Mixing it up

Co-fermentation and field blending justifies winemakers’ efforts

Although co-fermentation and field blending are well-established techniques, innovation in the area is producing some outstanding results by adjusting procedures and mixing up the selected varietals. Paul Le Lacheur explains what he’s learnt after speaking to fellow winemakers about some of their successful blending outcomes. This article was published in the March issue of Australian & New Zealand Grapegrower & Winemaker.

Neither co-fermentation nor field blending are new ideas. But in the Canberra district, new approaches to some related problems are reaping positive rewards. Clearly, these practices have been common in the Rhône, Tuscany and parts of Portugal for many generations.

Recently, I had the pleasure of speaking to a number of outstanding practitioners of the winemaking craft.

Tim Kirk is chief executive/winemaker at Clonakilla, the vineyard and winery he established in the Canberra district in 1971. I gained invaluable knowledge from him on the subject: Clonakilla specialises in the co-fermentation of Shiraz with Viognier.

According to Kirk, particular attention to picking at lesser ripeness levels in the Viognier is a key issue.

“We might only use five to seven per cent Viognier but we need to get in and pick it a little earlier, before that apricot-like varietal character dominates the blend,” he said.

“In the top quality vintage of 2015, the Viognier percentage was merely five per cent.”

Clonakilla’s seemingly boundless complexity is achieved by strict attention to detail.

“Our fermentation capacity is extremely adaptable. Batches can range from ten tonnes down to just half a tonne,” explained Kirk.

“We always co-ferment our Shiraz and Viognier. Batches often come in small lots, representing as many as 27 different parcels of fruit from parts of the vineyard we feel offer subtlety and ultimately, complexity,” he enthused.

This ‘micro-control of ferments’ effect allows Clonakilla to capture the minute differences drawn from each different soil profile.  Most soils are sandy clay-loam in nature.

These topsoils sit over sub-soils of decomposed dacite (a volcanic influence).

Kirk went on to explain the advantages of vineyard elevation.

“At around 600 metres above sea level, we have yet another cooling influence over our already cool district, making it describable as a truly cold climate,” he said.


The owner of the Canberra region’s Collector Wines, Alex McKay, also provided some rare insight.

He believes in using both field blending and co-fermentation to produce the best results possible from available viticultural resources.

“The science of co-pigmentation through the co-fermentation process is not very well understood, especially by me,” he revealed.

“Purple hues seem more prominent when you co-ferment, but we don’t want too much of that in our wines,” he explained.

“We also use lots of whole bunches and stems to extend palate length.”

Co-fermentation is often thought of as a technique to simply treat Shiraz and Viognier as one entity. But this is not the case at Collector wines.

“Sure, we often co-ferment, but we also field blend the white Rhone varieties, like Marsanne and Rousanne, in with the Shiraz,” McKay said.

Once again, a theme here at Collector is dealing with ‘small parcels’.

“Typically, we’ll have about 20 parcels of Shiraz fruit, picked over perhaps a two-and-a-half week period.

“Sometimes it’s as little apart as eight days, but we have the option to hold the fruit and co-ferment because of our long harvest window.

“Historically, we had Viognier which was quite ripe, giving us that apricot character, but we now pick it much earlier, for delicacy,” he added.

Collector Wines also sees great value in having the capacity to treat parcels in differing fermentation sizes.

McKay often ferments in three-tonne lots, but is able to handle ferments down to one tonne or even 500 kilograms.

This variable fermentation capacity allows options such as field blending the white Rhone varieties together, fermenting as one, and then back blending with Shiraz.

Here, both co-fermentations and field blending options are pursued as vintage conditions dictate. For example,   in 2016, especially in the Murrumbateman area, vintage was surprisingly early, putting (unwanted) pressure on fermentation and storage capacity.

Blending complexity

Matt Bloomhead, winemaker at Three Dark Horses is another exemplar of the craft. Now, I have to declare my bias immediately: Matt is an old friend of mine who sometimes makes wine with his heart, not just his head.

His winery is in McLaren Vale. Three Dark Horses is perhaps seen as one of the stalwarts of ‘old-school’ red making.  Matt makes some of his best reds based on old vine Grenache, Shiraz and of course, Mouvedre.

Three Dark Horses has established an enviable reputation for complex blends. So what’s news in their winemaking pursuits?

Matt was overseas, in Cambodia, when I enquired about the latest vintage of Grenache and Touriga. Even with vintage on his doorstep, he was still keen to respond. He was both willing and able to enlighten me as to how and why he gained such silky tannins and that much sought after palate complexity.

“Indeed our Grenache/Touriga (labelled as GT) is co-fermented,” he admitted down the phone line. Tick one for yours truly.

I felt it impossible to explain the complexity of this wine any other way at a recent blind tasting.

The viticultural and oenological rule book for this rustic red is disarmingly simple: “Two vineyards, picked at the same time. Half of the fruit was as whole bunch, half was simply crushed on top”.

“We fermented with wild yeast and the wine was made completely unoaked, un-fined and unfiltered,” Matt added.

The secret here is harmony. Matt is convinced that, “the co-fermentation adds harmony to the blend earlier in the process, which is essential for a wine that is released only six months after vintage.”

It’s clear to me that the wine shows at its best when fresh and young, rather than with extended bottle age. Not to say a medium cellar term of three to five years won’t show secondary characters, merely to say there is a small cost. The taster runs the risk of losing some of those simple, aromatic primary fruit characters. They are replaced by an earthy, mushroom bouquet with bottle age.

Earlier fermentation results

Norbett Baumgartner, winemaker at Mia Valley Estate, located in Victoria’s Heathcote region, is another co-fermentation devotee.

He and his wife Pam have produced a number of unique wines, not the least of which is their Cabernet Shiraz blend.

When I spoke with him recently, his message was unequivocal: “My experience has been that when these varieties are fermented separately, it can take forever to get the components to come together. In some vintages that process took up to seven or eight years. I can’t wait that long.”

Naturally, Norbett believed the reverse was the case when he started co-fermentation.

“When we fermented our Cabernet Sauvignon and our Shiraz together, the parts of the puzzle all came together at an earlier age, even more quickly by comparison with the separately fermented wines,” he said.

Co-fermentation is not the only string to Baumgartner’s bow.

“We planted many different clones,” he explained. “1654, PT 23, 1127, R6WV28, the list goes on and on.”

“I admit I’ve lost track of where each clone exists in each row. Having said that, we can still visually identify clonal differences and we ferment each of them as a distinctly separate batch.”

Baumgartner went on to explain how he recognises the more obviously elongated bunches of the PT 23 clone and how this makes separation much easier.

“From that point on (identification), our oenology is relatively traditional.  We still leave our reds in barrel for three years, then hold them for one to two years before release.

“So when they’re finally released, they are seen as fairly mature wines.” he said.

Blending reds and whites

Tallavera Grove Wines in the Hunter Valley is another producer using both co-fermentation and field blending for reds and whites alike.

Two examples are a Shiraz Viognier and the Carillion Riesling, from the Central Western NSW region of Orange.

The family-and-friends team hand picks the fruit, and then optionally separates the ferments within any given variety.

In addition to this selection, they almost invariably co-ferment around three to four per cent Viognier in with the Shiraz.

Earlier vintages (such as 2009) have taken both trophy and gold awards at wine shows, vindicating this approach.  Another wine in the range showcases field blending.

The 2016 Wild in the Wood is a case in point. Semillon, Viognier and Chardonnay are vinified together, having been field blended.

Originally, these varieties came into production after rootlings were scattered randomly through a special ‘odds and ends’ block.

Each year, some portion of these wines are barrel fermented ‘sur lie’, to yield wines of depth and satiny texture without sacrificing precious varietal fruit.

Husband and wife team Elena and Zar Brooks own and operate Dandelion Vineyards, dealing with fruit from McLaren Vale and the Adelaide Hills. They have been co-fermenting McLaren Vale Shiraz on approximately   five per cent Riesling skins, but for some different reasons than those expressed by other producers of this style.

“We ferment whole bunches of our McLaren Vale Shiraz on Riesling skins, but we do so for tannin, structure and balance,” revealed Elena.

“Riesling skins can be quite tannic, in a good way,” she said.

Even such a small percentage of Riesling adds perfume notes of rose petals to the otherwise spicy Shiraz character. Importantly, Dandelion Vineyards are keen to acknowledge the influence of Riesling prominently on the label.

Having looked at a number of co-fermented Shiraz and Viognier blends from right across Australia’s diverse viticultural sites, one thing is abundantly clear. The best wines show restraint, both in the tiny percentages of Viognier used and the baume at which the Viognier is picked. Those wines with more Viognier in the blend all had that tell-tale apricot aroma and the oily viscosity typical of more varietal Viogniers.

For me, the lesson to all winemakers who are intending to co-ferment these varieties is clear – less is more.

Statistics taken from a 2016 University of SA survey of more than 5,000 consumers on exit from retail liquor outlets, showed 86% of wines bought that day were consumed within three days.

Small percentages of Viognier ‘lift’ varietal Shiraz fruit, making it much more aromatically accessible when released as a young wine.

In my opinion, analysis of these figures points to the need for winemakers to produce styles which have a positive aromatic impact on consumers. As a nation, we are drinking our wines immediately on purchase.

Naturally, those producers showing discretion in the Viognier percentage can still make wines worthy of age.

Those examples will still retain dominant Shiraz fruit, structure and tannin levels for the patient drinker with a cellar and will also satisfy those who demand a wine with secondary characters in its bouquet.

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