Plastic or cork?

by Wine

There is something romantic about opening a bottle of wine.  You strip off the cap in circles.  The cork is removed using a special tool, and the whole event feels a bit like Christmas.  When surveyed, 69% of Americans responded in favor of cork over other enclosures “because of its tradition”.  Since much of wine price is demand and emotion, it would be hard to believe that winemakers would use anything else.  Despite all these emotions, the wine industry seems to be moving away from natural cork and towards synthetic enclosures.

The heart of the matter is the number of wine bottles going bad.  An estimated 5-12% of wines on merchant shelves are “corked”.  A corked wine is a wine rendered undrinkable by the presence of  2,4,6-trichloroanisole (TCA).  TCA has a distinct odor, smelling like moldy newspaper or wet dog.  TCA is produced by naturally-occurring airborne fungi, commonly found in the cork.  It can also come from the barrel, but it is likely that a barrel infection would be detected long before reaching the consumer.  To reduce wine spoilage from TCA, winemakers are turning to less traditional enclosures.

About half of Australia’s recently harvested 2006 vintage will be sold with screw caps or other manmade closures, and 85% of the 2006 New Zealand wines will be cork free.  This change in direction with enclosures has resulted in a very heated battle between traditionalists and the different alternative enclosures.

Portugal accounts for 30% of the world’s natural cork, and is worth almost 1 billion US dollars in trade.  The cork industry is worth more to Portugal than port wine.  Taking this industry from Portugal would have serious economic and environmental repercussions.  Losing the battle to synthetic enclosures would result in economic pressure to remove the forests for other more profitable industries.  Winning the battle of wine tops could prove a major coup for the synthetic enclosure industry.

Natural Cork

For centuries, cork has been the enclosure of choice.  Natural cork has a very solid foundation in tradition.  One survey commissioned by the Portuguese Cork Association, albeit slightly biased, reported that nine out of ten consumers believe plastic corks cheapen wine.  While the report may be biased, there is a romance with natural corks.

Natural corks are the romantic option, but are they the best option?

Natural corks are the romantic option, but are they the best option?

Natural corks are biodegradable and come from a renewable source.  Portugal, which represents one third of the world’s cork oak forests, has 720,000 hectares of cork forests.  A cork oak tree must be at least 30 years old before you can harvest the bark.  It will be another 10 years before cork can be harvested from the same tree.

Wine sealed with natural cork, however, is susceptible to trichloroanisole (TCA).  Wine must be stored on its side to avoid a dry cork.  Natural corks often break apart into the wine, or worse separate into two (top and bottom halves) leaving a much more difficult cork to remove from the bottle.  These problems, especially the TCA, caused winemakers to look at alternatives for their wines.

Synthetic Corks

Branding synthetic corks is a fun way to stand out.

Branding synthetic corks is a fun way to stand out.

Synthetic corks have replaced natural corks for many winemakers.  Companies like Supreme Corq and Nomacorc are experiencing booms to their business.  Supreme Corq is the largest manufacturer of synthetic corks and produces corks for over 1600 wineries in 32 countries.  The main reason for their popularity is that the corks are not susceptible to TCA or “corking”.  A synthetic cork cannot rot, and will never separate in the bottle.  Many winemakers are using the synthetic corks as a marketing device.  Corks are now coming in different colors, displaying logos, and adding to the overall look-and-feel of the wine.

Synthetic corks are not without problems however.  For small winemakers or home winemakers, inserting the synthetic cork can be a challenge.  Handheld corkers will not work well with synthetic corks unless the person applies great force.  Recorking the wine after pouring a glass is impossible with a synthetic cork.  Some winemakers believe that synthetic corks do not allow the wine to “breathe” or age properly, since the synthetic cork does not allow oxygen to pass through.  Many manufacturers are releasing newer generations of corks that are O2-permeable (allow the passage of oxygen).  Others point out that the aging happens in the bottle, not from exposure to oxygen.  A synthetic taste is reported by some winemakers.  They say that the wine takes on a synthetic taste after 5 years.  Tinhorn Creek Vineyards confirmed these reports on their website, stating that their in-house trials on a chardonnay bottling three years ago had a synthetic taste from the corks.

And unlike their natural counterparts, synthetic corks are not biodegradable or renewable.  some corks, such as the ones from Nomacorc, are 100% recyclable.

Screw Tops

Screw tops are showing up on premium wines

Screw tops are showing up on premium wines

Screw tops are starting to come in vogue.  Some winemakers even herald their choice of enclosure in the name, such as Nappa Valley’s “Screw Kappa Nappa”.  Tinhorn Creek Vinyards uses the popular Stelvin™ cap, to avoid the TCA problems and the synthetic flavors from synthetic corks.  A screw top has no reported synthetic tastes imparted to the wine.  Screw tops are very easy to open, and very easy to reseal.  This alone has made the screw tops very popular.

Still a screw top is missing that romantic “pop” that only a cork can provide.  Screw caps are commonly associated with very cheap wine.  This is a very common stereotype that a screw top would need to overcome to be successful.

The caps are typically aluminum, but some have experimented with other metals or plastics.  For a small winemaker or home winemaker, the screw top is an impossible choice.  Screw tops require machinery added to the production line.  This is out of reach for most small winemakers.  According to the Small Business Administration, 95% of American wineries are classified as small businesses.
One winemaker in New Zealand, Alan Limmer, has written many articles about aging wines in screw tops.  He claims that many bottles he has tested contain larger levels of H2S which give the wine a rotten egg smell.  He asserts that this is not from the SO2 at bottling, but from the screw cap itself.  Since screw caps are relatively new to quality wines, more studies will be required before this can be refuted or substantiated.

Wine in a bag in a box

A final enclosure that is popping up not only replaces the cork, but the bottle itself.  The wine is contained in a sterile bag inside a box.  Companies like Rapak offer wineries a new way to package their wine.  The bag is completely sealed and does not allow oxygen to pass through.  A 3 liter box is 38% lighter than the same amount in bottles, and ships better since it takes up less room.

Better wines are showing up in boxes

This method was made popular in the late 80s and early 90s by Franzia wine.  The large box wines can reseal with a special tap on the side of the box.  A box of wine can last for months.  The box even fits well in the refrigerator.  Some wineries are experimenting with smaller versions of this packaging.  The wine is in a milk carton like container with a plastic screw top.  There are even some retailers selling kits for the home winemaker to package their wine this way, but the solution is really meant for the large winemaker.

As for romance, this solution is as unromantic as you can get.  There is no pop.  There isn’t even a bottle.  Unfortunately there are no studies about aging wine in these containers since the wine produced in these containers is meant to be consumed soon after purchase.  This is acceptable since 80% of all wine is created to be consumed immediately after purchase.


Despite the problems of each enclosure, there are many very good wines that are using alternative packaging.  Don’t be afraid to try these newer wines.  You won’t see the really expensive wines with a screw top, they rely too much on emotion, but you will find many good wines with synthetic corks, screw tops, and yes, even wine-in-a-bag-in-a-box.

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DJ Spiess

DJ Spiess

Beer buddy

I live in Denver, Colorado. This blog is everything about beer, wine, cider, mead and other spirits.
I am a avid homebrewer and winemaker. I’ve been making my own beer and wine for many years. I started making beer when I was in college (mostly because the drinking age in the United States is 21). My first few beers were horrible. The beers are much better now, and I often supply my neighborhood with free beer! It is a great hobby!