news

When we use a microwave to heat food at home, in addition to paying attention to the "ding" sound, we must also be careful not to get burned when taking the food out of the oven, because the heating process in the microwave can generate high temperatures for the heated objects in the compartment.

We all know that many microorganisms are afraid of heat, so the question is, under the effect of microwaves and such high temperatures, can bacteria and other microorganisms still survive? If microwave ovens can kill microorganisms, can they be used for sterilization? Next, let's talk about it in detail.

First the answer:Can kill some microorganisms。

The main working principle of a microwave oven is to use microwaves (usually 2.45 GHz electromagnetic waves) to vibrate water molecules in food. This vibration causes friction between molecules, which generates heat. When microwaves irradiate food, the water molecules inside the food quickly absorb energy and begin to vibrate, causing the temperature to rise. High temperatures are the main mechanism for killing microorganisms. When the temperature reaches the tolerance limit of microorganisms (usually above 60°C), proteins and other important biological molecules will denature, causing the microorganism to die.

Unlike traditional heating methods, microwaves can penetrate most foods and heat the interior, not just the surface.This heating method can more effectively heat food to a high enough temperature to kill microorganisms inside the food.

Many studies have also shown that microwave ovens can kill some microorganisms, such as Escherichia coli, Enterococcus faecalis, Clostridium perfringens, Staphylococcus aureus, Salmonella and Listeria.Microwave ovens can kill some microorganisms, but that does not mean that microwave heating can be used as an ideal means of disinfection.

First the answer:cannot!

Scientists at the University of Valencia in Spain sampled 30 microwave ovens from different environments, including those in homes, offices and laboratories, swabbing the inner surfaces of these microwave ovens and then culturing the samples in petri dishes to see if there was any microbial growth.

They also used DNA sequencing technology to analyze the types and diversity of microorganisms in the samples. One of the purposes of this study is to find out whether microwave ovens can really completely kill microorganisms?

The results of the study found thatMicrowave ovens may not be able to provide a good sterilization effect because there are a large number of microbial communities inside these microwave ovens, including up to 101 different bacterial strains.

These included Bacillus, Micrococcus and Staphylococcus, which are commonly found on human skin and kitchen surfaces. These bacteria were found in all types of microwave ovens, but were found in relatively high numbers in microwave ovens used at home and in public.

The researchers also found some bacteria associated with foodborne illness, such as Klebsiella and Brevimonas, which were particularly common in home microwaves.

To the researchers' surprise, they also found extremophiles in laboratory microwaves（extremophiles）This discovery not only challenges the traditional concept that microwave ovens completely sterilize bacteria, but also reveals that these extreme microorganisms may have potential biotechnology applications, such as in environmental remediation such as cleaning up toxic waste.

Extremophiles are microorganisms that can survive and reproduce in extreme environments that are usually inhospitable to most organisms.Examples include extremely high or low temperatures, extreme pH, high salinity, high pressure, strong radiation, and extremely dry environments.The existence of extreme microorganisms challenges our understanding of the limits of life and reveals the ability of life to adapt under a variety of extreme conditions.

These microorganisms can be found in some extreme environments on Earth, such as hydrothermal vents in the deep sea, where temperatures can reach hundreds of degrees Celsius; Antarctic ice, where temperatures can drop to tens of degrees below zero; and highly radioactive nuclear waste storage areas. Extremophiles are able to survive in these extreme environments through unique physiological and biochemical mechanisms, such as the formation of proteins or cell membrane structures that can withstand extreme conditions. This ability to survive enables them to maintain life under conditions where other organisms cannot survive.

Some of these microorganisms found in microwave ovens (especially in laboratory microwave ovens) do have characteristics of extremophiles, such as Deinococcus spp.（Deinococcus）, Thin-layered bacteria（Hymenobacter）and Sphingomonas（Sphingomonas）These microorganisms have strong survival ability in extreme environments. They also have certain similarities with microorganisms living in extreme environments such as near volcanic craters.

Although these microorganisms typically live in extreme environments, they are also widely distributed in nature and enter the household environment through everyday contact.These microorganisms may enter the microwave oven through external environments such as air, dust, food residues or water.For example, dust particles and water molecules suspended in the air often carry various microorganisms. Especially in daily use, the opening and closing of the microwave oven door will cause air flow, thereby introducing these microorganisms into the interior of the microwave oven.

There are also some common relatively heat-resistant bacteria in microwave ovens, such as some Bacillus（Bacillus）and Pseudomonas（Pseudomonas）These bacteria are also common in our daily life, but due to the influence of specific environmental factors in the microwave oven, their tolerance is further selected - those that can survive are better able to withstand the extreme environment in the microwave oven.

Seeing this, some friends may start to worry that extreme microorganisms can even withstand microwave heating, so what if they infect humans? Will they become "super bacteria"? This is actually unnecessary worry.

Let me give you the answer first:Basically not.

The extreme microorganisms currently found in microwave ovens can survive under extreme conditions, but this does not mean that they can infect humans and make them sick.In fact, most of the extreme microorganisms that have been discovered have a low ability to survive in the human body because the conditions inside the human body are "not extreme enough" and are not the most suitable environment for their survival.

There is currently no evidence that the extreme environment in a microwave oven will select for drug-resistant pathogens. Superbugs usually refer to those bacteria that have developed drug resistance due to the overuse of antibiotics.Although extreme microorganisms can survive in harsh conditions, this is completely different from being able to resist antibiotics.

However, it should be pointed out that, as mentioned above,In addition to extreme microorganisms, microwave ovens also contain some common bacteria in our daily lives, some of which may cause disease.Therefore, scientists suggest that although extreme microorganisms do not currently pose a direct threat to the human body, it is still necessary to regularly clean daily necessities such as microwave ovens. This can reduce the number and types of microorganisms in the microwave oven and reduce potential health risks.