Can regional microbiota influence wine style over the longer term? Research is increasingly suggesting that it can.
Two years into a formal four-year study funded by Wine Australia, the ancient practice of ‘bioprospecting’ is emerging as an exciting new buzzword in the wine sector.
‘The term bioprospecting is relatively new on the scene, however winemakers have been practising it for millennia in processes such as wild fermentation and “pied de cuve” (pre-fermenting a small parcel of fruit with wild yeast and then using this active ferment to inoculate others)’, said Dr Anthony Borneman, Principal Research Scientist – Molecular Biology, at the Australian Wine Research Institute.
However, Dr Borneman said traditionally, these practices have been performed based on empirical results, ‘with no information regarding the underlying microbiology.’
The AWRI team, led by Dr Borneman, is providing the science to back up the idea that a region’s microflora can help shape its terroir – and thus the wines that are made there.
‘Since 2016, we have mapped the fungi and yeast present in almost 2000 wild ferment samples from more than 30 wineries from all the major winemaking regions of Australia. We have identified hundreds of individual species that can be present in wild ferments, with wineries – and ferments – often showing unique patterns of yeast species and abundances.’
With the invaluable assistance of winemakers around the country, another large set of samples is currently being processed from the 2018 vintage and the research team is now looking to see if they can detect reproducible microbial communities across vintages.
The next step will be to investigate the potential for regional microbiota to influence wine style over the longer term.
Dr Borneman said he was confident bioprospecting would gain traction as a means to provide winemaking diversity, ‘while retaining the potential for local influences from yeast and bacteria.’
‘We have seen that the strains of Saccharomyces and Oenococcus present in wild ferments are generally not simply commercial – even when inoculated ferments are being performed concurrently in the winery – and can even be specific to the winery.’
‘Furthermore, at least in the case of Saccharomyces strains, we have data to suggest that the same strains can be detected across vintages.’
Outside of the classic Saccharomyces wine yeast, the team has already found some interesting microbiota lurking in Australian ferments, including a potentially brand-new species of yeast and another case where they believe a non-Saccharomyces species is playing a significant role in finishing fermentation.
Dr Borneman said the results were ‘exciting’ and provided the basis for further investigation into the fermentative properties of the yeasts.
‘Do they add specific characteristics to the wine? Do these characters contribute to regional wine styles? That is what we want to determine next.’
Dr Borneman said the ultimate aim of the research was to give winemakers the ability to understand this microbiota – preferably in ‘real time.’
‘Ultimately, we want to be able to identify key yeast species and strains. These strains may even then be developed to provide some of the benefits with respect to positive attributes provided by wild fermentation (complexity, mouth feel etc.), without some of the perceived risks that come with them.’
This is not the first time that the AWRI has developed specific yeasts for Australia’s wine sector. In one recent project, the AWRI identified a uniquely Australian malolactic bacterial isolate that is now available commercially through Lallemand. The isolate is very robust: it is tolerant not just to temperature but also to alcohol and pH.