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The Centers for Disease Center and Prevention estimates that Salmonella causes more than 1.3 million infections and over 400 deaths in the United States each year. What’s more alarming is that Salmonella poisoning outbreaks have been associated with foods you typically eat, including eggs, chicken, raw tuna, vegetables, fruits, and even processed foods like nut butter. If you love using microwave ovens to prepare your foods like most Americans, then, you may be wondering if the microwave can kill salmonella. I’ve done extensive research and here’s what I found.
Does microwave kill salmonella? Microwave heat can kill harmful pathogens causing foodborne illnesses, including salmonella, as long as the food is microwaved to a safe minimum temperature of 165℉ or 73.9℃. People also need to follow other microwave practices to ensure the food is free of salmonella and safe to eat.
Can microwaves kill bacteria in food? Does Microwave Kill Salmonella?
According to the CDC, salmonella poisoning or salmonellosis accounts for over $350 million in direct medical expenses every year.
It is a vital pathogen infecting both humans and animals.
In fact, Salmonella is one of the leading causes of foodborne diseases in the United States; amongst the many foodborne pathogens, it ranks second and results in the most number of infections, hospitalizations, and even deaths.
You can get salmonella infections from various types of foods.
Foods commonly associated with salmonella outbreaks are undercooked or raw products from animal sources, including poultry, eggs, and milk.
Fruits and vegetables like tomatoes and bean sprouts have also been linked to salmonellosis outbreaks.
There have also been reports of the infections with unpasteurized fruit cider and juice.
The scary thing about salmonella-contaminated foods is that you won’t even be able to notice that they are contaminated; they look and smell normal!
That is why it is crucial for you to know the basics of food safety and how you can prevent salmonellosis.
Fortunately, a microwave oven can kill salmonella, that is if you use it the right way.
While conducting research on the magnetron, Dr. Percy LeBaron Spencer discovered that microwave ovens can cook food quicker Compared to conventional ovens.
Nowadays, the microwave oven is considered one of the greatest inventions in the twentieth century and can be found in more than 93% of American households.
✅ This microwave oven with a smart sensor is the most popular with Amazon’s customers
It is an irreplaceable, easy-to-operate, and energy-efficient electronic appliance that helps you cook faster and gives you higher heating rates.
Similar to other cooking techniques, the microwave has its own way of handling when it comes to salmonella prevention.
The USDA’S Food Safety and Inspection Service in its report on the microwave oven and food safety stated that you can destroy bacteria, including salmonella, during microwave cooking.
Food cooked with the microwave oven is also considered safe.
But before we dive into the basics of using a microwave oven to kill salmonella, you should probably know how microwaves actually kill this bacteria.
So, how does microwave kill salmonella anyways?
It’s the heat.
Microwave heat that reaches the right temperature can kill bacteria, including salmonella.
You can read more about heat and salmonella below.
Does Heating Kill Salmonella?
Lucky for you and me, multiple research showed that salmonella can die with heat, including microwave heat.
In fact, researchers from Penn State University proposed heat as the most economical method to kill bacteria causing foodborne illnesses, which is mainly caused by Salmonella.
But as I mentioned earlier, you can only kill salmonella with a microwave if you do it right (more on this later).
A 2002 research by Beuchet and Scouten reported that Salmonella species can survive in a temperature range of 5°C to 47°C, and their ideal growth temperature is between 35°C and 37°C.
However, when it comes to heat sensitivity, salmonella exhibits different heat sensitivity depending on the types and conditions of the bacteria and foods.
In a review published in the Journal of Food Protection, researchers from the United States evaluated the thermal resistance of salmonella.
They reported that although salmonellae are sensitive to heat, the bacteria’s heat resistance can vary greatly.
In particular, salmonella in dried food products is extremely heat-resistant.
Moreover, if you leave foods contaminated with salmonella at room temperature for some time, the salmonella will become more heat resistant compared to those living in cold refrigerators.
Other factors that may significantly affect the thermal resistance of salmonella are the foods’ acidity, alkalinity, as well as sugar and salt concentrations.
The most prominent salmonella serotype which is notorious for resisting thermal treatment is the Senftenberg 775W.
This is the main reason why even if this serotype is not a critical foodborne pathogen, it is always used as a test organism. Researchers believed that if it is destroyed in a specific thermal procedure, then the thermal treatment may be effective in destroying another common salmonella in foods.
Food Tips: Some foods, such as packaged fresh vegetables, nuts, and shell eggs, are hard to sterilize with heat since excessive heat may change their flavor and texture. So the best way to weaken or kill the salmonella in them is by using lower temperatures after using irradiation treatment, additives, or some preservatives.
The heat produced by a microwave oven can also kill salmonella.
In early studies, researchers have investigated the effect of microwave heat on salmonella.
A 1994 study published in the Journal of Food Science, for instance, studied the relationship between time of heating, temperatures obtained during heating, and the resulting destruction of Salmonella species with four microwave ovens made for home use.
The researcher discovered that post-heating holding times of 2 or more minutes can destroy the Salmonella better while a microwave oven with lower wattage, such as those with 450 W, caused less significant destruction.
In a 2005 study by researchers from Argentina, the impact of microwave heating (800 W) was tested on fresh chicken inoculated with Salmonella enteritidis.
The Salmonella destruction was determined in relation to the heating time at two distinct power settings: medium (power level 6) and high (power level 10). The researchers also studied the relationship between the time of heating and temperature.
They discovered that all Salmonella enteritidis was destroyed after heating the chicken for 110 seconds at a high power setting.
However, when treated with a medium power setting, the food pathogens were still detected even after 140 seconds.
A 2009 study published in the Iranian Journal of Veterinary Research concluded that the microwave radiation, which improves the surface temperature to over 72°C, can eradicate Salmonella typhimurium contaminating chicken meat.
In another 2012 study released in the Journal of Food Science, researchers from USDA’s Food Safety and Intervention Technologies Research Unit tested the feasibility of a new generation microwave in providing better and consistent cooking.
Unlike the traditional rectifier-based oven that depends on the on-off control mechanism, the new generation microwave oven, which is known as a modified or smart microwave oven, gives continuous and adjustable power output and cooking.
The study successfully showed the usefulness of microwave energy application in eliminating foodborne pathogens.
The findings also demonstrated that the smart microwave oven design may boost microwaveable food safety and quality.
In a more recent study published in the Journal of Food Microbiology, researchers from the Republic of Korea investigated the effectiveness of a 915 MHz microwave with three distinct levels (2, 4, and 6 kW) in inactivating Salmonella in peanut butter.
The peanut butter is inoculated with three serovars of Salmonella enterica, namely, Senftenberg, Typhimurium, and Tennessee.
The result of the study showed that treatment of peanut butter with 6 kW for 5 minutes microwave heating has significantly reduced all three serovars of Salmonella with no significant change in color, acid, and peroxide values. It also eliminates more Salmonella serovars compared to the 2 and 4 kW microwave treatments.
The study also demonstrated that microwave heating can be utilized as a control strategy for the pasteurization of peanut butter.
So now that you know microwave heat can indeed kill salmonella, you might be wondering how to kill them properly with your microwave?
Luckily, health authorities, including CDC and USDA, provide the necessary steps and guidelines for you to prevent and kill salmonella.
More on this in the following.
How Do You Kill Salmonella in Food with Microwaves? Best Microwave Tips to Ensure Food Safety
You usually use a microwave to defrost, cook, and reheat foods.
If you use the microwave to reheat an already fully cooked food, then you probably don’t really have much to worry about since the bacteria are already killed during the initial cooking (if you cook them thoroughly).
The recommended safe internal temperature ensures that your heat is hot enough to kill harmful bacteria that cause foodborne illness, including salmonella.
The recommended minimum internal temperature is 165℉ or 73.9℃.
You can follow FoodSafety’s guidelines below for minimum cooking temperatures and rest time (before eating or carving) for common foods, including poultry, meat, seafood, and other cooked foods:
- 160℉ for ground meat or meat mixtures of beef, lamb, veal, and lamb
- 165℉ for ground meat or meat mixtures of turkey and chicken
- 145℉ for fresh lamb, beef, and veal, be it prepared as steaks, roasts, or chops. Their rest time is three minutes
- 165℉ for all poultry, including whole bird, breasts, wings, thighs, legs, and stuffing
- 160℉ for egg dishes. Eggs should be cooked until their yolk and white are firm while egg dishes
- 165℉ for casseroles and leftovers
- 145℉ for fish and fins or until their flashes are opaque and can be separated easily with a fork
- Crab, lobster, shrimp, and scallops should be cooked until their flesh appear somewhat pearly and nontransparent
- Oysters, clams, and mussels should be cooked until their shells are open
Although microwave heating can heat faster than conventional ovens, its major drawback is that it cooks food unevenly, much like grilling and frying.
This non-uniform heating results in hot and cold spots, where pathogens like Salmonella can survive.
In fact, in the past, microwave heating guidelines have failed to ensure salmonella-free not-ready-to-eat foods (NRTE), causing a multistate outbreak of Salmonella poisoning.
A study by Pucciarelli and Benassi in 2005 reported that factors like food types, shape and size, configuration, microwave oven’s power, and intrinsic traits of every food may cause the differences in microwave heating.
So regardless of whether you are using the microwave to cook your food the first time or use it to reheat leftovers, you should use a food thermometer or an instant-read thermometer like this one to test the internal temperature.
Place the food thermometer on several places of the food to test the temperature. You can start with the thickest part of the food.
Make sure that every location you check on the food has reached the minimum recommended temperature to destroy pathogens causing foodborne illness.
Also, pay close attention to the food package instructions, especially when you are dealing with NRTE or frozen microwavable foods.
Unlike fully cooked and pre-cooked microwavable food products that you only need to reheat for a short time in a microwave before eating, the NRTE products contain at least one raw ingredient.
So you must cook the product thoroughly to eliminate any foodborne pathogen that may present in the product.
Be sure to follow the cooking instructions as closely as possible to ensure the foods are thoroughly cooked and safe to eat.
Cooking instructions usually consist of the following:
- Stirring or rotating: Stirring your food midway during the microwaving process helps remove potential cold spots where harmful pathogens may be able to linger.
- Stand or rest time: Allowing your food to stand or rest for the recommended time before consuming it helps promote complete cooking. During such times, the food’s temperature can increase to several degrees.
Did you know? The multistate outbreaks of salmonella food poisoning reported by the CDC are caused by NRTE frozen pot pies. Surprisingly, researchers found that consumers’ failure to understand and follow the microwaving instructions may contribute to the infection and its hospitalization.
For better execution of the cooking instructions, you should at least know your microwave’s wattage.
Your microwave oven’s wattage affects the cooking time; those with higher wattage are more powerful and can cook food faster. Most microwaves are between 600 and 1,200 Watts.
Apart from ensuring your food is safe by following the food safety guidelines and cooking everything to a minimum of 165 ℉, you should also never leave your food in the danger zone.
According to USDA’s FSIS, the danger zone is when you keep the food between 40℉ and 140℉ for 2 hours or more.
These temperatures provide the ideal growth condition for bacteria, including bacteria that cause food poisoning and foodborne diseases.
To keep your food out of this zone:
- Always keep hot foods hot at or more than 140°F. You can place your cooked food in a preheated steam table, slow cooker, chafing dishes, or warming tray.
- Always keep cold foods cold at or less than 40°F. You can refrigerate them quickly or try placing them in containers on ice.
In addition, to ensure your food is exceptionally safe and further reduce your chances of getting infected with salmonella, you should follow good food handling practices, including:
- Washing your hands before preparing, handling, and eating food
- Cleaning the working areas and kitchen utensils properly
- Staying away from raw or undercooked foods and unpasteurized milk or dairy products
Salmonella is indeed sensitive to heat and can be killed if the temperature is high enough.
However, not all salmonella share the same attributes. Some salmonella species are more heat-resistant than others.
Health and food authorities recommend cooking food to a safe minimum temperature of 165℉ which can kill harmful pathogens, regardless of which cooking method you are using.
To ensure your microwave eliminates all possible salmonella in your food, consider the following microwave cooking and food safety tips:
- Use an instant-read thermometer like this one to check the internal temperature of every part of the food. Be sure all parts reach the recommended safe temperature.
- Meticulously follow the microwave instructions, such as rotations or stirring, for frozen foods, especially the NRTE products.
- Make sure the food is left standing or resting appropriately before consumption.
- Never leave food in the danger zone.
You should also avoid contaminating or recontaminating your thoroughly cooked foods by practicing good food handling and preparation habits.
Does microwave disinfect food?
Microwave oven’s heat can disinfect food if the food is microwaved to a safe minimum internal temperature of 165℉, which kills bacteria. But since microwaves do not heat evenly, consumers should use an instant-read thermometer to ensure all parts of the food are properly disinfected.
Does microwave kill bacteria in chicken?
Microwave heat can kill bacteria in meat, including chicken, as long as the heat is hot enough to destroy them. CDC and FoodSafety.gov recommend cooking chicken to a safe minimum temperature of 165℉. Use a food thermometer to ensure every part of the chicken reaches the minimum temperatures.
Does marinating kill bacteria?
While marinating tenderize and add flavor to meat, it does not eliminate bacteria. People should keep their marinate meat in the refrigerator to stop the bacteria from growing and never reuse unboiled marinade. Cooking the meat to a safe minimum temperature of 165℉ would help kill harmful pathogens.