Is this aluminium tray microwaveable or not? Response to NF D21-314 standard

This may seem counter-intuitive to a whole generation of consumers who would have been wary of putting metal utensils in microwave ovens. And yet, aluminum trays and other steel packaging are microwaveable. A godsend, at a time when all-recycling and reuse are encouraging the use of these materials.

Microwavable and safe, provided you’ve been properly tested! In this case, standard NF D21-314, published in January 2023 in the AFNOR collection, describes a method for determining the suitability for microwave reheating of metal or part-metal articles (bare or coated) used as food or beverage containers, whether they are intended to be used once or many times. In a metal tray, the food is heated through the opening, so the waves don’t penetrate the metal, but the result is very homogeneous,” Gilles Mangin, research engineer at ArcelorMittal, who drew up this document, explains to Enjeux magazine. 85.5% of steel packaging sold (such as cans) is recycled. What’s more, they’re robust and don’t break.

No sharp edges

The standard details the principle, the equipment, the test specimens, the calibration of the microwave oven (determination of useful power), the operating procedure (performance tests, safety tests), the marking, labeling or instructions for use (which must be communicated to consumers), and the test report. Tests were carried out by independent laboratories, which verified that nothing abnormal was happening in the oven and that the packaging was fit for use,” explains Gilles Mangin. The shape of the packaging is important: there must be no sharp edges. Issue no. 1 is user safety. Recommendations on proper use must be communicated: place the container in the center of the oven, not near the sides, do not use a metal lid… Safety instructions are described in the standard.” The method used aims to exclude both items that could damage the oven, for example by arcing, and items that could be damaged by microwave heating.

The NF D 21-314 standard fills a real gap, says the expert. Today, claims for the compatibility of metal items with microwave ovens are sometimes based on standard NF EN 15284, which deals with ceramic, glass, glass-ceramic or plastic cookware… Nothing to see! There was therefore a need for a reference document, and the plan to submit this French standard to CEN will enable us to meet this objective on a European scale.

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