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Fri, Mar. 20th, 2009, 06:12 pm

I can't find the autoignition temperature of beef fat on the net. I am saddened.

Sat, Mar. 21st, 2009 03:00 am (UTC)
twomorrow

I still can't find that damned math functions gallery art whatever thingy. T_T

Sat, Mar. 21st, 2009 03:02 am (UTC)
zqfmbg

Well, serves you right for deserting me! >.<

Sat, Mar. 21st, 2009 03:03 am (UTC)
twomorrow

:O

Sat, Mar. 21st, 2009 03:12 am (UTC)
sleeplessone

Strangely you are now the top hit on google for autoignition temperature of beef fat.

Sat, Mar. 21st, 2009 03:39 am (UTC)
zqfmbg

Heh. I didn't do it!

Sat, Mar. 21st, 2009 05:06 am (UTC)
dr0ss

I really want to know why you need this information.

Sat, Mar. 21st, 2009 05:44 am (UTC)
zqfmbg

I had a cast iron pan that read above 750 F (according to my infrared thermometer), and when I dropped in chunks of short rib to brown, they started smoking immediately, and the fat that rendered out at that point also started smoking immediately, and I had a kitchen full of smoke. I'm mostly curious to know if it was anywhere close to lighting on fire.
(Deleted comment)

Sat, Mar. 21st, 2009 06:24 pm (UTC)
nagekinoki

http://en.wikipedia.org/wiki/Tallow

Firstly, all you need to do is find the lowest flash point of any of the fatty acids and you're set. Because saturated fat enters a denser conformation than unsaturateds or poly (because the atoms of saturated fat follow a specific pattern as opposed to others), you're likely looking at the poly's for the lowest FP because they will be the least structurally 'comfortable' in the whole molecule and well, as soon as one of those ignites the whole temperature of the fat will rise to the point of ignition of everything else.

Ah! And here we go. http://en.wikipedia.org/wiki/Flash_point - look at canola oil. 620F. Since canola oil contains a very high % of monounstaurates, you know that at 620F this part of beef fat will ignite. Now because of the %s and the fact that the freezing point of canola oil is 0F whereas that of beef fat is somewhere in the 100-120F range (just from practical observation - I've never seen beef spontaneously melt on a hot day), I'd say yes, you were rather close. There is an equation for determining a given ignition or boiling point from physical chemistry which states that in a mixture you take the partial fractions of everything and -then- multiply by that a factor of less than 1 (because of the molecular chaos), my guess is something like:

620F + ~150-200F * .95 or something (to account not only for the mixture we know of but also for cholesterol, which is another molecule that destabilizes the overall stability of the mixture) = ~760-780F.

Of course, the other thing you can do is go to a chem lab, use a fumehood and go nuts with a heating coil, a metal pan and beef fat if you need perfect numbers.

Sat, Mar. 21st, 2009 06:28 pm (UTC)
nagekinoki

Oh, and for the record:

Another convienient equation is by the fire researchers at Factory Mutual:

tF=0.683tB-71.7

whre
tF = closed cup flash point ( °C)
tB= initial boiling point (°C) or NBP for pure compounds.

(from http://www.cheresources.com/invision/index.php?showtopic=6394&hl=Flash+Point )

So there you go. If I'm not mistaken, the NBP is taken for the highest temperature pure compound because the aX-b function already has factors to account for being a mixture.