The non-stick coatings used in pans are responsible for, for example, the tortilla sliding and the rice not sticking. In the last fifteen years, alternative non-stick coatings to the questioned PFAS have emerged. They are ceramic coatings, also called green, and we have put them to the test.
Specifically, at the University of Córdoba we have examined four types of novel non-stick coatings, two of them based on fluoropolymers (PFA and PTFE) and two others on ceramics.
We have tested everything that is required of a frying pan: its ability to repel water (hydrophobicity), roughness, surface damage, take-off strength and pressure, etc. They are measures of their release and non-adhesion capacity. It depends on whether the tortilla sticks or not and whether it is more or less easy to damage.
The work has proposed a simple protocol to compare the efficiency of various non-stick coatings. We prepare up to 90 pancakes consecutively from a very adherent dough, without any type of fat, and we analyze the behavior of the coatings. The study has been published in the Journal of Food Engineering.
Why do we test green materials? It remains unresolved what materials to use for coating pans. PFAS, perfluoroalkylated and polyfluoroalkylated, are chemical compounds that have been present in many everyday products, from kitchen utensils to food packaging materials, since the 1940s.
All PFAS contain carbon-fluorine bonds, which are among the strongest in organic chemistry. Hence, they can persist in the environment and in the human body for a long time. PFAS have been linked to potential adverse health effects, including hormonal and developmental problems, among others. Certain PFAS are no longer manufactured in the United States and phase-out plans have been initiated.
Teflon® is not exactly the same. It is polytetrafluoroethylene, better known as PTFE. It is a synthetic polymer with an amazing ability to prevent food from sticking and has been a lifesaver in the kitchen for decades. But is it a PFAS? That’s where the controversy begins!
Although it shares some similarities in its carbon-fluorine bonds, PTFE has a unique chemical structure that distinguishes it from traditional PFAS compounds. In any case, the European Union is debating limiting the use of PTFE in the future. Given this panorama, it is urgent to find materials that can replace it.
Ceramic coatings have come to the rescue as promising alternatives. They are based on organically modified silica and are produced using sol-gel techniques. This means that a gel is formed from a suspension of particles in a liquid (sol) that begin to add to each other forming a capillary network (sol-gel process). They are the lightest solid materials known.
In laboratory tests, these materials have been shown to offer excellent toughness, high temperature resistance, wear resistance, good adhesion to metals and impressive hydrophobic and non-stick properties. Promising progress has also been made in the development of self-healing solutions.
But not all is perfect. They have a reduced release capacity, lose their non-stick properties sooner, change color, stains appear and cleaning difficulties arise.
Since PFAS and Teflon® are very effective in terms of non-sticking, the interesting thing is to find materials that have the same properties. In our study, ceramic coatings showed potential: they are very hard, wear-resistant, and withstand much higher temperatures than fluoropolymers. But they still need to improve their non-stick ability.
So what does all this tell us about the future of nonstick pans? First, it shows that there are more options available beyond Teflon®. With science constantly evolving, ceramic nonstick coatings and other alternatives are expected to continue to improve in terms of performance and durability.
From PTFE to ceramic coatings, there is a wide range of options available to meet different needs in the kitchen and find the perfect pan.
This article was originally published on The Conversation. Its authors are: Oscar Rodríguez Alabanda, Contracted Professor Doctor of the Manufacturing Process Engineering Area, Department of Mechanics of the University of Córdoba; Guillermo Guerrero Vacas, Professor of the Manufacturing Process Engineering Area at the University of Córdoba.
