Gold nanoparticles – a new solution to the problem of winemakers

Researchers from the Australian Wine Research Institute and Flinders University in Australia have proposed a new method for removing volatile sulfur compounds (VSCs) from wine using gold nanoparticles. This method is environmentally friendly and more effective than the current approach of adding copper sulfate.

VSCs such as hydrogen sulfide, methantiol and ethantiol are responsible for about 30 percent of all wine defects. They are associated with “reducing” flavors in wine and can have a significant impact on wine quality and consumer preference.

Gold nanoparticles were chosen because gold binds to certain sulfur molecules. The team applied a specially designed thin plasma polymer coating to the surface of a neutral substrate before attaching the nanoparticles to it.

In the lab, small nanoparticle-enhanced coating strips were tested on small samples of red and white wine with high LSS content. The researchers found that after 24 hours of exposure, up to 45 percent of free hydrogen sulfide was removed from the wine, along with other unwanted VSCs, including methantiol.

This surface coating is also quite versatile. It can be used on equipment throughout the entire winemaking process, from filtration devices (to remove solids) and decanters to the packaging materials in which wine is placed.

“The key advantage of the new approach is that it’s easy to deploy and retrieve,” says Agnieszka Mierczynska-Wasiljew, chief scientist at the Australian Wine Research Institute.

“It’s essentially a one-step process where the smart surface is added directly to the wine and then removed after a certain period of time.”

The new method is more effective at limiting VSC than the current approach of adding copper sulfate, which has its own problems: it can introduce other undesirable flavors, and its use is regulated by health.

Moreover, the copper sulfate option is a multi-step process, whereas the gold nanoparticle material is simpler. It is applied to the wine for a certain period of time and then removed.

“Thus, adopting a sustainable, non-toxic alternative to copper refining could have a beneficial effect on the environment and the economy,” the researchers write.

Translating this process from the lab to commercial processes will take time, but the early results are very promising in improving wine quality without any psychological tricks.

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