works
3) solid parts cannot pass through the filter
4) can filter wine very quickly, there are no replacement sheets
5) expensive so suited for large and or well funded wineries
As with fining, some winecritics and winemakers believe that filtration can negatively affect a wine’s character, especially stripping it of texture. for this reason wines are bottled unfiltered. however, others argue that any immediate loss of texture is compensated in two ways:
1) first the wine will recover from the shock of filtration after some months
2) there is much less chance of wines developing faults as bacteria and yeast have been removed
What is stabilisation of wine ?
Some interventions carried out to prevent undesirable effects on the final wine. This includes;
1) tackling potential of unwanted hazes or deposit
2) rapid change of browning
3) Tartrate stability
4) fining and microbiological stability
What about the protein stability ?
Fining with bentonite is the key procedure to ensure protein stability
Tartrates are harmless deposits of crystals that can form in the finished wine, principally Potassium and bitartrate and, less frequently, calcium tartrate.
As many customers will regard these crystals as a fault, all high volume winemakers will prevent this. there are several options:
1) cold stabilisation
2) Contact process
3) electrodialysis
4) Ion exchange
5) Carboxymethylcellulose (CMC)
6) Metatartaric acid
tartrate stability: Cold stabilisation:
1) Most common in a cold cellar -4°c 25°f for around 8 days
- - crystals can form before bottling (because tartrates are less soluble at cold temp) and then can be filtered out
2) it requires the equipment and the cost of energy to refrigerate the wine
3) Colloids must be removed by fining: because they could prevent the crystals from forming at this stage
4) this process only removes the more common potassium bitartrate, not the calcium tartrate
Tartrate stability: contact process:
1) quicker, continuous, more reliable and cheaper form of cold stabilisation
2) potassium bitartrate is added to the wine and speeds up the start of the crystallisation process
3) wine is usually cooled to around 0°C 32°F
- - after 1-2 hours the resulting crystals are filtered out
Tartrate stability: Electrodialysis:
1) uses a charged membrane to remove selected ions
2) after high initial cost, the total cost is less than cold stabilisation and uses less energy and is faster
3) removes both potassium and calcium ions and to a smaller extend tartrate ions
4) allowed in EU and other territories
Tartrate stability: Ion exchange:
1) this process does not remove tartrates, but instead:
- - it replaces potassium and calcium ions with hydrogen or sodium ions which will not drop out of solution
2) this process is not allowed in some territories as it replaces the potassium with sodium, which is not conductive to health
- - however the resulting levels in wine are well below the legal limit
Tartrate staility: CMC
1) Carboxymethylcellulose CMC
2) extracted from wood and prevent tartrates from developping to a visible size
3) widely for inexpensive white and rosé wines
4) not suitable for reds, because it react with tannins (rendering it ineffective) and causes haze
5) much cheaper than chilling
6) Keeps the wine stable for a few years
Tartrate stability: Metatartaric acid:
1) prevents the growth of potassium bitartrate and calcium tartrate crystals
- - reducing the need for cold stabilisation
2) compound is unstable and its positive effect is lost over time (especially if wine is stored at high temp 25-30°C
3) quick process, good for reds
