Certain plastic compounds are transferred to the potatoes when they are cooked in the microwave, as confirmed by a team of researchers from the University of Almería. The study, published today in the scientific journal Food Chemistry, concludes for the first time that during this process substances are formed whose impact on health is still unknown.
There is a wide variety of tricks and tips to cook potatoes quickly and easily, among which cooking in the microwave stands out. It is a practice that many already practice in their daily lives, to save time, and now it has been proven that bags of potatoes already prepared for cooking in this appliance can transfer some plastic compounds to the food.
The researchers analyzed packaged potatoes sold in supermarkets, which, like other products, go through a series of processes that guarantee their food safety. This includes plastic, they indicate, which if it does not receive a specific treatment to withstand high temperatures, it can melt or cause the migration of harmful substances to food.
To avoid possible adverse effects, they explain, there are special containers prepared to withstand cooking, such as those used for pre-cooked meals. The study focuses on how small changes in the way food is prepared, such as cooking in the microwave, can have a significant effect on long-term chemical exposure.
This is proven by the conclusions of the article ‘Cooking food in microwavable plastic containers: in situ formation of a new chemical substance and increased migration of polypropylene polymers’, which the Discover Foundation reported in a statement. The analysis was carried out only on the bags of potatoes prepared for cooking. “We chose this food because it is basic and is usually consumed frequently. In addition, it has a chemical composition that could interact differently with plastic materials,” says Francisco José Díaz Galiano, one of the researchers.
This first case study was carried out in what scientists call “untargeted analysis,” so they did chemical analytical tests without knowing what exactly they were looking for. To do this, different bags of potatoes prepared for cooking that they purchased in local supermarkets in Almería were analyzed, and all the substances that arose during the cooking process were identified in different ways: crushed and whole, with and without the bag.
In addition, they used boiling and microwave distilled water, with the original container and in a microwave-safe glass container. The experts explain that they cooked them for the time established on the product labeling according to the type of cooking and that they also analyzed the uncooked potatoes.
After tests in the laboratory, experts identified a series of polymers (plastics) that are transferred only when the potatoes are cooked inside the bag in the microwave. Specifically, they found an unknown compound made up of two molecules, the first of which comes from a natural product, maltose (a sugar produced when cooking some foods and potentially harmful as it has a high glycemic index). Consuming large amounts of maltose, however, can affect blood sugar levels due to its rapid conversion into glucose. The other molecule comes from a synthetic product that they have not been able to identify at the moment.
What they have been able to verify is that the compound is formed in situ due to the chemical reactions that occur in the plastic and the food when heated in the microwave. “Although we know how it is formed, we have not yet determined exactly what it is or where exactly this compound comes from. Only because it is produced in this way, and because it is partially made up of maltose, its effects on health are not clear,” explains Díaz Galiano.
The team of experts will continue the research to check whether this compound appears when cooking other packaged foods and evaluate these molecules to check their effects on human health.
