Australian wine producers could stand to benefit from new winemaking technology that’s been developed in Europe by an Australian wine stylist who’s returned home due to COVID-19 travel restrictions.
Graham Dixon now hopes to continue to develop his project locally in South Australia, to promote what he calls ‘low carbon wine’.
Graham Dixon, now a wine stylist, got his start in the industry over 30 years ago as chief chemist for Leo Buring in the Barossa Valley.
At the time, Australian winemakers were pioneering new ‘fruit-driven’ wine styles by using refrigeration to ferment at low temperatures and inert gas blanketing with CO₂ or nitrogen to preserve delicate aromas.
The new styles took the wine world by storm, and Leo Buring was one of the leaders in the charge. For the past two decades however, Dixon’s work as a wine stylist has helped winemakers in Eastern Europe and China adapt their wine styles to suit target markets.
Now stranded in Australia due to COVID-19 travel restrictions, Dixon is turning his attention to local winemakers in the hope that he can introduce them to ‘low carbon wine’ (LCW), a unique project he has been working on in Europe for several years.
According to Dixon, LCW is made by recycling CO₂ from fermentation, and by returning volatile aromas captured from the CO₂ stream back into the wine.
“The greenhouse gas emissions from making LCW are significantly less compared to conventional winemaking,” he said.
Dixon says his start with this unique, world-first process occurred a decade ago.
“Ten years ago, I won a grant from the Tarac Environmental Future Fund for my project proposal to find the economically optimal way to recycle wine ferment CO₂.
“I built some prototypes and tested them with the help of several Australian wine companies, and found the best way.
But then another opportunity presented that was too good to pass up, so I put the project on ice for a while.”
When he resumed the project, an exciting new development fired his enthusiasm.
“We discovered that capturing the volatile aroma compounds escaping from the ferment with the CO₂ and returning them to the wine, is an alternative to keeping the volatiles in by cooling down the whole volume of must,” he explained.
“I [had been] working on a European Investment Bank project to help Moldovan winemakers adapt their wine styles to suit Western markets, after the Russians put an embargo on their wine exports into Russia. Russia was by far their biggest market, so things were pretty dire.
“It was a politically motivated embargo, much like what’s happening now for Australian wine exporters to China. The Moldovans had replaced their pro-Moscow government with a pro-European government.
“So the Moldovans needed a style make-over. I knew from the work I had done in Australia that capturing the volatiles, and returning them to the wine, gives an interesting complexity to a wine’s flavour profile. Linking that complexity to reduced greenhouse gas emissions was the sort of marketing edge they needed.”
Dixon persuaded some winemakers in Moldova to give the new method a try and, over a couple of vintages, the process was refined.
“We established that low carbon wine is comparable to conventionally made wine, but with a specific aroma signature discernible by experienced tasters,” he said.
“This signature can be enhanced by increasing the time between capturing and returning the volatiles to the ferment. We think this is because the extra time allows for esterification of some aroma compounds into more intense aromas.”
During these trials, Dixon says it was also found that when capturing and returning escaping volatiles, winemakers don’t need to cool down the whole mass of must to keep them in.
“In effect, you can ‘de-industrialise’ winemaking by taking out the refrigeration needed for ferment cooling,” Dixon commented.
He says that by avoiding refrigeration for ferment cooling, lower production costs can be achieved.
Potential cost savings
“LCW isn’t just about reducing greenhouse gas emissions; there are the savings on electricity used for ferment temperature control, and you don’t have to buy as much CO₂,” he said.
“Also, because warmer ferments progress more rapidly, you don’t need as much fermenter capacity to process the same tonnage. And of course, you need less refrigeration capacity.”
Dixon said making wines using his method is not overly complicated, and the equipment to get started is relatively affordable.
“The equipment needed is cheap and low tech, basically a smaller version of what has been used routinely in the brewing industry for decades,” he explained.
“The CO₂ stream is captured by the fermenter lid attachment, which uses a 200L Scholle bag as the gas buffer. The captured CO₂ is periodically compressed by a small, inexpensive oil-free air compressor, and the entrained aroma volatiles are condensed out by a small refrigerated dryer.
“You’ll also need a receiver vessel to store the captured CO₂ under pressure, and plumbing to distribute the CO₂ to where it is needed in the cellar. You could use an air receiver, but a pressure vessel is ideal.”
However, Dixon explained that winemakers may need to change their cellar procedures to use more CO₂ as gas and less dry ice or nitrogen.
Being unable to travel outside Australia for the time being, Dixon is now turning his expertise to local wine production to explore the possible benefits for Australian producers.
“I’m duplicating the project in Australia. Australian winemakers suddenly need to pivot away from their hitherto biggest market, just as the Moldovans needed to do, so the need for an environmentally friendly marketing edge is just as urgent here now,” he said.
“The plan for Moldova this year was to split a batch of Chardonnay into two 5000L batches, and ferment one conventionally, with temperature controlled at a maximum 16⁰C, and the other with the return of captured aroma volatiles, letting the ferment run up to 24⁰C. I want to do the same thing here next vintage. This will enable validation of the process by an objective third party.”
Dixon is now hoping that winemakers in South Australia may be intrigued enough by the potential of his developments to work with him to push them further.
“I’m looking for partners in McLaren Vale or the Barossa,” he said, “Many winemakers are interested in reducing greenhouse gas emissions here.
“I’ve had discussions with people at the AWRI about them validating the process and hosting a comparison between the low carbon style and the conventional style – what I call the ‘industrial style’, due to its dependency on energy-intensive ferment cooling.”
Although Dixon says he had to leave his latest prototype in Europe, he’s now ready to continue his project in Australia.
“I am building one from equipment sourced locally, which also incorporates an improvement to minimise the need for cellar crew attention,” he concluded.
This article was originally published in the January 2021 issue of the Australian & New Zealand Grapegrower & Winemaker. To find out more about our monthly magazine, or to subscribe, click here!
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