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I was reading about frying in On Food And Cooking this weekend and it mentions that frying works so much better than oven cooking because oil has a far higher specific heat than air so it is able to transfer that heat to the food being cooked much faster than an oven. It then went on to mention that oil has significantly less heat storage capacity than water - according to this specific heat table, it looks like water has around 2.5 times the heat capacity as most oils. This got me thinking about whether there’d be any way to “deep fry” something in water. What I mean by “deep fry” in water is - get the water up around the temperature you’d get in a deep fryer, and then drop some food in. This way you’d get the same temperature as the oil, and therefore hopefully you’d have the same Maillard reactions, but none of the oilyness from frying. I’d like to give this a try. but there are a few important hurdles I’d have to get over first and I’m wondering if anyone here has any guidance. around a few questions this raises:

  1. I did some calculations and it looks like I’d have to get the pressure up to around 70 psi above atmospheric pressure in order to get the water up around 155C - Probably I’d want to go a bit higher than this in practice. It doesn’t seem to be out of the realm of possibility that a pressure cooker could exist that could handle this kind of pressure (bicycle tires go a lot higher than this), but I only see pressure cookers that go up to around 15psi. Do pressure cookers that handle this high of pressure exist? Otherwise, might there be other kitchen-sized industrial equipment that could achieve this high of pressure and temperature?

  2. Can I expect a maillard reaction to occur at high pressure, or will the pressure make the reaction require relatively higher temperature and therefore preclude it from occuring?

  3. Can I expect a maillard reaction to occur under water? Everythíng I read about the maillard reaction mentions that it will only happen after the water on the surface of the food evaporates specifically because water keeps the temperature too low. This makes sense at standard pressures, but will the water in and of itself make the maillard reaction difficult or impossible (since one of the outputs of maillard is more water), or is the water mentioned ONLY because it keeps the temperature so low. All of the references I've found that say water deters the reaction specifically state that this is because of the temperature factor.

  4. Is there any chance that I’d get any crisping through this process? I’m thinking that if I depressurize the food while the surface is superheated (obviously I’d have to figure out a way to get it out of the water bath first), I’d get some amount of the water in the surface boiled away as the pressure dropped, and thus some crisping. Might this work?

Obviously I’d have to set up a pretty crazy rig inside the pressure cooker to get the water and food pressurized without significantly cooking the food in the process, then have a setup inside the pressure cooker that drops the food into the water at a given temperature, and then pulls it back out after a set time. I’m thinking that my first step would be to get a super-high-pressure pressure cooker and drop some chicken into it, get it up to 160C or so, cool it and see what I get. It’d be way way overcooked I’m sure, but I think I’d be able to tell if I could get any reasonable browning in water, and proceed from there if the results were favorable.

I'd really appreciate any insight, either from experience with pressure cooking of non-traditionally-pressure-cooked foods, or other experience, or possibly from understanding more about how maillard works and what I would expect at high pressure and submerged.

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The first paragraph here is a little off. Conventional ovens (not convection ovens) use radiation to cook. And deep-frying is technically conduction, like pan-frying - the oil is acting as a conductor of heat. –  Aaronut Feb 21 '11 at 20:14
I giggling to myself because this is a really fun thought experiment you've got going. I have serious doubts it's practical but it'll be fun to see what answer come out. –  bikeboy389 Feb 21 '11 at 20:20
Also, I won't post this as an answer due to lack of hard data, but the results ought to be virtually the same as steaming the food, since water vapor has the same high heat capacity. Pressure cooking is still moist heat, so it probably won't cause a Maillard reaction no matter how high a pressure you get. –  Aaronut Feb 21 '11 at 20:21
Oh, hah! Turns out he's already done what you are talking about: cookingissues.com/2009/06/11/maillard-pipe-potatoes –  Michael at Herbivoracious Feb 22 '11 at 6:22
@michael - I think you should post that link and a summary as the answer. –  bikeboy389 Feb 22 '11 at 13:58

3 Answers 3

up vote 10 down vote accepted

Unless you are prepared to build some industrial strength equipment of your own design and then move everyone in the neighborhood away while you experiment with this, I fear you are taking your life in your hands.

Normal pressure cookers add a maximum 15 PSI to achieve a water boiling point of 121 C or 250 F. Autoclaves, used for surgical sterilization, go to 30 PSI. You are talking about going more than twice that.

There is no reason, based on the science of Maillard reaction, to believe that it would not occur at a high enough temperature. The presence of excess water would normally inhibit the process because of temperature reduction, but your "super duper pressure cooker" would keep the temperature at a high enough level to allow the chemical breakdown to occur. You might, in fact, discover that it occurs a bit earlier, as water tends to facilitate many reactions. Caramel making comes to mind as an indicator of what might be achieved, as sugar syrup (OK, most of the water is gone, but in principal) browns when you get in the above 330F-165C degree range.

As to crisping based on quick pressure reduction (perhaps when your device explodes?) That seems less likely as most crisping comes at the loss of water, and you are, in effect, keeping water in contact with your food both in liquid and superheated steam form. It would, most likely, be similar to a braised food surface, than a fried one.

Interesting thought. Please don't try this.

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I was thinking about the pressure involved here. For some other reference, tractor-trailor tires are inflated to around 100 psi. They also have significantly more volume than you'd get in even a large pressure cooker (at least a few cubic feet). These do sometimes blow out on a freeway yet I've never heard of significant damage being caused from the explosion itself (wouldn't there be stories of car windows blown out, etc?). Obviously I'd have to take significant safety precautions, but I'm not sure this is really as dangerous as you imply in your first paragraph. –  timmyp Feb 22 '11 at 17:34
Now that I search a bit more, it sounds like truck tire explosions are quite dangerous, so I guess I'm wrong on this front. If I try this, I'll make sure I go somewhere very remote and stay pretty far away. I am thinking of hiring a machining company to build industrial strength equipment for this. It looks like there are many large pipes that can withstand pressures up to thousands of psi so it might be that I could get something machined/welded that would be safe at this pressure. –  timmyp Feb 22 '11 at 17:54
Remember that truck tyres aren't heated to the same extent that your pressure cooke will be. More heat means more energy to dissipate in the eventual explosion. Also, steam is much more deadly than air. In fact, it is a very dangerous thing to keep pent up, as it wil happily transfer all of its heat energy to any skin it comes in contact with. –  Carmi Feb 22 '11 at 18:37
Fascinating - I did some more calculations and taking into account that in an explosion at 155C, you'd get basically immediate vaporization of around a tenth of the water, during the explosion, the volume of the material would increase 173 times. In comparison, at constant temperature in an exploding tire scenario, you'd get an increase in volume of only 7 times. So, the super-heated water would make that explosion more than 20 times worse than a comparable tire. I'm pretty convinced that this is a bad idea now. Thanks for helping me avoid disaster! :) –  timmyp Feb 22 '11 at 22:24
One of the biggest detriments to a wider use of pressure cookers is that the early ones exploded often, so EVERYONE has a story of someone who had to scrape food off the kitchen ceiling. It doesn't help that the inventor of the device was killed by an exploding pressure cooker. There are much better and multiple safety devices on the modern cooker/canners, but the old stories live on. The thought of cooking with anything in the pressure range you were discussing is scary. –  Doug Johnson-Cookloose Feb 23 '11 at 14:32

Heat help in creating the Maillard reaction, but PH are also very important, by increasing the PH you can achieve a Mallard reaction at 120C in a pressure cooker.

See SCIENCE OF COOKING . Or example that you can try is the Onion soup in Modernist Cuisine basically 500% onion, 100% onion juice (or stock), 0.75% baking soda, see link for all ingredients. Put in jar, put on lid but do NOT tighten fully or it might explode, put on a rack ( do not put jars directly on the bottom of the cooker), fill pressure cooker with water just under the rack. Cook on full pressure for 40 min. Season as per link above.

So as answers:

1) You can achieve Maillard reaction in water at 120 C if you increase the PH

2) Since it can happen at 120C at 15PSI, I say that pressure does not effect the reaction.

3) As per above Onion soup, the Maillard reaction happen in liquid, so it is only since liquid at normal pressure lowers the temperature to 100C it does not happen, at higher pressure it does.

4) I think crispiness and water does not happen at the same time, and you need water/steam to get heat in a pressure cooker.

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Check on ebay you can buy a used "pressure vessel" these are industrial/laboratory things that normally cost a few grand but there is no demand for them so you could get something that does 100psi and holds 10-15 liters easily for a C note and regular pressure cookers do 15 psi so that would be 6-7 times more powerful.

Those are perfectly safe and most likely in your price range to experiment with. I just wanted to throw this in there, but I saw one that does 1,000 psi used for 2 grand it only holds 1 liter though and that is 60-70 times more powerful than a regular pressure cooker if you wanted to take it to the extreme =)

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Using a lab vessel to cook food might not be the best idea as you never know what was used in it before you put food in it, not to mention the safety issues of using that much pressure. –  lemontwist Oct 20 '12 at 12:54

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