The time has come to answer some sparkling questions

Plenty of Australians are looking forward to popping the corks on a few bottles of sparkling wine as Christmas approaches, but Dr Fiona Kerslake has a professional interest as well.

How a batch of wines made back in 2011 has changed with time may provide more weight to the argument that vineyard as well as winemaking influences are at play as sparkling ages. A few bottles from 2010 have already provided some enticing clues.

The wines were bottled as part of a series of viticultural trials funded by AusIndustry and the Tasmanian wine sector. Nine different vineyard treatments – involving changes in pruning method, crop load and leaf removal – were tested at two ends of the state, using two varieties (Pinot Noir and Chardonnay) and over two seasons.

Adding to the complex mix of factors at play, the seasons could not have been more different – 2010 was warm and dry, 2011 cool and wet – and this led to some quite distinct differences in the base wines.

Dr Kerslake was keen to know more, however, and ‘rather ambitiously tiraged a whole bunch of wines in the hope that one day we might get the chance to evaluate the mature wines’. That time has come.

As part of a Wine Australia-funded project, she and colleagues at the Tasmanian Institute of Agriculture, part of the University of Tasmania, are taking a detailed look at how the wines have developed.

They’ve done their own matrix analysis on the 2010 wines, sent samples to the Australian Wine Research Institute (AWRI) to learn more about the volatiles and proteins, and sought input from some of the country’s leading sparkling winemakers during a technical day at last year’s Effervescence Sparkling Wine Festival.

‘We tasted the wines last November and were really surprised at just how much you could still taste the viticultural effects’, she said. ‘We thought the effects of autolysis might have overridden the vineyard influence but that was not the case.’

And there’s more to the story. ‘In 2013, we looked at some of the wines at a local producer workshop in Tassie and we saw some quite clear preferences towards the higher crop load wines rather than the lower ones. But it’s looking like some of those strong preferences might have slipped a bit as the wines have matured even further.’

The researchers are now working through the reams of data already generated and waiting to add the 2011 chapter to the story come November. The results could help determine whether different vineyard techniques might be appropriate for wines designed to age compared with those for more immediate consumption.

A related part of the project is looking at the equally contentious question of whether the autolytic characters in sparkling are age- or yeast-derived (or a combination of the two) and whether novel technologies could hasten their development and contribute to the identification of flavour impact compounds for these characters.

The work, which is being carried out by PhD candidate Gail Gnoinski, involves treating a sacrificial culture with everything from microwave to ultrasound or enzymes, with assessment of the impact on yeast cells.

‘The general aim is to try to help producers get product onto the shelves sooner while maintaining or possibly even improving the quality. That’s the producer outcome’, Dr Kerslake said. ‘For us as scientists, what we’re really looking to do is to tease apart what is ‘autolytic character’; where it is coming from, whether it is solely yeast derived or if  you can get that into the wine in some other way?