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Building & measuring quality of Australian sparkling wines through identification of the impact compounds responsible for autolytic character in sparkling wine & novel technologies to hasten autolysis


Summary

Objective

A new objective measure for sparkling wine quality using spectral methods in the ultra-violet and visible (UV-Vis) range will be used as a means of discriminating flavour impact compounds and the provenance of juice.

The research will investigate whether the desirable ‘autolytic character’ of premium sparkling wine is due to yeast lysis, as expected, or is simply an ageing effect.  It will investigate novel technologies that could hasten yeast lysis and contribute to the identification of flavour impact compounds for ‘autolytic character’.

Background

The compounds which impact upon quality in white and sparkling wines are poorly defined, if at all, particularly those associated with ‘autolytic character’ ‘aged wine’ .

Long aging on lees delays the release of sparkling wines, adding significant cost to the producer. If autolysis is not the mechanism for this character, then alternative processes may be available to streamline winery efficiency. 

The AusIndustry project ‘Improving Australian Sparkling Wine and Pinot noir’, co-funded by the Tasmanian wine industry resulted in the development of a novel, rapid, objective measure of juice and base wines using UV-Vis spectral phenolic fingerprinting. This measure has the potential to be adapted to an in-line juice quality sensing method for automated press fractions.

Research approach

This research has three components.

It will examine objective measures of juice/wine quality and viticultural impacts on these, by comparative tasting and spectral analyses of flavour and aroma compounds in stored wines (five or more years).

The second component will look at methods to hasten yeast lysis in lees from Chardonnay and Pinot Noir base wines, using various treatments including microwaves, ultrasound and enzymes. The impact on yeast cells will be examined visually, using scanning electron microscopy. Base wines will be dosed with treated lees at tirage and the wines tasted by an expert winemaker panel after storage for 6, 12, 24 and 36 months. The wines will again be assessed using spectral methods. The third component involves investigation of in-line sensing using spectral phenolic fingerprinting to determine press cuts and comparison of this method with a conventional approach using conductivity measurements. These results will be verified against laboratory analyses, with chemometrics used to link the in-line sensing and laboratory results.

The final phase will investigate methods (e.g. spectral phenolic fingerprinting, NIR and UV-Vis) to detect and predict juice provenance.

Sector benefits

This project will develop tools and techniques for sparkling wine production that will enhance quality and value and increase productivity. These include real-time juice quality assessment and the potential to automate press cuts and reduced time on lees.

Associated knowledge of the effect of viticultural treatments on juice quality and of the impact compounds associated with ‘autolytic character’ will support viticultural and winemaking decisions and provide greater control over sparkling wine style.