Screwcaps

From the 2006 vintage we are pleased to announce that every single wine we produce here at Martinborough Vineyard will be sealed by a screwcap, even our 2006 Marie Zelie Reserve Pinot Noir to be released late 2009.

Why?

Simply because we believe that this form of bottle closure is the best available option to us. This is not a rash decision by us, nor are we merely following other NZ and international producers who have converted to using screwcaps.

We have been conducting our own trials using screwcaps (or Stelvins as they are otherwise known) on all our wines since 2001 and are convinced that they give us the most uniform and best result.

What was wrong with corks?

There are two main problems we have had with cork. Firstly the variation between corks that comes from being a natural product leads to large bottle to bottle variation depending on the state and quality of the cork. A fascinating experiment is to go through a bag of corks and feel each one individually. Some will have a degree of firmness to them whilst others have a soft almost flabby feel. In the bottle this variation leads to random oxidation of the wine, something you don’t realize until you line up a lot of bottles and try them side by side. Some will taste fresh and vibrant whilst others will seem dull and lifeless. From our own trials we estimate that up to 20% of our wines suffered from this random oxidation.

The second and more obvious fault of corks is tainting. When a wine smells like musty, old wet cardboard then the wine is said to be corked. This is caused by a chemical called TCA (Trichloranisole). Again from our own tests, we estimate about 5% of our wines have been affected by TCA. Lower levels of cork taint are the most unpleasant in that they it takes an experienced taster to identify it as corked: most people just don’t think the wine is very nice. Badly corked wine is easy to spot, but somewhat rarer. Considering if we only get about .001% of our wines returned as being ‘corked’ then there must be a lot of experiences where people haven’t had the full pleasure of one of our bottles of wine.

Why doesn’t the cork industry try to remove TCA before selling their corks?

They have been and for some time but the problem is that TCA is such a potent chemical that it has be at levels of below two parts per trillion (that’s a million millions) before it is undetectable. It is said that one drop of TCA is enough to affect up to 65,000L of wine, so you can see just how potent it is.

Our own screwcap vs cork trials

Many of our followers will know the Te Tera Pinot Noir has been bottled under screwcap since its first bottling in 2002. In this vintage we also put a small portion of our Estate Chardonnay and Pinot Noir under screwcap and placed these in the cellar so we could conduct a trial on which bottle closures worked best for our wines. We repeated the trial with the 2003 wines.

Since then we have had several tastings of this trial and everytime we conduct a tasting of these wines there is always a clear favourite – screwcap wins every time.

In their youth the screwcap sealed wines are always more fresh, lively, aromatic and with age show positive bottle development much the same as a good cork sealed wine.

The cork sealed wines are invariably inconsistent, prematurely aged or corked and sometimes all three.

Don’t red wines need air to age properly?

No is the simple answer. Research by esteemed French professor Emile Peynaud suggests that ‘it is the opposite of oxidation, a process of reduction, or asphyxia by which wine develops in the bottle” or his colleague Professor Pascal Ribéreau-Gayon: “Reactions that take place in bottled wine do not require oxygen”.

In fact good corks (yes there are such a thing) don’t actually breathe – they form a perfect seal which allows very little air in, much the same as a screwcap.