The _______ heat cooking methods use water, liquid or steam to transfer heat to food. (5 letters)

Did you know that an estimated 1 in 6 Americans will get sick from food poisoning this year alone? Food poisoning not only sends 128,000 Americans to the hospital each year—it can also cause long-term health problems. You can help keep your family safe from food poisoning at home by following these four simple steps: clean, separate, cook and, chill.

Clean: Wash Hands, Utensils, and Surfaces Often

Germs that can make you sick can survive in many places around your kitchen, including your food, hands, utensils, cutting boards, and countertops.

Wash your hands the right way:

• Use plain soap and water—skip the antibacterial soap—and scrub the backs of your hands, between your fingers, and under your nails for at least 20 seconds. Need a timer? Hum the “Happy Birthday” song from beginning to end twice.
• Rinse hands, then dry with a clean towel.
• Wash your hands often, especially during these key times when germs can spread:
  • Before, during, and after preparing food
  • After handling raw meat, poultry, seafood, or their juices, or uncooked eggs
  • Before eating
  • After using the toilet
  • After changing diapers or cleaning up a child who has used the toilet
  • After touching an animal, animal feed, or animal waste
  • After touching garbage
  • Before and after caring for someone who is sick
  • Before and after treating a cut or wound
  • After blowing your nose, coughing, or sneezing
  • After handling pet food or pet treats.

Wash surfaces and utensils after each use:

• Wash cutting boards, dishes, utensils, and countertops with hot, soapy water, especially after they’ve held raw meat, poultry, seafood, or eggs.
• Wash dish cloths often in the hot cycle of your washing machine.

Wash fruits and vegetables, but not meat, poultry, or eggs:

• Rinse fruits and vegetables under running water without soap, bleach, or commercial produce washes.
• Rinse fruits and vegetables before peeling, removing skin, or cutting away any damaged or bruised areas.
• Scrub firm produce like melons or cucumbers with a clean produce brush.
• Dry produce with a paper towel or clean cloth towel.
• Don’t wash meat, poultry, eggs, or seafood to avoid spreading harmful germs around your kitchen.
• Produce labeled as “pre-washed” does not need to be washed again.

Additional Information:

Food Safety Quick Tips: Clean (FDA)

Cleanliness Helps Prevent Foodborne Illness (USDA)

Separate: Don’t Cross Contaminate

Use separate cutting boards and plates for produce, meat, poultry, seafood, and eggs:

• Use one cutting board for fresh produce or other foods that won’t be cooked before they’re eaten, and another for raw meat, poultry, or seafood. Replace them when they are worn.
• Use separate plates and utensils for cooked and raw foods.
• Use hot, soapy water to thoroughly wash plates, utensils, and cutting boards that touched raw meat, poultry, seafood, eggs, or flour.

Keep certain types of food separate:

• In your shopping cart, separate raw meat, poultry, seafood, and eggs from other foods and place packages of raw meat, poultry, and seafood in plastic bags if available. When you check out, place raw meat, poultry, and seafood in separate bags from other foods. 
• At home, place raw meat, poultry, and seafood in containers or sealed, leakproof plastic bags. Freeze them if you’re not planning to use them within a few days.
• In the fridge, keep eggs in their original carton and store them in the main compartment—not in the door.

Additional Information:

Food Safety Quick Tips: Separate (FDA)

Be Smart. Keep Foods Apart. Don't Cross-Contaminate. (USDA)

Cook to the Right Temperature

Food is safely cooked when the internal temperature is high enough to kill germs that can make you sick:

• Use a food thermometer to be sure your food is safe. When you think your food is done, place the food thermometer in the thickest part of the food, making sure not to touch bone, fat, or gristle.
• Refer to our Minimum Cooking Temperatures Chart to be sure your foods have reached a safe temperature.

Keep food hot (140˚F or above) after cooking:

If you’re not serving food right after cooking, keep it out of the temperature danger zone (between 40°F -140°F) where germs grow rapidly by using a heat source like a chafing dish, warming tray, or slow cooker.

Microwave food thoroughly (165˚F or above):

• Read package directions for cooking and follow them exactly to make sure food is thoroughly cooked.
• If the food label says, “Let stand for x minutes after cooking,” follow the directions — letting microwaved food sit for a few minutes allows food to cook thoroughly as colder areas absorb heat from hotter areas.
• Stir food in the middle of heating. Follow package directions for commercially prepared frozen food; some are not designed to be stirred while heating.

Follow special guidelines for barbeques and smokers:

Additional Information:

Food Safety Quick Tips: Cook (FDA)

Grilling and Food Safety (USDA)

Kitchen Thermometers (USDA)

Chill: Refrigerate and Freeze Food Properly

Refrigerate perishable foods within 2 hours:

• Bacteria that cause food poisoning multiply quickest between 40°F and 140°F.
• Your refrigerator should be set to 40°F or below and your freezer to 0°F or below. Use an appliance thermometer to be sure.
• Never leave perishable foods out of refrigeration for more than 2 hours. If the food is exposed to temperatures above 90°F (like a hot car or summer picnic), refrigerate it within 1 hour.
• Leftovers should be placed in shallow containers and refrigerated promptly to allow quick cooling.
• Never thaw or marinate foods on the counter. The safest way to thaw or marinate meat, poultry, and seafood is in the refrigerator.
• Freezing does not destroy harmful germs, but it does keep food safe until you can cook it.
• Know when to throw out food by checking our Safe Storage Times chart. Be sure you throw food out before harmful bacteria grow.

Additional Information:

Food Safety Quick Tips: Chill (FDA)

Refrigeration and Food Safety (USDA)

Leftovers and Food Safety (USDA)

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In the 1940s, Percy Spencer at Raytheon was testing a magnetron — a device that generates microwaves — when he realized a candy bar in his pocket had melted.

This accidental discovery would lead him to develop what we now know as the modern-day microwave oven. Over the years, this kitchen device has become one more item that makes domestic work that much easier.

Yet questions surrounding the safety of microwave ovens remain. Is the radiation used by these ovens safe for humans? Is the same radiation destroying the nutrients in our food? And what about that study performed on plants fed microwave-heated water (more on this later)?

To answer some of the most popular (and pressing) questions surrounding microwaves, we asked the opinion of three medical professionals: Natalie Olsen, RD, LD, ACSM EP-C, a registered dietitian and exercise physiologist; Natalie Butler, RD, LD, a registered dietitian; and Karen Gill, MD, a pediatrician.

Here’s what they had to say.

Natalie Olsen: Microwaves are a form of nonionizing electromagnetic radiation and are used to heat food rapidly. They cause molecules to vibrate and build up thermal energy (heat).

According to the FDA, this type of radiation does not have enough energy to knock electrons out of atoms. This is in contrast to ionizing radiation, which can alter atoms and molecules and cause cellular damage.

Natalie Butler: Electromagnetic radiation waves, or microwaves, are delivered by an electronic tube called a magnetron. These waves are absorbed by water molecules in food, causing [the molecules] to vibrate rapidly, resulting in heated food.

Karen Gill: Microwave ovens use electromagnetic waves of a very specific length and frequency to heat and cook food. These waves target specific substances, using their energy to produce heat, and it is primarily the water in your food that is being heated.

NO: Very minimal molecular changes happen with microwaving, due to the low energy waves given off. Since they are considered nonionizing waves, chemical changes in the molecules in food do not occur.

When food is heated in the microwave, energy is absorbed into the food, causing ions in the food to polarize and rotate [causing] mini-collisions. This is what generates friction and thus heat. Therefore, the only chemical or physical change to the food is that it is now heated.

NB: Water molecules in microwaved food vibrate rapidly as they absorb the electromagnetic radiation waves. Cooked and overcooked microwaved food will gain a rubbery, drier texture due to the rapid movement and accelerated evaporation of water molecules.

KG: Microwaves cause water molecules to move rapidly and cause friction between them — this generates heat. The water molecules change polarity, known as “flipping,” in response to the electromagnetic field created by the microwaves. Once the microwave is turned off, the energy field is gone and the water molecules stop changing polarity.

NO: When heated, some nutrients in food will break down, regardless of whether it is cooked in a microwave, on a stove, or in an oven. That said, Harvard Health stated food that is cooked for the shortest period of time, and uses as little liquid as possible, will best retain nutrients. A microwave can accomplish this, as it is a faster method of cooking.

One 2009 study that compared the nutrient losses from various cooking methods found that griddling, microwave cooking, and baking [are the methods that] produce the lowest losses of nutrients and antioxidants.

NB: Water content within microwaved food is reduced as it rapidly heats. When cooked or overcooked in a microwave, food texture may become undesirable. Protein may become rubbery, crispy textures soften, and moist foods become dry.

Likewise, vitamin C is a sensitive water-soluble vitamin and is more prone to degradation by microwave cooking than in convection cooking. Yet, while microwave cooking can decrease the antioxidant (vitamin and phytonutrient concentrations of certain plants), they can preserve other nutrients better in the same plants than other cooking methods, like roasting or frying.

Microwaving, can also reduce the bacterial content of food, which can be a useful method of pasteurization and food safety. For example, microwaving red cabbage is superior to steaming for protecting anthocyanin but worse when trying to preserve vitamin C.

Microwaving better protects quercetin, a flavonoid in cauliflower, but is worse in protecting kaempferol, a different flavonoid, when compared to steaming.

Moreover, microwaving crushed garlic for 60 seconds greatly inhibits its allicin content, a powerful anticancer compound. It has been found, however, that if you rest the garlic for 10 minutes after crushing it, much of the allicin is protected during microwave cooking.

KG: All methods of cooking foods cause some loss of nutrients due to heating. Microwaving food is good for retaining nutrients because you don’t need to use a significant amount of extra water (such as with boiling) and your food cooks for a short time.

Vegetables are particularly suited for microwave cooking, as they are high in water content and, therefore, cook quickly, without requiring extra water. This is similar to steaming, but faster.

NO: The Scientific American offered an explanation from Anuradha Prakash, assistant professor in the Department of Food Science and Nutrition at Chapman University, which stated there is not sufficient evidence to support that a person’s health is negatively impacted by the microwave.

It was stated that, “as far as we know, microwaves have no nonthermal effect on food.” In other words, aside from changing the temperature of food, there is very little to no impact.

NB: Plastic food containers that are microwaved may leach toxic chemicals into the food and should thus be avoided — use glass instead. Radiation leakage may also occur in poorly designed, faulty, or old microwaves, so make sure to stand at least six inches from a microwave when cooking.

KG: There are no short- or long-term effects from microwaving food. The biggest risk with microwaving liquids or foods with high water content is that they can heat unevenly or to very high temperatures.

Always stir foods and liquids after microwaving them and before checking the temperature. Also, choose microwave-safe containers for heating and cooking.

NO: The research on this wavers. Some studies have shown an impact on plants in a negative way when microwaved water is used. It has been shown that radiation on plants can affect their gene expression and life. This, however, is primarily seen with ionizing radiation (or higher energy radiation) [rather] than with the radiation that is emitted by microwaves (nonionizing, low energy).

NB: The original science fair project that studied the effect of microwave water on plants went viral back in 2008. To this day, microwaved water is still under question.

Microwaved water has been shown in some studies to actually improve plant seed growth and germination, like in the case of chickpea seeds, while it had the opposite effect on other plants, possibly due to changes in pH, mineral function, and water molecule mobility.

Other research also shows conflicting results on the chlorophyll content of plants: Some plants have decreased color and chlorophyll content when watered with microwaved water, whereas others exposed have increased chlorophyll content. It appears some plants are more sensitive to microwave radiation than others.

KG: No, this is not accurate. This myth has been circulating for years and appears to come from a child’s supposed science experiment. Water that has been heated in a microwave and then cooled is the same as that water before it was heated. There is no lasting change in the molecular structure of water when it is heated in a microwave.

NO: Microwave ovens have better cooking efficiency since you are heating food from the inside out, rather than outside in, as is the case with a stove or oven. Therefore, the main difference between food cooked on a stove or oven versus a microwave is the cooking time.

According to the World Health Organization (WHO), food cooked in the microwave oven is just as safe and has similar nutrient values as food cooked on the stove.

NB: Yes, differences in food cooked in a microwave versus other methods could be measured by color intensity, texture, moisture content, and polyphenol or vitamin content.

KG: In general, no, there is not. The type of food you are cooking, the amount of water added to cook it, and the container you use can all affect cooking times and the amount of nutrients lost during cooking.

Microwaved food can often be healthier due to short cooking times and less of a need for extra fat, oil, or water needed for cooking.

Natalie Olsen is a registered dietitian and exercise physiologist specializing in disease management and prevention. She focuses on balancing the mind and body with a whole-foods approach. She has two Bachelor’s degrees in Health and Wellness Management and in Dietetics, and is an ACSM-certified exercise physiologist. Natalie works at Apple as a corporate wellness dietitian, and does consulting in a holistic wellness center called Alive + Well, as well as through her own business in Austin, Texas. Natalie has been voted among the “Best Nutritionists in Austin” by Austin Fit Magazine. She enjoys being outdoors, warm weather, trying new recipes and restaurants, and traveling.

Natalie Butler, RDN, LD, is a foodie at heart and passionate about helping people discover the power of nourishing, real food with an emphasis on a plant-heavy diet. She graduated from Stephen F. Austin State University in east Texas and specializes in chronic disease prevention and management as well as elimination diets and environmental health. She’s a corporate dietitian for Apple, Inc., in Austin, Texas, and also manages her own private practice, Nutritionbynatalie.com. Her happy place is her kitchen, garden, and the great outdoors, and she loves teaching her two kids to cook, garden, be active, and enjoy a healthy life.

Dr. Karen Gill is a pediatrician. She graduated from the University of Southern California. Her expertise includes breastfeeding, nutrition, obesity prevention, and childhood sleep and behavior issues. She has served as chair of the Department of Pediatrics at Woodland Memorial Hospital. She was a clinical preceptor with the University of California, Davis, teaching students in the physician assistant program. She now practices at the Mission Neighborhood Health Center, serving the Latino residents of the Mission district in San Francisco.