The avoidance of taints and contaminations during winemaking Geoff Cowey Senior Oenologist Industry Development and Support geoff.cowey@awri.com.au The_AWRI
Taints in 2005 & 2006 Tainted batch of yeast hulls Tainted batch of tartaric acid Cl OH CH 3 Cl OH Cl 6 chloro-o-cresol 2, 6 dichlorophenol
What happened next AWRI investigations started 2006, resolved 2007 Legal recourse in 2010, involving: the manufacturer supplier a contract winery number of other wineries Court ruled in favour of the supplier in 2011
What happened next It was accepted that the contaminated tartaric acid provided by the supplier was not reasonably fit for use by the winery as an additive in the making of wines for human consumption for itself or for others, and that the tartaric acid delivered by the supplier to the winery was not of merchantable quality However the supplier's terms and conditions included clauses which absolved the supplier of any responsibility T&C signed in a credit application by the winery accountant over five years prior to purchase of this batch of tartaric acid from the supplier
Impact of taints & contaminations
Flavours, taints and faults What is a wine aroma flavour? An odour that can be derived from grapes, the winemaking process or wine development Consumer preference e.g. Sauvignon blanc What is a wine fault/off flavour? Fault internal contamination A characteristic which leads to spoilage, attributed to poor winemaking practices or unsound storage conditions. e.g. volatile acidity/ VA or vinegar aroma, Brettanomyces flavour What is a wine taint? Taint external contamination an odour or flavour that is foreign to, and reduces the acceptability of the product e.g. cork taint
Major faults at wine shows Micro Other 2008 wines 6 to 7% of wines in the International Wine Challenge in 2006, 2007 & 2008 were judged to be faulty Data by Sam Harrop, International Wine Challenge
Musty compounds Threshold (ng/l) 2,4,6-trichloroanisole (TCA) 1.4 2,4,6-tribromoanisole (TBA) 3.4 musty, mouldy aroma, bitter metallic taste 2-methylisoborneol 30 geosmin 25 mouldy, earthy, dirty water 1-octen-3-ol 20000 1-octen-3-one 20 Fungal must (2-methoxy-3,5-dimethylpyrazine) 2.1 Chocolate, dirty, dusty, mouldy, mushroom
plastic-like, chlorine-like, antiseptic Threshold (ng/l) 2,4-dichlorophenol (2,4 DCP) 890 2,6-dichlorophenol (2,6 DCP) 32 2,4,6-trichlorophenol (TCP) 2000 2, 6-dibromophenol (DBP) 50 2,4,6-tribromophenol (TBP) >890 plastic, paint-like, medicinal or phenolic 6 chloro-o-cresol 70 Chemical-like, plastic, chlorine-like and hot, burning aftertaste
Mothballs, chemical, styrene Aromatic hydrocarbons naphthalene alkyl naphthalenes styrene xylene toluene
Smoky, ash, burnt, ashtray Threshold (µg/l) Guaiacol 23 4 methyl guaiacol 65 m-cresol 20 o-cresol 62 p-cresol 64
Guided wine taint tasting Assess carefully Aroma only (taste if you need to) 6 White wines Wine 1 is a control Nothing spiked at harmful to health levels
Wine 1. Control
Wine 2. Smell wine 2
Wine 2. Chlorine/plastic - Chlorophenol (2,6-dichlorophenol at ~ 100 ng/l) 'plastic', 'paint-like', 'medicinal' or 'phenolic' taint 2,6-dichlorophenol: 32 ng/l odour threshold in white wine (300 ng/l threshold in water) widely used in cleaning products (biocides)
Sources of Chloro and bromophenols Chlorophenols Timber floors treated with Chloroanisoles chlorophenols & Bromophenols bromophenol Bromoanisoles preservatives Aromatic hydrocarbons Smell barrel exhibit
Contamination in the vineyard Australia 2002: 2,4-dichlorophenol taint from agrochemical breakdown
Wine 3.
Wine 3. Cork-type taint: 2,4,6-tribromoanisole (TBA) at 5 ng/l distinct musty, mouldy aroma similar aroma threshold to TCA (3.4 ng/l) precursor is 2,4,6-tribromophenol (TBP) TBP is both a flame retardant and fungicide, and is widely used to treat wood and wood products TBA has been found on winery surfaces: barrels, plastics (including synthetic closures), natural corks and wood structures including walls, floors and ceilings
Wine 4.
Wine 4. Cork taint: 2,4,6-trichloroanisole (TCA) at 5 ng/l distinct musty, mouldy aroma suppresses fruit intensity red wine aroma threshold 1.4 ng/l precursor is 2,4,6-trichlorophenol (TCP) other compounds which impart musty, mouldy, earthy or mushroom aromas to wine include: 2-methylisoborneol (threshold of 30 ng/l), geosmin (threshold of 25 ng/l), 1-octen-3-ol (threshold of 20 µg/l) and 1-octen-3-one (threshold of 20 ng/l) 2-methoxy-3,5-dimethylpyrazine (2.1 ng/l in wine)
Sources of Chloro and bromoanisoles
TCA Vs TBA Over last 10 years (1999-2009) AWRI Commercial Services have analysed over 2000 wines for a variety of musty taints 109 positive cases of TBA taint 861 positive cases of TCA taint
Wine 5.
Wine 5. 6-chloro-o-cresol (6CC) at 100 ng/l Chemical-like, plastic, chlorine-like and hot, burning aftertaste Threshold 16 ng/l Contaminant in yeast hulls (> 500 ng/l in one wine) disinfectant-type taints in chicken meat and biscuits and softdrinks
Wine 6.
Wine 6. Geosmin at 20 ng/l earthy, musty, muddy, dirty fish tank threshold ~25 ng/ L metabolites of soil bacteria and algae off-flavour in town water supplies/water storage Can contaminate wine when used to push wine through lines, used to make up additions to wine metabolite of Botrytis cinerea (Kikuchi et al 1983)
Guided wine taint tasting Tip out your glasses, and pour the next 6 wines Assess carefully Aroma only (taste if you need to) 6 Red wines Wine 1 is a control Nothing spiked at harmful to health levels
Wine 7. Red wine control
Wine 8.
Wine 8. Guaiacol at 30 µg/l threshold 23 µg/l smoky, phenolic, medicinal high toast level in barrels; formed during barrel toasting process/degradation of lignin then extracted into wine at typically 10 40 µg/l Component of cork taint? formed by soil bacteria and moulds, but at low quantities Bushfires and burn-offs
Smoke is more than just guaiacol - cresols GuaiacolAND cresols, and their multiple glucosideconjugates are produced during a smoke event
Aerial contamination in the vineyard Switzerland m-cresol and p-cresol taints pollution of vineyards from nearby factories Italy ethylphenol taints vineyards contaminated from industrial air pollution Australia creosote-crudded posts burn-offs
Contamination in the vineyard Australia 2005: 2,4-dichlorophenoxyacetic acid from herbicide spray drift
Wine 9.
Wine 9. Eucalyptus character at 40 µg/l eucalyptus, fresh, cool, medicinal and camphoraceous Aroma mentioned in Australian, Californian, South American wines, Cabernet Sauvignon or in wines grown near Eucalypt trees Eucalyptol or 1,8-cineole Threshold 2.2-3.2 µg/l, consumer rejection threshold 27 µg/l Airborne transfer Binds to fatty berry layers Extracted from skin during fermentation MOG is the major contributor
Wines from a vineyard in WA Distance of vines from blue gums [Eucalyptol] in finished wine (µg/l) First 4 rows running 11-18.5 m 9.5 Second row running 15 m 6.4 Seventh row running 27 m 1.1 Sixteenth row running 50 m 1.6 Twenty-seventh row, 77 m 0.6 Remaining rows 230-430 m 0.4
Wine 10.
Wine 10. Reduction - Methyl mercaptan at 40 µg/l methyl mercaptan (methane thiol) threshold: 3.1 µg/l rotten cabbage, onion, rubbery Other reduction or sulfide compounds: Hydrogen sulfide (rotten egg) Disulfides (rotten onions) Dimethyl sulfide (canned corn, tomato sauce) Chemical & biological formation often wines that have experienced fermentation problems Elemental Sulfur agrochemical residues Often confused with Brett spoilage
Wine 11.
Wine 11. 4-ethylphenol: 4-ethylguaiacol at 400: 45 µg/l bandaid 4-ethylphenol HO medicinal Intrinsic sensory attributes metallic taste phenolic spicy 4-ethylguaiacol HO medicinal clove-like H 3 CO smoky horsy 4-ethylcatechol HO antiseptic Dekkera (Brettanomyces) bruxellensis smoky HO smoky-bacon
Brett Compounds 40:1 survey data 30:1 4-EP & 4-EG are always present together Ratio of 4-EP:4-EG 20:1 10:1 97.5% = 23:1 50% = 9:1 2.5% = 3:1 Shiraz Cabernet, Nebbiolo Pinot Noir 0 Frequency
Variable threshold, depending on the wine Aroma thresholds for Brett compounds in three base wines 1800 Aroma thres shold (µg/l) 1600 1400 1200 1000 800 600 400 200 158 209 373 368 425 569 774 1131 1528 0 Neutral Green Oaky Neutral Green Oaky Neutral Green Oaky 4-EG 4-EP 4-EC
The Brett zone - prevention Cell growth (log cells/ml L) 8 6 4 Alcoholic fermentation The Brett zone Maturation and bottling Healthy ferments Minimise residual sugar >0.8 mg/l Molecular SO 2 ph control Sanitation Filtration Saccharomyces cerevisiae Non-Saccharomyces yeasts 2 O.oeni (post-ferment) Dekkera bruxellensis 0 Indigenous bacteria Vinification time
Wine 12.
Wine 12. Sorbic acid metabolism (Geranium off-odour) odour reminiscent of crushed geranium leaves result of metabolism of sorbic acid by LAB (mainly only Oenococcus oeni not Pediococcus and Lactobacillus spp.) pathway: hydrogenation of sorbic acid to sorbinol which rearranges in the presence of acid to 3,5-hexadien-2-ol 3,5-hexadien-2-ol then reacts with ethanol to form 2-ethoxyhexa- 3,5-diene (geranium tone) If use sorbic acid, must sterile filter to remove LAB
Main contaminants Hydraulic oil Hydrocarbons (aliphatic and aromatic) Refrigerant brines Alcohol solutions containing ethanol/methanol rhodamine dye ethylene glycol solutions
2-pack epoxy paint taint plastic, PVC, styrene, solvent/chemical/oily in harvested grapes in grape bin 2 pack epoxy paints: Not contain phenols Not contain solvent Suitable for potable water Tested by approved water authority 7-12 days curing before use Truck and trailer had just been painted with a non-food grade paint which was not fully cured for 2 weeks
Taint from pump stator Red wine had a petroleum/grease-like taint Taint observed after simple wine transfer Winemaker suspected that the mono pump
Oils aint always oils! Grapeseed oil Fluorescent green Unique acrid smell Heavily pressed wines
The basic steps in managing quality Specify the quality requirements (no taints) Control the processes Monitor the processes Corrective action system Continuous review
Winemaking flowchart critical control points? CCP3 - MOG CCP4 Oil leaks 1. Harvest & Transport 2. Crushing 3. Must holding & Settling 4. Inoculation & fermentation 5. Protein Stabilisation CCP1 - Pesticides CCP2 Hydraulic oil, brine leaks Acid adjustment Yeast & DAP Bentonite CCP5 - taints 6. Tartrate Stabilisation 7. Fining Filtration Casein, PVPP & Copper CCP6 taints 8. Wine adjustments RS & Acid adjustment 9. Sterile Filtration 10. Bottling CCP7 Removal of microorganisms
Example - Taints from agrochemicals Risk illegal additives, taints from pesticide breakdown, contaminated pesticide or non-adherence with withholding period Control AWRI Registered Agrochemicals booklet & spray diary Spray Diary Frequency check each batch of incoming fruit Responsible person winemaker Corrective action - reject grapes
Refrigerant brine Risk leaks from Brine refrigeration Control engineer out risk no interior tank dimple plating no brine lines over open tanks Frequency monitor brine reservoir level weekly annual R&M of hoses, clamps etc Responsible person winemaker Corrective action analyse for rhodamine quarantine batch, dispose of as waste recover through insurance
Additives and processing aids Any additive or processing aid has the Any additive or processing aid has the potential to taint juice or wine if that additive or aid is tainted!
Aerial contamination of additives & processing aids Directly from the air during production From containers during transport Through packaging materials
Screening techniques - Distributors http://news.reseau-concept.net/images/oiv/client/codex_2006_fr.pdf
Example - Taints from additives Risk taints from contaminated additives Control foil barriers during transport assess additives before use Frequency check each batch Corrective action reject batch inform supplier Responsible person lab staff
L-Tartaric acid Procedure: (SolubilityTest) Dissolve 1 g of tartaric acid in 1 ml of water or 4 ml of 95% v/v ethanol. Interpretation: Tartaric acid should be soluble in its own weight of water and in four times its weight of ethanol, i.e. no residue should be apparent). (2006 OIV Oenological Codex) A B Fail D/L Tartaric acid Pass L-Tartaric acid
Bentonite Bentonite should not have any undesirable odour (e.g. mould), and should not change the taste of wine. International Oenological Codex, 2006 Procedure: Make up a 10% slurry of bentonite as per normal. (rehydrate using warm clean water). Important that the water is the same water used when performing bench fining trial. Safety note: Take care when handling. Wear appropriate breathing protection, due to fine dust hazard. Simply place some of this bentonite in a glass and assess the aroma for any mouldy odour and any taints. Capitol Reef National Park, Utah, USA
Bentonite Interpretation: If the bentonite is tainted or exhibits mouldy odour, then the bentonite is unsuitable for use. (2006 OIV Oenological Codex)
Diatomataceous earth filter aid (DE) Procedure: Place 2.5 g of DE into 1L of wine. Mix and leave for 24 hours. **Safety note. Take care when handling. Wear appropriate breathing protection, due to fine dust hazard. Compare the taste to wine not containing any DE. Interpretation: The DE should not impart any odour or foreign taste to the wine. (2006 OIV Oenological Codex)
Copper sulfate (CuSO 4.5H 2 O) Procedure: Dissolve 10g in 50 ml of clean water. Swirl and assess aroma of solution. Interpretation: The solution should be clear and free from turbidity and taint aromas. (2006 OIV Oenological Codex)
Yeast hulls Procedure: Add ~5 g of yeast hulls to 50 ml of 95% ethanol and place on a magnetic stirrer for approximately 24hrs. Next, dilute this solution down to ~30% v/v ethanol (16mL of yeast hull solution and make up to 50mL with water). Interpretation: Yeast hulls should not impart any odour or foreign taste to the wine.
Paint and other surface coatings Procedure: Paint 2 microscope slides or stainless steel (approx 25mm x 70mm) with the article to be tested. Place in a schott bottle and immerse in 3% NaOH for approximately 10 minutes. Thoroughly rinse off NaOH with water. Transfer slides into 2 separate schott bottles and add 100 ml of wine simulant (~14% ethanol and water solution) to each and soak for 5-7 days. After 5-7 days, mix thoroughly, divide into 2 equal portions and place in schott bottles. Chlorinate one of the samples by adding approximately 50 mg/l of chlorine (sodium hypochlorite), mix and allow to stand for 24hrs.
Paint and other surface coatings Interpretation: Assess aroma of both samples as well as noting any discolouration of the sample and the colour and turbidity of the extraction medium.
Hoses Procedure: Use approximately 300mm of hose. Attach a stainless steel plug to one end of the hose and secure with a clamp to make an effective seal. Carefully fill with 3% NaOH and soak for approximately 10 minutes. Thoroughly rinse off NaOH with water. Using the following table as a guide, fill the hose with wine simulant (~14% ethanol and water solution), seal with a stainless steel plug or alfoil and soak for 5-7 days. Hose Diameter 38mm 75mm 100mm Volume of wine simulant 200 ml 200 ml 400 ml
Hoses After 5-7 days, mix thoroughly, divide into 2 equal portions and place in schott bottles. Chlorinate one of the samples by adding approximately 50 mg/l of chlorine (sodium hypochlorite), mix and allow to stand for 24hrs. Interpretation: Assess aroma of both samples as well as noting any discolouration of the sample and the colour and turbidity of the extraction medium.
Screening techniques All products should be sampled when entering and leaving your premises. (Irrespective of where you are in the supply chain)
Quality assurance program Check approved material Obtain product information Evaluate & select supplier QC Assessment of material Ordering system (Traceability) Purchase of material Receive material Quarantine material QC Assessment of material Pass Release to production Fail Return to supplier Transfer to general use or storage
Approved supplier system Contracts liability Legal compliance for purity Legal additives Food grade Absence of GMOs Non tainting
Spray Diary Traceability
Traceability How do you keep records for: Fruit, juice and wine: R07COWEYSHZBLKA Tank 1004 11:56 L7103 RL Additives 11:56 L7103 RL Batch #: 14314DE
Corrective action Quarantine wine batch/additive Prevent cross contamination Product Recall System Reassess controls to prevent reoccurrence
Take home messages Taints = potential health risks to consumers serious economic & brand loss unsaleable wine Prevention is better than cure avoid taints with a QC/QA/food safety program Implement a screening program to prevent accidental introduction of taints from winemaking additives and processing aids Recognise and be aware of your own sensitivities to taints
Acknowledgements Institute of Masters of Wine Staff & students of The AWRI Con Simos, Adrian Coulter, Matt Holdstock Wine Australia Australian wine industry partners Australian Grapegrowers and winemakers discussed in this presentation The AWRI s research is financially supported by Australia's grapegrowers and winemakers through their investment body the Grape and Wine Research and Development Corporation with matching funds from the Australian Government