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Microwave Cooking Might Be a Game Changer. But Is It Safe?

Posted in Our Blog on July 5, 2024

The microwave oven is one of the great conveniences invented in the 20th century. Over 90% of American homes have at least one microwave. But microwave cooking is still not a commonly performed task.

Why are we comfortable with heating our food, but not cooking in it?

Overwhelmingly it is due to not only the novelty of the application, but also due to safety concerns.

Microwave cooking doesn’t have to be scary. A few safety tips can help you cook confidently in the microwave.

How Do Microwaves Work?

Microwaves are one of those commonly used, but often misunderstood appliances.

Contrary to popular belief, no radiation is involved in microwave cooking appliances.

So, how does it work?

An apparatus called a magnetron is inside the oven. It converts the electricity from the power outlet through the plug into short radio waves (around 4 inches from crest to crest). These are invisible bits of energy bouncing around inside the unit.

These waves are transmitted at a frequency of around 2450 Megahertz. This is the perfect power frequency for water, fats, and sugars to absorb. As a result, molecules within the food begin to vibrate, resulting in internal friction that converts to high temperatures. That is how it cooks food.

The Importance of Power Levels

When using a microwave, be mindful of power levels.

On high power, the magnetron is producing “microwaves” at full capacity. This subjects the food to the highest amount of microwave energy. Your microwave may note this as 100%

For other levels, such as 50%, the magnetron cycles on and off. For example, a setting of 50% (or medium power) signals to the microwave to produce microwaves 50% of the time. The remaining 50% of the time, no microwaves are produced. This gives the food molecules small amounts of time to slow, which slows the cooking speed.

Certain foods work better at particular power settings.

Foods with a high moisture content like fruits, vegetables, poultry, and ground beef cook best on high power.

Solid meat, cheese, and eggs can become tough if cooked on high power. These foods work better when cooked at reduced power.

Is Microwave Cooking Safe?

Microwave cooking, while safe, is not without potential risks.

Microwave cooking still heats food to safe internal temperatures, like other forms of cooking. However, microwave ovens cook foods unevenly. This leaves “cold spots” in the food. These areas of lower temperatures allow harmful bacteria to survive. Grilling and frying can leave cold spots too. Testing multiple places within the thickest part of the food with an instant read food thermometer is an important part of microwave cooking safety.

How to Cook Safely in the Microwave

A few simple steps can increase microwave cooking safety.

Arrange Food Evenly

To help food cook more uniformly, arrange items evenly spaced in a covered dish. If needed, add some liquid to encourage steaming. This helps increase the microwave oven temperatures.

When possible, debone large pieces of meat. Bones can shield microwaves from entering all parts of the meat. Removing them will promote more even cooking.

Loosely Cover Food

Loosely covering food with a microwave safe lid or plastic wrap can help create moist heat. This moist heat will help destroy harmful germs that may be in the food.

Rotate Food Halfway Through Cooking

Rotate, stir, or turn foods upside down (if applicable) midway through cooking time. This helps to eliminate cold spots where those germs might be lurking. This step is important, even if the unit has a turntable. Stirring food promotes even cooking, which increases microwave cooking safety.

Follow Cooking Instructions

If a product label or recipe instructions includes microwave cooking instructions, follow them. Start with the fewest minutes in the cooking time and add more time if needed to reach a safe internal temperature.

Cooking will continue a bit after the microwave stops. Many recipes include a “standing time” to account for this in their cooking procedures. Don’t skip “standing time.”

What is Standing Time

Microwaves vibrate food molecules to a rate of 2.5 million times per second. Even as the molecules begin to slow down and eventually stop, they are still generating heat. Recipes include a period of resting or standing time to account for the carryover cooking time. Removing items from the microwave oven prior to the allotted standing time reduces cooking time, and therefore can affect food safety.

Thawing Frozen Food

Frozen food can be conveniently thawed in a microwave.

In fact, most microwaves have a “defrost” setting. This is usually 30% power.

Just as when cooking in a microwave, rotate and turn food over throughout the defrosting process to encourage even defrosting.

Break apart pieces and place them evenly on a microwave safe dish to help with even thawing.

For ground meat items, scraping off softened portions and removing them from the oven will help prevent thawed areas from cooking and allow for more even results.

Certain foods must be cooked immediately after defrosting. These include meat, poultry, egg casseroles, and fish. Holding partially cooked food to use later may promote the growth of harmful bacteria, putting yourself and your family at risk.

Do’s and Don’ts of What Goes in a Microwave

You can’t just put anything in a microwave. Approved cookware that is specifically designed for use in a microwave oven is your safest bet.

Glass, ceramic containers, and certain plastics (usually labeled for microwave oven use) are great options. There are, however, certain items you should never put in a microwave.

Safe Options

Any item labeled “for microwave use” is safe to use. Heatproof glass like Pyrex and similar brands or glass-ceramic like Corning Ware are safe options.

Oven cooking bags, wax paper, parchment paper, paper plates, paper towels, napkins, and paper bags are all safe microwave cooking options. Even straw or wood baskets are safe for short periods of time to heat up rolls or bread. For best results, lines the basket with absorbent paper towels or napkins to reduce moisture.

Unsafe Items

Never use cold storage containers, even if they are designed for food. These items that are not approved for cooking may leach chemicals into the food or compromise the integrity of the container.

Metal pans, China with metallic paint or trim, Chinese “take-out” containers with metal handles, and metal twist ties on package wrapping should never be placed in the microwave.

Foam-insulated containers, such as bowls, plates, trays, or cups should not be used in the microwave.

Never heat food completely wrapped in aluminum foil in the microwave.

Aluminum Foil in the Microwave?

Wait… You can’t use metal in the microwave, but aluminum foil is fair game?

Small amounts of aluminum foil can be safely used in a microwave. However, check your manufacturer’s recommendations for using it to be sure.

If using aluminum foil in the microwave, do not completely cover the food with it. Microwaves cannot pass through metal. Operating the oven completely empty or when food is completely wrapped in foil provides not place for the energy to be absorbed. This can cause major issues.

If you decide to use aluminum foil, cover no more than ¼ of the food with it. Only use new, smooth foil. Wrinkled foil can potentially create sparks

Keep foil away from the oven walls and the turntable.

If you see arcing (sparks), immediately stop the microwave and remove it.

If You See Sparks…

Arcing, or sparking happens when microwaves react to metals. Some foods, due to salt or mineral content can also cause this phenomenon.

Raw carrots and hot dogs are common foods that can create these sparks.

If you see sparks, immediately turn off the microwave oven. Otherwise, these sparks can damage or break your appliance.

Superheating Can Also Be a Problem

A phenomenon known as superheating or erupting is also a concern when cooking in a microwave. Liquids can be heated beyond the conventional 212° F boiling temperature in a microwave. When adding an ingredient, such as tea, coffee, or gelatin to superheated water, the liquid could erupt violently when removed from the appliance.

This is a rare occurrence, but serious enough to take precautions against.

To reduce the chance of eruption due to superheating, stir occasionally while heating. Adding a pinch of what you plan to add to it at the beginning or halfway through the heating process can also help prevent this from happening. Opt for a vessel with sloping wall, like a measuring cup or keep a microwavable spoon in the dish while heating. Both are great options to reduce the chance of eruptions due to superheating.

How Comfortable Are You with Cooking in a Microwave?

In the modern world, you have likely used a microwave to heat food at some point in your life. But have you ever fully cooked something in one? How comfortable are you with cooking in a microwave?

Stay in Touch with Make Food Safe!

If you’d like to know more about food safety topics in the news, like Microwave Cooking Might Be a Game Changer, check out the Make Food Safe Blog. We regularly update trending topics, foodborne infections in the news, recalls, and more! Stay tuned for quality information to help keep your family safe, while The Lange Law Firm, PLLC strives to Make Food Safe!

By: Heather Van Tassell (contributing writer, non-lawyer)