How long does a steak last in the fridge? Three Spanish scientists invent a label to tell if food has gone bad.

Pilar Granado, Pablo Sosa, and Luis Chimeno never imagined that a steak forgotten in the refrigerator of their student apartment in Elche would unite their lives. Was it safe to eat? Was it better to throw it away? Years later, that anecdote would become the seed of an invention that has taken them to Iceland as one of the promising young inventors vying this year to win the Young Inventors Prize 2025 , a recognition awarded by the European Patent Office (EPO) to innovators under 30.

The device is a biosensor in the form of a smart label that allows suppliers and consumers to check the freshness of perishable foods in real time. “The technology we designed uses smart indicators (molecules) within the label. As bacteria multiply, they generate compounds that interact with the label's indicator, causing a gradual color change from white to black,” explains Pilar Granado. The Oscillum team describes the label as “a shield” against various invisible enemies. This color transition reacts to Salmonella , E. coli , and Listeria , among other bacteria, and also works for packaged foods once they are opened. “The expiration date is a reference as long as the packaging remains in the same conditions, but once it is opened, its entire microbiological environment changes,” adds Luis Chimeno.

The WHO estimates that each year, some 600 million people become ill from eating contaminated food. To avoid this, many consumers often rely on the appearance of products or standard expiration dates to assess their freshness; however, this leads to unnecessary waste of still-edible food. The device invented by these Spanish biotechnologists works on meat, fish, fruit, and prepared foods. Its creators hope that its use will reduce waste while offering certainty to the public. “We realized how often we throw away forgotten food by eye and that we all have the same problem in our refrigerators,” replies Pablo Sosa.

It is estimated that more than 1 billion plates of food are wasted every day , according to a recent report by the United Nations Environment Programme, which amounts to 132 kilograms per person, or one-fifth of all food available for human consumption and 8% of global greenhouse gas emissions. “We have seen that in those markets where food safety infrastructure is not 100% optimized or is not a priority, such as certain countries on the African continent or in Latin America, this technology solves a huge problem with little investment,” explains Chimeno. Of the total food wasted in 2022, according to the UN, 60% was discarded by households, 28% by food service providers, and 12% by retail outlets.

The EPO awards the European Inventors Prize each year to recognize significant contributions to innovation and technological development, and every two years organizes the Young Inventors Prize for young researchers who use technology and creativity to address global challenges in line with the UN Sustainable Development Goals , 17 interconnected objectives adopted by the United Nations in 2015 as a universal action plan for building a better and more sustainable future. In Spain's case, the label is biodegradable and seeks to reduce emissions, foodborne illnesses, and food waste.

The project has been funded so far with public funds, including those from the Spanish Government's Center for Technological Development and Innovation (CDTI), which allowed them to complete the technology a few years ago. In 2017, they won the first prize for entrepreneurship and the Miguel Hernández University of Elche granted them space in its science park. Granado, Sosa, and Chimeno have also won The Gap in Between awards, organized by the Social Nest Foundation platform, and were finalists in the EIT Food Innovation Prizes , among other accolades.

The Oscillum project is in the commercialization phase and is seeking partners to manufacture the device. “We've found great consumer acceptance in Europe. What we're looking for here is to sell it directly in supermarkets, since the industry is a bit more conservative when it comes to this type of technology. What we want is for people to buy the label and be able to use it at home,” says Sosa.

Each of the 10 projects selected in this 17th edition of the awards has been awarded €5,000. “[The competition] puts inventors at the front of the field against other competitors and gives prestige to the invention and its commercial development,” says Luis Berenguer, communications director and spokesperson for the European Patent Office. “At the same time, it helps make our lives, the lives of all citizens, better,” he emphasizes. The jury will select the winners in three special categories this Wednesday, June 18, who will each receive €15,000. The winner of the public vote, via the EPO website , will receive an additional €5,000.