What ‘microwave-safe’ on your takeaway box really means

She further explains that the safety of the container depends on factors such as the “type of plastic, the temperature reached, the fat and sugar content of the food, and how long it is heated”

In other words, a microwave-safe label should be viewed as guidance for its intended use rather than a guarantee that no substances will migrate into food under all circumstances.

DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.

Can chemicals or microplastics still leach into food?

Microwaving takaway boxes with oily, greasy, or very hot foods should be especially avoided (Ai generated image)

Potentially, yes, says Pandey adding that there is evidence that some food-contact plastics can release small amounts of chemicals and microscopic plastic particles during normal use, including heating.

“Migration tends to increase with higher temperatures and with foods that are rich in fat or oil, as these can enhance the transfer of certain compounds from packaging into food,” she says.

While regulatory authorities establish migration limits intended to keep exposure within safe levels, research on the long-term health effects of repeated, low-level exposure to microplastics is “still evolving”.

From a nutrition and public health perspective, Pandey says it is sensible to minimise unnecessary exposure by avoiding prolonged heating in plastic containers, especially for oily, greasy or very hot foods.

How can you tell if a takeaway box is suitable for reheating?

Before microwaving a takeaway container, Pandey advises looking for a clear “microwave-safe” label or the microwave symbol and ensuring the container is intended for food contact.

“Containers made from microwave-safe polypropylene (PP), identified by recycling code #5, are generally among the better plastic options for microwave reheating,” Pandey tells indianexpress.com.

However, she cautions that the recycling number alone does not guarantee microwave safety and should always be accompanied by a “microwave-safe designation” from the manufacturer. If the container has no label or is visibly damaged, cracked, stained or has become brittle with repeated use, it’s best not to microwave it.

Which takeaway containers are best avoided?

Some types of takeaway packaging are best avoided for microwave reheating, even if they don’t visibly melt.

Pandey says “expanded polystyrene foam” (Styrofoam) can soften and deform when exposed to heat, while “thin, clear plastic containers” that are not specifically labelled microwave-safe may also warp or degrade at microwave temperatures.

She also points to black plastic takeaway containers, which have come under increased scrutiny in recent years due to concerns about recycled electronic waste contaminants in some products.

Thin, clear plastic containers that are not specifically labelled microwave-safe may also warp or degrade at microwave temperatures (Ai generated image)

“Although regulations and manufacturing practices continue to improve, many experts recommend transferring food to glass or ceramic when possible rather than relying on black plastic for reheating,” she says.

She adds that a container remaining intact after microwaving does not necessarily indicate that it is appropriate for repeated heating or that no chemical migration has occurred.

What’s the safest way to reheat takeaway food?

Pandey recommends a simple habit: transfer your takeaway food to a microwave-safe glass or ceramic dish before reheating. “These materials are stable at high temperatures and do not pose the same concerns about chemical migration associated with some plastics.”

She also recommends:

• Reheat food until it is steaming hot throughout, ideally reaching an internal temperature of 74°C for leftovers.
• Stir food midway through heating to reduce cold spots.
• Avoid microwaving food in damaged or heavily scratched plastic containers.
• Never microwave containers made of metal or aluminium foil unless specifically designed for microwave use.

“Using glass or ceramic for reheating is a simple habit that helps reduce unnecessary exposure to packaging-related contaminants while ensuring food is heated more evenly. It is particularly advisable for foods that are high in fat, contain oils or sauces, or require longer reheating times.”

To put it straight, “microwave-safe” label simply means a container is designed to withstand microwave heating under specific conditions. It does not automatically mean it is the safest option for reheating every type of takeaway food.

DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.