Impact of closures on wine Dr Eric Wilkes Group Manager Commercial - - PowerPoint PPT Presentation

Impact of closures on wine

Dr Eric Wilkes Group Manager Commercial Services

What is the most common (mis)conception about wine

All wines mature with age!

Well lots don’t. But many of the great ones actually do.

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In other words winemaking does not end when the wine leaves the winery.

Closures, more than just a seal

The primary role of the closure is to keep the wine in the bottle. However apart from some extreme examples the closure never provides a 100% gas tight seal The performance of the seal to

• xygen ingress can lead to significant

variation in wine flavour outcomes and possible wine faults.

Cork taint, 32% Oxidation, 35% Sulfides, 33%

Wine show rejection rate Cork taint: 0.9% Oxidation: 1.0% Sulfides: 0.9%

Closure choice can have an impact

• n wine quality

Range of colour 63 months post bottling, Semillon wine, 14 different closures The availability of oxygen can drive much of the chemistry in bottle.

But it isn’t the only factor!

Godden et al (2001) Aust. J. Grape Wine Res. 7, 62-105 4

Cork Taint

2,4,6-trichloroanisol

• Still having an impact in cork closures
• A number of companies have introduced

technology to screen 100% of corks!

One study showed that

• nly 60% of wines rejected

from a wine show for cork taint had halo anisoles present!

What about reductive characters?

H2S 1ug/L MeSH 1.5ug/L DMS 25ug/L DMDS 10ug/L MeSAc 40ug/L Sulfurous, cheesy, egg Vegetal, cabbage, intense onion like Blackcurrant, cooked cabbage, asparagas,canned corn rotten cabbage, burnt rubber, putrification rotten egg, sewage like

 Depends on closure oxygen transfer rate (OTR) and storage environment  OTRs range from <0.005 to 5 mg/L/year*

* in 750 mL bottle

 In the first 3 to 6 months, the contribution of the oxygen trapped in the closure and in the headspace should not be ignored  After 6 months, ingress through the closure is more important  Therefore, controlling OTR means that winemaking can continue after bottling

How much oxygen after bottling?

Headspace oxygen Dissolved oxygen Oxygen present in the atmosphere Oxygen reacts with wine components

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What wine factors are involved?

We must remember that in many case the die is set before we get anywhere near the bottling line.

• Phenolic content including tannins.
• Initial oxygen levels
• Oxygen exposure history
• Volatile sulfur compound precursors
• Levels of metals available in the wine.

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Closures, the usual suspects

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Cork

• Shoving a lump of bark

in your finely crafted wine.

• Traditional
• Liked by customers

(don’t stuff with my ritual)

• OK OTR
• Issues with cork taint
• Like all natural products

variable

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Technical Closure

• Usually made from

ground up bits of cork.

• A bit like cork
• Similar experience to

cork

• OK to low OTR
• Not many taint issues

(although some people claim a glue like taint)

• Less variable than

natural cork

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Extruded or synthetic closures

• i.e. a lump of plastic
• Can look a bit like cork?
• Similar experience to

cork, but the customers are not always convinced.

• Original ones had crap

OTR, but claims to have improved.

• Taint free
• Very little variability

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Screw caps

• Not even remotely like

a cork

• Dominating in Australia
• Market acceptance

varies from region to region.

• Low to very low OTR
• Taint free
• Very little variability

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Glass Stoppers

• Glass core
• Plastic does the work
• Looks very flash
• Market acceptance

varies from region to region.

• OTR depends on

brand, but is OK to good.

• Taint free
• Very little variability
• Some need high spec

bottles

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Zork

• Plastic construction
• Tamper proof and

reusable.

• Looks, different
• Limited market

pentration.

• OTR OK.
• Taint free
• Very little variability

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And the trendy new ones…

Lots of variations on the above that claim to manage OTR in detail. Often described as functional closures. Many do as they suggest and replicate the oxygen transmission of “good corks”. Still to be proven in the market place. Definitely not a silver bullet, need to get the wine right to make a difference.

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Breaking news Industry level trials are just beginning for a screwcap liner which actively scavenges bad sulfur compounds. Watch this space

Expanded Polyethylene (EPE) White paper Aluminium Polyethylene (PE) Acceptor Layer

O2 Contribution from different closures

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0.000 0.002 0.004 0.006 0.008 0.010 0.012 Screw Cap (Saran/Tin) Screw Cap (Saranex) Technical Cork Glass Synthetic Cork Natural Cork cc O2 / day

Indicative Closure OTR Values

How much oxygen at bottling?

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00

Oxygen (mg/L)

Headspace (mg/L) Dissolved (mg/L)

• DO can be significant.
• Headspace oxygen dominates under screwcaps
• Cylindrical closures outgas too
• Generally less than during must processing:
• 2 to 10 mg/L oxygen during crushing
• Up to 4 mg/L oxygen during pressing

1-10 mg/L

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The level of oxygen in the closure itself is not trivial

1 2 3 4 5

20 40 60 80 100 120 140 160 180 Time after bottling (days) Oxygen ingress (mg/L)

Regular closures Bottles stored in air Regular closures, bottles stored in nitrogen Closure stored in N2, bottles stored in N2

Oxygen introduced by the closure itself. Oxygen contributed transmitted through the cork. A major part of oxygen exposure in the first three months comes from the closure itself (desorption) TPO region OTR region

Impact of headspace oxygen

White wine controlled TPO dosing trial

5 10 15 20 25 30 50 100 150 200 250 300 350 400

Free SO2 (mg/L)

Time (days)

TPO =1 mg/L TPO = 5 mg/L

Natural cork, synthetic or screwcap?

20 40 60 80 100 120 Screwcap Synthetic Cork SPK cork + mus Zork g CO2 e

Don’t forget the environment!

Cork and Screwcap are not so different

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0.0% 1.0% 2.0% 3.0% 4.0% 5.0% 6.0% Cork Screw-cap Synthetic All Fault rate Closure Other Volatile Sulfides Rot Oxidation Excessive phenols Cork taint

80,000 samples over 7 years Fault rates in international bottled wines 1.8% 5%

And the rates change with time.

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0.0% 1.0% 2.0% 3.0% 4.0% 5.0% 6.0% 7.0% 8.0% 9.0% 10.0% 1 2 3 4 5 6 7 8 9 10 >10 NV All Fault rate Age (years) = Competition year - Vintage Other Volatile Sulfides Rot Oxidation Excessive phenols Cork taint

Time in bottle

1 2 3 4 5 Day 1 Month 1 Month 3 Month 6 Month 12 Concentration (µg/L)

Shiraz - H2S

Control Cu

Odour Threshold 1.1 -1.6 µg/L Odour Threshold 1.1 -1.6 µg/L

1 2 3 4 5 6 7 8 9 10 Day 1 Month 1 Month 3 Month 6 Month 12 Concentration (µg/L)

Shiraz - MeSH

Control Cu

Odour Threshold 1.8 -3.1 µg/L

• xygen depletion
• xygen depletion

Wine decides reductive potential more than closure

0.00 2.00 4.00 6.00 8.00 10.00 12.00 5 10 15 20 25 30 35 40 MeSH

Months in Bottle

MeSH (rotten cabbage or burnt rubber) Average results for 9 different closures. For at least the first 2 years the differences are no greater than impact of metals in

• ther trials

Pattern typical of what we see as the available O2 / SO2 environment changes.

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For the whole trial the differences due to closures is smaller than the impact of the wine chemistry.

Take home points

• Closure choice can modulate the amounts of;
• Reductive compounds
• Varietal thiols
• Oxidative characters.
• TPO at packaging has a bigger impact in the first 6 months
• And possible long term effect on final outcomes
• OTR effects are not obvious until later in the wines life.
• Wine composition and history is likely to have a bigger impact on

reductive characters than closure choice

• Residual metals in the wine can accelerate the development of

reductive characters. Get the wine right and the closure is going to be a marketing issue.

Thankyou

Questions?