Screwcaps for Wine

1
Screwcaps for Wine

• The Start of a Revolution
• 26 June 2002

2
Recent History

• Clare Valley Winemakers
• End of 1999 results of new cork treatments trial
  prove disappointing.
• Frustrated winemakers look at alternatives.
• A group of like-minded Riesling producers decide
  to bottle all or part of 2000 vintage with
  screwcaps.
• Resultant publicity stirs curiosity of New
  Zealand winemakers.

3
Recent History

• New Zealand Winemakers
• Similar Frustrations with poor quality cork.
• Marlborough Winemakers hold meeting February 2001
  to consider alternatives to cork.
• Long-skirted screwcaps identified as the most
  promising closure to replace cork.
• Technical subcommittee formed to investigate
  systems and viability of screwcap closures.

4
Recent History

• NZ National Body Formed
• Marlborough activity leads to great interest
  shown from all around the country.
• Decided to form a national body to promote the
  use of screwcap closures.
• New Zealand Screwcap Wine Seal Initiative formed.
• Manual published and seminars held.

5
Role Functions

• Promote the use of Screwcaps.
• Educate our members on the technical aspects of
  screwcaps usage.
• Educate the wine trade, wine press and consumers
  about the benefits of using Screwcaps to seal
  wine.

6
Wine Tradition

• For several centuries, since the use of glass
  bottles for packaging wine became common, the
  cylindrical cork seal has been the closure of
  choice.
• Revolutionary, at the time.
• Wine more easily transported.
• Convenient size.
• Benefits of bottle age apparent for the first
  time.

7
Cylindrical Stoppers

• Cork or (more recently) Synthetic
• Compressed and inserted into the bottle neck.

8
Cylindrical Stoppers
9
Cylindrical Stoppers

• Cork or Synthetic
• Compressed and inserted into the bottle neck.
• Relies on the elasticity of the material to
  provide the seal between closure and glass.
• Low pressure elastic seal, over the entire length
  of the closure.

10
Cylindrical Stoppers

• Problems
• Pressure changes in the bottle can cause movement
  and/or wine creep.
• May permit gas permeability, and this may be
  extremely variable.
• Compression of air into wine if insertion
  machinery faulty.
• Absorption of taints.

11
Screwcap Wine Seals

• Screwcap closures differ greatly from cylindrical
  stoppers in their mode of sealing.
• The main difference is that they seal around the
  rim of the bottle, rather than along the internal
  surface of the the bottle neck.

12
Screwcap Wine Seals

• There are two major screwcap wine seals available
  in New Zealand currently
• Stelvin, produced by Pechiney of France
• Supervin, produced by Auscap of Australia.
• Other competing brands will soon be available, in
  particular GlobalCap from Europe.

13
Screwcap Wine Seals

• The current standard size for Screwcaps in New
  Zealand is 30 X 60.

14
Screwcap Construction

• The Roll on Tamper Evident (ROTE) closure, or
  Screwcap, consists of two parts
• Outer, made of malleable aluminium alloy rolled
  on to fit the bottle.
• Liner, provides the seal between the closure and
  the bottle.

15
Screwcap Configuration
16
The Outer

• Four main functions
• Presents the liner in the correct position for
  sealing.
• Moulds to the bottle and holds the liner in place
  against the bottle mouth with the required
  pressure.
• Provides the thread to help the eventual removal
  of the cap.
• Space for decoration.

17
Screwcap Configuration
18
The Liner

• The Liner is a polylaminate of three parts
• 80 micron layer of neutral PVDC film, which is in
  contact with the wine, and the bottle rim.
• 19 micron layer of tin foil, which provides the
  gas barrier.
• Wad (approx. 2mm) of expanded polyethylene, which
  provides the elastic resilience to maintain
  compression.
• New generation liners much more reliable than
  in the past.
  

19
Screwcap Configuration
20
Screwcap Closures

• Liner compressed onto surface of the bottle rim
  (120 kg) and held in place by aluminium Outer.
• High pressure hermetic seal, capable of
  withstanding relatively large pressure and
  temperature increases.
• Total gas barrier, perfect inclusion/exclusion.

21
Past Problems

• Leakage has been a problem, usually due to side
  impact at the top of the closure

22
Past Problems

• Leakage has been a problem, usually due to side
  impact at the top of the closure
• Now prevented by a process called Redraw.
• Pressure block modified to wrap the outer much
  closer to the glass finish.

23
Screwcap Redraw
24
Screwcap Profiles

• Without Redraw With
  Redraw

25
Past Problems

• Liner rupture.
• Prevented by
• Accurate pressure control at sealing (120 kg)
• New liner materials, as described earlier.

26
Experience

• Screwcaps have been in commercial use for wine
  for over 30 years.
• Accumulation of practical, commercial experience.
• Several key research projects, particularly in
  Australia.

27
Research Results

• Eric, Leyland Rankine (1976)
• Stelvin Evaluation of a New Closure for Table
  Wines
• The results of this investigation indicate that
  the metal closure with 358 wad performed well on
  the wines tested in comparison to cork and the
  other two wadding materials, justifying its use
  as a commercial closure for table wines.

28
Research Results

• Rankine, Leyland Strain (1980)
• Further Studies on Stelvin and related wine
  bottle closures
• The results obtained in this study confirm the
  superiority of the Stelvin 358 and 323 closures
  over cork under the conditions used in the
  comparison.
• These results point to the suitability of
  certain of these closures as replacements for the
  traditional bark cork, where the wines stored
  under these conditions matured better than under
  cork.

29
Research Results

• P. Godden et al (2001)
• Australian Journal of Grape and Wine Research.
  (AWRI)
• Wide-ranging and complex research project which
  tested 14 different closures.
• White wine only (Clare Valley Semillon)
• Published first results after 20 months.
• Trial is ongoing.

30
Research Results

• P. Godden et al (2001)
• Conclusions about Screwcaps (Analytical)
• 1. Lowest Reduction in Free and Total SO2.
• 2. Highest retained Free SO2.
• 3. Highest retained Ascorbic Acid.
• 4. Lowest incidence of Browning (OD420).
• Least variation between bottles for all
  compositional variables.

31
Range of Brown Colour- 28 months after bottling
OD420 ? 0.19 au
OD420 ? 0.14 au
From P. Godden, Australian Wine Research
Institute
32
Research Results

• P. Godden et al (2001)
• Conclusions about Screwcaps (Sensory)
• 6. Highest in Overall Fruit.
• 7. Lowest in Developed and Oxidised Characters.
• 8. Effectively Zero TCA.

33
Bottle Maturation

• Questions that typically arise amongst consumers
  are
• But isnt the cork needed for the wine to
  develop and age properly?
• Thats OK for current consumption wines, but
  great wines need corks to age, dont they?
• The wine is a living thing, and it needs to
  breathe through the cork, doesnt it?
• In every case, the answer is no.

34
Bottle Maturation

• J. Ribéreau-Gayon et al (1976)
• Traité dOenologie Sciences et Techniques du
  Vin Vol.3
• les quantités doxygène qui pénètrent
  normalement dans les bouteilles sont infimes
  sinon nulles.
• Loxygène nest pas lagent du vieillissement
  normal en bouteille.

35
Bottle Maturation

• J. Ribéreau-Gayon et al (1976)
• Traité dOenologie Sciences et Techniques du
  Vin Vol.3
• the quantities of oxygen that normally
  penetrate into the bottles are negligible if not
  zero.
• Oxygen is not the agent of normal bottle
  maturation.

36
Bottle Maturation

• E. Peynaud (1984)
• Knowing and Making Wine
• It is the opposite of oxidation, a process of
  reduction or asphyxia, by which wine develops in
  the bottle.

37
Bottle Maturation

• The reactions are reductive rather than
  oxidative.
• Reduction

Acetaldehyde
as opposed to Oxidation
Ethanol
38
Bottle Maturation

• P. Ribéreau-Gayon et al (2000)
• Handbook of Enology - Vol.2 The Chemistry of
  Wine Stabilization and Treatments
• When a wine ages in the bottle, the oxidation
  reduction potential decreases regularly until it
  reaches a minimum value, depending on how well
  the bottle is sealed.
• Reactions that take place in bottled wine do
  not require oxygen.

39
Bottle Maturation

• P. Ribéreau-Gayon et al (2000)
• Handbook of Enology - Vol.2 The Chemistry of
  Wine Stabilization and Treatments
• During bottle aging, wines develop in a reducing
  environment, tending towards greater organoleptic
  quality than they initially possessed

40
Bottle Maturation

• The aging process which takes place in the bottle
  after sealing.
• Long time frame, years rather than months.
• Responsible for the development of bottle
  bouquet.
• High quality wines benefit the most.
• Arises from slow, reductive reactions, in the
  absence of oxygen.

41
Bottle Maturation

• Screwcaps are the ideal closures to exclude
  oxygen from the bottle, and thereby promote the
  development of bottle bouquet.
• Screwcaps are ideally suited to bottle maturation
  over a long time frame, not just for current
  consumption.
• Screwcaps are guaranteed against failure for 10
  years, but realistically can be expected to last
  at least 20 years.

42
Conclusion

• The Advantages of using Screwcaps to seal wine
  bottles may be summarised as follows
• Total absence of Taint
• Superior retention of wine quality
  characteristics.
• Ability to allow further bottle maturation.
• Convenience of removal and re-sealing.

43
References

• Ribéreau-Gayon, J., E. Peynaud, P. Ribéreau-Gayon
  and P. Sudraud (1976) Traité dnologie
  Sciences et Techiques du Vin. Tome 3
  Vinifications. Transformations du vin.
  Pp.661-668. Dunod.
• Eric, B., D.A. Leyland and B.C. Rankine (1976)
  Stelvin Evaluation of a new closure for table
  wines. Aust. Grapegrower Winemaker, No.148,
  April 1976.
• Rankine, B.C., D.A. Leyland and J.J.G. Strain
  (1980) Further studies on Stelvin and related
  wine bottle closures, Aust. Grapegrower
  Winemaker, No.196, April 1980.
• Peynaud, E. (1984) Knowing and Making Wine
  Pp.253-254. Wiley
• Ribéreau-Gayon, P., Y. Glories, A. Maujean and D.
  Dubourdieu (2000) Handbook of Enology Vol.2 The
  Chemistry of Wine.Stabilization and Treatments.
  Pp.368-372. Wiley
• Godden, P., L. Francis, J. Field, M. Gishen, A.
  Coulter, P. Valente, P. Hoj and E. Robinson
  (2001) Wine bottle closures physical
  characteristics and effect on composition and
  sensory properties of a Semillon wine. 1.
  Performance up to 20 months post-bottling.
  Australian Journal of Grape and Wine Research. 7,
  64-105.