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The Physics of Hot Pockets
StartsWithABang (3485481) writes "You've all had the experience: you're all excited to microwave your favorite snack. So you pull it out of the freezer, you throw it in, and you let it rip. A minute or two later, you pull it out, and there it is: boiling on the outside, frozen in the middle. Finally, a physicist answers the eternal question: why do microwaved foods remain frozen on the inside when they reach scalding temperatures on the outskirts? Starts With A Bang explains the whole phenomenon. Bonus for the crisping sleeve explanation!"
Also those with rotating microwave trays (because microwaves tend to heat unevenly) ought to be aware that anything at the center of the tray will not get the benefit of rotation and heat at the same rate the entire time. To roll around in a (relatively) even distribution, none of your food should sit in the center of the tray.
a microwave with more than 300 watts of power. I've never had the issue of hot outside/cold inside, my problems have always been of the hot outside/nuclear inferno/solar coronal mass ejection on the inside variety, regardless of where I've microwaved them. I don't even follow the instructions on the package very closely, just pull it out of the wrapper, put it in the sleeve, toss it in, slap the door shut, 3 or so minutes, and out comes an external breading hot to the touch with napalm in the center. Maybe there are just a lot of broken microwaves, or even more likely, people that don't know how to use them properly?
Most microwaves have a power control. 90 seconds at power 2 or 3, wait 1 minute. Flip, 1 minute at full power. Wait 3 minutes. Serve.
There exist websites and books devoted to this appliance and how to use it correctly. This is a non-story.
Caveat: there are some nice physics going on in the explanation but only for the layman. Look elsewhere for the gritty detail we /.ers are used to seeing.
Ever notice that Cobra Commander sounds an awful lot like Star scream?
I've never had a problem with Hot Pockets: Follow directions, learn how it works in a given microwave oven, and...done: Ridiculously-hot cheap, bubbly, unhealthy goodness.
Meanwhile, I don't need to read TFA to learn how the powdered aluminum wrapper turns RF energy into thermal energy. And I don't need TFA to know that any thing has a certain reluctance toward changing temperatures, as nothing is a perfect thermal conductor.
In fact: Dude, I've been cooking with a microwave since I was a little kid: It was the first kitchen appliance I was certified on other than -- maybe -- an electric can opener.
Up next on /.: How shoelaces work to keep our shoes on our feet, followed by a lesson in using a light switch to illuminate a dark room. Or "Toast: Why bread is caramelized only on the outside when using the every-day toaster."
*head in hands*
Kid-proof tablet..
My tray is rectangular and goes forward and backward as well as side to side. Screw that circular junk.
Scalding on the outside and frozen inside is a feature: it's the Hot Pocket's way of telling you it really isn't proper nutrition.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
I always assumed it was something to do with losing energy as the microwaves penetrated the substance, and I don't see how this explanation really changes that. After all, when the pocket comes out of the freezer it is ALL frozen. OK, so frozen stuff doesn't microwave easily, but then why does the outside heat first? My intuitive thought that the microwaves don't penetrate as well seems unrefuted.
Well, now I understand why hot pockets stay frozen in the middle, but the article doesn't tell me what I can do to heat it up...
Ever noticed when something is frozen (e.g. some minced meat) that the first little while defrosting does nothing, but at some point suddenly the outside edges are cooking?
Microwaves affect hot water and steam more than they affect cold water or ice. There's your physics.
And as someone mentioned there's a power control on microwaves, so that periodically the heat is allowed to spread into the food without putting more energy into the already hot bits.
Don't get me started on the shit choices of duty cycles though!
Hey, if idiots wrote it then RTFM is a bad idea, OK?
Simply keep the Hot Pockets in your fridge. Then place them in your toaster oven to cook them.
Jim Gaffigan sums up my feelings on Hot Pockets.
https://www.youtube.com/watch?...
I just wish there was a blog - probably most appropriately titled Ends With A Bang - that explains the bathroom devastation that occurs after eating one.
Could we please have some news that isn't so amazingly US-centric for a fucking change? There's more things happening in the world than in pathetic US-of-A. Provide some variety of topics ffs. I best the next story will be about Comcast or Netflix or some shit.
I know I'm going to eat a frozen dinner so I sit it on the counter for 10 minutes before i heat it. They heat up evenly and faster.
I also nuke for a 15% longer but at 80% power.
Of course, I also gussy frozen food up too. Adding just a teeny bit of herbs, or sour cream, more vegetables or some fresh cheese can make them quite tasty.
She was like chocolate when she drank... semi-sweet at first and then increasingly bitter.
Wow that guy is a great writer! I'd like to write more but I just got a warning that the Internet Exclamation Mark Hopper is running low on exclamation marks for some reason!
This. This very much so.
Once you learn how a microwave DOESN'T work, you can begin to use it correctly.
And when you do learn how to use it correctly, even the ready-meal generation of foods will cook brilliantly.
I literally haven't used an oven in years.
You can cook anything in microwaves as long as you Do It Right. And if you get a good solid microwave, it will last you for years. A nice big one at that.
You gotta play with the heat settings. Experiment a little, see how your microwave cooks dense and light foods.
Now half the power settings and see how it does. Compare the two and see how you can combine low and high powers to produce something that is both cooked and crispy.
And funnily enough, many of those ideas used for a microwave will also considerably speed up cooking in an oven as well.
The biggest of these is cutting meat up in to smaller pieces so they absorb more heat. Some purists will wank over how they put a whole chicken/turkey in the oven with stuffing and be ready in so many hours. Meanwhile smart people will say "screw this traditional nonsense", slice it up, maybe even shred it, add some stuffing on top it, or even some of it if some don't like it, it is considerably more customizable this way, then be done in less than half the time.
The one bit where that does fall apart is cooking one lump of meat to different levels of being cooked. But that is exactly where the microwave prevails! We just came full circle.
Ovens. Get rid of them.
[citation needed]
I've never seen the explanation for how a microwave works written as in your message until today. All the explanations I've seen are what's stated in the article; so I think it's your explanation that's wrong for how microwave ovens heat water.
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"We offer a Hot Pocket; the outside is boiling lava-hot and the inside is frozen solid."
"Will it burn the roof of my mouth?"
"Oh, it will destroy it. Everything will take like plastic for a week."
"I'll have the Hot Pocket."
He is right [RF engineer here] and the article is flat out wrong, along with all the other crud about water resonance. Yeah, water is resonant, but nowhere near 2.45 GHz. And they don't cook from the inside out. It's just the normal skin effect from a lousy conductor that allows the currents to penetrate deeper. Microwaves are also used for metal-ceramic sintering, and other industrial heating, along with 13.56 MHz. Those frequencies are ISM band; no specific resonance.
microwave ovens simply induce massive current and cause Joule effect heating. But only on objects near the size of the RF wavelength. The explanation is in the article itself:
This is not correct, because you can easily microwave things much smaller than the wavelength. And if your microwave is old or crappy enough to set up a standing wave instead of having a decent stirrer, you get get hot and cold spots corresponding to the nodes in the standing wave, instead of any heating from current sloshing back and forth.
The heating in a microwave comes from dielectric heating, which is basically directly shaking the water molecules. It has nothing to do with resonance, but it still is a moving of the water molecules by electric field. Even though they are much smaller than the wavelength, they can still couple to the RF field. It is not the same as an antenna which would be in efficient at the size, and to something on the scale of a molecule, the RF field looks effectively like a DC field at any given point, but that is all that is needed.
1100 watt oven 3 minutes 10 seconds, without the crisping sleeve, on a paper plate, on the outside of the turntable. Let cool for a minute, or two, Eat. Better tasting fillng that way too.
it is considerably more customizable this way, then be done in less than half the time.
It is odd to advocate a reduction of options as being more customizable. However customizable using a microwave oven is would still be less options than owning both an oven and a microwave (or a microwave oven with convection built in for those with limited space). Maybe sometimes we don't want meat that is shredded, or want to make something like bread or pastries that are bigger than the size evenly heated by a microwave, or want to cook something that does better with a long, slow heating, or want a crispy outside and moist inside. And it is not like the extra time is that big of a deal, since while something is sitting in the oven or microwave, the person cooking can go do other things.
It also just seems weird for a geek to advocate using fewer tools instead of the right tool for the right job. If situations limit your tool selection, whether due to costs, time, or space, sure, there is a lot you can do with fewer tools and a lot you can learn from trying to better use a single tool. But that is different than suggesting to avoid or get rid of a tool you may already have, or suggesting that there are no uses for a different too or ways to optimize when you have a choice in tools.
So it does take a whopping two hours for me to cook a whole turkey in the oven, and if it is a week day that I have to cook something after getting home late from work I will chose something that can be done in the microwave. But on a weekend when I have time to start early, I'll chose the oven every time for the turkey even though I've cooked turkey from raw in a microwave before. And I wouldn't gain any extra time by using a microwave in those cases, because I would be doing something else for those two hours, either way needing about ten minutes of prep work.
you learn that in physics classes normally
A quick google search came up with a Maytag Microwave with WideGlide(TM)
Just an aside, the stuffing people are public nuisances, you need to get stuffing to 165 to get rid of the raw turkey juices it is exposed to. To get it to 165 while inside the turkey requires cooking the entire bird until the slow cooking dark meat is overdone and the fast cooking white meat is burned and cracked jerky like substance. If you cook until the turkey meat is ready, you are serving still raw meat juices in the stuffing.
Cook the stuffing outside the bird for everyone's sake food poisoning should not be a family tradition.
I used to eat 3-4 Lean Pockets a week, so I've got a pretty good idea what I'm talking about: I've never had the problem he describes with the outer portions being lava-hot but the center being frozen. This has been so across 3 different microwave ovens, one of which was an ancient late-'80s unit made when turntables were a premium feature and you set the time with a dial.
My secret? Following the goddamn directions on the box and adjusting for the microwave's rated power. The directions are usually for a 1000 Watt microwave (some products calibrate for 1100W for some reason). That's what my current unit is, so that's easy. If the microwave is 900W, you nuke the food for 10% longer, so if the directions call for 3.5 minutes you convert that to seconds (210) and add 10% (21), giving 231, then convert that back to minutes and seconds, which is what the microwave groks (3 min 51 sec). Stupid easy.
I have had the author's described problems when heating up leftovers, especially stews.
Hail Eris, full of mischief...
E pluribus sanguinem
Microwave bacon.
Seriously. This coming from a bacon lover who saved the rendered bacon lard from all his bacon frying adventures. Once you go microwave bacon, you never go back. Perfectly crispy every time.
But you don't get to save all the bacon lard, unfortunately. Good thing I still have a solid 8 oz. left from my frying days.
Chuuch. Preach. Tabernacle.
You can preheat the stuffing, which can actually help the turkey cook more thoroughly if done just right. It helps a lot if you have water proof oven mitts (like some of the silicone ones) for stuffing the turkey while the stuff in is hot. Or you can stuff the turkey with stuff that you don't plan to eat and still get some of the flavor benefit to the turkey (e.g. head of garlic and some bunches of herbs, or some dried fruit).
Part of the problem is that those shoes also don't last long enough to earn after-market laces. I have replaced original-equipment faux laces on new shoes with good results.
They feared that it could be used to suppress protest or support unpopular rule.
I'll second that statement. Microwaving is especially nice for me because I can make the bacon crispy without having to char it, which was always my pet peeve about bacon.
A reasonable compromise is to stuff the skin around the neck area. Extra stuffing can be rolled into balls and cooked next to the bird (the bottom tends to get a little soggy but tastes great)
I thought every college student knew that.
Mind you, Hot Pockets are nasty. Lean pockets are slightly less nasty.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
Microwave bacon.
But you don't get to save all the bacon lard, unfortunately. Good thing I still have a solid 8 oz. left from my frying days.
What, you don't wring out the paper towels to recover the bacon fat?
Get yourself a microwavable rack and enjoy both your crispy bacon and the lard.
I'm aware of the rack, but I've already got way too much shit in the kitchen. One day, it came down to the microwave bacon rack or the immersion blender, and I decided the immersion blender was way more valuable to me.
That being said, wringing out the paper towels would be blasphemy. By that point, the lard has already been tainted with that paper towel flavor. Don't ask me how I know.
Chuuch. Preach. Tabernacle.
Look, the EM wavefront doesn't "know" what the hell is in front of it, it doesn't "do" one thing to water and another to metal. It's ALWAYS induced current.
Except that microwaves work quite well at heating decent purity or high purity water. If it was just induced currents, then it would only heat things with low resistivity, since it is setting up essentially a certain electric field, you would get a 1/R dependence on heating. This is why it heats low resistive metals like aluminum well, but not stainless steel as much (magnetic permeability helps though too at changing skin depths). But with even crappy quality water, the resistivity is higher than metal, and you have something acting like a dielectric instead of a conductor.
If you are an RF engineer, then you should be well aware of dielectric loss. You can work out the skin depth of 2.45 GHz in reasonably conductive drinking water and get a skin depth of ~50 cm if only treating it as a simple conductor, but if incorporating dielectric losses you get something on the order of a couple centimeters depending on the temperature of the water. For salty water or something like meat, you get a combination of effects, but the dielectric loss is still the dominant effect.
Or you can stand your turkey on it's head (or where it used to be) and spoon the stuffing into the carcass..
He tried to kill me with a forklift!
Microwaves are useful for heating small amounts of water, and that is about it. They destroy/alter the texture and taste of food to the point of being uneditable.
Yes, I am a microwave hater.
Apparently, you aren't too fond of spelling either.
Dielectric loss ... of the current induced by the RF field. That's why the metal crisper thingies have a complex pattern etched into them. If it's just a flat piece of aluminum foil, it will induce such a massive current that even a low resistance piece of metal will have high voltage across it. If you break up the metal into a pattern so not all of it picks up the wave, you have less current and therefore a controlled Joule effect heating as opposed to a shower of sparks.
And your number for the skin depth is wildly off.
Finally someone who got it right. GP is wrong about the Joule heating; ultra-pure water with near-zero conductivity heats just fine in the microwave, as do oil and dry carbohydrates, and insects do die if they don't manage to go sit at a node in the standing wave, only they seem to actively seek these nodes by moving to where it feels least hot. That said, it seems plausible that there is some joule heating in actual food, and it could even help explain some weird heating patterns; it's just not the most important contribution overall.
TFA at the very least used unfortunate wording suggesting rotational resonance, which would also be wrong. This is a pervasive urban legend even amongst people who should know better, and can even be found in some entry-level textbooks (see the scan in TFA). The misconseption is based on the fact that molecular rotations for gases are indeed located in the microwave spectrum. However, molecules don't really rotate freely in the condensed phase (and the peaks for water vapor are at 22.2 and 183GHz anyway so the frequency of the microwave oven would be far off). Dielectric heating is the only correct explanation. That said, it does seems plausible that the dielectric heating of liquid water is more efficient than that of ice because of the more persisten hydrogen bonds, so TFA probably got that part right.
In summary, both GP and TFA got their basic mechanism wrong but contain some good arguments nevertheless.
Bacon in the oven, 400F for 20 minutes. Putting the bacon on a rack over a pan to catch the fat keeps it out of the melted fat and makes it a little crispier.
slice it up, maybe even shred it,
Because mince > steak, obviously.
Learn to cook bacon in the oven. On a rack.
Deliciously crispy, and no splatters.
Yes, you get induced currents in metal, that doesn't contradict that when you stick a dielectric in there you get dielectric heating, which is not from induced currents. It is from changing in the polarization due to the electric field, a lossy process that doesn't involve any bulk currents, and works in materials with very high resistivity. (Yes, you can talk about a polarization current caused by a change in polarization density, but this is still distinct from the free charge current you get when putting a piece of metal in an RF field.)
A clear distinction this makes is that the dielectric loss in water decreases with increasing temperature, despite the resistivity to free charge current decreases allowing for larger losses and higher coupling for induced currents. The heating of water by RF decreases with temperature at 2.45 GHz, while the heating of salty water that has a much higher component of induced current increases with temperature.
As for skin depth, that was done with the conductivity of around 500 Ohm-m for tap water (maybe we have really good tap water where I am), with most impure tap water being on the order of 10-1000 Ohm-m even at high frequency measurements. Even at the lower end of that scale, you're an order of magnitude off of what you would get including the dielectric loss.
the fact that you read off the calorie, fat, etc. content shows how clueless you are.
No one should ever eat Hot Pockets. They (like Jack n' the Box) should not exist in the first place.
Its ok if you don't understand. I know... I know... You _like_ Hot Pockets.
You _like_ Jack in the Box.
Here's a test for you: ever notice that a fly in the microwave survives?
Not longer than 3 seconds. https://www.youtube.com/watch?v=Kdsyq6RnjO4
jason.arthur.taylor at gmail dot com;240-471-5613. I respond to all emails, if only with "ok." If I did't respond, I did
I've never ever experienced a Hot Pocket that was anything less than flesh-searing hot on the inside.
That said, TLDR: Energy is supplied to the outside faster than it can be conducted to the inside of the food.
I'm too lazy to count, but I'm pretty sure that would fit in a tweet, and hopefully it was a "no shit" situation for 99% of people with brains. Essentially it's the same reason a steak can be burnt on the outside and raw on the inside.
https://www.eff.org/https-everywhere
Given that we are being repeatedly told -- most recently in a troll Ars Technica article -- that microwave radiation is harmless...What did he die of?
Perhaps you missed the direction about cooking the hotpocket inside the crisper it comes with in a 1100 watt microwave oven; preferably in a microwave with a rotating carousel. Or possibly the direction to let it sit for 5 minutes after cooking.
A minute or two later, you pull it out, and there it is: boiling on the outside, frozen in the middle. Finally, a physicist answers the eternal question: why do microwaved foods remain frozen on the inside
Because the microwaves are high energy, they are absorbed or dispersed near the surface, when they come into contact with compounds such as water.
The heat takes much longer to conduct through the material, than microwaves take to hit the material, therefore: the center takes longer to be heated.
Would microwaving frozen food in a vacuum (or conversely under high pressure) make any useful difference in how evenly the food cooked? A lower pressure would lower the boiling point and a higher pressure would raise it. What about subtly modifying the wavelengths or amplitude? I'm not a physicist so I have no idea. Just throwing that out there to see if someone smarter than me can make it stick.
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Because of some combination of the consistency of the stuffing I make that doesn't stay in a spoon easily, and the tendencies to not use over-sized birds (I would rather cook two 10-15 lb turkeys than a 20+ lb one), I've found a spoon to not work very well. A cloth oven mitt with a plastic baggie over it or a silicone mitt allowed for much quicker stuffing with out making a mess, but still involved sitting it up.
"as long as you don't eat nothing but too many of them or some other junk food"
I'm glad I have convinced you that Hot Pockets are junk food.
"And the rest says it is bad because it might make you eat too much?" The answer is no, that's not what the rest says.
Again you bring up the "salt, sugar and fat content". Do you understand that some fat is good for you and some fat is bad for you? Do you think hydrogenated vegetable oil is ok? How about wood? Do you like eating wood? If you read about the recall you would start to get an idea of the kind of meat that goes into Hot Pockets.
Its weird that you brought up alcohol, but I guess your point would make sense if I was arguing that Hot Pockets are bad for you because they might make you eat too much. Which I'm not. One Hot Pocket is bad for you. Its junk food.
Junk food is unhealthy at any quantity. That's why it is called junk food.
The links in my post argue many reasons why junk food is bad. The fact that junk food tends to make people hungry is just one of many. You could just man up and admit "Yes, Hot Pockets are bad for you". But instead you keep trying to win an argument while being ignorant of the topic.(nutrition)
But if you want to focus on that one thing (a desperate attempt to "win") then fine, junk food makes you eat more. Are saying that is not a problem in the western world? Where do you live? The US? Are there not way too many overweight people in your neck of the woods? You are keeping in mind how much heart disease and diabetes there are in the US, right?
Jeez, Hot Pockets should not exist. The people who run that company should be ashamed of themselves, marketing trash as food, even worse encouraging parents to feed it to their children. How many Americans have fed there kids Hot Pockets because they actually believed it was food? I mean its got ham in it, right? well.. sorta... umm... not really. Though yes, you are legally aloud to refer to what is in a hot pocket as ham.
Are you trying to defend your feeding of your kids with hot pockets? is that it?
well don't.
And get your kids some quality junk food instead. Something with like 4 or 5 ingredients, like cookies. Is there any cookie less healthy than a hot pocket? i doubt it. unless of course, you get cookies from the people who make hot pockets...
And yet people are trying hard to find easier ways to slow down cooking, not speeding it up, because some things do better when not trying to race to the finish, appliance fanboyism aside.
You're right, and the other AC(s) are wrong... if a microwave used eddy currents and was unable to heat things as small as a fly, then we wouldn't be using microwaves to make popcorn.