Unwanted volatile sulfur compounds (VSCs), often referred to as ‘reduced sulfur’ compounds, can give wine aromas described as ‘rotten egg’, ‘cabbage’ or ‘rubber’. Copper fining is commonly used to manage these characters, but it has limitations, including the addition of residual copper to wine and potential impacts on desirable sulfur-containing aroma compounds.
The Smart Surfaces project is investigating whether specially engineered surfaces could provide an alternative way to selectively remove unwanted VSCs from wine. The technology uses a thin plasma coating containing immobilised gold nanoparticles, which bind target sulfur compounds as wine comes into contact with the surface. The long-term aim is a regenerable treatment system that could be incorporated into a practical winery process, such as a cartridge or modular flow-through system.
Progress to date
Earlier AWRI research demonstrated that Smart Surfaces could selectively remove key unwanted VSCs, including hydrogen sulfide, methanethiol and ethanethiol, while retaining desirable varietal thiols.
Development work has since focused on whether this laboratory proof of concept can be translated into a practical and reusable treatment technology. Testing in both red and white wines has demonstrated effective VSC removal across five treatment and regeneration cycles, without evidence of a progressive decline in performance or systematic loss of desirable aroma thiols. The treatment effect has also been shown to persist during wine storage. Informal tasting with winemakers has not identified obvious adverse sensory effects, although more formal sensory validation is still required.
The project has also expanded the types of materials that can be coated and investigated more reproducible sources of the functional gold nanoparticles, helping to build the manufacturing pathway for a future product.
The next technical challenge is translating this performance from batch treatment to continuous flow. Initial flow trials have highlighted background VSC losses within the experimental system and analytical variability that need to be resolved before the effect of the Smart Surface itself can be assessed confidently. Work is also needed to quantify how treatment capacity relates to coated surface area, which will ultimately determine the size and configuration of a winery-scale system.
What’s next?
The next stage will focus on establishing a reliable flow-testing system and demonstrating VSC removal under controlled flow conditions. This will include quantifying treatment capacity, confirming coating consistency and performance, and determining the conditions required for repeated treatment and regeneration in a flow-based system.
Alongside this work, the project will investigate how the surfaces could be manufactured consistently and at larger scale, and what a practical winery treatment system could look like. Further sensory assessment will be undertaken, together with work to clarify the regulatory pathway for use of the technology in wine, including relevant FSANZ requirements.
Resources
Further information and resources will be added as the project progresses, including relevant project documents and research outcomes.