Many people use plastic bags for storing or freezing leftovers or fresh foods. It seems convenient to take the plastic bag out of the refrigerator or freezer and just pop it into the microwave to reheat or defrost. But is it safe?
Yes, it’s safe to use plastic storage bags in the microwave, provided you leave the top open at least an inch to vent the steam. You should also place the bag on a microwave-safe plate to catch any drips or juices from the food as it cooks or defrosts. Also, avoid overheating the food, as the bag may start to melt.
Plastic bags will melt at very high heat, so you must watch that the food you are microwaving doesn’t reach a temperature high enough to cause the melting to begin. Food storage bags are typically made of polyethylene, which has a melting point of about 230° F (110°C). Food in the microwave is usually fully cooked at 165° F (74° C).
For that reason, foods that need to get very hot or cook for a long time are not suitable for microwaving in a plastic bag.
Can You Microwave Ziploc Bags?
Ziploc is a brand name for bags that close securely with a plastic zipper. These bags are great for storing small things like frozen vegetables and foods with sauces or liquids. But if you freeze leftover creamed peas and want to both defrost them and heat them in the microwave, is it safe?
It is safe to defrost and heat food in Ziploc bags, but Ziploc recommends that you open the zipper closure about one inch to vent. The company also cautions that you should be careful picking it up because the bag may get hot.
You may wonder whether the bags contain chemicals that may contaminate the food when the bag gets hot. Ziploc assures its customers that the bags are BPA free. BPA is a chemical that imitates estrogen and is associated with the growth of prostate cancer.
Ziploc bags are also free of dioxins, which are also associated with cancer.
Ziploc also makes bags with slider closures, which are easier for some people to open and close. These bags can be used the same way as the zipper-close bags.
For steaming foods such as vegetables and fish, you can buy bags specially made for the microwave from Ziploc. These are vented to allow steam to escape while cooking.
How Long Can You Microwave A Ziploc Bag?
In a microwave, the cooking time needed depends on the type and amount of food, as well as the power level you are cooking on. The kind of container can increase or decrease the cooking time needed, but not significantly.
It’s the food inside the bag, not the bag itself, that determines how long you can microwave a Ziploc bag. If the food inside the bag exceeds the maximum temperature the plastic can withstand, there is a chance the bag will begin to soften or melt.
Consider that it is possible to boil water in the microwave. Water boils at a temperature of 212° F (100° C), so if you are heating something that contains a liquid, such as soup or gravy, and it begins to boil, it could cause the bag to soften or stretch.
In any case, boiling water or other liquid in a plastic bag is a bad idea because of possible leakage. You could burn yourself. Instead, pour the contents of the food into a microwave-safe bowl.
Microwave cooking is always inexact because there are so many variables, including the wattage of the microwave oven you are using. When heating any food in the microwave, no matter whether it’s in a bag or a bowl, it is always advisable to initially set a timer for less time than recommended.
When your timer is up, check the progress of the cooking and add more time in small increments to finish the process. If you’re cooking in a plastic bag, this will also allow you to check the soundness of the bag.
Keep in mind you can pause the microwave and check the food (and bag) at any time during the cooking process.
Can You Microwave Other Freezer Bags?
It’s convenient to microwave food that’s been frozen in freezer bags. You can first defrost the food in the bag at a lower power level, and then finish cooking it at full power.
It is safe to microwave any kind of freezer bag, as long as you follow precautions about venting and avoid high food temperatures. Freezer bags are made of the same polyethylene material as regular storage bags. The only difference is that freezer bags are a little thicker.
Therefore, the same cautions for microwaving food in a regular storage plastic bag also apply to freezer bags.
Are Foodsaver Bags Microwave Safe?
Foodsaver is a brand name for a kitchen appliance that creates a vacuum seal on food placed within special storage bags. Foodsaver bags are plastic and are available in several sizes.
It is safe to microwave certain foods in Foodsaver bags, according to the manufacturer. The Foodsaver company recommends that you do not cook raw foods or foods with a lot of oil. Vent the bag by cutting off a corner to let the steam out while cooking.
Foodsaver bags are made of polyethylene with a layer of nylon on the outside. The nylon strengthens the bag, and they can be used for heating food that’s already been cooked or for sous vide cooking, which involves simmering below the boiling point.
Foodsaver makes a bag specially for microwave cooking. The quart-sized bags can be vacuum-sealed and placed into the microwave without cutting them to vent. The bags are recommended for preparing meals ahead of time, freezing, and then cooking at a later time.
Are Microwave Popcorn Bags Safe?
Commercially-made microwave popcorn bags are made of paper, so they don’t have the same problems with overheating that plastic bags tend to have. However, there are concerns with certain chemicals in the bags.
Microwave popcorn bags may contain perfluorinated compounds (referred to as PFCs, PFAs, or PFOAs), the same chemical found in Teflon non-stick finishes. These have been linked to certain kinds of cancer in tests on animals, but the link to human cancer is inconclusive. Still, the American Cancer Society classifies PFCs as a “potential” health risk.
Over the past decades, manufacturers of microwave popcorn have been designing bags with lower levels of PFCs or eliminating them altogether. In a study done in 2019, only two brands of bags out of seven examined were above limits of PFCs; the remainder had levels that were not detectable.
Are Stasher Bags Microwave Safe?
Stasher bags are reusable storage bags made of platinum silicone. They are designed to be used, washed, and used again many times. Properly cared for, the bags can last many years.
Stasher bags are microwave safe, according to the manufacturer. You can freeze prepared foods in them and then defrost and reheat. Just be sure to open the bag a little to vent them.
Are Ikea Ziplock Bags Microwave Safe?
IKEA makes a zipper-lock bag called the ISTAD that is designed to be reusable. IKEA states that it can withstand temperatures of up to 122° F (50° C).
Some microwave foods cook at a higher temperature than IKEA ISTAD bags can handle, so if you use them in the microwave, use short cooking times and low power.
Are Great Value Ziploc Bags Microwave Safe?
Great Value bags are the house brand of storage bags sold by Walmart. The bags are similar to Ziploc brand and are also made of polyethylene plastic.
Like Ziploc, Walmart recommends that you place the bag on a microwave-safe plate and vent the bag by opening it one inch.
Walmart also states you should not microwave anything in the bags for longer than two minutes. They advise that heating food above temperatures of 120° F (48-50° C) will cause damage to the bag.
Further they, state that you should only defrost or reheat food in Great Value bags, and you should avoid boiling or cooking raw foods.