Charles Sturt University
Charles Sturt University

Wine Composition

An extensive body of work and knowledge has been established by the NWGIC wine oxidation and chemistry group. Researchers are investigating the impact of light on oxidative spoilage of wine, and also the measurement of specific metal forms to better predict wine stability.

Selected Research Projects

Metal ion speciation: Understanding its role in wine development and generating a tool to minimise wine spoilage

Dr Celia Barril (NWGIC/CSU), Dr Andrew Clark (NWGIC/CSU), Nikolaos Kontoudakis (NWGIC/CSU), Dr Leigh Schmidtke (NWGIC/CSU), Prof. Geoffrey R Scollary (NWGIC/Uni. Melb.), Dr Mark Smith (AWRI), Dr Paul Smith (AWRI), Dr Eric Wilkes (AWRI)

Funding: $708,962 (AUD)
Wine Australia

The metal-induced spoilage of wine can impact the colour, aroma, taste and texture of wines, including the ability to induce oxidation or reductive characters in wines. These latter two characters have been identified in past consumer preference studies as being particularly negative traits in wines. This project will provide novel tools and knowledge that will enable winemakers to more confidently identify wines with the potential for metal-induced spoilage processes, and allow them to utilise copper during winemaking in a more judicious fashion. Both outcomes will increase the efficiency of wine production in terms of inputs during the production process and will lower the likelihood of consumers rejecting wine that has been impacted by metal-induced spoilage processes.

This Research Changes Wine Industry Practices by:

  • Providing a new practical tool for wineries to measure specific forms of metals that have the potential to impact on wine oxidative or reductive stability;
  • Knowledge generated, in conjunction with the practical tool, will circumvent unnecessary copper additions to wine, and thereby minimise the associated detrimental effects of excess copper concentrations; and,
  • Measurement of different forms of copper, will potentially indicate the efficiency of copper to remove sulfidic-off odours in wine.

The impact of light on model white wine systems

Ms Paris Grant-Preece (NWGIC/CSU), Dr Celia Barril (NWGIC/CSU), Dr Andrew Clark (NWGIC/CSU), Dr Leigh Schmidtke (NWGIC/CSU)

Funding
Charles Sturt University/NWGIC PhD Scholarship

Light exposure has been shown to contribute to the deterioration of wine flavour and colour. Although the presence of riboflavin in wine has been linked to such photochemical processes, organic acids in combination with iron(III) are also known to be photoinitiators. Past studies at the NWGIC showed that iron(III) tartrate exposed to visible light in a wine-like solution could form products able to consume the main preservative in wine (sulfur dioxide), and generate detrimental coloured compounds. This research was conducted to assess the impact of wine compositional factors on the iron(III) organic acid photochemical process, to better gauge the impact of such a photochemical mechanism on white wine spoilage and shelf-life.

This Research Changes Wine Industry Practices by:

  • Providing knowledge on the ability of sulfur dioxide, dissolved oxygen and other wine compositional factors to impact iron(III) organic acid photochemistry;
  • To understand the specific organic acids that can significantly contribute to such photochemistry in wine conditions, and hence which types are wines are more prone to such spoilage; and,
  • An understanding of which particular organic acid can contribute most to spoilage pigmentation via photochemical mechanisms.