Yeast: The secret ingredient that makes a good wine rise to the occasion

In experiments conducted using Australian Shiraz, UWS Associate Professor Geoffrey Skurray found the particular characteristics of top quality Shiraz - like smell, colour and flavour - can be achieved by carefully choosing the yeast strain used in the fermentation process.

Associate Professor Skurray says different strains of yeast can produce different wine smells, such as blackberry and plum, or black pepper and other spice aromas.

"Our research clearly shows that the yeast strains used during alcoholic fermentation play a significant role in determining the colour, aroma, mouthfeel and overall flavour of Shiraz," Associate Professor Skurray says.

The findings mean that winemakers could adjust the flavours and aromas of their wines through appropriate yeast strain selection - allowing them to tailor their preferred style of Shiraz when targeting a specific marketing demographic.

Associate Professor Skurray's latest yeast research follows on from a paper he published in the 'Australian Journal of Grape and Wine Research' last year which looked at manipulating the levels of antioxidants in wine.

These latest findings were published in the October 2006 edition of 'Australia and NZ Grapegrower and Winemaker'.

The project was conducted in conjunction with industry partner, Mauri Yeast Australia, which supplied the 10 different types of yeast used in the experiments.

Yeast is a living organism that is critical to winemaking. Yeast does all the hard work and without it, there would be no beer, wine or spirits, bread, yoghurt or cheese.

In the past, winemakers stuck to one type of yeast and did not think of it as contributing to the wine's flavour, according to Associate Professor Skurray.

"French winemakers talk about "terroir" - the influence of geography on the grapes," he says.

"However this research shows is that you can influence the character of wine."

Source: University of Western Sydney