Accusations that screwcap bottles can cause wine to smell like rotten eggs have been labelled a beat-up driven by supporters of the traditional cork sealed bottles.
The use of screwcaps has come under the spotlight in Britain where researchers have said it can lead to wines with high sulphide levels that can smell like rotten eggs.
But the New Zealand wine industry, which has embraced screwcap technology, has been praised from Australia where experts say it should be lauded not criticised.
The Australian Wine Research Institute says winemakers here are doing an excellent job of controlling excessive sulphides which are produced during fermentation.
Peter Godden, the institute's general manager industry development and support, said the issue was a beat-up by the cork lobby and close associates of it. "We are getting pretty annoyed about this."
Mr Godden, a winemaker who uses screwcaps, said it was an orchestrated campaign to undermine the use of screwcaps and potentially damaging to the New Zealand industry where up to 90 per cent of wines used screwcaps.
"New Zealand has done a technically fantastic job of moving from an old to a new technology ...
it is used in business schools around the world as an example of a successful technical adaptation."
Mr Godden accepted where a sulphide problem was not dealt with in the winemaking process, such as by adding nitrogen or copper, it could be exacerbated under screwcaps because they let in less oxygen. But that was countered when the wine was poured as it was exposed to air, he said.
Mr Godden did not believe such wine would smell of eggs as that would require ridiculously high levels of sulphides.
Dr John Forrest, executive member of the New Zealand Screwcap Initiative, said when the industry decided to go the way of screwcaps in 2001 they identified potential problems that would have to be countered, including sulphide levels.
He said that had obviously been successful as the New Zealand screwcap wines sold in Britain had been far less affected by sulphide problems than others. Tests on screwcap wines by the International Wine Challenge in London had also shown the problem was twice as frequent in corked bottles.
A Marlborough wine maker and former member of the New Zealand wine research committee, Dr Forrest said: "Sulphide problems arise from sloppy winemaking not screwcaps."
He had used screwcaps without any detrimental affects, including for wine aged six years or more, and had never heard of the wine being returned at restaurants because of sulphide.
John Barker, manager policy and membership New Zealand Winegrowers, said screwcap wines had been very well received both domestically and internationally. Wine exports were tasted to ensure batches were free of fault and further laboratory tested for the British market, he said.
Steve Green, owner of Carrick Winery in Central Otago, said sulphides levels depended on the winemaking. Mr Green said his winery used both corks and screwtops and in a recent blind tasting the screwcaps were preferred every time.