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Tasmanian Institute of Agriculture

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Project name Building and measuring the quality of fine Australian sparkling wines
Funding bodies Wine Australia $1.4M
Chief Investigators Dr Fiona Kerslake
Contributors WineTQ, University of Adelaide, Australian Wine Research Institute, Hill-Smith Family Vineyards, Apogee Wines Tasmania, Josef Chromy Wines, Central Science Laboratory

Dr Fiona Kerslake is leading a four-year project to identify impact compounds that contribute to the flavour, mouthfeel and textural properties of premium Australian sparkling wines.

The project has four main objectives:

  1. To identify impact compounds for sparkling wine quality including ‘autolytic character’ and associated mouthfeel, texture and aromas.
  2. Further develop a novel objective measure of sparkling juice and wine quality. This could be adapted to in-line sensing with the potential to automate press fraction cut-offs, providing significant cost-savings to industry.
  3. Investigate novel technologies to hasten the autolysis of yeast and therefore produce higher quality sparkling wines in a shorter amount of time.
  4. Evaluate sparkling wines, after over 5 years maturation, from viticultural trials and analyse the wines for quality markers.

What is autolysis?

As part of the process for making sparkling wine, a still wine undergoes a secondary fermentation in the bottle after a fresh yeast addition. After the yeast have produced their CO2 which gives the wine it’s effervescence, as the yeast cells break down they begin to leak their contents which contribute to the flavour and aroma of the wines which comes with ageing the wine on these lees (the spent yeast).

This process, called autolysis, is believed to be a vital component in shaping also the mouthfeel of premium wines by imparting a creaminess and reducing astringency.

The practice dates back to Roman times, and in France there are strict regulations for how long Champagne must remain ‘on lees’ from 15 months for non-vintage wine to three years for vintage wines, with some wineries extending this period to seven years or beyond.

However, an expert tasting of sparkling wines in 2010 revealed that sensory cues for 'autolytic character' were not clearly distinguishable nor agreed upon from 'aged wine' character and industry is now questioning whether this 'autolytic character' is entirely attributable to autolysis or if some of this character is simply aged wine character.

Benefit to industry?

Long ageing on lees delays the release of sparkling wines, adding significant cost to the producer.

Dr Kerslake's research, along with PhD candidate Gail Gnoincki, will look at whether the long ageing in lees is responsible for producing the 'autolytic character' in aged wines.

If autolysis is not the mechanism for this character, then alternative processes may be available to streamline winery efficiency.