Screw caps better for sav blanc than corks

A scientific study has determined that screw caps are better for sauvignon blanc wine than the traditional corks stoppers used for centuries.

Researchers at the University of Auckland tested the effectiveness of the fruity wine by using a machine that analyses aromas to determine freshness. Screw caps were found to be better than corks at preserving the fruity bouquet of New Zealand's signature sauvignon blanc wines.

The cork is already under fire for "corking" a percentage of wines, something the screw cap has already been proven to prevent.

"We compared the aromas of bottles that had been sealed with corks and screw caps using a GCMS machine, which is a scientific instrument used to measure and analyse smells. The analysis revealed that the two fruity thiols (aromatic elements) we looked at were up to 23 per cent higher in the bottles using screw caps," research team leader Laura Nicolau said.

The two thiols studied were those with aromas of passion fruit and box tree, as well as those with a grapefruit element. These tropical smells lose their power markedly when they come into contact with oxygen, which explains why sauvignon blanc can lose its fruity character after one or two years.

Further analysis by the research team, however, showed that the cork and the screw cap were equally efficient at preventing oxygen getting into the bottle. Dr Nicolau said the team suspects the difference is either a result of more oxygen getting into the bottle when it is corked up or that the aromas are actually absorbed by the cork over time.

The team plans to do more research into this area.

- NZPA