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. In other words winemaking does not end when the wine leaves the winery. 2

Closures, more than just a seal The primary role of the closure is to Wine show rejection rate keep the wine in the bottle. Cork taint: 0.9% Oxidation: 1.0% However apart from some extreme Sulfides: 0.9% examples the closure never provides a 100% gas tight seal Cork taint, 32% Sulfides, 33% The performance of the seal to oxygen ingress can lead to significant variation in wine flavour outcomes and possible wine faults. Oxidation, 35%

Closure choice can have an impact on 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 4 Wine Res . 7, 62-105

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 only 60% of wines rejected from a wine show for cork taint had halo anisoles present!

Blackcurrant, cooked cabbage, What about reductive characters? asparagas,canned corn Sulfurous, cheesy, egg H 2 S 1ug/L DMS 25ug/L rotten egg, sewage like MeSAc 40ug/L MeSH 1.5ug/L DMDS 10ug/L Vegetal, cabbage, rotten cabbage, intense onion like burnt rubber, putrification

How much oxygen after bottling?  Depends on closure oxygen transfer rate (OTR) and storage environment Oxygen present in the atmosphere  OTRs range from <0.005 to 5 mg/L/year* * in 750 mL bottle  In the first 3 to 6 months, the Headspace oxygen contribution of the oxygen trapped in the closure and in the headspace should not be ignored Dissolved oxygen  After 6 months, ingress through the closure is more important Oxygen reacts with wine components  Therefore, controlling OTR means that winemaking can continue after bottling 7

What wine factors are involved? We must remember that in many case the die is set before we get anywhere near the bottling line. o Phenolic content including tannins. o Initial oxygen levels o Oxygen exposure history o Volatile sulfur compound precursors o Levels of metals available in the wine. 8

Closures, the usual suspects 9

Cork o Shoving a lump of bark in your finely crafted wine. o Traditional o Liked by customers (don ’ t stuff with my ritual) o OK OTR o Issues with cork taint o Like all natural products variable 10

Technical Closure o Usually made from ground up bits of cork. o A bit like cork o Similar experience to cork o OK to low OTR o Not many taint issues (although some people claim a glue like taint) o Less variable than natural cork 11

Extruded or synthetic closures o i.e. a lump of plastic o Can look a bit like cork? o Similar experience to cork, but the customers are not always convinced. o Original ones had crap OTR, but claims to have improved. o Taint free o Very little variability 12

Screw caps o Not even remotely like a cork o Dominating in Australia o Market acceptance varies from region to region. o Low to very low OTR o Taint free o Very little variability 13

Glass Stoppers o Glass core o Plastic does the work o Looks very flash o Market acceptance varies from region to region. o OTR depends on brand, but is OK to good. o Taint free o Very little variability o Some need high spec bottles 14

Zork o Plastic construction o Tamper proof and reusable. o Looks, different o Limited market pentration. o OTR OK. o Taint free o Very little variability 15

And the trendy new ones … Lots of variations on the above that claim to manage OTR in detail. Breaking news Often described as functional closures . Industry level trials are just beginning for a screwcap liner which actively scavenges bad sulfur compounds. Watch this space Expanded Polyethylene (EPE) Many do as they suggest and replicate the oxygen transmission of White paper “good corks”. Aluminium Acceptor Layer Polyethylene (PE) Still to be proven in the market place. Definitely not a silver bullet, need to get the wine right to make a difference. 16

O 2 Contribution from different closures cc O2 / day Indicative Closure OTR Values 0.012 0.010 0.008 0.006 0.004 0.002 0.000 Screw Cap Screw Cap Technical Cork Glass Synthetic Cork Natural Cork (Saran/Tin) (Saranex) 17

How much oxygen at bottling? 14.00 Headspace (mg/L) 12.00 Dissolved (mg/L) Oxygen (mg/L) 10.00 8.00 6.00 4.00 2.00 0.00  DO can be significant.  Headspace oxygen dominates under screwcaps 1-10 mg/L  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 18

The level of oxygen in the closure itself is not trivial 5 Regular closures TPO region OTR region 4 Bottles stored in air Regular closures, Oxygen ingress 3 bottles stored in nitrogen (mg/L) 2 Closure stored in N2, bottles stored in N2 1 0 0 20 40 60 80 100 120 140 160 180 Time after bottling (days) 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)

Impact of headspace oxygen White wine controlled TPO dosing trial 30 25 20 Free SO2 (mg/L) 15 TPO =1 mg/L TPO = 5 mg/L 10 5 0 0 50 100 150 200 250 300 350 400 Time (days)

Don’t forget the environment! Natural cork, synthetic or screwcap? 120 100 80 g CO2 e 60 40 20 0 Screwcap Synthetic Cork SPK cork + mus Zork

Cork and Screwcap are not so different Fault rates in international bottled wines 6.0% 5% 5.0% Other 4.0% Volatile Fault rate Sulfides 1.8% 3.0% Rot Oxidation Excessive phenols 2.0% Cork taint 1.0% 0.0% Cork Screw-cap Synthetic All Closure 80,000 samples over 7 years 22

And the rates change with time. 10.0% 9.0% 8.0% 7.0% Other Fault rate Volatile 6.0% Sulfides 5.0% Rot Oxidation 4.0% Excessive phenols Cork taint 3.0% 2.0% 1.0% 0.0% 1 2 3 4 5 6 7 8 9 10 >10 NV All Age (years) = Competition year - Vintage 23

Time in bottle Shiraz - MeSH Shiraz - H 2 S 10 5 Control Control 9 Cu Cu 8 4 Concentration (µg/L) Concentration (µg/L) 7 6 3 5 4 2 3 Odour Threshold Odour Threshold 1.1 -1.6 µg/L 1.1 -1.6 µg/L Odour Threshold 2 1 1.8 -3.1 µg/L 1 0 0 Day 1 Month 1 Month 3 Month 6 Month 12 Day 1 Month 1 Month 3 Month 6 Month 12 oxygen depletion oxygen depletion

Wine decides reductive potential more than closure Average results for 9 MeSH (rotten cabbage or burnt rubber) different closures. 12.00 Pattern typical of 10.00 what we see as the available O 2 / SO 2 8.00 environment changes. MeSH 6.00 4.00 For at least the first 2 2.00 For the whole trial the years the differences differences due to are no greater than 0.00 0 5 10 15 20 25 30 35 40 closures is smaller impact of metals in Months in Bottle than the impact of the other trials wine chemistry. 25

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?