Puzzle: Identify This Phenomena

[Guest iiiii]

I have a, hopefully, interesting puzzle for someone who has more time to spare

than myself.

 

4 pork sausages were placed in a frying pan and approximately one table spoon of pure vegetable oil added. The frying pan was placed on an electric hob and the heat turned up to mark 6, after a couple of minutes the heat was turned down to mark 3. The sausages were cooked for between about 15-18 minutes. And then consumed.

 

The pan was then placed on a cool hob to cool down inself. After consumption of the sausages, the pan was inspected ready for washing and a strange pattern had formed in the oil. If the pan was shaken to disturb the oil, the pattern returned (I'm not sure if it was the same pattern, but it was another regular pattern). Some photos of the pan can be found attached.

 

The puzzle question is, if you choose to accept it:

 

1) What scientific phenomena caused such a regular pattern to emerge, and re-emerge upon disturbance and subsequent settling?

 

Some details that might be useful:

 

Observations:

The pan is tilted slightly so the oil is not evenly distributed over the pan.

 

Sausage ingredients:

Pork (52%), Water, Pork Fat, Rusks, Salt, Potato Starch,

Emulsifier: Pentasodium Triphosphate; Dextrose,

Stabiliser: Sodium Sulphite; Spice Extracts, Herb Extracts,

Colour: Carmines. Casings: Beef Protein.

 

Oil:

It it TESCO Pure Vegetable oil, it says it is "Made from rapeseed".

 

I don't know the answer myself, but I would love to know what caused the patterns.

 

Good luck if you attempt this one.

 

Regards

 

iiiii

[Cap'n Refsmmat]

I think the sausage oil deposited something that caused the oil to stick.

[rockstarjaiden]

that is pretty wicked. maybe it's the particles in the non stick pan that constantly gets hot and burns itself on to the actual metal itself? wicked is all i can say....

[agaubr]

My guess is degradation or the rapeseed oil so you made regions of higher viscosity with lower viscosity material surrounding the material. When the pan is tilted you gte flow from lower viscous oild but the higher viscous oil remains and creates the pattern. Oxidiation of oil at higher tmeperatures is not unusal.

 

Ag

[Guest iiiii]

I forgot to mention something. Near the end of cooking, the oil was smoking a lot. I have also made an observation. It appears as though the size of the patterns is proportional to the deepness of the oil.

 

I think the idea of the differing viscosity and flow might have something to do with it. But why these patterns?

 

If it is related to oil viscosities, I wonder how many viscosities have been combined, is it two, or three? or maybe even more?

 

Is this experiment readily repeatable? How does using different types of oil and so on, effect the results?

 

iiiii

[YT2095]

when the oil smokes, it`s breaking some polymer bonds making smaller molecules, it would seem that some terminate in a carbon due to the discoloration, these will more readily bond to each other form loose but very large chains that will result in that patern.

a bit like soap molecules, one end is hydrophilic and the other hydrophobic, one end grabs grease the other water. in this case it seems to prefer it`s own type rather than the unaffected oil

 

that`s my guess anyway

 

[Radical Edward]

probably a combination of things really. I would posit that the pattern in the thinnest bit of the oil is related to the grinding of the pan, So the junk, which I ammume would have some water in it (and hence would separate from the fat) is more likely to be deposited in the dips. This would start the seed for the rest of the pattern to form, since the fat would cause all the hydrous elements of the fat to clump together. the effects of the original seeding would get weaker and weaker the further from the shallow oil you get.

 

I would suggest trying to tilt the pan at different angles to see if the rate of pattern change from the thin bit changes, and also different depths of oil too. with shallow oil you will probably get a very fine pattern all over the pan

[Radical Edward]

I think it seems YT and I pretty much agree. excellent start post by the way

[Guest iiiii]

OK, great! Looks as though we are piecing the puzzle together. I've got some more pictures. The top one is the pan close up so you can see the type of grinding and scratches.

 

Referring to the seed idea, we now have the concentric nature of the pan and the scratches. I'm not yet sure how these relate, but I might postulate that the scractches add an element of randomness to the pattern generation.

 

Is the degradation of the rapeseed oil crutial for the generation of the patterns? Or does it rely on the the combination of sausage oil and rapeseed oil? Is the breakdown of the rapeseed oil different in the presence of the sausage oil, than it would be on its own?

 

Ok, this is pretty interesting. If I get some time I'll try and do an experiment with just rapeseed oil and see what happens, and then perhaps repeat this with one sausage and some oil.

 

It would also be interesting to see rapeseed oil and lard, rapeseed oil and butter, margarine, and perhaps other combinations, but I think just working out this first question is going to be pretty hard, so let's see.

 

Oh, btw, the second picture is an attempt at doing the experiment with beef burgers. The effect did not emerge, at the end of cooking the oil looked much less dirty, and no smoking was observed during the cooking phase.

 

If time permits, Ill try and be more methodical, and get exact quantities, and temperatures and so on...

 

iiiii

[agaubr]

Yes he chemistry and physics can be affected y many impurities. My guess is the majorfactor is formation of acid grousp due to oxidation of the oil and the inital formation of small molecules ( smoke formation ) and then fromation of larger molecules. the acid groups can from metal-acid links which will anchor the chain in a local region. This achoring is similar to what happens in lubricating systems designed for high temperatures or extreme cases of thinning. This formation of the metal-acid interactions allows the oil to not thin and lubricate a metal metal surface.

 

Ag

[agaubr]

if these moelcuelsare anhcored by this metal-acid interaction then as the system cools of the low viscosity oil will tend to move in the direction of the higher visocus oil with larger molecules since these will contract on cooling nd pull the material toward these points of anchor and you get regions of hihg oil concnetration and valleys of,low concentration. Why the patteren foorms wit some apparent order would not seem logical since a random pattern would have the highest entropy for the system. So some other overrding factor must be presence.

 

Ag

[agaubr]

Lastly, if the regions of high concentrations are thicker one might expect the cool dwon rate for these localares is lower than for the valleys due to insualtion from the oil presence in the sregions at hgier concentration. Nw how this causes this pattern I cannot explain.

 

Ag

[Guest iiiii]

OK, I've lost interest in pursuing this any further as something else more interesting took its place for me. So I doubt I'll carry out the other experiments. But I'd like to say thanks to everyone for their responses, I think we were pretty close to getting it right.

 

I think that chaos theory might have something to do with the patterns, and the complex interactions between the oils of differing viscosity could probably be modelled in some manner, which would be interesting.

 

But anway, it's great to see a flourishing science forum.

 

Thanks again for your responses and time

 

iiiiii