Is every plastic container microwave-safe? Let us delve deeper into the understanding of appropriate type of plastic materials and their respective safety standard symbols.

What is food-grade plastic made from?

Food-grade plastic containers are usually made from type #5 plastic, or Polypropylene (PP), which comes in various opaque and translucent colors such as white, red, etc. This is due to the material’s wide range of suitable applications. The key characteristics of PP plastic are as follows:

1. Free from Contaminants

   Polypropylene is a safe material for food use because it does not contain harmful substances that could potentially impact health, such as Bisphenol A (BPA), which can interfere with hormonal functions in the body and is often referred to as an endocrine disruptor.

2. Heat Resistant

Polypropylene is a heat-resistant plastic material, capable of withstanding temperatures up to approximately 100°C without deforming or melting. Therefore, when it comes to hot food, polypropylene is an excellent choice.

3. Resilient to Chemicals

Polypropylene does not react with chemicals found in food, such as oil, alcohol, acids, and alkalis. It has high chemical resistance, making it safe for storing a diverse range of food items.

4. Preserves Food Freshness

Thanks to its excellent permeability, polypropylene effectively prevents water and oxygen penetration, helping to slow down food deterioration, including its smell and taste. Thus, when using polypropylene for food storage, you can be confident that it will help prolong the freshness of the food.

5. Impact Resistant

Polypropylene is a sturdy and resilient plastic material that can withstand impact well. This makes it ideal for transporting goods and storing food that requires safety and durability.

Photo by Alesia Kozik

How to Check if Plastic Containers Are Microwave Safe

Even though PP #5 plastic is safe and suitable for food usage, it is advisable to use polypropylene that has been certified safe for food standards to ensure that no harmful substances are mixed in with the product. This is particularly important when warming food at high temperatures in a microwave. To know which plastic container symbols are safe for microwave use, follow these steps:

1. Check the Label on the Packaging

Those with keen eyes might have noticed symbols, the word ‘Microwaveable’ or a microwave icon beneath plastic food storage containers. If these symbols are on any plastic container, you can confidently use them to warm food in a microwave.

2. Understand Microwave Heat Levels

Additionally, the packaging will display a symbol indicating the recommended heat level. So, be mindful of the heat level used in the microwave. If the temperature exceeds what the plastic can withstand, the container may melt or deform.

3. Read the Manufacturer’s Instructions

Read the instructions from the plastic product’s manufacturer, which may include specific recommendations for microwave use, such as appropriate timing, correct usage, and more. Generally, we should not use them to cook food that requires high temperatures for extended periods to ensure that the food is thoroughly cooked. Plastic containers are suitable for warming only.

Photo by Erik Mclean

Precautions for Using Plastic Containers in the Microwave

1. Do Not Microwave the ‘Lid.’

Even though plastic containers can withstand heat, it is not advisable to microwave the ‘lid .’If the lid is ‘transparent,’ it is likely composed of other types of plastic, such as PETE1 or PS6, unsuitable for microwaving. Therefore, always remember to remove the lid before warming food, or if certain types of equipment are unsuitable for microwave use, avoid using them to prevent potential hazards.

Avoid using objects containing metal components or chemicals that could react when exposed to microwave heat. This could cause an accident, such as a fire.

2. Avoid High-Sugar and High-Fat Foods

Microwaving foods high in fat or oil, such as bacon, garlic-fried pork, or sugary food, such as sugar-glazed donuts, including sauces with high concentrations of sugar and fat, should be avoided. Sugar retains moisture and can absorb heat. Meanwhile, foods high in fat often heat up quickly, causing an accelerated thermal reaction in the microwave. This can damage plastic containers that come into contact with the food.

3. Single-Use Plastic Containers from Convenience Stores

Single-use plastic food containers from convenience stores

Ready-to-Eat meal containers that are microwaveable are designed for single use only.

For safe microwaving with plastic, pay attention to reading the instructions or labels on the packaging to make informed and safe decisions. Furthermore, reusing plastic food containers can be convenient for transporting meals, and it also helps to reduce the amount of single-use packaging waste.