Peppery quaff: The finding could have major implications for the multi-billion dollar Australian wine industry, as Shiraz constitutes one-fifth of its output.

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SYDNEY: Australian chemists have isolated a substance that gives red wine its peppery aroma, and it may allow them to tinker with the bouquet of one of the nation's most popular varieties.

Black pepper aroma and flavour are important to some red wines, such as those made with Shiraz grapes, but prior to this analysis no method to assess the peppery aromas had been developed and the compounds had not been identified.

Now, the Australian Wine Research Institute in Adelaide says its scientists have spent five years trying to track down the fragrance and have succeeded in isolating a single compound responsible for the spicy smell.

Known as alpha-ylangene, that compound is so pungent that a single drop is enough to make an entire Olympic-size swimming pool smell peppery, institute chemist Mango Parker told a wine industry conference today.

Major implications

The discovery, made by examining grapes from Victoria and South Australia, is also detailed in a recent edition of the Journal of Agriculture and Food Chemistry.

Parker said the finding could have major implications for the multi-billion dollar Australian wine industry, as Shiraz constitutes one-fifth of its output and is by far the most popular red variety.

"If you can measure something, you can understand its behaviour and how to control it," she said.

Winemakers might one day alter the pepper aroma in red wine the same way they now alter its characteristics with different yeast varieties or oak barrel fermentation, said Parker.

While scientific instruments such as a mass spectrometer were used to track down the aroma compound, which has a concentration of one part per billion, Parker said old-fashioned methods were the most effective.

"At the end of the day, a lot of people did a lot of sniffing throughout the research," she said. "Our noses were our most sensible and reliable detectors."