A ‘tantalising’ taste of microflora’s significance

New research testing whether a region’s microflora helps shape its terroir – and thus the wines that are made there – is showing some ‘tantalising’ results.

That’s the very word AWRI Research Manager Dr Paul Chambers used in the abstract for his presentation at the recent Australian Wine Industry Technical Conference, and in person he goes further. ‘It’s fantastically exciting and likely to deliver big wins’, he said.

Along with defining microbial contributions to terroir, the new research is paving the way to enable winemakers to quickly and cheaply determine the microbial composition of their vineyards and wineries. This could eventually be used as a diagnostic tool to determine the ‘microbial health’ of wine environs, including ferments.

‘It’s very likely that in the not-too-distant future, winemakers will want to measure the microflora of their ferments each vintage; it will become routine, like measuring other parameters in a grape juice such as sugar’, Dr Chambers said. ‘They will keep a record of this and how it varies, giving them some indication of what’s happening over consecutive vintages to the microflora and how this impacts on wine quality.’

Much of the early legwork is being done by the AWRI’s Principal Research Scientist – Molecular Biology, Dr Anthony Borneman, who has expertise in the advanced DNA sequencing technologies that enable a new approach called metagenomics, which is revolutionising the study of microbial ecology worldwide.

In practical terms, metagenomics allows Dr Borneman to do in a few hours for less than a hundred dollars what might have taken weeks and thousands of dollars just a few years ago. He recently completed a four-year project using DNA sequencing to learn more about commonly used yeast strains while also carrying out trial work for the current study.

Now a formal four-year project funded by Wine Australia is under way and around 30 wineries from as far afield as Margaret River, Tasmania and Queensland have begun sending their ferments to the AWRI in Adelaide for analysis. This is expected to increase significantly into the second year.

‘When we went out and told people we had the potential to do this, a lot of winemakers who are using wild ferments said “this is great, this is the information we need, we’d like it yesterday”’, Dr Borneman said.

‘Even for those who aren’t doing wild ferments, the microflora that are present in juice or must can still have a big impact.

‘For winemakers who are doing wild ferments, the microflora is often their bread and butter. They don’t shake a yeast packet in. The strains they’ve got are what they work with, so having as much knowledge as possible about what’s in there is key – it’s no different from knowing what clones of grapes you have.’

The biggest hurdle is getting samples to Adelaide in the right state to be analysed, which usually means frozen. Fresh ferment is the ideal, but even an express overnight courier can’t deliver before things have changed. ‘What they send and what we receive can be very different’, Dr Chambers said.

Even with new technology the science is pretty complex, as there are hundreds of different species of microflora, including some you might not expect to find in a wine ferment.

‘There are organisms that disappear once the ferment gets going; species that live on the grapes and leaves that are present in some abundance at the start of fermentation and could potentially secrete enzymes or other compounds’, Dr Borneman said. ‘They may well leave a legacy but they just aren’t studied.

‘Getting some data on those non-wine-yeast species that are present and then being able to correlate that after the fact with different wine attributes is important too.’