This project is supported by funding from the Australian Government Department of Agriculture, Water and the Environment as part of its Rural R&D for Profit program.
Valuable new research suggests the effects of smoke on wine flavour may be limited and very regional.
‘Obviously the location and the size of the fire is particularly important – and some bushfires have had huge impacts on the wine sector – but in general, that’s what we are finding’, said co-project leader, Dr Ian Porter.
A research consortium from La Trobe University and the Victorian Department of Jobs, Precincts and Regions has been evaluating the effects of smoke on the development of smoke taint in wine in a wide-reaching project supported by funding from the Australian Government Department of Agriculture as part of its Rural R&D for Profit program and Wine Australia.
The project team last year measured smoke composition data at 65 sites around 8 controlled burns and 1 bushfire in Australia.
‘Our aim was to determine thresholds for the levels of smoke that lead to increased levels in wine and potential smoke taint’, said Dr Porter.
Preliminary analysis of eight commercially produced and eight small-scale wines prepared from bushfire affected grapes showed only some with significant elevation of smoke phenols in the wine, and only in those varieties closest to where bushfire smoke entered vineyards – and only when temperature inversion conditions occurred.
‘The conditions during controlled burns mean that smoke generally rises into the atmosphere and many taint compounds degrade before reaching grapevines – thus avoiding any taint problems. Strong winds during bushfires are of greater concern for spread of the compounds and this is where the research is now focused.’
Dr Porter said measurements of smoke from the mandatory controlled burns conducted in Victoria in the 2017–18 season were also low for the presence of smoke taint compounds.
However, he said the correlation of all the smoke, grape and wine data was providing important information on the effect of distance and environmental parameters on the profile of smoke taint compounds in grapes and wine.
The team has recently begun a new study to reconfirm the effect of grape developmental stage on the relative uptake of smoke taint compounds by grapes ‘to confirm that developing grapes are less susceptible.’
In addition to the research trials, a regional network of seven smoke detectors in Victoria is continuing to operate in the Otway, Yarra, Ovens and King Valley winegrape growing areas to provide real time data on smoke in key wine regions.
‘The data from this network have shown low levels of smoke and smoke taint compounds in key wine regions in Victoria throughout the autumn 2018 controlled burn season.’
The team, together with the Australian Wine Research Institute, is also assessing if there are any protective sprays that could be used in vineyards during smoke events. After screening a wide range of commercial products, fungal and crab-derived chitosan grape coatings were found to reduce the uptake of smoke taint compounds by grapes by greater than 50 per cent in controlled smoke chamber experiments.
The issue now is to determine if these products can be sprayed cost effectively within vineyards.
Dr Porter said the smoke taint project was a valuable resource for growers and the wider wine sector.
‘Linking smoke to smoke taint is not easy due to the variability in varieties and peoples’ perception of taint, however the data play an important role in helping to reduce the impact of potential smoke taint throughout the sector.’
The study is being continued throughout the 2019 vintage and Dr Porter said the findings have the potential to be used to develop a model for the wine sector to assess and reduce the risk of smoke taint in the future.
