Researchers from the University of Almería conducted a study to understand what happens when packaged foods are heated in their original containers. They found that certain compounds can migrate into potatoes when they are cooked in microwaveable plastic bags sold with the product. The study, reported by Europa Press, shows for the first time that substances with unknown health effects can form in situ during this heating process.
According to a statement from the Discover Foundation, researchers evaluated packaged foods available in supermarkets. The investigation considered the various steps that ensure food safety, including packaging materials. When plastics are heated beyond their designed tolerance, they can melt or release potentially harmful substances into food. This is why many products come with guidance on whether they are safe for microwave use or require special containers.
To prevent possible negative effects, consumers are often advised to use containers specifically designed to withstand cooking. Yet, researchers noted that not all possible transfers of chemicals during the heating of packaged foods are fully understood. Francisco José Díaz Galiano emphasized this uncertainty, underscoring the need for continued study.
It is important to note that the food studied is a staple in many households and is consumed frequently. Its chemical makeup can interact differently with plastic materials, affecting the nature of any substances that migrate during heating. The first phase of the study used an undirected analysis approach, a method in which chemical tests are performed without a predefined target. This approach allowed scientists to screen for a wide range of substances released when potatoes are heated in plastic packaging.
Researchers purchased bags of potatoes that specify suitability for cooking, and they tested several cooking methods. They prepared potatoes in crushed form and whole form, with and without the bags, using both boiling distilled water and a microwave. The microwave was used in its original packaging as well as in a microwave-safe glass dish. Potatoes were cooked for the time indicated on the product label and, for comparison, raw potatoes were also analyzed.
The investigation employed a mimetic substance to simulate the interaction between packaging materials and real food. This technique helps replicate how plastic packaging may influence the molecular composition of cooked potatoes, a common practice in the agri-food sector to assess packaging safety. An analytical method known as high-resolution mass spectrometry was used to identify chemicals and compounds in the samples, including potatoes prepared in different ways.
Compound formation
Through this process, several polymers released from plastics were detected only when potatoes were cooked inside the bag using a microwave. The researchers identified an unknown compound formed by two molecular components, suggesting a complex interaction between packaging and food at high heat. One component originates from maltose, a natural sugar that can form during cooking. Maltose has a high glycemic index, meaning that consuming large amounts can rapidly raise blood sugar levels, a consideration for individuals managing glucose metabolism.
Another part of the unknown molecule appears to come from a synthetic source not yet identified. The team concluded that this compound forms in situ due to chemical reactions between plastic and food when heated in the microwave. Although the formation mechanism is understood, its exact identity and origin remain unclear. Because this compound is produced only under these specific conditions and partially comprises maltose, its potential health effects are not yet established.
These findings contribute to a growing body of knowledge on how packaging interacts with food during microwave heating and highlight the importance of continued research into the safety of microwaveable plastics. The study references a peer-reviewed article for further detail: S0308814623004697. [Source: University of Almería study]
Overall, the work underscores that while packaging innovation improves convenience, it also requires careful assessment of potential chemical transfers during cooking. As consumer habits include frequent reheating of ready meals, ongoing collaboration among researchers, industry, and regulators will help ensure that the foods people rely on remain safe when heated in common home appliances.