Winemaking in the Classroom 3

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Winemaking in the Classroom 3

• Clarification, Finishing and Bottling

Sirromet Wines Pty Ltd 850-938 Mount Cotton
Rd Mount Cotton Queensland, Australia
4165 www.sirromet.com   Courtesy of Jessica
Ferguson Assistant Winemaker Site
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What next?
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Clean-up, add preservative

• When wine is dry, or by desired sweet style
• cool vessel down colder the better, to help
  stop yeast and encourage settling of dead yeast
• add SO2 when cool Camden tablets or Potassium
  Metabisulphite (PMS) salt
• aim for gt35mg/L Free SO2
• Consider that PMS is only 57 SO2
• At least 50 of added SO2 will convert to bound
  SO2 directly following fermentation

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Clarification - Racking

• Initially, allow wine to settle
• Ensure that containers are full
• Transfer carefully (no splashing) to smaller
  containers, or top up containers and seal.
• Avoid oxygen/air exposure
• May need successive rackings to achieve
  clarification more settling occurs following
  each racking

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Racking

• Separation of clear wine from settled solids
  (lees)
• Best to use a siphon with the end of the hose
  held above the lees
• Rack wine into a smaller container so that vessel
  is full
• Always keep wine vessels full unless fermenting
• This prevents spoilage due to oxidation or
  aerobic microbes

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Further clarification aids

• Bentonite clay mineral used for clarification
• Try 0.25gm/L dose in wine
• Make up as 5 slurry in water
• Make up day before use to allow swelling of
  particles
• mix vigorously (use electric beater) while adding
  powder slowly to hot water
• Add to wine immediately after SO2 addition, or
  after racking for further clarification
• Rack clear wine 2 days after bentonite addition
• Wine should not be chilled bentonite works
  better over 10C

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Safe wine storage

• Full containers
• low dissolved oxygen
• Free SO2 gt35mg/l _at_ pH 3.20
• no fermentable sugars left
• Keep wine cool 15C is great, but at least
  lt20C.

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Finishing wine fining and stability

• Consider acid addition trial for flavour and
  balance (can use citric or tartaric acid)
• Other fining agents powdered milk, gelatine,
  isinglass - to alter or reduce bitterness,
  phenolics, tannins
• Good idea to trial all finings on bench first
• 100mL wine samples, add solution of fining agent
  equivalent to final dose in wine
• For example, to trial a 0.2g/L tartaric acid
  addition
• add 0.2mL of a 10 tartaric acid solution to
  100mL of wine on the bench

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Finishing Wine - Stabilising

• Protein stability More an issue for white-style
  wines, prevents protein haze in bottled wine
• Proteins are removed by bentonite fining
• Test for protein stability heat a filtered wine
  sample for 6 hours at 80C, cool and check for
  haze formation
• Cold stability Prevents tartrate precipitation
  in bottle, difficult to achieve on small volume
  wines and without a way of cold filtering without
  air exposure
• Could try refrigerating wine and racking wine off
  of any crystals that precipitate

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Finishing Wine - Filtration

• May not be necessary for some red wines that have
  achieved good clarity through racking/fining
  alone
• Filtration options depends on sweetness levels,
  persistent turbidity or clarity issues
• Gravity or small electric pad filters are
  available
• Suggest pad filter just prior to bottling gives
  brilliance to wine
• Wine should not be chilled when filtering as this
  exacerbates dissolved oxygen pick-up

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Bottling Logistics

• In industry we would check the following
  pre-bottling
• pH, titratable acidity, free/total SO2, CO2,
  H2S,
• alcohol, flavour, colour, dissolved oxygen,
  protein stability, tartrate (cold) stability,
  residual sugar, turbidity/clarity, specific
  gravity
• Adjust Free SO2 levels to 35-40mg/L
• Use clean, preferably sterilised bottles
• Fill bottles carefully with no splashing (avoid
  increasing dissolved oxygen)
• Seal with screw-caps, crown seals or corks

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Finally.. A word of caution

• If wine is not dry at bottling, be aware of the
  risk of re-fermentation
• Increase SO2 levels pre-bottling to FSO2 gt 40mg/L
• Can also use Potassium Sorbate at 100-150mg/L as
  an extra preservative (ensure SO2 levels are
  adequate for sorbate to be effective)
• Advise that wine should be drunk earlier rather
  than later!