Microwave

[Mila]

There was some discussions about cleaning and/or sterilizing drift wood, rocks and other stuff.
What do you think about using microwave oven to do that?

Thanks

Mila

[PNA]

I was thinking the same.  But I haven't seen anything about it.

[Nelson]

There was some discussions about cleaning and/or sterilizing drift wood, rocks and other stuff.
What do you think about using microwave oven to do that?

Thanks

Mila

Absolutely not :shock:  Air/water tarpped in the wood WILL cause an explosion as the result of very high heat generated pressure.  Good way to blow up your microwave and hospitalize nayone in the vacinity.

[blueturq]

There was some discussions about cleaning and/or sterilizing drift wood, rocks and other stuff.
What do you think about using microwave oven to do that?

Thanks

Mila

Absolutely not :shock:  Air/water tarpped in the wood WILL cause an explosion as the result of very high heat generated pressure.  Good way to blow up your microwave and hospitalize nayone in the vacinity.

Yeah.... boiling the driftwood seems to be a better and safer idea, because as Nelson said... the microwave will explode, you also mentioned rocks? I would boil those too, DO NOT microwave them!  :shock:

[Mila]

Well, I did it few times already and nothing like that happen. Max time was 1 minute. Waves should kill everything fast, I guess.??

Mila

[Nelson]

Well, I did it few times already and nothing like that happen. Max time was 1 minute. Waves should kill everything fast, I guess.??

Mila

Do what you think is best...I'll listen for the bang :wink:

[DARKPHREAK]

Not much as far as sterilizing is getting done in 1 minute in the microwave. You need to boil in water(30+mins) to get everything off.

[Sam]

I found this article... its about killing microorganisms in food using microwaves and how it doesn't work.  I remembered hearing about it in my microbilogy class but I needed a source to be reliable.

http://www.foodscience.afisc.csiro.au/micwave1.htm

The main line of importance is: "Food cooked in a microwave oven does not heat uniformly and unwanted microorganisms may survive in portions of poorly heated food."

There is also the point that there are very few water molecules in a microorganism which is required for a microwave to work.  The same is true of the average fruit fly who can survive a trip in a microwave due to their low water content (I saw a demo on the discovery channel a few years ago, I also repeated it in a genetics lab, they all survived.)  

SAM

[Sam]

I forgot to add, if you microwave the wood in water it would kill everything as the water would boil up, but it would be much easier to just boil water in a pot and pop it in there.

The best way to sterilize something at your home without chemicals is to put whatever you wanted sterilized in a pressure cooker with a little water and cook it for at least 30 minutes.  The high pressure steam in pressure cookers reaches temperatures that will kill the majority of microorganisms including most thermophiles.


**One must always be careful boiling water in a microwave, especially filtered water, as it can go above 100C and still not boil and then explode on your hand when you reach in to grab it.  I woul just use a stove.

[Mila]

Microwaves doesn't kill microorganism without boiling water?

Thanks Sam

Mila

[Sam]

Microwaves doesn't kill microorganism without boiling water?

Microwaves can kill microorganisms without boiling water [see radiation below]... But your microwave oven just doesn't shoot out enough photons to make it a productive method to sterilize a piece of wood. It would take days to sterilize something a big as a piece of wood in a microwave oven. The reason is the sterilization by microwaves has nothing to do with heat and everything to do with DNA modification.  Simplified, the microwave photons hit the microorganism's DNA and modify it, most modifications will cause death, other will cause the offspring of that microorganism to be mutated and will most likely die.  There is also the extremely rare possability that the microwaves will cause a change in the DNA of the microorganism which will cause make it better than before...not like in the hulk, or spiderman, but on a very small level (without mutation there is no evolution).  

Here is an abridged copy of my notes from my Microbio class on non-chemical sterilization techniques: (We are most interested in *HEAT* and Radiation)


*HEAT*
1. Moist heat kills microbes by denaturing enzymes
2. Thermal death point (TDP) is the lowest temp at which all bacteria will be killed in 10 mins
3. Thermal death time (TDT) is the length of time required to kill all bacteria at a given temperature.
4. Decimal reduction time (DRT) is the length of time in which 90% of a bacterial population will be killed at a given temp.
5. Boiling (100 degrees C) kill many vegetative cells and viruses within 10 mins
6. Autoclaving (121 for 15 mins) most effective method of moist heat sterilization
7. Dry heat sterilization  direct flaming, incineration and hot air sterilization.

Filtration
1.   Passage of liquid or gas through a filter with pores small enough to retain microbes.
2.   They can be removed from the air by air filters
3.   Bacteria and viruses are usually filtered with nitrocellulose or cellulose acetate.

Low Temperature
1.   most organisms do not reproduce at refrigerator temp (0-7)
2.   many can survive at sub-zero temp (but do not grow)

Desiccation
1.   they cannot grow in the absence of water but can remain viable
2.   viruses can resist drought

Radiation (Modifies DNA preventing sucessful reproduction)
1.   Ionizing radiation  high degree penetration; forms reactive hydroxyl radicals.
2.   Ultraviolet  nonionizing. Low degree penetration. Cause Thymine dimmers
3.   Microwaves  can kill microorganisms, but only by bombarding them with huge amounts of photons (Not in a microwave oven)


Now I've done it, I promised myself I would try not to sound like a textbook...

Interesting Factoid...The inventor of the microwave oven discoverred the heating properties of microwaves by accident after he cooked his internal organs in his laboratory.

SAM

[TR]

Well put sam I couldn't have wrote it better myself. lol

                                         TR