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Author: voelkels Big gold star, 5000 posts Old School Fool Add to my Favorite Fools Ignore this person (you won't see their posts anymore) Number: of 259  
Subject: Re: 2 "New" Griswolds Date: 4/6/2011 8:30 AM
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Lemme change that:

We want to minimize the amount of unsaturated fat and maximize polyunsaturated fat, and monounsaturated fat is not too bad, as it at least has 1 double bond... if I'm not mistaken, or am I?


Bob, a quick organic chemistry lesson:
A animal or vegetable oil (fat or grease, which is just a solid oil) is an ester of three fatty acid bound to a glycerin molecule, which is an alcohol with 3 OH groups.

The ester’s bond can be broken by reacting it with water (and usually a caustic such as lye) in a reaction called saponification (s.p.?) This is how soap is made.

A saturated fat or oil is one which has no double bonds in the fatty acid chains. A monounsaturated oil has one double bond among the fatty acid chains. A polyunsaturated oil has more than one double bond among its fatty acid chains.

A double bond is weaker than a single bond and so is more chemically reactive. It can react with iodine, oxygen, etc. especially at higher temperatures. This is the reason that unsaturated oils “smoke” at lower temperatures than saturated oils, like beef fat (tallow).

All that being true, an oil that has many double bonds (the most reactive) would tend to be the best for seasoning cast iron as it would tend to make a harder, more durable finish than an oil with fewer or no double bonds (saturated oil).

The way the iodine number of an oil is determined is that a standardized iodine solution is dripped into an oil that is mixed with a mutual solvent. The iodine will react with the double bonds in the fatty acid chains forming a single C-C bond and two C-I bonds. When there are no more double bonds left, the next drop of the iodine solution will react with an indicator, probably starch, to give a color change in the solution that you are titrating, turning it from colorless to a blue, in the case of a starch indicator. The more of the iodine solution that you use to get to the blue endpoint, the higher the iodine number and the more double bonds of the oil.
;-)

C.J.V. - don’t axe me about triple bonds and resonance, NO!!!
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