More specifically, does almost boiling water have the same effect? Or is there something particularly special about boiling water that kills germs/bacteria? – if so what is it, and why is it special?
In: Chemistry
I think that it just gets too hot for them and they can’t really cool themselves off or sweat.
Imagine swimming in boiling water
I think that it just gets too hot for them and they can’t really cool themselves off or sweat.
Imagine swimming in boiling water
Heat causes protiens and nucleic acids to unfold (denature) by breaking their hydrogen bonds that hold them in a certain configuration. The protein unravels and can no longer serve its purpose (enzymes no longer work for example).
Heat can kill viruses as well. Some microbes (Botulism in spores) are much more resistant to heat and can survive some exposure to high tempreatures.
As many answered to the first part of your question, heat kills bacteria, and the higher of the heat the faster.
As to the second part of your question, boiling would kill much faster than almost boiling. The reason why is convection. Boiling water is essentially being stirred by the boiling, which causes much faster heat transfer. In a hypothetical world in which you could snap your fingers and make water any given temperature instantly, you would find that 100 Celsius actually kills bacteria significantly faster than 99.
In the real world, though, where water takes quite some time to heat up, you’ve probably pasteurized long before you hit the boil.
Heat is really just stuff jiggling around. Hotter things jiggle more. Getting the bacteria really hot literally tears them up from all the jiggling.
Very simply, boiling water kills almost anything. Most organisms simply can’t survive in hostile environments. Boiling water is a hostile environment.
Don’t believe me? Dip your hand in 100c (212f) water for a couple of minutes and you’ll be able to peel your skin off.
Generally, the heat changes molecules in the bacteria and this is what kills them. Most bacteria are killed by boiling, but some create endospores. These are like armored heat resistant escape pods for the germs, and boiling water won’t kill them in a reasonable time. The endospores will just hatch and grow a new colony of bacteria when things cool off. Botulism bacteria are an example of these germs. Therefore, canned goods that aren’t acidic (not tart or sour) have to be pressure canned since that uses higher temperatures to kill the endospores.
Some germs are killed at lower than boiling temps, say 160 F, most are killed by boiling, and others take higher temps.
Many of the proteins in any living creature are held in their shape by a type of weak bond called a Hydrogen bond. What makes a protein work is its shape.
Now, you may or not be aware, but what your DNA does is have the codes for proteins. Everything that makes you you is either directly proteins or is controlled by proteins. And if they can’t do there thing… life doesn’t work.
It’s the same for bacteria. If you get them hot enough they start to break down and life stops.
heat can cause proteins (the things that allow all living things to function) to denature. Proteins rely on having a certain shape to function and when they denature, they loose that shape (this is the same thing that happens when we cook food).
As for can this happen at lower temperatures, kinda. This happens in food all the time (chicken is safe to eat at 165, well below boiling). pasteurization can be done below boiling point as well. But it depends on the bacteria, and it depends on the proteins that you need to destroy. Another thing to keep in mind is that for pasteurization, the hotter the temp, the faster you can do it. So while it’s possible to do it at lower temperatures, it takes longer. Another thing to keep in mind is that boiling is readily identifiable, you don’t need a thermometer to identify the temp.
The increased temps denatures (ruins the function of) proteins. Like egg whites (high in protein) losing its elasticity and hardening when you cook them.
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