Ian Stirling said:Cooking in oil that has been used a long time is unhealthy, due to the
amount of free fatty acids that build up in the oil.
The process of making biodiesel removes these free fatty acids, and
converts them to a form that can be removed by washing the oil.
Washed biodiesel has no free methanol, near zero FFA, and no NaoH.
Can you then, instead of putting the biodiesel in a vehicle, simply
replace it back in the deep fryer, and cook with it?
I'd be most concerned with the methanol group coming off during
metabolism. It's a CH3-COO-R, right? It might cause some damage.
Biodiesel is also a great solvent. (I used some to remove marker
stains.) No telling what that great solvent will do to the cells
lining your mouth and esophagus...
Biodiesel also smells pretty funny - not at all like vegetable oil.
(At least, the stuff that I make... 😉
Oh, and it's VERY flammable. Much, much, much more so than vegetable
oil.