2026-06-24
Researchers have developed an electrochemical sensor made from discarded wine corks that can measure caffeic acid in red wine and grape juice, turning a common beverage waste material into a low-cost analytical tool for quality control.
The study, published June 23 in the Journal of Solid State Electrochemistry, describes how scientists produced laser-induced graphene electrodes from used natural cork stoppers and tested them as sensors for caffeic acid, a phenolic compound found in wine, grape juice, coffee, tea and other foods. In wine, phenolic compounds help shape color, texture and aroma, and the oxidation of phenols is tied to changes such as darkening, bitterness and loss of aroma and flavor.
The team made the electrodes from discarded cork stoppers taken from wine bottles and compared them with electrodes produced from a commercial cork sheet. The material was converted into graphene-like carbon through a single laser graphitization step using a 3D printer fitted with a 2.8 W laser module. Under the reported conditions, each electrode was produced in about three minutes.
According to the paper, the researchers then characterized the material with Raman spectroscopy, X-ray diffraction and scanning electron microscopy. Those tests showed the formation of porous graphene-like structures on the cork surface after laser treatment. The authors found that natural cork stoppers performed better than commercial agglomerated cork sheets, which they linked to differences in composition and structure. The commercial sheets showed greater heterogeneity and lower crystallinity, while some stopper-derived samples showed more organized graphitic domains.
The study also proposed a post-treatment step using acid and alkaline solutions to improve electrochemical performance. The authors said this simple activation process significantly improved the response of high-surface-area laser-induced graphene electrodes.
For caffeic acid detection, the researchers studied the compound’s electrochemical behavior on the cork-derived graphene surface under different pH conditions using cyclic voltammetry. They then used differential pulse voltammetry to quantify it. The sensor showed a linear response from 30 to 1000 µM, with a limit of detection of 133 µmol L−1 and a limit of quantification of 443 µmol L−1.
The device was tested on real beverage samples bought at a local supermarket: a dry red wine and an industrial grape juice. The researchers measured caffeic acid at 19.2 mg L−1 in the wine and 41.6 mg L−1 in the grape juice.
The work adds to growing interest in bioderived laser-induced graphene as an alternative to more conventional screen-printed electrodes. The paper notes that laser-induced graphene has been explored on synthetic substrates such as polyimide and PVC as well as natural materials including lignin, cellulose, wood, leaves, orange peel and cork.
For beverage producers, the approach could matter because it points to a simpler and potentially cheaper way to monitor phenolic compounds in real wine matrices while also reusing an industry byproduct. That could make it useful for quality assurance work or for checking consistency across batches, although the study was limited to commercial samples of red wine and grape juice rather than production-scale winery testing.
The authors said the sensor combines simplicity and low cost with the use of bioderived waste carbonaceous material. They also framed the use of discarded cork as part of a broader shift toward upcycling waste materials and reducing carbon footprint in analytical technologies.