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White winemaking flowchart

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by

Angeliki Tsioli

on 23 February 2017

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Transcript of White winemaking flowchart

White wine
Grapes
De-stemming and crushing
Pressing
gentle
Sugar - acid adjustments
Alcoholic fermentation
Sugars => CO2 + ethanol + heat
anaerobic metabolism of yeast Saccharomyces cerevisiae
Malolactic fermentation (optional)
malic acid => lactic acid (less "acid")
Lactobacillus, Leuconostoc (Oenococcus oeni), Pediococcus bacteria
White winemaking flowchart
Activity 2.9 - WSET Diploma
Pre-harvest preparations
clean harvest and processing equipment
and cellar
make space, buy tanks
buy oenological and cleaning products
WHEN?
ripeness monitoring
sugar (Brix, Beaumé)
acidity (ph, Titrable Acidity)
berry tasting
pips tasting
pesticides monitoring
Respect to the withholding periods of pesticides applied (if any), otherwise:
weather monitoring
if moderate rain => dries off and may help sugar accumulation
availability of resources
human (some workers can only harvest during weekends, etc.)
legal restrictions (EU)
For
PGI "Santorini" dry white
wine, it is needed:

min. potential alcohol at harvest:
12% vol
if lots of rain => creates dilution, risk of berry swelling and cracking, thus disease prone
if hail => can devastate harvest => please harvest EARLIER!
health problems for the consumer

MRLs have to be respected - they vary among countries
fermentation problems
sulfur => H2S, reductive stinky flavours
copper => brown haze, toxic copper salts
HOW?
Healthy
Ripe
Both white and red varieties (blanc de noir) can produce white wine.
Red varieties should be manually harvested as whole bunches!
depending on the style of wine to be made
For
PGI "Santorini" sweet wine from sundried grapes
, it is needed:

min. potential alcohol at harvest:
15% vol
Manual vs Mechanical
pre-sorting in the vineyard
less damage to berries
no limitation (slope, valley)
little equipment needed
expensive
slow rate
speed
low cost
may happen at night
no sorting possible
damage to grapes (though SO2 can prevent oxidation)
limitation of terrain and trellis systems
expensive to buy the machines, availability can be a compromise when leasing
wide rows required
it may depend on law or wine style, eg. Tokaj
mechanical (availability of a leasing machine has to be taken into consideration)
Transport
fast
cool
undamaged
limit
oxidation
=> use of SO2, CO2 or N2 coat, cool, quick
limit
microbial growth
=> avoid rotten grapes, clean equipment, berry integrity
limit
contamination
=> avoid rain, leaves, picking shears, MOG (material other than grape), soil, hydraulic oil, metal or plastic taints
STEP 1
Harvest, transport and reception of the grapes

STEP 2
Grape processing

STEP 3
Must treatments

STEP 4
Fermentation

Clarification (= débourbage)
level of clarification depends on
state of the harvest
grape processing method (violent methods => more clarification)
wine style (full bodied, complex wines => less clarification)
WHICH?
by hand or a vibrating unit
Sorting
sorting unhealthy, unripe grapes and MOG
raises costs, suitable for premium wines
Goals:
by foot
by a destemming machine

no stems => bitter and herbaceous
no MOG
more grapes in the press
more efficient drainage (stems provide channels)
broken stems => bitter and herbaceous
slower drainage
whole bunch press => fine must, low in phenolics, low solids
suitable for:
manual harvests (mainly)
mechanical harvest (rare, only to remove MOG)
SO2
De-stemming and crushing are usually combined and should be
gentle
Skin contact (optional)
adds aromatic compounds
adds flavour precursors
adds polysaccharides (cellulose, pectin, arabinose) => richer, fuller wine
needs monitoring
may add bitter phenolics
free run juice goes directly to the vats for fermentation
SO2
up to 24 hours
chilled (5-10°C)
adding a pectolytic enzyme
dry ice could also be added (CO2)
Types of press
Vertical screw press
Horizontal screw press
simple to fill/empty
can be automated
can be filled with inert gas => protects from oxidation
Pneumatic press
low pressures => higher quality
gentle breaking of the pomace
Tank press
Continuous screw press
high throughput
efficient (about 70% of grape weight)
in cycles => crumbling the pomace
simple
filter effect => clear must
slow
labour intensive
phenols extraction
oxidation
quite violent marc breaking
high pressures => reduced quality
e.g. Vaslin
longer press cycle
laborous cleaning
less or no contact with O2
low pressures => high quality
long cycles
most expensive
e.g. Bucher Inertys
high pressures, but with possibility to fractionate
free run juice
whole bunch grapes go directly to the press
Some additives
Dealing with gases
HOW TO CLARIFY?
Cold settling
5-10°C overnight
add pectolytic enzymes
rack the clear must off the sediment (thick lees) => some may use a filter for these and retrieve some more clear must...
Centrifugation
high level of clarity
Diatomeous earth filtration
for aromatic varieties
Flotation
bubbling N2, CO2 or air from the bottom of the vat
solid particles float to the surface
rotary suction device removes them
most usual
high risk of oxidation
mostly large wineries
can reduce nutritional content of must
can be combined with hyperoxidation (if air) => see next chapter
usually large wineries
SO2
O2
Sources
Unit 2 study guide
http://www.oiv.int/public/medias/3741/e-code-annex-maximum-acceptable-limits.pdf
Properties
antiseptic (selects yeast)
antioxidant (can be combined with ascorbic acid)
antioxidasic (denatures tyrosinase)
combines with acetaldehyde
Usage
in must before AF
60-100 mg/l
max. 200 mg/l (OIV)
higher if rotten grapes
higher if high pH
higher if sweet wines
Preparations
potassium metabilsufite powder
pure sulfur dioxide gas (compressed in liquid form)
dissolved in solution (5%)
generated from burning candles or tablets (for barrels)
Reductive handling
use of SO2
cool temperatures
inert gas
Oxydative handling
yeasts need O2
controlled O2 => complex aromas (Chardonnay)
enzymatic oxidation of phenolics => insoluble polymers
Hyperoxidation
colour stabilisation
impact on aromatic quality depends on the grape variety
wines of oxydative style (Sherry, vin jaune, Tokaj, tawny Port)
O2
O2
bubbling air or pure O2
only for white wines
... and other effects:
Enrichment
De-acidification
Acidification
sucrose (17g/l for 1%vol)
concentrated must (RCGM)
vaccuum evaporation
reverse osmosis
cryoextraction
potassium bicarbonate (easier to remove the formed crystals)
calcium carbonate (slow prepitations of the formed crystals)
double-salt (calcium carbonate and calcium tartaric-malate = Acidex)
malolactic fermentation
strictly regulated in EU
up to 1g/l tartaric acid
tartaric acid
1,5 g/l in must, and
2,5 g/l in wine
citric acid (
AFTER fermentation!
=> it can be metabolised into acetic acid)
bentonite
enzymes
clay that removes dissolved proteins
before or after fermentation
non-selective => may remove flavour compounds
look at de-stemming - crushing chapter
By-products:
glycerol
acetaldehyde
ethyl acetate
aroma esters
fusel oils
Parameters
Vessels
Selected yeast vs indigenous
Nutrients
Density => stable rate of decrease
Temperature (
10-18°C
)
Aeration (in early stages)
Stainless steel tanks
Wooden vessels
Cement tanks
rapid onset AF
even rates
efficiency
less risk of stuck AF
low VA
Di-ammonium phosphate (max 200 mg/l)
Thiamine (max. 1 mg/l)
Ammonium sulfate
risks (undesirable flavours)
more complex wines
Conditions:
in tanks or barrels
< 50 mg/l SO2
pH: 3,3 - 3,5
18-25°C
nutrients
lees protect from oxidation
add texture
reduction problems
if H2S => aeration
if mercaptans
copper sulfate
HOW?
rod with chain in barrel
barrel stackers with rollers
bubbling gas in tank
Effects:

deacidification (reduce malic acid)
stability
loss of primary fruit aromas (ok for Chardonnay, not ok for Riesling and Gewürztraminer)
diacetyl (may spoil the fruit aromas of Riesling, Sauvignon blanc)
increase in VA
spoilage risk, if out of control
Monitoring:
see or hear the "spritz-spratz" - release of small quantities of CO2
paper chromatographic test
enzymatic analysis
Lees contact - stirring
Full transcript