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)