Are Compostable Containers Microwavable?

Compostable containers are gaining popularity. This is nothing to be surprised about when we take into account the dangers of single use plastics.

Companies like Starbucks (which are notorious for their takeaway coffee) now use compostable containers with no plastic lining. Their cups can either be composted or recycled with single-stream recycling.

The same goes for Sun Basket, a company that delivers organic and sustainable meal kits in 100% recyclable and compostable containers. Compostable packaging is replacing single-use plastics and that leads to unique questions like the one below.

Can compostable containers be heated in the microwave?

Not all compostable containers are microwavable.

Some containers are made with raw materials not capable of withstanding a lot of heat, thus not being microwave-compatible. Typically, containers that can be heated in the microwave are adequately marked.

In this article, we’ll explore the topic of compostable microwavable containers and determine what type of compostable containers may or not be microwavable.

What are compostable containers?

Compostable containers can be made with raw materials such as paper, corn, sugarcane, and bamboo, which can be decomposed.

In other words, compostable containers can be disintegrated and return nutrients to the soil so that new plants can grow. However, for that to happen, they need to be in a specific setting to properly be broken down.

Some compostable containers (or packaging) can be broken down at home with a simple compost bin (link to Amazon), while others must be decomposed in industrial composting facilities.

The reason why some materials need to be decomposed in an industrial facility is that they require high temperatures to decompose.

According to Eater.com, compostable food serving ware made from plants do not decompose in a simple backyard compost bin and needs to be processed in an industrial facility, using one of the following methods:

Windrow composting: This method involves creating several rows with compostable waste so that they can be rotated periodically and enough heat is generated to achieve the temperature needed to decompose compostable waste.

ASP composting: This method involves mixing organic waste with layers of bulking agents (such as shredded paper or woodchips) so that the air can traverse from the bottom to the top of the pile. Because this method is weather-sensitive, the compost is usually covered.

In-vessel composting: With this method, specially designed vessels or rotative drums are used to compost organic waste. This method is capable of decomposing a wide variety of waste in just a few weeks, and it takes less space than windrows.

What is a microwavable container?

People stationed at microwave towers in cold climates used to stand in front of microwave generators to warm themselves.

That was possible because we are made of water.

A microwave is able to heat food because the water molecules inside the food absorb the microwave radiation and thereby heat up and heat the surrounding food.

In other words, a microwave is not capable of heating something without water.

One might argue that a plate feels hot to the touch after being taken out of the microwave but that’s only because of the food perpetuating the heat.

Here is what the FDA has to say about microwavable containers:

“Glass, paper, ceramic, or plastic containers are used in microwave cooking because microwaves pass through these materials. Although such containers cannot be heated by microwaves, they can become hot from the heat of the food cooking inside.”

Food & drug administration

Some containers are made from raw materials that cannot handle high food temperature and may burn, melt, or get deformed from the heat.

Another thing to consider is that some containers may have chemical properties (like ink) that are transferred to the food, which you need to be careful about.

In fact, here are some thing you should never put in a microwave:

  • Aluminum foil: When metal is placed inside the microwave, the waves are reflected off of the item, which may cause the aluminum foil to burn rapidly and ignite.
  • Paper bags: Not all paper is created equal. Popcorn bags, for instance, are equipped with susceptors, a material that is made to consume radio waves produced by microwaves. Typical paper bags, however, do not come with susceptors and may catch fire.
  • Plastic bags or containers: When heated, plastic releases Bisphenol A, or BPA, an organic compound used to make plastic clear, and phthalates, which allow it to be supple. These may be transferred to your food.
  • Travel mugs: These are typically constructed with plastic or steel. Steel cups prevent your beverage from being heated and may cause friction from the waves emitted by the microwave. If it’s built from plastic, you have to verify whether or not it’s microwave-friendly, otherwise, it may spoil your food.
  • Styrofoam: Polystrene foam containers are also referred to as styrofoam containers. They should not go into the microwave because the material may melt and allow chemicals to be transferred to your food.
  • Chinese takeout boxes: Typically, Chinese takeout boxes include a thin metal handle, which may cause sparks or flames. Needless to say, it’s very dangerous.

Examples of compostable containers that are microwave-friendly

Lets Go Green is the name of a company that produces a variety of green products from utensils like forks, knives, and spoons, to disposable eco-friendly dinnerware like plates, bowls, and platters, and even compostable containers.

They have a wide range of compostable containers made from different raw materials like corn, sugarcane, bamboo, fallen palm leaves, and more.

Additionally, you can find info on whether a compostable container is hot and/or cold food-friendly, microwave-friendly, or compostable in commercial facilities.

For example, they have bowls made from 100% renewable sugarcane that can be heated in the microwave. Here is screenshot from their website:

Conversely, they also have compostable containers made from 100% corn that are not microwave safe, which means you shouldn’t heat food inside them.

In other words, it depends on the raw materials used, and whether or not they can withstand the heat generated within the microwave without getting damaged or leaching dangerous compounds to the food.

Bottom line

Compostable containers are microwavable, but pay special attention to the materials used, and whether or not the container is marked as “microwave-friendly”.

We know that it all comes down to the raw materials used, and unfortunately, some are not microwave-compatible as they are too brittle.

If you feel like this article was helpful, feel free to share with friends or family that may also find it useful. Lastly, thank you for reading.