Brazilian Scientists Create Cork Sensor to Detect Banned Sodium Nitrite in Wines

Researchers at the Federal University of São Carlos (UFSCar) in Brazil have developed a new sensor made from cork that can detect sodium nitrite in beverages, including wine, mineral water, and orange juice. The team, led by Bruno Campos Janegitz, head of the Laboratory of Sensors, Nanomedicine, and Nanostructured Materials (LSNano), created the device to address concerns about sodium nitrite contamination in drinks. Sodium nitrite is commonly used as a preservative and coloring agent in processed meats like bacon and ham. However, its use in beverages is banned in Brazil and most other countries because it can form nitrosamines, compounds linked to cancer.

The research was published in the journal Microchimica Acta. According to Janegitz, the motivation behind the project was to develop a simple, fast, and accessible method for detecting sodium nitrite to ensure the safety and quality of liquid foods. The sensor offers a low-cost way to identify this contaminant, which is important for both producers and regulators who monitor food safety.

To build the sensor, the team selected cork for its sustainability, availability, and low cost. They used a laser to convert the surface of the cork into graphene, a highly conductive form of carbon. This process creates pathways on the cork that are essential for detecting sodium nitrite through electrochemical oxidation. After lasering, they applied a waterproof spray to prevent liquid absorption and used nail polish to define the active area of the sensor. The pieces were then oven-dried at 40°C to optimize their properties.

Testing involved exposing the sensor to diluted solutions of water, juice, and wine containing sodium nitrite. The device demonstrated strong sensitivity and stability, successfully detecting concentrations relevant to food safety standards. The researchers emphasized that their process does not require toxic chemicals and is environmentally friendly.

Currently, the project is undergoing laboratory validation and further design refinement. The team believes that with additional development, this technology could become a practical tool for monitoring contaminants in the food and beverage industry. The next phase will focus on adapting the sensor for real-world applications outside of laboratory settings.

The development comes at a time when food safety remains a global concern. Rapid and affordable detection methods like this cork-based sensor could help prevent harmful substances from reaching consumers and support regulatory efforts to maintain high standards in food production.