Sciencemadness Discussion Board

Solid fat and Vacume question

NEMO-Chemistry - 8-8-2017 at 11:16

I cant try this at the moment as my vac pump is waiting on new seals. So I thought I would ask.......

I have a vac pump that can easily pull a vac strong enough to boil water at 5c, my vac gauge is broken so I dont actually know what it could pull at maximum.

Does solid animal fat (lard and mixed animal species) liquefy under strong vacuum?

Secondly if it does or even if it dosnt, if you pull a strong vacuum on animal fat, does anyone know of any human pathogens that can survive the process? I am aware most bacteria cant take that kind of vacuum.

However I have seen yeast cysts survive a fairly strong vacuum, what i am really interested in however is human pathogenic virus. Will a vacuum kill off any present?

Failing that the obvious other way would be heat, but being mixed animal source the smoke point etc is unpredictable and I am unsure if any pathogens can survive temps below the smoke point of animal fat.

Sorry if the question seems slightly disjointed, I do have a good reason for asking however.

Many thanks

Lillica - 8-8-2017 at 12:02

What's your vacuum model? You can find vacuum spec ratings online fairly easily for pretty much all brands. To my knowledge vacuum is not going to effect the melting point of any substance, but a high enough vacuum can certainly enable sublimation of a solid directly into a gas.

I think it would be easier to help you if you said what specifically you were trying to do? For food safety, it is generally said that above 140f (60c) is when bacteria and viruses die. Though, the issue with tainted meat isn't always a living virus or bacteria. Many times pathogens can produce chemical wastes which are dangerous, and heat isn't necessarily going to destroy these.


I would suggest the possibility of doing a sublimation of the fat under vacuum, but this may not be practical for you since it may be difficult to do at scale.

[Edited on 8-8-2017 by Lillica]

NEMO-Chemistry - 9-8-2017 at 09:12

Its a javac twin vane model with 8CFM on the plate. Its a good pump but your answer has thrown up some answers I wasnt expecting.

What I wanted to do was make sure I ruptured any cell walls by pulling a vac and using a heat if needed. the application is cosmetic based, what I hadnt figured in was metabolites etc which you point out. So maybe with say soap i could get away with it, but other things like body lotions etc are a no no. the material is from fallen stock supplies, so 'could' contain rendered material from diseased animals.

Having read your reply i think its better to pay more and get the material direct from human consumption sources like slaughter houses. having said all that......... no reason i couldnt use the cheap stuff for bio diesel :D.

Thanks for your answer, it made me think about some things i had missed out.

zed - 10-8-2017 at 16:48

Ummm. Viruses aren't alive. At least, not technically. Further, some may be crystalline, have negligible vapor pressure, and be hard to denature.....except by chemical, photonic, or thermal means.

I expect vacuum exposure, to have little effect on their "Viability?".

In the case of Prions.....They can be difficult to de-toxify, even by extreme heat.

I expect vacuum to have little effect in removing other potential pathogens from your fat.

I wouldn't trust such a process at all.

CRUSTY - 13-8-2017 at 04:28

As zed said, you will have no luck with viruses. Even if you do somehow manage to lyse the cell membranes of bacteria, I would be amazed if that had any effect on viruses. Not only are they magnitudes smaller, on the order of nanometers across, which will greatly reduce the force of a pressure differential over any capsid or membrane, many viruses do not contain any lipid envelope, as is the case with most of the classic icosahedral viruses like adenoviridae.

I doubt you'll have to worry about prions, but then again, I wouldn't take my chances with them. Prions are, for those unaware, nothing more than improperly folded proteins (albeit in an extremely dangerous way). A vacuum will do nothing, since there is no internal pressure. Maybe an extremely high vacuum would cause a bit of denaturing, but I'd be surprised. Then again, I'm not aware of their vapor pressures or thing like that.

In short, use heat.

ave369 - 14-8-2017 at 03:05

Well, the viruses and prions, most likely, will not be killed by vacuum... but neither will they distill, they are nonvolatile. If fat can be volatile under vacuum (which, in my mind, is a thin maybe), it will distill over and viruses and prions won't.

NEMO-Chemistry - 14-8-2017 at 06:00

I decided it wasnt worth it, I can use the 'fat' for bio fuel which i dont have to worry about anything nasty in it. For other things I can get hold of human consumption quality fat (costs more is all).

The chances of a disease organism, being present in the fat i was offered, is fairly high. The mixed animal fats are from 'fallen stock', so by definition most of these died of unknown causes. Not all will be disease (most, probably not). But you cant rely on people notifying suspect dead animals around here.

Hence why we are getting our first cases of Bovine TB for years :(.

NEMO-Chemistry - 14-8-2017 at 06:04

Quote: Originally posted by ave369  
Well, the viruses and prions, most likely, will not be killed by vacuum... but neither will they distill, they are nonvolatile. If fat can be volatile under vacuum (which, in my mind, is a thin maybe), it will distill over and viruses and prions won't.


Ave I am going to give it a try and see what happens, purely because I have no idea what happens to a solid fat under a high vacuum.

Also I wonder what happens when you dissolve the fat in a solvent and then distill under vacuum. Or more to the point i wonder how good the separation of the fatty acids etc are?

So something else I will try. Order the seal for my pump as the first one was wrong size!! They are expensive for what they are though!! I will go back to changing the pump oil every couple of weeks and using traps before the pump where poss.

feacetech - 15-8-2017 at 17:02

have you rendered the fat yourself or has it come from a rendering plant

was it processed in eye wells or MIRNZ low temp

I use to grade tallow

FFA (free fatty acid) test (dissolve in nuetralised enthanol and tirtrate against std NaOH), the older and more rotten the offal the higher the FFA content

we use to measure Free colour and bleached colour

we did moisture in air oven for 3 hours if you did it to long it would bleach and lose voltile compounds.

some times i would reneder the viscera and paunch in the lab and measure the ffa contenet to identify where in the process it was degrading

we had a vacuum moisture oven but didnt use it for this test maybe it would evaporate

On the odd ocasion it analysed it in the soxhlet but i cant remeber why maybe i was just playing or it was high water content stick water from the centrifugal seperators

anyway the AOCS has lots of methods for looking at different fats and oils

https://www.aocs.org/