Are all plastics microwave safe?

(Published on 1 May 2007 in 'Women at Work' - W @ W - a supplement of the Daily Mirror, Colombo, Sri Lanka)

Every visit to my Aunt Jigna is a nightmare. I return with frayed nerves and a splitting headache. She has an opinion about everything. As she rambles on, I comatose myself taking comfort in a beautiful world where silence prevails. Just as I had reached into a blissful stupor – I heard my Aunt shriek. She held in her hand a deformed plastic bowl and bore a flabbergasted look.

As I sat her down, I learnt that it was the microwave that was to be blamed. “Was the bowl microwave safe?” I enquired. All I could hear was a volley of abuses hurled at the microwave oven. This brought us to the most obvious question: Are all plastics microwave safe?

Today, there is a lot of kitchen ware that is made of plastic. Different plastics serve different purposes in the kitchen. Storage and reheating, being the main two functions. Majority of the plastic kitchen ware is specially designed to withstand high temperatures. But this does not mean all of them are. It is wise to check the item before presuming that it is microwave friendly.

Plastics that are designed to withstand microwave temperatures will be marked accordingly. Some products are labelled with the term ‘Microwave Safe.’ or carry a microwave symbol. This is the manufacturer’s way of letting consumers know that a product has been designed to withstand microwave heat without melting or warping. Others provide instructions for proper microwave use – informing you of the temperature that it is able to with-stand. If used inappropriately, the plastic container may warp or melt when exposed to extremely hot temperatures. It is best to look for plastics that are labelled for microwave use and follow the manufacturer’s instructions. Why take chances? If your container isn’t labelled for microwave use, it’s best to choose something that is.

However it is not necessarily unsafe to use a plastic container in the microwave if is not labelled as microwave compatible. But it is wiser to select a microwave safe dish and have the assurance of knowing that the item was tested and evaluated for this purpose.
Frozen meals are often packaged in microwavable trays made of PET, a type of plastic which is also used to make jars and bottles. While microwavable PET trays are specially fabricated for high heat resistance, the jars and bottles made with PET could warp if subject to high heat.

For some time there has been an email doing the rounds that claims that microwaving food in plastic containers or plastic wrap is dangerous. The message warns that chemicals can seep out of the plastic and into the food, causing cancer and other diseases. That is when food is placed in a plastic container and cooked in a microwave; substances used in manufacturing the plastic may leak into the food. However, this is not true as manufacturers of food products that belong to well known brands, closely regulate the quality of the plastic containers and ensure that no such chemicals migrate from the plastic into the food.

Here are some tips from Miss Know All’s kitchen to keep in mind when using your microwave:

( Don’t microwave food in plastic storage bags from the grocery store.

(Vent the container before microwaving food that is leave the lid ajar.

(Takeout containers, water bottles, and plastic tubs or jars made to hold yogurt and foods such as cheese, mayonnaise, and mustard are not for use in the microwave.

(Takeout dinner trays that can be put in the microwave are designed for one-time use only and this will be mentioned on the package.

(Don’t allow plastic wrap to touch food during microwaving as it may melt.

(If you’re confused about use of plastic containers in the microwave, transfer food to glass or ceramic containers labelled for microwave use.

(Microwaving in containers that are round or oval in shape can help foods heat more evenly. With rectangular containers, the corners tend to receive more energy, which can cause food to dry out or overcook in these areas.

This quote by Bryan Miller is for all the great cooks I know (including Aunt Jigna, who I must admit makes the most awesome prawn curry!) - “The qualities of an exceptional cook are akin to those of a successful tightrope walker: an abiding passion for the task, courage to go out on a limb and an impeccable sense of balance.”

Miss Know-All
miss.know.all@gmail.com