1. Winemaking in the Classroom 2 Alcoholic Fermentation Sirromet Wines Pty Ltd 850-938 Mount Cotton Rd Mount Cotton Queensland, Australia 4165 www.sirromet.com Courtesy of Jessica Ferguson Assistant Winemaker & Site Chemist Downloaded from seniorchem.com/eei.html

2. What is the primary objective? Making clean wine with an aim to bottling (giving to parents etc)? Making clean wine with an aim to bottling (giving to parents etc)? No plan to bottle wine for drinking, making wine to test or investigate parameters? No plan to bottle wine for drinking, making wine to test or investigate parameters? Study of fermentation process only? Study of fermentation process only? In all cases, aim for clean, complete fermentation to dryness In all cases, aim for clean, complete fermentation to dryness

3. Preparation of Fruit/Juice: If preparing from fresh fruit, crush or press fruit to separate gross solids/skins (do not puree!) If preparing from fresh fruit, crush or press fruit to separate gross solids/skins (do not puree!) Some fruit should be peeled prior to pressing (citrus, apples, pears etc) Some fruit should be peeled prior to pressing (citrus, apples, pears etc) If making red wine from grapes – ferment on solids (crush only, don’t remove skins) If making red wine from grapes – ferment on solids (crush only, don’t remove skins) Can add 20-30mg/L SO 2 to prevent browning (optional) during settling Can add 20-30mg/L SO 2 to prevent browning (optional) during settling Suggest cold settling (<10˚ C) 24-48hrs to remove solids (protect from light and air) Suggest cold settling (<10˚ C) 24-48hrs to remove solids (protect from light and air) Cold settling may be assisted by adding enzyme which will break down the pectins Cold settling may be assisted by adding enzyme which will break down the pectins

4. Preparation of Fruit/Juice (cont) If cold settled, rack off cold juice and discard heavy solids If cold settled, rack off cold juice and discard heavy solids Allow juice/must to warm back up to at least 15˚C Allow juice/must to warm back up to at least 15˚C If SO 2 has been used (to prevent browning or clean up juice), check that FSO2 is <20mg/L If SO 2 has been used (to prevent browning or clean up juice), check that FSO2 is <20mg/L Consider adjusting sugar to 17-22˚ Brix (9-12˚ Baume) by adding table sugar (or diluting juice with water) as necessary Consider adjusting sugar to 17-22˚ Brix (9-12˚ Baume) by adding table sugar (or diluting juice with water) as necessary Adjust acidity to taste, ideally pH between 3.2 – 3.6 (some fruits may be higher, pH>4.0 to be avoided) Adjust acidity to taste, ideally pH between 3.2 – 3.6 (some fruits may be higher, pH>4.0 to be avoided)

5. Treatment of Yeast The viability of the yeast is the single most important factor to a successful fermentation The viability of the yeast is the single most important factor to a successful fermentation Critical parameters are : Critical parameters are : correct culture preparation correct culture preparation avoid temperature and/or mechanical shock (no vigorous mixing) avoid temperature and/or mechanical shock (no vigorous mixing) ensuring that nutrient levels are adequate ensuring that nutrient levels are adequate Always prepare a yeast culture (starter) – never add dry yeast to must/juice Always prepare a yeast culture (starter) – never add dry yeast to must/juice

6. Starting Fermentation - Culture Prepare culture: hydrate yeast at 35 o C in 10x vol water Prepare culture: hydrate yeast at 35 o C in 10x vol water Stir very gently to wet yeast grains and leave to sit Stir very gently to wet yeast grains and leave to sit Add a little juice or sugar solution within 10-15 minutes (juice must be within 5˚C of culture temp) Add a little juice or sugar solution within 10-15 minutes (juice must be within 5˚C of culture temp) Continue to add juice at regular intervals once yeast is active (note: fermentation will generate heat) Continue to add juice at regular intervals once yeast is active (note: fermentation will generate heat) Build culture up to 5% of final ferment volume Build culture up to 5% of final ferment volume Temperature difference between culture and juice <5 ° C before adding culture to bulk of juice/must Temperature difference between culture and juice <5 ° C before adding culture to bulk of juice/must Pour culture gently into top of must/juice in one motion Pour culture gently into top of must/juice in one motion Don’t mix or stir the culture into the must, it will gradually expand and mix into the must as yeast growth occurs Don’t mix or stir the culture into the must, it will gradually expand and mix into the must as yeast growth occurs

7. Temperature Control Temperature tolerance depends on yeast strain Temperature tolerance depends on yeast strain Too cold will inhibit or kill yeast (<10˚C) Too cold will inhibit or kill yeast (<10˚C) Too hot will ‘cook’ yeast (problems may start once temp >30˚C), plus ‘burnt’ flavours Too hot will ‘cook’ yeast (problems may start once temp >30˚C), plus ‘burnt’ flavours Ferment will generate considerable heat of its own, particularly in the first 3-8 days Ferment will generate considerable heat of its own, particularly in the first 3-8 days Start ferments with cool musts (15˚C) Start ferments with cool musts (15˚C) If ‘cool store’ available (16-18˚C) use it! If ‘cool store’ available (16-18˚C) use it! Otherwise set air-conditioning to low in room Otherwise set air-conditioning to low in room In general white wines 14-20°C, red wines 18-27˚C In general white wines 14-20°C, red wines 18-27˚C Consider fermenting in winter! Consider fermenting in winter!

8. Red Wine – Cap Immersion For red (grape) wine, ferment on skins For red (grape) wine, ferment on skins Colour and astringency from skins Colour and astringency from skins Skins will rise into a thick ‘cap’ on top of liquid Skins will rise into a thick ‘cap’ on top of liquid Must keep immersing cap into liquid at regular intervals to aid extraction Must keep immersing cap into liquid at regular intervals to aid extraction Don’t let cap dry out – spoilage can occur Don’t let cap dry out – spoilage can occur Leave solids in ferment 5-10 days Leave solids in ferment 5-10 days

9. Red wine - Dejuicing Around ⅔ to ¾ through ferment duration Around ⅔ to ¾ through ferment duration Usually assessed on taste Usually assessed on taste Solids removed to avoid over-extraction of bitter compounds Solids removed to avoid over-extraction of bitter compounds Lift cap off with a sieve or strainer Lift cap off with a sieve or strainer Strain and press liquid through coarse stainless sieve into narrow-necked vessel and fit fermentation valve Strain and press liquid through coarse stainless sieve into narrow-necked vessel and fit fermentation valve Note: don’t remove yeast solids that may have sunk to bottom – ensure they stay in ferment Note: don’t remove yeast solids that may have sunk to bottom – ensure they stay in ferment Discard skins and gross solids Discard skins and gross solids

10. Nutrient – What to add DAP – Diammonium Phosphate, inorganic source of nitrogen and phosphorus DAP – Diammonium Phosphate, inorganic source of nitrogen and phosphorus DAP alone can be ineffective and may exacerbate VA production DAP alone can be ineffective and may exacerbate VA production DAP + Vitamin formulations – also supply essential B Vitamins and trace nutrients DAP + Vitamin formulations – also supply essential B Vitamins and trace nutrients Fermaid® – includes DAP, MgSO 4, yeast hulls, B vitamins – more ‘healthy’ supplement Fermaid® – includes DAP, MgSO 4, yeast hulls, B vitamins – more ‘healthy’ supplement Other similar ‘organic’ mixed nutrients ok too Other similar ‘organic’ mixed nutrients ok too

11. Nutrient – When to add If using highly clarified/filtered juice, add to juice prior to ferment If using highly clarified/filtered juice, add to juice prior to ferment For ‘cloudy’ white juices, add once specific gravity has begun to drop (after lag phase) For ‘cloudy’ white juices, add once specific gravity has begun to drop (after lag phase) For red wines on solids, may not need to add nutrient For red wines on solids, may not need to add nutrient Consider adding to reds if they get a bit smelly (hydrogen sulphide, rotton egg) Consider adding to reds if they get a bit smelly (hydrogen sulphide, rotton egg) Nutrient added late in ferment is not very effective – add prior to 50% sugar depletion Nutrient added late in ferment is not very effective – add prior to 50% sugar depletion

12. How long does fermentation take? Anything from 7 days to 4 weeks Anything from 7 days to 4 weeks Monitor sugar content daily using hydrometer (S.G. preferred) Monitor sugar content daily using hydrometer (S.G. preferred) when S.G. reaches 1.030, raise temperature by up to 5 o C (to a max of 25 deg) when S.G. reaches 1.030, raise temperature by up to 5 o C (to a max of 25 deg) Once S.G. near or under 1.000, test for residual sugar using Clinitest® tablets, (not Clinistix ® ), Once S.G. near or under 1.000, test for residual sugar using Clinitest® tablets, (not Clinistix ® ), Sugar must be under 20gm/lt to use Clinitest (otherwise dilute into range) Sugar must be under 20gm/lt to use Clinitest (otherwise dilute into range) Benedict’s Test can also be used (same principle) Benedict’s Test can also be used (same principle)

13. Observe your ferment regularly Smell, taste, think, check, style, structure, primary indicators Smell, taste, think, check, style, structure, primary indicators Bad smells can be a warning sign of undesirable side reactions Bad smells can be a warning sign of undesirable side reactions Consider addition of Diammonium Phosphate or other N or B vitamin supplement to the ferment Consider addition of Diammonium Phosphate or other N supplement or B vitamin supplement to the ferment Add nutrients pre 1.040 SG to be effective Add nutrients pre 1.040 SG to be effective Don’t leave it indefinitely if nothing seems to be happening! Don’t leave it indefinitely if nothing seems to be happening!

14. ‘Stuck’ fermentations Indicators are: Indicators are: SG flat-line – no change for 3+ days SG flat-line – no change for 3+ days smell of bruised apples/sherry notes (indicates presence of excess acetaldehyde) smell of bruised apples/sherry notes (indicates presence of excess acetaldehyde) Other smells that are unpleasant (H 2 S, ‘vegetable’ or ‘rubber’ smells, acetic smell) Other smells that are unpleasant (H 2 S, ‘vegetable’ or ‘rubber’ smells, acetic smell) Most common causes are: Most common causes are: Poor yeast culture preparation Poor yeast culture preparation Initial S.G.>1.100 – very high sugar must can cause alcohol stress in yeast Initial S.G.>1.100 – very high sugar must can cause alcohol stress in yeast Nutrient deficiencies Nutrient deficiencies

15. How to fix stuck ferments If temperature is <16 o C and SG<1.020 – raise temperature If temperature is <16 o C and SG<1.020 – raise temperature Add nutrients (‘Go-Ferm®’ or ‘Fermaid’®) (less effective late in ferment) Add nutrients (‘Go-Ferm®’ or ‘Fermaid’®) (less effective late in ferment) Extreme solution: Rescue ferment – labour intensive Extreme solution: Rescue ferment – labour intensive Involves growing a fresh yeast culture up Involves growing a fresh yeast culture up acclimatising it gradually to high alcohol environment by additions of wine from stuck ferment acclimatising it gradually to high alcohol environment by additions of wine from stuck ferment Increase addition volumes to fresh culture each day Increase addition volumes to fresh culture each day Combine with stuck ferment when new culture is 10% of ferment volume Combine with stuck ferment when new culture is 10% of ferment volume Pray… Pray…

16. When to call it quits…. even when sugar remains….? depends on desired style to be achieved Keep in mind that an untrained palate probably won’t detect up to 10gm/L residual sugar At 1-1.5g/L reducing sugars, generally no fermentable sugar remains Safer to wait until sugar <2g/L (Clinitest dark green/blue)

17. What next?

18. Stop ferment, add preservative when sugar is @ dryness, or by desired sweet style when sugar is @ dryness, or by desired sweet style cool vessel down – colder the better, to help stop yeast and encourage settling of dead yeast cool vessel down – colder the better, to help stop yeast and encourage settling of dead yeast add SO 2 when cool – Camden tablets or Potassium Metabisulphite (PMS) salt add SO 2 when cool – Camden tablets or Potassium Metabisulphite (PMS) salt aim for >35mg/L Free SO 2 aim for >35mg/L Free SO 2 Consider that PMS is only 57% SO 2 Consider that PMS is only 57% SO 2 At least 50% of added SO 2 will convert to bound SO 2 At least 50% of added SO 2 will convert to bound SO 2

19. Post ferment clarification Bentonite – clay mineral used for clarification Bentonite – clay mineral used for clarification 0.25gm/L dose in wine 0.25gm/L dose in wine Make up as 5% slurry in water Make up as 5% slurry in water Make up day before use to allow swelling of particles Make up day before use to allow swelling of particles Add to wine after SO2 addition Add to wine after SO2 addition Rack clear wine 2 days after SO2/bentonite addition Rack clear wine 2 days after SO2/bentonite addition

20. Racking Separation of clear wine form 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

21. Safe wine storage Full containers low dissolved oxygen Free SO2 >35mg/l @ pH 3.20 no fermentable sugars left Keep wine cool

22. Clarification and finishing Consider acid addition trial for flavour and balance Consider acid addition trial for flavour and balance Fining with bentonite for further clarification and protein stabilisation Fining with bentonite for further clarification and protein stabilisation Check flavour, colour, bitterness, and structure first Check flavour, colour, bitterness, and structure first Other fining agents: PVPP, powdered milk, gelatine, isinglass - to alter or reduce bitterness/phenolics/tannins/low MW phenols. Other fining agents: PVPP, powdered milk, gelatine, isinglass - to alter or reduce bitterness/phenolics/tannins/low MW phenols. Cold stability: cool to -2oC - +2oC, add 3gm/lt KHT, mix 1 hr, hold @ these temps, then earth or pad off lees within 24hrs. Prevents tartrate precipitation in bottle Cold stability: cool to -2oC - +2oC, add 3gm/lt KHT, mix 1 hr, hold @ these temps, then earth or pad off lees within 24hrs. Prevents tartrate precipitation in bottle Filtration options – depend on sweetness levels, persistant turbidity or clarity issues Filtration options – depend on sweetness levels, persistant turbidity or clarity issues Earth or pad filter only after wine is protein and cold stable Earth or pad filter only after wine is protein and cold stable

23. Bottling Logistics In industry we would check the following pre-bottling: In industry we would check the following pre-bottling: pH, titratable acidity, free and total SO 2, CO 2, H 2 S, pH, titratable acidity, free and total SO 2, CO 2, H 2 S, alcohol content, flavour, colour, dissolved oxygen, alcohol content, flavour, colour, dissolved oxygen, protein (heat) stability, tartrate (cold) stability, protein (heat) stability, tartrate (cold) stability, residual sugar, turbidity/clarity, specific gravity residual sugar, turbidity/clarity, specific gravity Adjust Free SO 2 levels to 35-40mg/L Adjust Free SO 2 levels to 35-40mg/L Use clean, preferably sterilised bottles Use clean, preferably sterilised bottles Fill bottles carefully with no splashing (avoid increasing dissolved oxygen) Fill bottles carefully with no splashing (avoid increasing dissolved oxygen) Seal with screwcaps, crown seals or corks Seal with screwcaps, crown seals or corks