Winemakers spend a lot of time tasting juice as it is being pressed to pinpoint the right time to stop the pressing process. This is important to produce sparkling wine that has desirable flavour qualities – and prevent excessive extraction of undesirable phenolic compounds.
However, repetitive tasting is time consuming and impractical on a larger scale. And sometimes, the winemaker’s senses might become overloaded.
Dr Rocco Longo – a former winemaker turned wine researcher – knows first-hand the need for a rapid, objective and reproducible tool to ensure the quality and consistency of sparkling wine. The project he currently works on aims to develop one.
Now, Dr Longo’s efforts have been recognised with a Wine Australia-supported Science and Innovation Award.
The device – which he hopes to start manufacturing in May this year – uses spectroscopy to determine the concentration of phenolic compounds in the juice. This information is then fed back to the winemaker in real time.
‘The more you press, the more phenolics you are able to extract. But when you’re making sparkling wine you don’t want too many phenolic compounds because they give you that gritty mouthfeel when you drink the wine.’
Currently, the most common way to determine the level of phenolics is for the winemaker to physically taste the juice – and therein lies the problem, says Dr Longo.
‘There are so many factors that can influence the winemaker’s tasting’, he said. ‘For example, the winemaker might have a cold, which could dull their senses. Or the weather might be extremely hot, or cold, which can have a negative sensory impact.’
Dr Longo says his instrument will not only relieve the winemaker from tasting juice at the press, but will also automate the pre-fermentation process that currently relies on a high labour input.
‘The instrument fitting can be attached to any press outlet, and will feature a spectral sensor that can automate valves being turned on and off for automatic tank switching.’
Dr Longo said the ultimate aim of his project was to make the process of sparkling wine production more efficient and objective.
‘It is about making sparkling wine that is consistent quality by objectively measuring the compounds that give wine its flavour, colour, aroma and mouthfeel as they are extracted during the pressing process.’
Dr Longo grew up in Italy and completed his BSc and MSc in Viticulture and Oenology at the University of Turin.
However, he found it was the Australian wine sector that held his interest.
After working vintages in Piedmont, Italy, Dr Longo decided to take the plunge and move to Australia in 2009 to pursue his dream.
After a stint as an oenologist with Gapsted Wines in the Victoria’s Alpine Valleys, Dr Longo, in 2014, undertook a PhD on lower alcohol production with Charles Sturt University at the National Wine and Grape Industry Centre (supported by a Wine Australia scholarship) . He is currently pursuing postdoctoral research in Pinot Noir provenance and sparkling wine at the Tasmanian Institute of Agriculture in Launceston*.
He said the Science and Innovation Award was a good opportunity for him to gain a deeper understanding of the gaps in R&D in the sparkling and still white wine sector and the impact on the Australian wine sector, in particular on larger scale wineries.
‘From a research standpoint, the award will allow me to build a prototype for testing in commercial wineries, which is very exciting.’
*This study is being carried out in collaboration with Dr Fiona Kerslake from TIA/UTAS; Dr Bob Dambergs from AWRI/WineTQ; and input from the sector.