Cat's pee or passionfruit? Making Sauvignon blanc taste and smell better

Dr Robert Keyzers is working on how we can make customised, designer wine for overseas markets—by understanding the composition of grapes.

In the future, Dr Keyzers’ research may mean that grapes can be analysed while they are still growing on the vines, to establish what they require to make them grow with a particular flavour and aroma.

“If we could analyse a grape really early on in the growth cycle, then tell the vineyard manager to ‘give that vine more water’, or ‘give that vine more phosphate’, for example, they could produce a grape with specific chemical composition that could produce a wine with a flavour and aroma profile to hit specific target markets,” says Dr Keyzers.

Sauvignon blanc gets part of its distinctive aroma from thiols—volatile, sulphur-containing molecules, which give the characteristic aromas such as gooseberry and passionfruit. While thiols are crucial to the aroma and flavour of Sauvignon blanc, no one knows quite how they are created—free thiols are present in wine but not in grapes.

Understanding how thiols are biosynthesised, and at what stage of the winemaking process, is now a major area of wine research in New Zealand, and is the focus of Dr Keyzers’ work.

“We’re trying to develop better methods to do the analysis,” says Dr Keyzers. “Once we’ve got robust numbers on how much thiol is in the wine, we can work backwards to try and track back to what the precursor is.”

Dr Keyzers and his students, Eva Weatherall and Danica Carter, are collaborating with Brancott Estate Wines, which has provided them with access to sophisticated robotics technology at Brancott Estate’s Marlborough laboratories.

Thiols are widespread in foods as well as wines, and the technology Dr Keyzers is developing could eventually be used to analyse taints and contaminants in a range of white and red wines as well as foods like cheeses and meat products.