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A clearer future for smoke affected fruit

RD&E News | February 2020
07 Feb 2020
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A new cutting-edge screening approach suggests there are other potential smoke taint markers beyond the phenol compounds used in current diagnostics.

Researchers deployed new spectrometry techniques to help them determine smoke exposure markers in wine.

They found that broad chemical changes occur in wine made from smoke-damaged fruit which supports the initial hypothesis that there may be other compounds outside of the current diagnostic markers that are indicative for smoke impacts.

The results come as some regions of Australia are recovering from recent bushfires and have potential to provide new options for testing for smoke exposure.

The project was conducted as a collaboration between The Australian Wine Research Institute (AWRI), Metabolomics South Australia and the Centre for Advanced Imaging at The University of Queensland, and the research used NCRIS-enabled Metabolomics Australia infrastructure.

The research team, headed by 2017 Wine Australia-supported Science and Innovation Award winner and AWRI Research Scientist Dr Natoiya Lloyd, used a range of metabolomics approaches during the project.

Metabolomics is a ‘broad brush’ technique that allows researchers to study all of the compounds in a wine, rather than just the ones they already know about. This ‘untargeted’ approach gives a much broader picture of what exactly is going on.

Nuclear Magnetic Resonance (NMR) metabolomics – which Dr Lloyd explored during the project in collaboration with Dr Horst Schirra from the Centre for Advanced Imaging at The University of Queensland – uses a novel approach that can capture additional classes of compounds.

This allowed Dr Lloyd and her team to evaluate smoke damage in a holistic manner to detect and understand all the chemical changes that can occur in wine due to smoke exposed grapes.

A total of 166 red wine samples from three vintages were categorised into either ‘smoke-affected’ or ‘control’ groups, based on information on vineyard smoke exposure, sensory analysis and the concentration of smoke taint glycosides measured in grapes using conventional methods. A sample set of 77 red wine samples was defined, with 42 samples allocated to the ‘smoke- affected’ group and 35 samples allocated to the ‘control’ group.

‘We found a clear differentiation could be made between affected and non-affected wines based on their chemical composition as measured by the analytical chemistry technique called Liquid Chromatography Mass Spectrometry (LC-MS) and NMR’, said Dr Lloyd.

Dr Lloyd said untargeted metabolomics also provided evidence to suggest there were other potential markers beyond the phenol compounds used in current diagnostics for the potential for smoke taint.

The research found:

  • 380 chemical entities (out of 1130) detected by LC-MS were important in discriminating the 2 groups; with 156 of these specific for the ‘smoke- affected’ group, and
  • defined regions in the NMR data (i.e. specific compound classes) were important in discriminating control and smoke-affected wines.

Dr Lloyd said the research could play an important role in helping wine growers address the problem of smoke exposure in the future.

‘The ultimate objective of this work is to develop faster tools and techniques to detect low levels of smoke exposure in grapes’, she said.

‘The knowledge gained during this research project provides a platform to build improved diagnostic tests for grape growers and winemakers. Importantly, the ability to discriminate between affected and unaffected vineyards will be of significant value to the grape and wine industry in mitigating smoke taint.’

Dr Lloyd said the next step of the research was to confirm their findings in smoke-affected white wine and smoke-affected grapes from the 2019–20 season.

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This content is restricted to wine exporters and levy-payers. Some reports are available for purchase to non-levy payers/exporters.