The Avoidance of Taints and Contaminations During Winemaking1

8/18/2019 The Avoidance of Taints and Contaminations During Winemaking1

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The Australian WineResearch Institute

The avoidance of taints andcontaminations duringwinemakin

Geoff CoweySenior Oenologist

Industry Development and Support

[email protected]_AWRI


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Taints in 2005 & 2006

Tainted batchof yeast hulls

CCl

OH

CH3

Tainted batchof tartaric acid

CC

l

OH

Cl

6 chloro-O-cresol 2, 6 dichlorophenol


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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


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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 anadditive in the making of wines for human consumption foritself 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 whichabsolved the supplier of any responsibility

T&C signed in a credit application by the winery accountant over fiveyears prior to purchase of this batch of tartaric acid from the supplier


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Impact of taints & contaminations


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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 theproduct e.g. cork taint


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Major faults at wine shows

2008 winesMicro

Other

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


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The Australian WineResearch InstituteThreshold(ng/L)

2,4,6-trichloroanisole (TCA) 1.4

2,4,6-tribromoanisole (TBA) 3.4

musty, mouldy aroma, bitter metallic taste

2-meth lisoborneol 30

Musty compounds

geosmin 25

mouldy, earthy, dirty water

1-octen-3-ol 200001-octen-3-one 20

Fungal must (2-methoxy-3,5-dimethylpyrazine) 2.1

Chocolate, dirty, dusty, mouldy, mushroom


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‘plastic-like’, ‘chlorine-like’, ‘antiseptic’

Threshold(ng/L)

2,4-dichlorophenol (2,4 DCP) 8902,6-dichlorophenol (2,6 DCP) 32

2,4,6-trichlorophenol (TCP) 2000

2, 6-dibromophenol (DBP) 502,4,6-tribromophenol (TBP) >890

plastic, paint-lie, me!icinal or phenolic

6 chloro-o-cresol 70

Chemical-like, plastic, chlorine-like and hot, burning aftertaste


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Aromatic hydrocarbons

naphthalene

alkyl naphthalenes

‘Mothballs’, ‘chemical’, ‘styrene’

xylene

toluene


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Threshold (µg/L)

Guaiacol 23

4 methyl guaiacol 65

m-cresol 20

o-cresol 62

‘Smoky’, ‘ash’, ‘burnt’, ‘ashtray ’

p-cresol 64


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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


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Wine 1. Control


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Wine 2.

Smell wine 2


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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)


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Sources of Chloro and bromophenols

ChlorophenolsTimber floors

treated with

Bromophenols

Bromoanisoles

Aromatic hydrocarbons

chlorophenols &bromophenol

preservatives

Smellbarrelexhibit


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Contamination in the vineyard

Australia 2002:2,4-dichlorophenol taint

− from agrochemical breakdown


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Wine 3.


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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 totreat wood and wood products

TBA has been found on winery surfaces: barrels, plastics (includingsynthetic closures), natural corks and wood structures includingwalls, floors and ceilings


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Wine 4.


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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 mushroomaromas 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)


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Sources of Chloro and bromoanisoles


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TCA Vs TBA

Over last 10 years (1999-2009) AWRI Commercial Services haveanalysed over 2000 wines for a variety of musty taints

109 positive cases of TBA taint 861 positive cases of TCA taint


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Wine 5.


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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


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Wine 6.


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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)


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Guided wine taint tasting

Tip out your glasses, and pour the next 6 wines

Assess carefully

6 Red wines

Wine 1 is a control

Nothing spiked at ‘harmful to health’ levels


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Wine 7. Red wine control


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Wine 8.


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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 bacteriaand moulds, but at low quantities

Bushfires and burn-offs


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Smoke is more than just guaiacol - cresols

"#aiacol $%D cresols, an! their

m#ltiple gl#cosi!e congates

are pro!#ce! !#ring a smoe

e'ent


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Contamination in the vineyard

Australia 2005:2,4-dichlorophenoxyacetic acid− from herbicide spray drift


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Wine 9.


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‘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

Wine 9. Eucalyptus character at 40 µg/L

Airborne transfer Binds to fatty berry layers

Extracted from skin duringfermentation

MOG is the majorcontributor


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Wines from a vineyard in WA

Distance of vines from bluegums

[Eucalyptol] in finishedwine (µg/L)

First 4 rows running 11-18.5 m 9.5

econ row runn ng m .

Seventh row running 27 m 1.1

Sixteenth row running 50 m 1.6

Twent-seventh row! 77 m 0.6

"em#ining rows 2$0-4$0 m 0.4


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Wine 10.


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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

Wi 11


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Wine 11.

Wi h l h l h l i l


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4-eth%&heno%

HO

medicinal bandaid ®

phenolic metallic taste 'ntrinsic sensor #ttri(utes

Wine 11. 4-ethylphenol: 4-ethylguaiacol

at 400: 45 µg/L

Dekkera (Brettanomyces) bruxellensis

4-eth%gu#i#co%

HO

H3CO

4-eth%c#techo%

HO

HO

smoky

spicy

clove-like

medicinal

horsy

smoky smoky-bacon

antiseptic


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30:1

40:1

survey data

4-EP & 4-EG

are always present together

“Brett” Compounds

0

10:1

20:1

50% = 9:1

2.5% = 3:1

.

Frequency

R a t i o o f 4 - E P : 4 -

E

Cabernet, Nebbiolo

Pinot Noir


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Aroma thresholds for ‘Brett’ compounds in three base wines

1200

1400

1600

1800

h o l d ( g /

L )

1131

1528

Variable threshold, depending on the wine

0

200400

600

800

1000

4-EP

A r o m a t h

r e

368425

569

4-EG

158 209

373

Neutral Green Oaky Neutral Green Oaky

4-EC

774

Neutral Green Oaky


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The ‘Brett’ zone - prevention

8

Alcoholic fermentation

)

Maturation and bottling

The ‘Brett’ zone Healthy ferments Healthy ferments

Minimise residual sugar Minimise residual sugar

>0.8 mg/L Molecular>0.8 mg/L Molecular SO pH control pH control

SanitationSanitation

0

2

4

Vinification time

Saccharomyces cerevisiae

Non-Saccharomyces yeasts

O.oeni (post-ferment)

Dekkera bruxellensis

Indigenous bacteria

C e l l g

r o

w t

( l o g c e l l s

/ m


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Wine 12 Sorbic acid metabolism


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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, - - -

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

M i t i t


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Main contaminants

Hydraulic oil

Hydrocarbons

(aliphatic and aromatic)

Refrigerant ‘brines’

Alcohol solutions containing

ethanol/methanol

rhodamine dye

ethylene glycol solutions


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!pac" epo#y paint taint“plastic”, “PVC”, “styrene”, “solvent/chemical/oily”

in harvested grapes in grape bin

Truck and trailer had just been painted with anon-food grade paint which was not fully

cured for 2 weeks

pac epoxy pa n s:• Not contain phenols• Not contain solvent• Suitable for potable water• Tested by approved water authority• 7-12 days curing before use

$ i t f t t


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The Australian WineResearch Institute$aint from pump stator

Red wine had a “petroleum/grease-like” taint

Taint observed after simple wine transfer

Winemaker suspected that the mono pump


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Oils aint always oils!


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Oils aint always oils!

Grapeseed oil

Fluorescent green

Unique acrid smell

Heavily pressed wines

The basic steps in managing quality


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The basic steps in managing quality

Specify the quality requirements

(no taints)

Control the processes

Monitor the processes

Corrective action system

Continuous review

Th A li WiWinemaking flowchart


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1. Harvest &

Transport

Yeast & DAP

2. Crushing

3. Must holding& Settling

4. Inoculation

& fermentation

Acid adjustment

g – critical control points?

CCP1 - Pesticides

CCP3 - MOG

CCP4 Oil leaks CCP5 - taints

CCP2 – Hydraulic oil, brine leaks

5. Protein

Stabilisation

7. Fining

Bentonite

6. Tartrate

Stabilisation

Casein, PVPP & Copper

8. Wine adjustments RS & Acid adjustment

9. Sterile Filtration

10. Bottling

Filtration

CCP7 – Removal of microorganisms

CCP6 taints

The Australian Wine

Example - Taints from agrochemicals


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Example - Taints from agrochemicals

Risk – illegal additives, taints from pesticide breakdown,contaminated pesticide or non-adherence withwithholding period

Control – ‘AWRI Registered Agrochemicals booklet” &spray diary

Frequency – check each batch of incoming fruit

Corrective action - reject grapes

Responsible person – winemaker

The Australian Wine

Refrigerant brine


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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

Corrective action – analyse for rhodamine

– quarantine batch, dispose of as waste

– recover through insurance

Responsible person – winemaker

The Australian WineAdditives and processing aids


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Additives and processing aids

An additive or rocessin aid has the

potential to taint juice or wine if thatadditive or aid is tainted!

The Australian Wine

Aerial contamination of


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Directly from the air during production

Aerial contamination of

additives & processingaids

From containers during transport

Through packaging materials

The Australian WineScreening techniques - Distributors


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Research InstituteScreening techniques Distributors

http://news.reseau-concept.net/images/oiv/Client/Codex_2006_FR.pdf

The Australian Wine

Example Taints from additives


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Research InstituteExample - 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

The Australian WineR h I i

L-Tartaric acid


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Research InstituteL 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 waterand in four times its weight of ethanol, i.e. no residueshould be apparent). (2006 OIV Oenological Codex)

A B

Pass – L-Tartaric acidFail – D/L Tartaric acid

The Australian WineR h I tit t

Bentonite


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Research Institute

“Bentonite should not have any undesirable odour (e.g.mould), and should not change the taste of wine.”

International Oenological Codex, 2006 Procedure:

u u y . -

hydrate using warm clean water). Important that thewater is the same water used when performing benchfining trial.

Safety note: Take care when handling. Wear appropriatebreathing protection, due to fine dust hazard.

Simply place some of this bentonite in a glass andassess the aroma for any mouldy odour and any taints.

Capitol Reef National Park, Utah, USA


Bentonite


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Research Institute

Interpretation:

If the bentonite is tainted or exhibits mouldy odour, then

the bentonite is unsuitable for use. (2006 OIVOenological Codex)


Diatomataceous earth filter aid (DE)


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Research Institute

Procedure:

Place 2.5 g of DE into 1L of wine. Mix and leave for 24hours. **Safety note. Take care when handling. Wearappropriate 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 thewine. (2006 OIV Oenological Codex)


Copper sulfate (CuSO4.5H2O)


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Research Institute

Procedure:

Dissolve 10g in 50 mL of clean water. Swirl

and assess aroma of solution.

Inter ret tion:

The solution should be clear and free fromturbidity and taint aromas. (2006 OIV OenologicalCodex)


Yeast hulls


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Procedure:

Add ~5 g of yeast hulls to 50 mL of 95% ethanol and place on amagnetic stirrer for approximately 24hrs. Next, dilute this solution

down to ~30% v/v ethanol (16mL of yeast hull solution and make upto 50mL with water).

Interpretation: Yeast hulls should not impart any odour or foreign taste tothe wine.


Paint and other surface coatings


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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 ofwine simulant (~14% ethanol and water solution) to each and soakfor 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


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Interpretation:

Assess aroma of both samples as well as noting any

discolouration of the sample and the colour and turbidityof the extraction medium.


Hoses


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Procedure:

Use approximately 300mm of hose. Attach a stainless steel plug toone 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.Thorou hl 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 plugor alfoil and soak for 5-7 days.

Hose Diameter

Volume of wine

simulant

38mm 200 mL

75mm 200 mL

100mm 400 mL


Hoses


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After 5-7 days, mix thoroughly, divide into 2 equal portions andplace in schott bottles.

Chlorinate one of the samples by adding approximately 50 mg/L ofchlorine (sodium hypochlorite), mix and allow to stand for 24hrs.

Interpretation:

Assess aroma of both samples as well as noting any discolourationof the sample and the colour and turbidity of the extractionmedium.


Screening techniques


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All products should be sampled when entering and leaving yourpremises.

(Irrespective of where you are in the supply chain)

Check approved materialCheck approved materialQuality assuranceprogram


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Obtain product information

QC Assessment of material

Purchase of material

Evaluate & select supplier

Ordering system

(Traceability)

Obtain product information


Purchase of material

Evaluate & select supplier

Ordering system

(Traceability)

program

Receive material

Quarantine material

Release to production Return to supplier

Transfer to generaluse or storage


Pass Fail

Receive material

Quarantine material

Release to production Return to supplier

Transfer to generaluse or storage


Pass Fail


Approved supplier system


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Contracts – liability

Legal compliance for purity

Legal additives Food grade

Absence of GMOs

Non tainting


Spray Diary


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Traceability


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How do you keep records for:

Fruit, juice and wine:

R07COWEYSHZBLKA

Tank 1004

Additives11:56 L7103 RL Batch #: 14314DE


Corrective action


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Quarantine wine batch/additive

Prevent cross contamination

Product Recall System

Reassess controls to prevent reoccurrence


Take home messages


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Taints =

potential health risks to consumers

serious economic & brand loss

unsaleable wine

–

safety program

Implement a screening program to prevent accidental introductionof taints from winemaking additives and processing aids

Recognise and be aware of your own sensitivities to taints


Acknowledgements


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Institute of Masters of Wine

Staff & students of The AWRI

Con Simos, Adrian Coulter, Matt Holdstock

Wine Australia

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

Australian wine industry partners

Australian Grapegrowers and winemakersdiscussed in this presentation

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