Scientists find the key to designing peppery wines

Australian scientists have identified the single aroma compound that produces the spicy ‘black pepper’ smell so popular with many Shiraz drinkers, so paving the way for winemakers to design wines to better suit the tastes of drinkers in the future.

Scientists at The Australian Wine Research Institute (AWRI) have spent nearly five years trying to find the compound responsible for the distinctive aroma. Senior scientist Dr Alan Pollnitz said, ‘What we discovered was a previously unrecognised major aroma compound, which is responsible for the peppery characters in Shiraz grapes and red wine.’

Another scientist involved in the project, Mango Parker, added, ‘We were concerned that we would discover that this aroma was caused by a mix of compounds all working together in various ways. If that was the case, it would have been much more difficult for winemakers and grape growers to modulate the spicy character of red wine.’

Wine comprises a complicated array of aromas and scientists say it has hundreds of aroma compounds. However, the so-called pepper aroma is among the 10 most powerful compounds in wine. ‘Just one drop of this compound would be enough to make an entire Olympic-sized swimming pool smell peppery,’ Mango explained.

The discovery by the AWRI team involved identifying grapes that seemed to have a high concentration of the compound in the first place, then using chemical analysis and the sensory skills of wine experts to track down the source of the aroma. Mango said, ‘Despite the complexity of the science behind what we did, at the end of the day a lot of people did a lot of sniffing throughout the research. Our noses were our most sensitive and reliable detectors.’

The fact that the pepper aroma compound can be found both in Shiraz grapes and Shiraz wine means it is not altered by the winemaking process. This is key because it could enable grape growers and winemakers to select, in advance, particular clones of Shiraz grapes or particular parcels of land that either minimise or maximise the pepper aroma characteristic, according to the AWRI.

‘Our next step is to conduct viticultural and winemaking trials to work out just how much we can manage the pepper aroma compound,’ said Dr Pollnitz. ‘If it’s something that consumers find delicious, winemakers could maximise it.’