Understanding polymerization

[powerstroke73L]

Being that I'm a dyed-in-the-wool centrifuge user I've been going over this in my head a lot lately. There's been a lot of talk about polymerization, what causes it, what causes it to happen faster, etc... I've heard from a lot of people that heat and exposure to air greatly accelerates the process, which to me makes sense. Except for one thing. Most fryer oil has been used everyday (or at least six days a week) for two weeks-sometimes more. Many restaurants I find are trying to get the absolute most out of their oil because of the sharp rise in price. So this means that the oil is being heated to 350 degrees every day for at least 12 hours a day if not more. Not to mention the fact that the entire time it's exposed to air and is constantly being circulated due to water vapor steaming out of the food being cooked. Why then is the oil not polymerized so badly that its unusable by the time it leaves the fryer?

[lamintdog]

Why then is the oil not polymerized so badly that its unusable by the time it leaves the fryer?

My guess why would be exactly what you said.

It's not a lightning fast reaction as far as I understand it. I'd bet that there's probably some initial stages apparent on the heating coils at the bottom of the fryer after a week or so, but I'm not a cook and cannot verify that.

[Clay]

The cookers are SS which i believe is not a catalyst like copper or steel. I could be wrong, I'm no expert on the subject, just read alot about it. I have seen Poly on my HWH element and it was nasty. That was after a year of using it and several hundred batches but the element was copper i believe. Never seen it in a tank but those that have (from using a copper HE in the tank) talked like it occurred over several months and formed chicken skin inside the tank. So no, it is not a lightning fast occurrence. The oil does go through some sort of change after being used in a fryer...not sure what it would be called or if it has a name. The grease tends to soak into the food alot more when cooking with it after it has been used a long time...don't know if thats relevant or not.

[powerstroke73L]

I'm just kind of wondering out loud because I can't seem to wrap my head around the whole thing. It just doesn't seem consistent. For example, I've been using oil that I started storing nearly three years ago. I mixed it with diesel/power service gray bottle and it sat outside in sealed 55 gallon drum, but it seems to be working just fine now.

[lamintdog]

Maybe the additive is stalling poly? Does it have a paint thinner scent? Maybe get crazy and measure the peroxide level in that drum and compare it to a newer sample?

Question: Do you have a special requirement for storing VO for 3 years prior to you using it? Is there a reason you're waiting so long to burn it or a reason why you can't burn fresher VO?

[powerstroke73L]

Question: Do you have a special requirement for storing VO for 3 years prior to you using it? Is there a reason you're waiting so long to burn it or a reason why you can't burn fresher VO?

The only reason I have oil so old is because when I first discovered this whole thing (VO as fuel in diesels) I was broke and a senior in college. I happened to work at a place with a snack bar that didn't have a place to get rid of their oil so I started taking it home to my parents' house on weekends. At the time I had never heard of polymerization, etc...I was still learning about the basics of heated systems and whatnot/figuring out what kind of truck I wanted to buy. I got ahold of some plastic 55 gallon drums and figured why not save the stuff for the future. I filtered it through a t-shirt and added 5 gallons of diesel to each drum, reasoning that it would probably keep it from going rancid.

I didn't buy the General until I had been out of college and working for a year and didn't pick up the V3 until nearly a year after that. All the while I was collecting oil. The more I learned about poly the more concerned I got, but here I sit with nearly 200 gallons of oil. I am still collecting fresh VO, and basically I've been mixing it all together via my cold upflow system that feeds into the CF barrel. So far I've burned nearly an entire 55 gallon drum of the old stuff and no issues with clogging or chicken skin that I can see. Maybe what's happening is that the oil IS polymerizing but it's being diluted by the mixture of diesel and fresh oil?

[lamintdog]

I'll bet the addition of #2 is, for whatever reason, prolonging the inevitable onset of poly... I'm basing this on Jason's home baking class research on poly [picturing DFA branded, doily edged, paisley apron w/ matching oven mitts - "mmm, mmm I think it's just about done"] that he posted the results for on the site... Regardless, VO is organic right? So it's going to break down at some point... If it's workin' for you now by mixing what you've got with fresh oil, then I'd say just roll with it... I mean, we're all just rolling around using setups that I'd consider "testing in production" anyway right? Everyone's got something slightly different, but they're all providing the same end result. If you were clogging filters after hundreds of miles and scraping chicken skin off your barrels all the time it'd be a different story....

The only thing I noticed when running 8month old oil compared to that week's freshness was a slight drop in power, which I mentioned could have been all in my head anyway...

I assume you've read Joe Beatty's report on poly on the frybrid site...if not, get your periodic table out and have at it.

If it ain't broke...!

[Elvia]

I also have hundreds of gallons of 2 year old oil that I have been collecting till I bought my kit. It has been filtered and dewatered, stored in 275 gallon totes. No additives. I am now using it and sharing with travelers. I nor them have any problems with this oil.
My supply now is less that one year old and declining, so, It is newer oil. It is MY belief that if the oil is filtered and dewatered you can store oil for a very long time. As stated in MY circumstances.

[skyskijason]

Sounds like y'all have a pretty good handle on it. I ain't too brite, so it took patient folks much smarter than me several tries, talking - very - slowly before I understood what little I do.

I can attempt to answer the question about the fryer life. THAT is why they add TBHQ, etc to the oil (including hydrogenation)- it helps 'stabilize' it, or slow down the natural degradation that occurs in all things organic. I keep saying we need some of these preservatives like TBHQ, but also metal inhibitors and anti-chelating agents for our FUEL. The fryer lifespan is largely determined by how it makes the food taste. If this time was longer or if the fryers were made of carbon steel or copper - they would have to add more 'stabilizers'/preservatives to the new VO.

As for the 'old' oil. Depending on how it was used, whether it is PH or not, how it was collected, treated and stored - it could be JUST FINE. I have used 'old' VO on several occasions. I have also opened a drum that smelled like paint thinner. So many variables, its hard to say what all was different.

So, if it passes HPT and don't smell like paint - BURN IT BABY!!