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Can You Put a Plastic Bag in the Microwave?

When you are in a hurry and need to warm up food quickly, you may find yourself wondering, “Can you put a plastic bag in the microwave?” This is an important question to consider as you do not want to harm your health or ruin your food by taking an inappropriate shortcut. In this article, we will answer this question and discuss safety concerns associated with microwave heating Ziploc bags or other types of plastic bags.


Plastic bags in the microwave?

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The short answer is that yes, you can microwave plastic bags as long as certain precautions are taken. Many plastic bags meet the guidelines of the Food and Drug Administration concerning microwave safety.

Ziploc bags are commonly used to store food that will be kept in the refrigerator or the freezer. The convenience of keeping the food in the bag and then placing it in the microwave sounds nice. However, should you do it? As long as you follow certain steps, you can safely heat your food in a plastic bag in the microwave.


Vent the steam

Before you microwave bags, you need to properly vent the steam. To do so, you should leave the top of the bag open at least one inch. This will allow the steam to escape during the heating process.


Use a microwave-safe dish

Put a microwave-safe dish, such as a plate or bowl, underneath the bag. This will allow the dish to catch any juices that may drip out of the bag as the food gets warm. Microwave containers will have an icon on the bottom to indicate that they are microwave safe.


Do not overheat

It is essential that you do not overheat the bag. If you do, it may begin to melt, which will cause a mess and ruin your food. Typically, food storage bags are made with polyethylene. The melting point of polyethylene is about 230 degrees Fahrenheit.

Usually, food being defrosted or warmed up in the microwave does not reach this temperature. However, if you are preparing something that needs to get very hot or cook for a long time, you should not keep the food in a plastic bag when microwaving. In essence, it is generally safe to defrost or reheat food in a plastic bag, but you should not cook food in a Ziploc bag.


Be careful when removing the bag from the microwave

Regardless of whether you are reheating food or using the microwave to defrost the food, you need to be careful when taking the bag out of the microwave. The bag will probably be very hot and can burn you.


Ziploc Plastic Bags

One of the most popular brands of plastic bags is Ziploc. This brand name is synonymous with bags that close securely at the top with a plastic zipper. Ziploc brand bags can be used for a wide variety of purposes. You can store leftovers in them, portion out meat to go in the freezer, or put your lunch sandwich in one. When it comes to food in Ziploc bags, there is no shortage of options available.

According to the company, it is safe to microwave Ziploc bags as long as the precautions mentioned above are followed. However, you may be wondering about the chemicals in the bags and whether microwaving them will harm your food. Ziploc bags are BPA-free and free of dioxins. As such, you do not have to worry about these chemicals contaminating your food.

If you are uneasy about microwaving basic Ziploc bags, such as the Ziploc sandwich bags, the company makes other options. For example, there are Ziploc containers and vented Ziploc bags that are designed to steam foods like fish and vegetables in the microwave.


Microwaving Times

When it comes to how long to microwave food in plastic bags, the answer depends more on the food itself than the bag. The amount of cooking time needed varies based on the type of food as well as the amount of food. The microwave’s power level also modifies the cooking time. The type of container holding the food does not modify the required cooking time by a significant amount.

When in doubt, you can start the timer for less time than you think the food will need and then monitor the progress throughout. One benefit of using the microwave is that you can stop it at any time to check on the food’s progress and the integrity of the bag.


Freezer bags

Freezer bags are similar to plastic bags, but they are made with a little thicker plastic to endure the freezer temperatures. The composition is the same, though. Low density polyethylene plastic is used, just like with regular storage bags. For this reason, if you are heating food from a freezer bag, you should follow the same guidelines outlined above, such as venting the bag and being cautious when removing the bag from the microwave.


Dangers of microwaving plastic storage bags

There are numerous safety concerns to be aware of if you choose to microwave Ziploc bags or similar styles of bags. While these are not deal breakers, they are to be carefully considered before choosing to use the bags in the microwave.


The bag can melt

The bags are thin and made of plastic, so if they are exposed to high temperatures they can melt. Typically microwaves do not reach the temperatures needed to melt the plastic, but if you cook an item in the microwave for a long time, the bag’s structure may begin to get soft and melt.

A melted Ziploc bag can cause quite a mess. It can fuse to food which will ruin whatever you were cooking or reheating. It can also burn your skin. While microwaving Ziploc bags is possible, this is a risk to be mindful of before deciding to do so.


Steam burns

If you do not properly vent your plastic bag before microwaving it, steam can build up inside the bag. This is dangerous because when you open the bag and the steam escapes, it can easily burn your hand and cause an injury.

To avoid this, be sure to leave the bag open about an inch while you are warming the food up. This allows the steam to escape during cooking instead of building up inside the bag.


Microwave cooking guidelines


Step 1: Select the correct type of bag

You should check the product information to see what the manufacturer says about using plastic bags in the microwave. For example, Ziploc has a microwave safe line of bags that are designed to be used in the microwave. Other companies may have similar options too.

While Ziploc bags are made of polyethylene, other cheaper brands may use PVC plastic instead. The PVC plastic is not as safe to microwave, as it may release harmful dioxins. This is why you should read the packaging to check for guidance on maximum temperatures or how to properly use plastic bags.


Step 2: Do not overfill the bag

When you are placing your food in plastic bags, be sure not to overfill them. When you place the bag in the microwave oven, the food will likely expand and steam will build up. This poses a danger as the bag could tear, leak, or pop open and break.

Any of these results will likely tarnish the food and make a mess in your microwave. Instead, it is better to ensure the bag is not too full before placing it in the microwave. By placing less food in the bag, there is room for the food and steam to expand without reaching the opening of the bag.


Step 3: Use a microwave safe dish under the bag

Plastic storage bags are not made to stand up. This is why it is not uncommon for them to tip over when in the microwave. If the bag has a small tear or hole in it, the liquid will leak out and make a mess in the microwave.

To avoid a caked on food mess, place a microwave safe dish or plate underneath the bag. This will also make it easier to remove the bag when you are done reheating the food.


Step 4: Vent the bag

Leave a small opening in the bag’s seal before microwaving. This allows the steam to escape and prevents it from building up in the bag, which can cause the food to get soggy and could cause pressure to build up in the bag to the point where the bag bursts.


Step 5: Use a low power setting

The safest options are to only microwave plastic bags to defrost food or for reheating food. Cooking food often requires too high of temperatures and should generally be avoided if you are keeping the food in a plastic bag. Ziploc bags melt when they reach too high of a temperature, so consider using a low power setting on the microwave to avoid overheating.

You do not want to use plastic bags with boiling water. So do not allow any liquids stored inside the bags to reach their boiling point or else the bag will begin to melt. Likewise, you should never submerge a plastic bag into boiling water.


Alternative options

If you are feeling uneasy about microwaving plastic bags when reheating foods or defrosting items, there are other options available. One idea is to buy Ziploc containers or other food storage containers that are deemed microwave safe. If you choose this option, you will not need to place a microwave-safe dish or plate underneath, as the storage container is holding all of the food.

Plastic products such as plastic containers should be used sparingly in the microwave. Check the bottom of the container to ensure that it is microwave safe before using it in the microwave. A better alternative is to use a glass dish or bowl for microwaving food.

You can also use proper bags that are designed for cooking or heating food, such as oven bags.

The cooking process is complex with multiple variables effecting food cooking time and ensuring that the food will cook evenly. Based on their chemical composition, some foods need very hot temperatures to properly cook, while others do not. Regardless of the type of storage container used or the brand used, the food inside matters and will dictate the amount of reheating time needed based on the components of the food. For example, if the food is high in fat or sugar, it can reach higher temperatures than water molecules which can cause the plastic bag to exceed its melting point.

To keep food fresh, you should use tightly sealed storage options such as Ziploc brand containers or other bags. The products are made to be durable and many are deemed safe for use in microwave ovens.

Related: Can Wax Paper Go in the Microwave?

Can you put a plastic bag in the microwave FAQ


Can you reheat food in a Ziploc bag?

Yes, you can. Be sure to check on the food regularly to avoid overheating it and damaging the integrity of the plastic bag.


Can I put a Ziploc bag in the microwave?

Yes. Just be sure to properly vent the bag to avoid having steam build up inside and do not use high power settings for a long duration of time.


How long can you microwave a plastic bag?

The manufacturer does not describe the standards. However, you should avoid overheating the contents or else the bag may melt. This is why it is a better option to set your microwave timer for less time and check on the food as it warms up in the microwave. You can always add more time if needed. A good rule of thumb is to use 30-second increments.


How do you know if a plastic bag is microwave safe?

Check the product packaging or manufacturer’s website for information about whether the bag is deemed microwave safe. When in doubt, choose a different option.


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