Does Microwave Kill Bacteria? [Solved]

Does Microwave Kill BacteriaThese days microwaves are kitchen appliances in almost every home; they are the fastest way to reheat, cook, grill, or defrost food, depending on the make.

However, does microwave kill bacteria?

The heat generated by microwaves can kill bacteria; however, it also depends on heat produced, for how long, and to what internal temperature the food is heated to. Most foods should be microwaved to a temperature of 165 degrees Fahrenheit to kill bacteria.

This article answers whether a microwave can kill bacteria, among other topics like How do microwaves work, Can bacteria survive in microwave? The Effects Of Microwaves On Bacteria. How long a microwave takes to kill bacteria, among others

How Do Microwaves Work

A microwave contains magnetrons that create wave energy which vibrates water molecules in the food to produce heat.

Microwaves consist of magnetrons responsible for the creation of radio wave energy. Once you place food inside the microwave, the created microwave energy begins to bounce back and forth on the microwave’s metal walls.

The more the microwave runs, the faster the wave energy bounces, penetrating the food in the microwave. The wave energy collides with the water molecules in the food, causing them to vibrate. As the vibration continues, more heat is produced and distributed into your meal.

Can Bacteria Survive in Microwave?

Yes, a microwave will not kill bacteria unless food is heated long enough to reach the expected internal temperature.

As earlier stated, most foods need an internal temperature of 165 degrees Fahrenheit and a bit of stirring to distribute the heat evenly. However, if the food is not heated to this point, it may still contain bacteria that need extreme heat conditions to die.

Also, uneven microwave cooking may leave your food with hot and cold spots. The cold spots are definitely not heated to the right temperature; therefore, they have just been made warm enough to make a conducive environment for the survival of bacteria.

Studies Conducted on Effects of Microwaves on Bacteria

Microwaves can kill 99% of bacteria on surfaces and food from as early as 30 seconds of microwaving. The surviving bacteria may become resistant to heat.

Below are studies conducted to determine the effect of microwaves on bacteria.

1. Microwaving a sponge at high power kills 99% of bacteria

A study by the National Library of Medicine in 2006 proved that a microwave would kill 99% of bacteria on a sponge after microwaving it for a minute or two. However, wet your sponge before microwaving so it does not catch fire. Disinfect your dishwashing sponge every day by microwaving it for atleast 2 minutes.

2. A microwave kills E. coli within 30 seconds

It is also in the same study that it was discovered that a microwave could kill E. coli in the first 30 seconds of microwaving your meal at high power. E. coli is a common bacteria responsible for food poisoning.

3. Bacteria that survive microwaves may develop resistance

In 2017, another study discovered that the surviving bacteria after microwaving a dishwashing sponge might become resistant to microwaves or extreme heat.

The Effects Of Microwaves On Bacteria

The bacteria may die due to high microwave heat or experience enhanced growth.

How microwaves affect bacteria depends on the quantity of energy absorbed by the bacteria. When the frequency is administered consistently at high power for a long time, the bacteria will likely absorb a huge amount of heat energy, killing it.

However, dying of the bacteria is not always the outcome. In some cases, when the frequency of microwaves is not administered at a higher level, enough to go past the estimated thermal destruction level, some bacteria survive; others even experience enhanced growth.

In cases where a bacteria is enhanced in growth instead of death while microwaving a meal, it is usually because the bacteria are already resistant to the microwaves. If not, the microwaves were not administered at high power, or there was an uneven distribution of heat in the food when microwaving.

How Long Does it Take a Microwave to Kill Bacteria

Microwave heat may begin killing bacteria in your food from as early as 30 seconds to 5 minutes.

How long it takes to kill bacteria in a meal when microwaving depends on certain things. For instance, the quantity of heat the microwave is producing. The best way to ensure you kill bacteria from your meal is by heating the meal at high power.

Secondly, heat the meal to the estimated internal temperature. Cooking time may vary from one microwave to another depending on their voltage level. Therefore ensure the meal reaches the proper internal temperature than focusing on the time. A kitchen thermometer will be helpful at this point.

Thirdly, the quantity of the food will also determine how long it takes for microwave heat to kill bacteria. Large amounts of food may take longer to cook and reach the expected internal temperature. The meal may also need some stirring to ensure the heat reaches all aspects of the food to eliminate the bacteria.

Can Microwave Kill Bacteria in Food

The heat generated by the microwave can kill bacteria in food.

The microwave ensures the food’s water molecules vibrate, brushing against each other rapidly to generate heat. The generated heat then warms up the food killing all the bacteria.

Some bacteria, like E. coli, do not require much time to die; therefore, they will die within the first 30 seconds of heating.

It is advisable to cook your meal at high power to an internal temperature of 165 degrees Fahrenheit unless stated otherwise.

How Long Should Food be Microwaved to Kill Bacteria?

Food can be microwaved for 30 seconds to 2 minutes for bacteria to die.

However, the time may also vary, especially if the food is in high quantity. More time may be required for heat to thoroughly distribute through the meal and eliminate all bacteria possibly hiding in the cold spots.

You may also be required to stop your microwave and stir through your meal to help with the heat distribution, which will take a bit of your time, increasing the microwaving time.

What Temperature Kills Bacteria in Food?

The appropriate food temperature to kill bacteria for most foods is 165 degrees Fahrenheit.

Unless indicated otherwise on the food package, ensure you microwave your meal to the above-mentioned internal temperature. Especially meals that contain poultry, beef, pork, lamb, or veal.

However, different foods may require different types of internal temperatures to be safe for consumption; it is, therefore, appropriate to gather as much information as possible on a meal before placing it in the microwave for cooking and reheating.

You wouldn’t want to eat a meal heavily infested with bacteria that causes severe food poisoning or an extremely overcooked meal that has lost its flavor and health benefits.

Does Microwave Kill Bacteria on Sponge

Yes, microwave heat kills 99% of bacteria on a sponge when microwaved at high power.

According to a study by the National Library of Medicine, microwaving a wet sponge for 2 minutes kills 99% of its bacteria, which proves that microwaving could be among the best methods to disinfect your dishing washing and surface cleaning sponge atleast every day.

However, ensure never to microwave a dry sponge; always ensure it is wet to prevent the possibility of it catching fire and causing damage to your microwave.

What are The Health Risks of Microwave Radiation?

The most common health risk associated with microwave heat radiation is the explosion of food and liquids in the microwave, burns from hot microwavable plates and mugs, and burns from overheated meals.

It is rare to hear of cases of health issues due to exposure to microwave radiation. Microwaves are designed to ensure such injuries do not occur in the kitchen, for instance, in cases where huge amounts of microwave radition leak from the microwave through an opening to the point of causing harm to human beings.

How to Properly Clean and Disinfect Your Microwave?

Microwave a mixture of water, vinegar, or lemon to a boiling point. Let the water cool and steam up the interior of the microwave, and use a clean towel and fresh warm water to wipe the interior and exterior of the microwave.


  • Water
  • Lemon or vinegar
  • Microwavable bowl
  • Two clean towels
  • Extra warm water in an extra bowl
  • Mildly scented liquid soup


  1. Pour some water into a large microwavable bowl, add reasonable amounts of lemon or vinegar.
  2. Place your mixture of water and lemon or vinegar into the microwave and heat at high power until the water boils.
  3. Unplug the microwave and allow the water to stay in the microwave to a cooling point without opening the door.
  4. After the water has steamed up in the microwave, open the door, remove it, and add a sizeable amount of your mildly scented liquid soap.
  5. Dip one clean towel into the water, squeeze it and throughly wipe the inside of the microwave.
  6. Repeat the rinsing process with the extra warm water and another clean towel.

Tips for Killing Bacteria Using a Microwave

Microwave your meal to the appropriate internal temperature, read and follow package instructions, stir your meal and clean your microwave frequently.

According to the United States Department of Agriculture Food Safety and Inspection Service consider the following tips to eliminate all types of bacteria from your food while microwaving.

1. Microwave your meal to the appropriate temperature

Most food packages have an estimated temperature label instructing you on what temperature to heat your meal.

However, on most occasions, 165 degrees Fahrenheit is always appropriate. Use a kitchen thermometer to ensure you do not eat undercooked or overcooked meals.

2. Read and follow package instructions

Package usage instructions including how to cook your meal, the microwave temperature, and the cooking and standing time. Following the instructions to the latter will save you from consuming a meal that may have some traces of survived bacteria.

3. Stir your meal

Stirring your meal halfway to the estimated microwaving time is a technique that ensures it cooks evenly.

Heat reaches all aspects of the meal, killing the bacteria that could have been hiding and would probably survive after microwaving.

4. Disinfect your microwave

Bacteria survives in the microwave even when running as long as the heat is not much to kill them.

Some types of bacteria thrive in a warm environment. Such bacteria can contaminate your food; therefore, disinfect your microwave as often as possible.

Faqs on Does Microwave Kill Bacteria

1. can microwave kill botulism

No, botulism can not be killed by microwave heat. Though they produce toxins that can be destroyed when microwaving; however, their pores remain alive to produce other toxins when temperatures return to normal.

2. Does a microwave kill salmonella?

Yes, microwave heat can kill salmonella as long as the food is microwaved for the appropriate time and to a minimum temperature of 165℉ or 73.9℃.s

3. Does heat kill salmonella in chicken?

Yes, heat can kill salmonella in chicken. It can be eliminated as long as the chicken is heated to a minimum internal temperature of 165° F or slightly more.

4. Does microwave kill viruses?

Yes, a microwave kills viruses ans well bacteria and germs.

It is believed as long as most meals are microwaved to the safest minimum cooking temperature, which is 165oF (74°C), viruses ans well bacteria, and germs are eliminated.

A study shows that the COVID-19 virus dies after being heated to 70oC (158oF.)

 5. Will microwave kill bacteria in meat

A microwave will kill bacteria in meat cooked to a safe internal temperature of 165oF (74°C). However, more heating may be required depending on the meat’s shape, quantity, and thickness.

6. Can microwave kill listeria

It is possible to kill listeria after microwaving your meal to a temperature of 165 degrees or slightly above.

7. Do microwaves kill germs

The heat produced by the microwave can kill germs from 30 seconds to 2 minutes of microwaving at high power.

8. Will microwave kill yeast?

Yes, a microwave will kill yeast in your food if you microwave it to a temperature of 120°F or more.

9. How long to boil water in the microwave to kill bacteria

water should be microwaved for 1 to 3 minutes to boil. Ensure to stop the microwave and stir every 30 seconds for equal heat distribution.

10. How long do you microwave a sponge to kill bacteria?

A sponge should be microwaved for at least 2 minutes at high power to eliminate existing bacteria. Make sure to microwave the sponge wet; a dry one might catch fire.

11. Can you get sick from using a dirty microwave?

Yes, a microwave that contains bacteria can contaminate your food, causing you to experience severe infections, food poisoning, or sickness.

12. Can microwave kill E.coli

Yes, a microwave can kill E.coli. A microwave running at high power can eliminate E.coli in the first 30 seconds to 1 minute.


It is not the microwave that kills bacteria but the heat it produces. The microwave uses the water molecules in a meal to vibrate and brush against each other to produce heat that kills most germs, viruses, and bacteria.

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