Wine aroma uncorked: Spanish researchers make quality preservation discovery

01 Dec 2023 --- Scientists have found that trichloroanisole (TCA) — a highly volatile organochlorine compound that migrates from corks to wine — explains the distinct “corked wine aroma.” The findings have sparked interest among cork companies as it could help beverage manufacturers preserve wine quality by preventing organoleptic deterioration.

For the study, the team compared gene activity in cork oak samples from Sardinia, Italy, and Girona, Spain — two regions with different TCA levels in the cork — through RNA sequencing, followed by bioinformatics studies to identify a list of phenolic metabolites present in the trees.

The findings are based on research by the Center for Research in Agricultural Genomics (CRAG), Spain, led by Dr. David Caparrós-Ruiz, head of the Bioengineering of Lignocellulosic Biomass group. This was a part of the Cork2Wine project, coordinated by the cork company Francisco Oller in Spain.

The Cork2Wine project was a consortium uniting various stakeholders in the cork sector and research groups. It lasted four years (from 2019 to 2023) with cash injections worth €5 million (US$5.45 million) funded by the Centre for the Development of Industrial Technology Innovation, Spain, and in part with FEDER funds from the EU.

A natural sealant
Cork is a natural polymer that has been pivotal in sealing bottles, with Market Research Future stating that global wine consumption is pushing the demand for cork closures and projected to drive market growth by a CAGR of 5% from 2023 to 2032.

The scientists performed RNA sequencing on cork oak tree samples. For Spain specifically, the CRAG study suggests that the country produces 50% of the world’s cork and 30% of all cork stoppers.

Meanwhile, the Cork2Wine project has helped the researchers explore how TCA is released inside wine bottles.

“The work twe have carried out in the Cork2Wine project has allowed us to obtain a list of metabolites that can be considered as the substrates that the fungus uses to produce TCA,” says Caparrós-Ruiz, which he considers the first step to understanding the complete TCA metabolic pathway.

He further remarks that this knowledge is crucial for building new biotechnological tools to reduce or eliminate TCA in cork.

A starting point
Meanwhile, Jordi Roselló, R+D+i head at Francisco Oller, flags that cork needs to persist in the future as a renewable raw material and natural polymer.

“The project has served as a starting point. Until now, we have reviewed the issue from a genetic and metabolomic point of view.” Now, the team plans to continue the research by adding the knowledge of microbiology to tackle TCA.

“Cork will continue to be ecological, sustainable and in a circular economy framework,” he concludes.

Meanwhile, Caparrós-Ruiz remarks that the next step would be to focus on the cork tree and work toward producing TCA-free trees.

Infographic summarizing CRAG’S technique to prevent TCA release in cork samples.

“This would be very important for the cork industry because after waiting for 20-30 years, extracting cork which is 100% from TCA would eliminate the problem,” he concludes.

In other cork-related wine news, the Australian wine industry is replacing the traditional cork with screw caps in a bid to combat climate change.

By Insha Naureen