Fast Facts for Fast Heating: The Microwave Oven

The microwave oven was invented in 1947 and is one of the most popular inventions of the 20th century; over 90 percent of homes in America have at least one. Microwaves are easy and convenient to use for cooking meals, preparing frozen foods, and reheating leftovers. However, it’s important to remember that microwaves differ greatly from conventional ovens. Here are some facts and tips from food scientists and IFT spokesperson, Kantha Shelke, PhD, that will help you make the most out of your microwaving experience.

WHAT TYPES OF COOKWARE ARE MICROWAVEABLE? WHAT TYPES ARE NOT?
Only use cookware that is specially manufactured for use in the microwave oven. Glass, ceramic containers, and all plastics that are safe to use usually will be labeled for microwave oven use. Containers and dishes that display a microwave-safe icon or that read “microwave safe”, mean that they’ve been approved by the U. S. Food and Drug Administration (FDA) for use in microwave ovens. Other plastic containers may cause chemicals to leak out of the plastic into your food. According to the U.S. Department of Agriculture Food Inspection Service (USDA FSIS) recommends the following when determining the type of container to use in your microwave:

Microwave Safe

• Any utensil specifically labeled for microwave use
• Heatproof glass (such as Pyrex)
• Glass-ceramic (such as Corning Ware)
• Specially labeled oven cooking bags
• Baskets (straw and wood) for quick warm-ups of rolls or bread; line the basket with napkins to absorb moisture
• Most paper plates, towels, napkins and bags; for optimal safety use white, unprinted paper goods.

Not Microwavable

• Restaurant and deli takeout containers
• Water bottles
• Plastic tubs or jars made for foods such as  margarine, yogurt, whipped topping cream cheese, mayonnaise, and mustard
• Plastic storage bags or plastic bags from the grocery store
• Metal or aluminum foil
• Microwavable frozen meal dinner trays (only for one-time use)

Use with Caution

• Plastic wrap shouldn’t touch food because it may melt
• Wax paper, kitchen parchment paper

HOW DOES A MICROWAVE WORK?
Microwave ovens convert ordinary electric power into short waves that cause water, fat, and sugar molecules to vibrate approximately 2.5 million times per second, which result in high temperatures that cook food. Dr. Shelke recommends the following tips for making sure the food you cook in the microwave is heated evenly and safely.

• Covering your food helps prevent splattering and retain moisture. Leave the lid ajar, or lift the edge off of the cover in order ensure ventilation.
• After the microwave has stopped, it’s important to leave the food in the microwave for a few minutes to make sure it’s fully heated or cooked. This is known as “carryover cooking time” or “resting time,” and it also prevents burns when handling or eating.
• Carryover cooking occurs for a longer time in dense foods such as chicken, turkey, beef, and cheese.

HOW HOT IS HOT?
USDA FSIS recommends using a food thermometer when cooking certain foods. This also ensures the food is cooked safely, evenly, and thoroughly. Here are recommendations for heating the following:

• Sauces, gravies, soups and stews must come to a boil before you serve them
• Cook ground meats to 160 degrees Fahrenheit
• Cook all raw beef, pork, lamb and veal steaks, chops, and roasts to a minimum internal temperature of 145 degrees Fahrenheit
• Cook all poultry to a  minimum internal temperature of 165 degrees Fahrenheit
• Cook eggs and casseroles containing eggs to 160 degrees Fahrenheit
• Heat fish to 145 degrees Fahrenheit
• Cook frozen meals according to the manufacturer’s directions on the box or container