The taming of the screw: celebrating Jackson Estate’s 30th anniversary

Cork or screwcap? Peter Ranscombe explores how the two closures allow New Zealand sauvignon blanc to age.

CORK was once king of the wine bottle closures – plastic, composite and glass seals may have eaten into its dominance, but the noble cork was still the top dog.

Then along came the screwcap; simple for consumers to open and providing winemakers with a tighter seal to let less oxygen into their creation over time.

Not all screwcaps are equal though – early examples were criticised for either being too tight or not tight enough, while modern versions have become much more reliable.

Just don’t dent the lid; while the metallic seal may be robust, it’s not indestructible as anyone who’s tasted an off wine that’s been bounced around on an airline drinks trolley will testify.

New Zealand – with its expertise in hi-tech farming – was one of the early-adopters, choosing the new seal to retain the freshness in its young and vibrant sauvignon blancs and pinot noirs.

Indeed, an argument could be made that, using a rough rule of thumb, screwcaps are better for wines that are designed to be drunk young – within, say, a year of being made – while corks are better suited to wines that are destined to age, developing richer aromas and flavours as tiny amounts of air pass through the cork and start to slowly oxidise the liquid.

But what happens when you leave a young wine under screwcap for longer than a year? Does it still develop those aromas and flavours associated with age?

That was the question that was running through my mind at a recent dinner hosted by Jackson Estate to celebrate its 30th anniversary.

The New Zealand winemaker greeted its guests with a glass of the 2017 Jackson Estate Stich Sauvignon Blanc bottled under a screwcap, which provided the expected high levels of acidity, balanced by concentrated lemon, grapefruit, guava and passionfruit flavours.

An interesting comparison could then be drawn with the 2009 Jackson Estate Stich Sauvignon Blanc – also under screwcap – which had developed more intense flavours of lemon rind and lemon curd alongside the grapefruit, as well as a rounder and oilier mouthfeel.

Part of those changes could be due to vintage variations between 2009 and 2017, but the differing characteristics are more likely to be due to the slow ageing taking place beneath the metallic closure.

What was even more intriguing was the opportunity to compare two bottles of the 2001 Jackson Estate Stich Sauvignon Blanc – one bottled under screwcap and the other under cork.

The 2001 screwcap had developed lime flavours, with a yeasty note, while still retaining its crisp acidity.

On the other hand, the 2001 cork had clearly been exposed to more oxygen, having leapt into apple crumble-like territory, with flavours of red apple, baked apple, cinnamon and oats – yet still with that characteristic grapefruit twang.

While both were developing some of the aromas and flavours associated with age, it was clear that they were following the same journey but at different speeds – the vinous equivalent of the hare and the tortoise.

A fascinating comparison – and one well-worth undertaking at home too if your local wine merchant can find you suitable bottles.