Vini Flashcards
What is the highest % abv most yeasts can handle?
15%
At what temperature and for how long does Thermovinification take place?
60~80c for 20~30 minutes
What is a Vaslin?
A horizontal screw press
What are the main advantages of Stainless Steel fermenters?
Neutral Easy to clean and maintain Easy to temperature control
All of the following are fining agents that remove excess colour except? Cassein Milk Carbon PVPP
Milk - used as a deodoriser
Can Reverse Osmosis be used to remove tannins?
No
What is the effect of higher fermentation temperatures of red wine?
Greater Tannin extraction
What are three states for SO2 Briefly explain each
Free = Active, protective, molecular SO2 and Sulphurous acid Ready to start work Bound = Combined with sugars, aldehydes, ketones, inactive Already working Total = Free+Bound
What might be added to maximise juice released from the grapes?
Pectolytic Enzyme
What acid is usually used for acidification? When is it normally added? Max g/L added?
Tartaric Acid Usually before ferment but can be after 1.5g/L in Must 2.5g/L in wine
What are Di-ammonium phosphate (DAP) and Thiamine (Vit B) and why might they be added to must?
They are nutrients and can be used to help re-start a Stuck fermentation
What are the 3 permitted additive methods of de-acidification? And one ‘Natural’ method
Tartaric only- Potassium Bicarbonate (Potassium Bi-tartrate crystals - quite easy to remove) Calcium Carbonate (leaves hi levels Calcium Tartrate - harder to remove because precipitates slowly) Malic only - MLF Both Tartaric and Malic - Double salt de-acidification - Acidex ££! Calcium Carbonate + small amount Calcium Tartrate-Malate Insoluble crystals Calcium Tartrate-Malate formed
By weight how much juice is extracted from grapes?
About 70%
What is often used as a fining agent in white wine making to remove dissolved proteins?
Bentonite
Due to the high levels of alcohol and acidity in wine all of the following can survive in wine EXCEPT what?
Lactic bacteria
Acetic bacteria
Antioxidasic bacteria
Yeast
Antioxidasic bacteria
What is the biggest risk of totally anaerobic winemaking?
Production of Hydrogen Sulphide - Rotten eggs, smelly drains
What is ‘Delestage’?
Rack and Return
List 4 benefits of using commercially available active dry yeast
Active fermentation onset Can handle highly clarified musts Fermentation rate more even and easy to control No off flavours or aromas Efficient conversion of sugar to alcohol Decreased risk of stuck fermentations Low Volatile (acetic acid) Acid production
Many countries permit the use of enzymes (usually added at crushing stage). List 4 potential benefits of using
Aid juice extraction Optimise extraction of aroma precursors Improve colour extraction Increase efficiency of settling
Saccharomyces generally prefer which sugar?
Glucose
What gives wines smoke and chocolate aromas
Thiols
Glycerol (or Glycerine) is a natural by by-product of fermentation, what does it contribute to wine?
Contributes smoothness and weight of a wine
What might be used in addition to gelatin or Isinglass to help floculation?
Silica Sol
What is max permitted concentration of Iron in the EU?
What treatments are available for excess iron?
Max 10mg/L
Addition Citric Acid (max 1g/L)
White wine - Potassium ferrocyanide
Red wine - Calcium Phytate
What are Anthocyanins?
The red pigments found in grape skin cells
What is the Algerian Ducellier System?
The Autovinifier
What are Thiols responsible for?
In small quantities gives aromas of Blackcurrant, Gooseberry, Passion Fruit and Grapefruit. In large quantities aromas of onion and garlic
What is considered the most gentle Cap Management process?
Punching Down
Which of these is NOT a property of Ascorbic Acid? Antioxidant Antiseptic Antioxidasic It combines with acetaldehyde
It is NOT an antiseptic
What 3 things most heavily control extraction of phenolic material from the grapes during fermentation?
The temperature of the fermentation Cap Management The duration of skin contact
If roughly 16~18g/L sugar is needed to produce 1% abv which is 8g/L alcohol what happens to the other 8~10G/L of sugar?
It is converted to CO2
What is the organic compound that gives aromas of earth and mushroom?
Geosmin
Why is it important for fermentation to start quickly and vigorously?
To avoid the risk of production of off-flavours, oxidation and/or microbial spoilage
What is the usual temperature and duration of Cold Soaking?
<15c 3~7 days
When using indigenous ‘wild’ Yeats what will take over to complete fermentation? Roughly at what abv will it take over?
Saccharomyces Cervisae From about 4% abv
What sugars are permitted for Must Enrichment?
Sucrose (Beet or Cane sugar) - Chaptelisation RCGM - Enrichment
What are the fermentation by-products?
Glycerol (Glycerine) Acetaldehyde Ethyl Acetate Aroma Esters Fusel oils e.g. Methanol
What causes a red wine to smell of clove and bacon?
Brettanomyces aka Brett
What are the two main types of phenolic compounds?
Flavenoids - benzoic acid Non-flavenoids - catechins, anthocyanins
Tannins are polymerised what molecules?
Catechin
What are the main advantages of Cement fermentation tanks?
Cheap Easy to clean and maintain Large vessels have thermal mass
What type is considered the most gentle grape press
Pneumatic
In what chemical form is SO2 usually added?
Potassium Metabisulphate
What is the cheaper alternative to Tartaric acid for de-acidification? What is max EU limit? When should it be added and why?
Citric Acid Max 1g/L NEVER before ferment, always after because yeast and bacteria can metabolise it into Acetic Acid = increase Volatile Acidity
Why might you add vitamin B to your wine?
Vit B = Thiamine, to re-start a stuck fermentation
What is a ‘usual’ fermentation time for: Light, easy drinking reds? Full bodied reds? High quality vintages? Why?
Light, easy drinking reds - 8 days Full bodied reds - 3 weeks High quality vintages - 4 weeks+ Longer contact period may soften tannins due to polymerisation
What compound adds subtle aromas or balsamic or pickle but in large quantities smells of acetone?
Volatile acidity
What does the breakdown of citric acid by bacteria during fermentation produce?
Volatile acidity
What is the best grape press for oxygen free gentle extraction?
Tank Press
What is the biggest risk of excess oxygen in must or wine
Production of Acetaldehyde (ethanal) - sherry like aromas and flavours
What are Esters responsible for?
Floral and fruity aromas in wine
Early / later in fermentation, when are Anthocyanins and Tannins extracted?
Early fermentation - Lower alcohol = Anthocyanins Later fermentation - higher alcohol = Tannins
What are Kloeckera/Hanseniaspora, Candida and Metschnikowia?
Indigenous ‘wild’ yeasts found on the bloom on grape skins
Isoamyl acetate is associated with which aromas?
banana / pear drop
What accounts for the black pepper aroma in Syrah?
Rotundone
In which country might an Oeschle be used?
Germany and Switzerland
Why are copper and bronze avoided in modern wineries?
They are inorganic oxidasic catalysts
What are Pyrazines responsible for?
Herbaceous aromas; Green bell pepper, grass
What is the name of the starter culture a winemaker will make from indigenous ‘wild’ yeasts?
Pied de Cuve
Which grape press has the advantage of being continually loaded with grapes delivering high must output.
The continuous screw press
What is a USP of Autovinification?
Can be used where there is no power
Polysaccharides are also called what?
Pectins
What are the 4 most common methods for white must clarification?
Cold settling (common) Centrifugation Diatomaceous earth filtering Flotation (quite rare)
How can Hydrogen Sulphide present in post-fermented wine be removed?
Anaerobic racking
How would you measure fermentation progress?
By measuring density - measures sugar decreasing not alcohol increasing When fermentation complete density drops <1
With which Cap Management process can seeds be removed from the bottom of the fermentation tank?
Rack and Return (delestage)
When does de-acidification of white wines happen?
After clarification and before fermentation
What is Rotovinification? Other than cost what is the biggest potential disadvantage?
Use of a Rotofermenter; cylindrical fermentation vessel that mechanically rotates and mixes the must and cap Can be over extractive
Why are Sweet wines permitted higher SO2 levels?
Because SO2 becomes bound by the sugars
What is Bentonite used for? Why must it be used sparingly?
Fining agent in White wine to remove dissolved proteins. Usually used after ferment but some add to must prior. Use sparingly as non selective and can remove flavour compounds
What process is this? Pre-heated grapes (65~90c) placed in an intense vacuum. Due to the decrease in pressure the grapes are cooled to 30~35c causing cell destruction and rapid release of Anthocyanins and tannins. The skins are discarded and the must fermented?
Flash Expansion / Flash Detente
List 3 ways to re-start a Stuck fermentation
- Reduce / increase temperature - Increase nutrients; di-ammonium phosphate (DAP) or Thiamine (Vit B) - Re-inoculate with yeast
What are the main advantages of wooden fermentation vessels?
Retains heat readily The shape of the vessel aids extraction (in reds)
What is the reason you might use Saccharomyces Bayanus
Effective in re-starting stuck fermentations
Reverse Osmosis is permitted in the EU to reduce alcohol in a finished wine. What is the maximum actual alcohol reduction permitted?
Max -2%
What do you call a press where grapes can be pressed anaerobically (protectively)
Tank Press
What does the following formula represent?
HOOC-CH2-CHOH-COOH —> CH3-CHOH-COOH+CO2
The Choo Choo Formula
Malolactic Fermentation;
Malic Acid —> Lactic Acid+CO2
Why does white grape must need to be clarified before fermentation?
To remove any solid particles To produce cleaner flavours, more intense and less bitter
Why might Tannin be added to grapes? What are other side benefits of adding?
Added to red grapes before ferment if natural levels too low May offer some protection from oxidation, can stabilise colour and improve mouthfeel
What is Remontage and why is it used in the early stages of red wine fermentation?
Pumping Over To aerate the must and encourage yeast growth
What must clarification process is best suited to aromatic varieties to deliver highly clarified must?
Diatomaceous earth filtration
What are 3 Must concentration technologies Briefly explain each
Vacuum evaporation - Under vacuum water in must evaporates at 20c. Risk; loss of aromas, use aroma trap Reverse Osmosis - High pressure against membrane, water passes through. Risk; everything (good and bad) is concentrated Cryoextraction - Part freeze grapes and crush, ice crystals half back OR partly frozen must and water crystals skimmed off
At what temperature would Skin Contact be for an aromatic white grape?
5~10c
What is ‘Remontage’?
Pumping over
What are 4 EU rules on enrichment?
-Base wine must be 8.5% -Max alc White 11.5% / Red 12.0% -Concentration not to increase alc by >2% or reduce volume >20% -Only one method allowed, cannot blend wines of diff methods
In red wine making how full should the fermentation vessel be and why?
No more than 80% Because the fermenting mass will expand
What is usually used for must acidification What are the g/L legal limits in EU
Tartaric Acid 1.5g/L in Must / 2.5 g/L in wine
What process might be favourable with Chardonnay, Garganega and Trebbiano but detrimental for Sauvignon Blanc?
Hyperoxidation
What are the 3 main instability problems in wine?
Tartrate instability
Oxidation
Microbial spoilage
What is Ascorbic Acid otherwise known as? If using Ascorbic acid what else must be added and why?
Vitamin C Sometimes used with SO2 as additional antioxidant, cannot be used without SO2 as no antiseptic effect. Ascorbic acid without SO2 will product Hydrogen Peroxide (Bleach!)
What is the best grape press for high throughput? What is the negative of this type of press?
Continuous screw press Generally poor quality juice with bitter phenolics
What is ‘Pigeage’?
Punching down
What type of filter can be washed and reverse flushed to be re-used several times?
Membrane filters
What is a Willmes?
A pneumatic press
What are 3 risks of fermenting at too high a temperature?
Oxidation, Microbiological spoilage, instability Loss of aroma compounds Alcohol evaporation Slow or stuck fermentation
What are the 4 forms of SO2?
Potassium Metabisulphate powder Compressed and liquified SO2 gas SO2 in solution (5%) Burning Sulphur tablets or candles
What is the name of the chemical produced by MLF that gives buttery richness to Chardonnay?
Diacetyl
What is the duration of Carbonic Maceration?
1~3 weeks
What fining agent might be used to soften excessively tannic red wines?
PVPP
What are the recommended SO2 levels for Grape Must Red? White?
Red 10~60mg/L White 60~100mg/L Less for Organic wines
What is this the Formula for? C6H12O6 —>2C2H5OH + Energy
Anaerobic fermentation Glucose/Fructose —> Ethanol + CO2 + Energy (heat)
What are the 2 Primary oxidises that combining with Oxygen to catalyse oxidation?
Laccase - Found in Grey Rot affected grapes, resistant to SO2. Only option = pasteurisation Tyrosinase- Found in healthy grapes
List 3 things that fermentation that govern the rate of fermentation
Concentration of sugars Availability of oxygen Temperature Type and quantity of yeasts Nutrient content of the must SO2 levels
During MLF when Malic acid is converted to Lactic acid what is a notable by-product?
Production of CO2
What is Leuconostoc oenosos and what is it used for?
An MLF bacteria Added to wine to encourage MLF
What are the 3 species of bacteria that can carry out MLF?
Lactobacillus Leuconostoc Pediococcus
Volatile aromas are commonly associated with which element?
Ethyl Acetate
Simply explain: Potential alcohol Actual alcohol Total alcohol Natural alcohol
P = Alcohol level if all sugars are fermented A = Actual alc in a wine after fermentation T = Actual alc + potential alc from residual sugar if fermented to dryness N = Total alc in a un-enriched must or wine
What is the extraction process called where the skins are thrown away before fermentation?
Flash expansion / flash detente
What aroma compound accounts for the chalk-like aroma in fine Chablis? What is there a smell of when there’s too much of these compounds?
Sulphur compounds Wet wool when too much
What are the 3 methods for Rose wine making?
Drawing-off method (saignée or bleeding) e.g Bordeaux Clairet, Anjou Direct Pressing e.g Cotes de Provence and Languedoc Blending (In EU only permitted for Champagne) e.g New World
What are Terpenes responsible for?
Rose, Lychee, Lavender aromas
What do cellulose filter pads need to be rinsed with to ensure no ‘papery’ taste in the wine?
1% Citric Acid
What is one risk of de-acidification?
Increases risk of microbial spoilage
What are released into a wine as the Lees autolyse?
Mannoproteins
How much Free SO2 added to wine to stop fermentation?
50mg/l
What is the difference between Uninoculated and Inoculated fermentations?
Uninoculated - Started by indigenous yeasts Inoculated - Started by commercial dry yeasts
Can Reverse Osmosis be used to remove alcohol and / or high levels of VA?
Yes
What are Potassium Bicarbonate, Calcium Carbonate or Double Salt used for?
De-acidification of must
How much sugar is req’d to make 1% alcohol?
White 17g/L Red 19 g/L
At the beginning of fermentation why are the crushed grapes / must lightly aerated?
To kick the fermentation off strongly. Yeast needs oxygen to multiply rapidly
What compounds account for vanilla and coconut aromas?
Lactones
What are the maximum Copper concentrations permitted in wine
In EU?
In USA?
What is the most effective way to eliminate excess Copper?
EU 1mg/L
USA 0.5mg/L
Blue fining - potassium ferrocyanide
Yeasts deprived of what element will break down amino acids to produce HS2?
Nitrogen
What are the ideal conditions for MLF to take place: pH? Temperature? Total SO2?
PH between 3.3~3.5 Temp 17~22c <50mg/L total SO2
What might you add (3) to your wine to re-start a ‘stuck’ fermentation?
Nutrients such as Thiamine, di-ammonium phosphate (DAP) or ammonium sulphate
If using Oak chips when is it best to add them?
During fermentation
What are the 5 main steps of red winemaking?
Pre-fermentation processing The alcoholic fermentation Draining and pressing MLF Maturation
List the 4 HUMAN factors of wine making
Grape growing Wine making Maturation The Market
What are 3 risks of fermenting at too low a temperature?
Retention of Isoamyl Acetate (banana/pear drop aromas) Reds - Poor extraction of colour and tannins Sluggish fermentation High levels of Ethylecetate = Volatile Aromas
