Cooking Splatter: What Happens & Why?

[bjarnidk]

So when me and my girlfriend cook, a typical setup might look something like a pan on one heater and a pot with something on the other.

Today I was cooking eggs and she was boiling water. Something was in her water (didn't look like eggs at all) and she said it was the eggs from my pan, jumping into her pot (assuming due to pressure).

What exactly happens when eggs, bacon and other things "blow up" on the pan? I'm guessing it's built up pressure in the fluids which then makes them pop. Obviously with bacon, you can feel these fluids on your hand if you're close but what is this fluid? Is it water? Grease? Is it dangerous? Does she have any reasons to remove her pot until I am done cooking my eggs (or whatever I am cooking).

 

[phinds]

I cannot connect your post to your subject. What does all that stove stuff have to do with superstitions?

 

[Electric Red]

I cannot connect your post to your subject. What does all that stove stuff have to do with superstitions?

Does it matter?

 

[STEMucator]

Does it matter?

Every post up to this point is so off topic lol.

 

[eigenperson]

Small amounts of food can be spattered over a considerable distance -- certainly far enough to go from one pan into the one on the next burner. The cause is the pressure created by the boiling of moisture inside your food.

The material that is spattered would be whatever you were cooking. If it's eggs, then the stuff that will be spattered is egg. If it's bacon, then the stuff that is spattered will be bacon.

 

[jbriggs444]

The material that is spattered would be whatever you were cooking. If it's eggs, then the stuff that will be spattered is egg. If it's bacon, then the stuff that is spattered will be bacon.

If one is frying eggs, the spatter will be, in large part, the oil being used. Perhaps bacon fat in the case at hand.

 

[davenn]

the obvious way to solve the problem would be to use pan/pot lids!

its not rocket science

Dave

 

[Aero51]

The popping is caused by a phase transition and a build up of gases, which is rapidly released.


The fluid is actually lava- a little known fact.

 

[SteamKing]

When I cook, my food rarely 'blows up'. Am I cooking it wrong? Would it help if I had a GF or someone else it would annoy? Don't you find that two (or more) people trying to cook on the same stove at the same time is somewhat crazy? When your breakfast (or whatever) blows up during cooking, don't you hate it when you have to track down every morsel from the walls/ceiling of the kitchen when you are trying to eat it? Do you only cook with the heat turned to its highest setting? I find that cooking time is greatly reduced, but the trade off is that the meal comes out crunchy, if it hasn't blown up all over the kitchen. What about baking or roasting in the oven? If the recipe calls for 300 degrees, do you say "What the hell? I'll set it on 600 degrees! Not only will it cook quicker, maybe it will blow up in the oven!"

 

[Jolb]

Thank you, SteamKing, for that highly insightful post.

I just want to say one thing. The spattering is not due to pressure building up nor a phase change ocurring. [Place a damp sponge on the frying pan. It won't spatter even though the pressure is increasing and a phase change is occurring]. The real, and somewhat obvious mechanism, is that bubbles of gas in the food/oil form (due to the phase change) and then they move to the surface and grow (due to the pressure) and eventually there is a critical point when the bubble pops, much like a balloon. This popping causes the high-frequency disturbances needed to eject a droplet of food/oil.

 

[SteamKing]

Sarcasm, aggravated, multiple counts.

 

[256bits]

And as an added note, I have heard of jumping from the pot to the frying pan, but never the other way around.

 

[Jolb]

Sarcasm, aggravated, multiple counts.

How could such a felonious act occur in the intellectually mature environment of PhysicsForums?


Anyway, this is a serious question. Take a look at the following high-speed video of a bubble bursting. At the very beginning of the video, you can see that the sudden breaking of the bubble can eject droplets from the fluid's surface. http://www.wired.com/wiredscience/2010/06/high-speed-bubble-video/

Edit:
You can see that bubbles rising to the surface can eject droplets in this video as well:
http://www.pond5.com/stock-footage/5035323/bubbles-rise-surface-water-5.html

 

[SteamKing]

Yeah, we get bubbles.

The funny part about the story in the OP was not that food occasionally spatters when cooking, but that the OP said his food 'blows up' while cooking. 'Blow up' is used sometimes to mean explode, as in 'the bomb hit the target and blew up.'

 

[Baluncore]

I think the spatter can only occurs when cooking a wet substance in a "thermal transfer fluid" above the boiling point of water. Water flows in the raw food and forms a droplet within the food, the food then coagulates as the droplet approaches boiling point. When steam is produced in the cavity containing the droplet, pressure ruptures the newly formed containment and the liquid droplet is released into the hotter oil. It immediately turns to steam. That steam burst propels drops of the surrounding oil into the air.

It is not quicker to boil things in a pan with a lid, it is just significantly more economic since a lid reduces heat loss. It also stops spatter.

A common cooking superstition is that when cooking pasta, a drop of oil should be added to stop it all sticking together, and salt should be added for taste. In truth, the oil prevents surface bubbles forming and overflowing the pot. The salt corrects the osmotic balance and so prevents excessive water absorption which would make the pasta stick together.

The truth really does not matter when you are hungry. Gödel starved to death while his wife was in hospital.

 

[sophiecentaur]

I think the spatter can only occurs when cooking a wet substance in a "thermal transfer fluid" above the boiling point of water. Water flows in the raw food and forms a droplet within the food, the food then coagulates as the droplet approaches boiling point. When steam is produced in the cavity containing the droplet, pressure ruptures the newly formed containment and the liquid droplet is released into the hotter oil. It immediately turns to steam. That steam burst propels drops of the surrounding oil into the air.

It is not quicker to boil things in a pan with a lid, it is just significantly more economic since a lid reduces heat loss. It also stops spatter.

A common cooking superstition is that when cooking pasta, a drop of oil should be added to stop it all sticking together, and salt should be added for taste. In truth, the oil prevents surface bubbles forming and overflowing the pot. The salt corrects the osmotic balance and so prevents excessive water absorption which would make the pasta stick together.

The truth really does not matter when you are hungry. Gödel starved to death while his wife was in hospital.

It will be quicker to heat the water up to boiling point and it will also cause the temperature at the surface of the water to be higher. So, on the whole, putting the lid on is likely to reduce cooking time in the same way that rapidly boiling pasta and potatoes will cook them faster, despite the upper limit to the temperature of the hottest bits of water in the pan as the mean temperature goes up.
I think it's a case of Old Wives 1...Physics Students 0
(Experience vs analysis: this is rare, in my experience but the analysis needs to be accurate)

 

[Jolb]

I think the spatter can only occurs when cooking a wet substance in a "thermal transfer fluid" above the boiling point of water. Water flows in the raw food and forms a droplet within the food, the food then coagulates as the droplet approaches boiling point. When steam is produced in the cavity containing the droplet, pressure ruptures the newly formed containment and the liquid droplet is released into the hotter oil. It immediately turns to steam. That steam burst propels drops of the surrounding oil into the air.

I don't buy this theory. The one I gave is better. I'd like to call your theory the "popcorn" theory of spattering because you seem to postulate that the food "coagulates" into a "cavity containing the droplet" and then the cavity explodes--basically a little popcorn kernel forms in the food and pops. I think this is silly because the surface tension of bubbles provides the needed sort of containment which suddenly bursts. You do not need "coagulation". If you've ever boiled pasta sauce, you'll see that the bubbles exploding on the surface often spurt out droplets of sauce. But they're clearly not "coagulated"; they're definitely just a liquid bubble supported by surface tension.

I mean, of course the popcorn effect can happen in cooking and probably does to a limited degree, but spattering from cooking, say, bacon probably has more to do with fluid bubbles than coagulated shells.

Also, Sophiecentaur is right about cooking with a lid on.

 

[sophiecentaur]

I don't think it can be "surface tension" in the liquid. However, when a liquid in a jar boils very rapidly you can get 'bumping' when the pressure in the bubble is higher than the hydrostatic pressure. Most boiling situations are more than that, I think. When you fry an egg, you aren't dealing with a liquid - it only splatters when the white starts to form and you have the possibility of small 'balloons' of the solid cooked protein forming, which can withstand higher pressures before bursting or before the edge of the egg lifts of the bottom of the pan. You can get a similar effect (rattling) if you put flattish ceramic pieces on the bottom of a pan (anti-bumping chips). The water boils explosively underneath by being constrained temporarily by the chip but the 'explosions' are very small and safer than a violent boiling.
I wonder if the GF is just winding the OP up by dropping debris in the water and seeing what sort of nerd reaction she will get? I have been suckered into things like that 'cos I can't help wearing my Physics hat.

You should cook Pasta in an open pan but Stir it Regularly, osib. I was served DISGUSTING spaghetti in Rome (of all places) with clumps of uncooked pasta. I chickened out of complaining.

 

[Jolb]

I don't think it can be "surface tension" in the liquid. However, when a liquid in a jar boils very rapidly you can get 'bumping' when the pressure in the bubble is higher than the hydrostatic pressure. Most boiling situations are more than that, I think. When you fry an egg, you aren't dealing with a liquid - it only splatters when the white starts to form and you have the possibility of small 'balloons' of the solid cooked protein forming, which can withstand higher pressures before bursting or before the edge of the egg lifts of the bottom of the pan. You can get a similar effect (rattling) if you put flattish ceramic pieces on the bottom of a pan (anti-bumping chips). The water boils explosively underneath by being constrained temporarily by the chip but the 'explosions' are very small and safer than a violent boiling.
I wonder if the GF is just winding the OP up by dropping debris in the water and seeing what sort of nerd reaction she will get? I have been suckered into things like that 'cos I can't help wearing my Physics hat.

You should cook Pasta in an open pan but Stir it Regularly, osib. I was served DISGUSTING spaghetti in Rome (of all places) with clumps of uncooked pasta. I chickened out of complaining.

All that is interesting but I don't see any argument for why my suggestion is wrong. Surely you agree that spattering of boiling pasta sauce is due to bubbles of fluid rather than "protein balloons"/popcorn kernels. When cooking an egg, don't you think it's possible that some water from the egg gets trapped in an oil bubble which pops? That would definitely open the possibility of spattering, right? And the theory would apply to any fluid [with surface tension], whereas the popcorn theories rely on specific chemistry happening. As an example that has no fancy chemistry going on, and one you can try in your kitchen, just pour a little water into a hot pan of oil. You'll get spatter [provided the oil's reasonably hot]. Nothing coagulates into a solid in that example.

 

[sophiecentaur]

All that is interesting but I don't see any argument for why my suggestion is wrong. Surely you agree that spattering of boiling pasta sauce is due to bubbles of fluid rather than "protein balloons"/popcorn kernels. When cooking an egg, don't you think it's possible that some water from the egg gets trapped in an oil bubble which pops? That would definitely open the possibility of spattering. And the theory would apply to any fluid [with surface tension], whereas the popcorn theories rely on specific chemistry happening. As an example that has no fancy chemistry going on, and one you can try in your kitchen, just pour a little water into a really hot pan of oil. You'll get spatter. Nothing coagulates into a solid.

I wouldn't disagree with that. Bubbles form whether or not you have a pure liquid or a composite material like pasta sauce. I say "composite" because things don't all classify as solid liquid or gas. When a bubble reaches the surface of water, it collapses harmlessly. When it cets to the top of the sauce, the situation is more complicated and it doesn't surprise me that it could form droplets around the edge of the main bubble. These droplets could easily be thrown out of the pan. The surface tension could be very low. There's the possibility of standing waves as the bubble releases and collapses. Nothing would surprise me as it won't behave like a straightforward liquid so I don't think you can predict on the basis of how water behaves.
When you have hot oil and water, the oil can exist as a liquid above 100C so the water is likely to boil explosively under those conditions, under hot oil.

 

[Jolb]

Here's another [surprisingly trippy] video of what happens to a water droplet in hot oil. All of this seems to be submerged in the oil/water but you can see violent things happening to the surface of the vapor bubble.