Robert Jueneman
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Posts posted by Robert Jueneman
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Using the small amounts of LN2 you used, as well as the low temperature of your fryer, appear to be major limitations.
I agree. I'm still learning. I have since found a way (using an iSi funnel) to safely pour the LN2back into the Dewar after using it, so I can be a little more liberal in its use.
And I tried to recalibrate my deep fryer, and it came up to temperature nicely and then quit entirely! I may rewire it and try to use a PID controller to control the temperature more accurately, if I can find a high temperature probe. Or buy another unit, such as the Krups, with a carbon filter to keep down the grease smell .
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Have you read the stuff in Modernist Cuisine on using LN2 this way? I believe they are pretty specific as to the length of time to leave the meat in the LN2 and then the length of time to deep fry and at what temperature. I don't have my copy in front of me, but I believe it is cooked to 54.5C/130F, then fully immersed in LN2 for 30 seconds, then deep fried at 235C/450F for 60 seconds.
Yes. As I said, MC has some recipes, but didn't provide any explanation as to WHY they worked, or how you might modify them for other applications. That was what I wanted to develop.
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There are several other liquid nitrogen topics, including a rather old one that addresses the safety issues, at
But other than making ice cream, there aren't many recipes or techniques discussed.
Modernist Cuisine has a fairly extensive discussion about using sous vide, liquid nitrogen, and a deep fryer to first cook the food, then freeze it, and finally deep fry it to get a nice crust, e.g., on an over-the-top hamburger.
Since I like doing this kind of experimentation, I tried it, but soon found myself floundering, because there didn't seem to be any underlying principles to guide me. The essence of sous vide cooking is the precision temperature control, but now I found myself wondering things like how much LN2 to use, how long the burger (for instance) had to soak in it, how long to leave it in the deep fryer, and what difference, if any, did the thickness of the meat make. My first attempts at the hamburger recipe ended up being overcooked.
So I turned to my friend Douglas Baldwin for some advice, since it's been over 50 years since my last class in thermodynamics, and I hoped some of his sous vide heating equations might be applicable.
He did a back of the envelope calculation of an impulse heat transfer, using the thermal diffusivity of water, which results in 1.4*10^-7 m^2/s, or 0.14 mm^2/s. So if you wanted a 2 mm thick crust, you'd soak it in LN2 for about 14 (=2/0.14) seconds, and then deep fry it for roughly the same length of time.
But that didn't seem to take into account the temperature of the liquid nitrogen, or the temperature of the oil. When I tried it, I SV'ed the burger at 55C, then froze it for 14 seconds, and then fried it for14 seconds at an indicated 380F or 194C, but in fact the measured temperature was only 174C. That burger was the best of four, and still medium rare. For the other burgers, I increased the time in the LN2 and the oil, to 30 and 60 seconds, as recommended by Modernist Cuisine.
However, because I was being super careful, I hadn't filled the double-walled bowl with enough LN2 to completely submerge the burger, and had to flip it. So instead of freezing it for 14 seconds, each side only got 7 seconds, and then the longer cooking time caused the burger to be overcooked. And it still wasn't clear what the ratio of the times (freezing vs. frying) should be.
So back to Douglas, who said we could estimate the ratio of the time in LN2 by comparing the difference in heating, including the latent heat (the energy required to melt the ice, before the temperature can start to go up) as follows:
(meat temp - LN2 temp + latent heat) / (oil temp - meat temp)
Since the latent heat of water is 80 calories per gram, the temperature of the LN2 is -196C, and assuming the oil is at 200C, we have
(55 - -196 + 80) / 200-55) = 2.3 (That doesn't take into account the surface heat transfer coefficients of LN2 and frying oil.)
So this agrees reasonably well with the recommendations in MC to fry for about twice as long as you freeze.
In my case, with a badly calibrated fryer, I would have had (55 + 196 + 80) / (174-55) = 2.8 as the recommended ratio.
(It is unfortunate, but I can't find a single electric fryer that will go over 375F/194C. I don't know if that is because some oils would start to smoke or break down at a higher temperature, or they are concerned about fires or liability, but the only way to cook "chips" or fries at the desired 425F/200C temperature is in a pan or dutch oven on the stove, which is a lot more dangerous, as I proved by having the oil spill over and being ignited by the gas flame. I quickly turned off the gas and blew out the flame, but I then had a lot of oil to clean up.)
I tried this again, using the last remaining burger (which I had rewarmed after the cook/chill) . I froze it in LN2 that was about 3 cm deep for about 14 seconds, flipping it a couple of times, and then frying it for 32 seconds. (This was before I discovered that the fryer wasn't getting hot enough.)
This produced a very nice, medium rare burger with a deeply seared crust, but one that was only about 1 mm thick. I think that if I had cooked it for the 14 * 2.8 = 39 seconds, the crust would have been slightly thicker.
My impression is that this technique produced a significantly better burger than I could have achieved by searing it with a torch or hot pan. But whether it is enough better to justify the cost of the LN2 Dewar and safety apron and gloves, plus the fact that I'm probably going to have to replace the deep fryer now that I know how inaccurate it is, I'll let others decide.
I hope this had been a useful discussion, and I hope that others will contribute new recipes and techniques to this thread.
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I'm at 10,000 feet; they sell pressure cookers here with interchangeable valves that go up to 20 psi.
Where is "here"?
Bob
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Interesting, but I wonder if all this is really necessary.
I have an WAFCO All-American pressure canner that is more or less the same thing you have, with a different top. Stocks don't strike be as acidic enough to particularly worry about the fact that it's made of aluminum, and none of the stocks I have made in there have suffered from metallic taste. So putting a stainless pot in there is probably a waste of capacity. I have also had perfectly good results in converting it to a "virtual unvented pressure cooker" simply by putting the weight on the vent at 15 PSI, placing 3-4 quarters on top of the weight, keeping my eye on the pressure gauge and backing off the heat when the pressure hit 18 PSI or so over atmospheric.
The one way that you may have a real advantage is in knowing the actual temperature inside the cooker. When pressure canning, the only way of being sure of the temperature is to vent steam for 10 minutes or so that the entire interior is filled with water vapor and not air. If the pressure cooker is not vented, the temperature is certainly not as high as one might suppose it is.
Interesting point that you make. I confess that I have a perhaps irrational bias against plain (non-nonstick) aluminum pots.
It's true that you can buy a different top for the All American Sterilizer that will convert it to a "regular" canner, if that's what you want. Even cheaper, I think you could replace the pressure regulator with more conventional jiggle weight.
What altitude are you working at?
Bob
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HIgh Altitude Pressure Cooking and Stock Preparation.
Please forgive the cross-posting,but I thought that readers of the Modernist Cuisine forum might enjoy seeing my post on this topic at http://forums.egullet.org/index.php?/topic/140749-high-altitude-pressure-cooking-and-stock-preparation/
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Modernist Cuisine (page 2-291 et seq.) has an extensive discussion about using pressure cookers and pressure canners to make stocks, and their conclusion is that cooking the stock at 1 bar or 15 psi over ambient, resulting in a temperature of 121C, generally produces the best results, although some recipes call for using an autoclave at temperatures up to 130C.
However, as I live in Taos, NM, at an altitude of 7000 ft/ 2133 m, some adjustment is required. To reach the same temperature, I would have to run the pressure up to 18.5 psi. Unfortunately, most pressure cookers either use "jiggle" weights or spring loaded valves which come in 5, 10 and 15psi increments. Also, most pressure cookers don't have an independent pressure gauge, and none that I am aware of have a means to actually measure the temperature of the water/steam, much less the temperature of the stock or other food you are cooking. In addition, experiments by Dave Arnold and Nils Norén have shown that pressure cookers that vent the steam cause an undesirable cloudiness in the stock, and some loss of flavor/quality, perhaps as a result of venting the aromatics. And finally, without venting steam, it is difficult to maintain a desired pressure/temperature, even with a pressure gauge, unless you are willing to stand there and monitor the pressure and adjust the gas flame.
There had to be another, better way. After discussing this with Douglas Baldwin, I bought a 25 qt. All-American Sterilizer, model 1925X, and proceeded to modify it to use a PID controller, the Sous Vide Magic (SVM) controller from Fresh Meals Solutions, to control an electric griddle to control the temperature, and a second SVM to monitor the temperature within the stock pot.
I removed the pressure regulator, fitted a T-adapter, threaded two SVM probes through it, and then reassembled the regulator. Now I can bring the water in the sterilizer to very close to the boiling point, drop in a stainless steal pot (an All-Clad Pasta Pentola) with the stock, secure the lid, and let the pressure build up. I can vent the steam manually, or not, as I see fit. And if I am canning something, I can monitor the temperature inside a jar filled with water to make sure it is getting hot enough to sterilize the food.
For further details, see http://freshmealssolutions.com/index.php?option=com_k2&view=item&id=71:high-altitude-pressure-cooking-and-stock-making&Itemid=100088.
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Ultrasonic Cavitation
MC has several recipes that involve ultrasonic cavitation. Most seem to use the Branson 8150, which costs somewhere around $1740, although smaller and less expensive units, e.g., the 5510 with a 11 1/2" x 9 1/2" x 6" 2 1/2 gal tank, might meet my needs, at around $1094.
But PolyScience now offers their SonicPrep, which instead of using a tank, uses an immersible tool that costs around $4500!
Has anyone compared these two devices, and can you offer any conclusions?
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You can buy, at least here in Atlanta, pasteurized eggs. They look and act entirely identical to unpasteurized.
Whole Foods generally carries them. I haven't seen them in more conventional grocery stores. But if I needed some, I would do it myself.
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I do practically no baking, so I can't answer the texture question.
However, the mass of the cookie dough would certainly slow down the heating process. Imagine if you were trying to cook a rib roast of the same size as the tub of dough -- it might well take more than the six hour maximum recommended time (depending on the size and shape of the tub), and therefore wouldn't be safe.
I would offer to pasteurize a couple of dozen eggs for the second coworker, instead.
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I don't want to get into a linguistic debate about home fries vs. French fries, vs. ....
But I've tried Heston Blumenthal's Pommes Pont Nuef (from Modernist Cuisine), and they are the best I've tried so far. I don't have a ultrasonic bath or any pectinase, so I haven't tried those methods.
For those who don't have MC or In Pursuit of Perfection, the recipe calls for boiling 500g of Russet potato batons (cut 1.5x1.5cm thick) together with 500 g of water, 15 g of sugar, 7.5 g of salt, and 0.75g of baking soda for 20 minutes, or until nearly falling apart. (I might reduce this to 15 minutes, even at my 7000 ft. altitude). Then drain and place the warm potatoes on a rack in a chamber vacuum. Pull vacuum, if necessarily repeatedly, until the chips are dry and cool, 3-4 minutes. Then blanch in 150C/300F oil until the chips are mostly cooked but still pale, about 7 minutes. Air cool in a single layer, if possible using a fan. Finally deep-fry in blisteringly hot 220C/430F oil until crisp, about 2 min. (My deep fryer won't go that high, so it may be necessarily to do this on the stove.)
The results are delightfully crunchy on the outside, yet meltingly tender on the inside.
Note that there is an error in MC -- steps 6 and 7 are reversed.
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I tend to dump tanks, using a gas siphon to drain into the sink, but that is primarily to heat up the tank with water from the hot water heater, rather than putting too much of an electrical load on the system. I've since run a 220 line (really, a double 110 in a so-called Edison circuit) to power two units simultaneously, but I still think it's a good idea to fill the baths with hot water.
If I had access to distilled water, like Pedro does, I might keep them up to temperature all of the time, at least 52C.
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Professionally, I'm a cryptographer/computer scientist, not a physician, and certainly not a professional chef, but I've been using sous vide for about five years now for virtually everything I cook. At last count I had a total of seven different sous vide machines/water baths in my kitchen, and I can barely remember how to cook on the grill, or in the oven, or the microwave. I use the stovetop primarily to sear my sous vide steak, lamb chop, etc., after removing it from the bath.
Some people complain about the cost of sous vide equipment, but the cost of all of my sous vide equipment put together cost less considerably less in total than just one of my high-end Canon cameras, yet has brought me more satisfaction, much less gustatory delight. You have to put things in perspective.
Some things simply can't be done any other way. Take for example a medium rare brisket, cooked for 72 hours at 55C, or a meltingly tender chuck steak for 24 hours at the same temperature, for far less cost than a filet or tenderloin.
Most vegetables are also greatly improved, e.g., corn on the cob sous vide at 60C for 30 minutes with a little butter and some chipotle powder.
Chacan a son gout!
Bob
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Excellent summary, Douglas. Thanks.
Now,let me ask a similar question about making stock.
I made some chicken broth by cooking 4 lb of chicken legs and thighs together with 8 oz of store-bought stock, for 12 hours at 70C, then drained it. Obviously that was well and throughly pasteurized, but not sterilized. I made chicken salad with the leftover meat.
Unfortunately, last night after adding the methylcellulose to fine it, I got distracted and forgot to refrigerate it then, but I did this morning. So it sat at room temperature for 8 hours or so.
Is there any safe way to reheat and use this, even by pressure cooking it, or should I dump it?
I'm inclined to dump it.
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ROTFLMAO! Sorry.
This sounds like what happens when I microwave a can of chile and it spatters everything. Some kind of localized boiling is taking place, obviously. But you said that the stock was too thin, so that doesn't make much sense.
Hmm. Had you degreased the stock after pressure cooking it? If not, perhaps there is a oil/water mixture, and somehow the water would begin to boil, but the oil would not. But the oil might keep the bubble from bursting for a while, until the steam pressure increases and goes supercritical. Then BOOM!
But this is purely speculation.
A watched (or at least stirred) pot never boils!
Assuming you haven't forsworn cooking entirely, the next time you try this, I would chill the pressure cooked stock, then skim off the congealed fat before reducing it.
But on a slightly different subject, what are the pros and cons of sous vide stock making vs. pressure cooking? I'm working with a professional chef for my forthcoming Modernist Cuisine class, and he suggested foie gras consumme, His recommended approach was to cook the legs and thighs sous vide at about 70C for 12 hours with about 2 oz of chicken stock per pound of chicken. I've done that, but haven't yet degreased or fined it, but it didn't make very much consumme -- I think i may have to add more stock before I add the foie gras, but I have't tasted it yet.
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I have been cooking sous vide for about four years and just run into this problem. I cooked a 48 hour, 4 pound brisket at 132F (55C), iced it, and then froze it in the sealed bag. I later thawed it out and reheated it in the same bag to the same temperature long enough for a second pasteurization to occur. This was for a diner, but the people could not make it at the last moment. I then re-iced it and put it back into the freezer. Since the brisket cost about $60 and I would rather not throw it out. Aside from the possibility of losing the texture of the meat, will it be safe to reheat again?
If I understand you correctly, the meat has been sealed in the bag all of this time, correct? If so, then it should be perfectly safe. In fact, I don't think there was any need to pasteurize it the second time -- you could have just rewarmed it.
If anything, your reheating will be comparable to just cooking it for a longer time, and since I cook mine for 72 hours at 55C, I think you will find it even better.
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What you've built is similar to the guard used on the PolyScience circulator (the big one).
You aren't cooking in the tank directly, so you could have made the guard out of lead, for all that it matters.
Bob
I figured the polyscience guard was made of stainless...no?
I do sometimes cook eggs, so i think i'll avoid the lead
Yes,I think the PolyScience guard is stainless steel.
However, if you are cooking eggs, I strongly recommend you follow PedroG's suggestion, and cook the eggs in a ZipLoc bag that is filled with hot water, rather than letting them bounce around loose. If one cracks and leaks albumin into the tank, you are going to have a very messy clean-up job.
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What you've built is similar to the guard used on the PolyScience circulator (the big one).
You aren't cooking in the tank directly, so you could have made the guard out of lead, for all that it matters.
Bob
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DOW SGA-150 Methylcellulose has been discontinued
I received the following from DOW in response to an inquiry as to where to find SGA-150, which is referenced in a number of MC recipes, e.g, the one for oxtail consommé.
"METHOCEL SG A150 FDG has been discontinued. Possible replacements are METHOCEL SG A7C, METHOCEL SG A16M, or METHOCEL MX.
For samples and pricing information please contact Ciao Imports at (866) 249-0400."
Now, Ciao Imports is perhaps better known as willpowder.com, and they carry (only) the SG A7C.
According to a data sheet they sent me, SA A7C has a medium viscosity (700 centipoise), an optimum hydration temperature of <10C, and makes a very firm gel at 38-44C.
That sounds like what I need for fining a consommé, or for making hot ice cream. A pound canister is $31 plus shipping. Smaller sizes are also available.
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I think the problem is that if you want to go to the immersion circulator route, you dont really have many other options in the low-mid price bracket. Its closest competitor is the Polyscience Sous Vide Professional, which costs a good amount of money more than the Swid
I would have to disagree slightly. The Fresh Meals Magic system from Fresh Meals Solutions is essentially an immersion circulator, although it uses a bubbler instead of a pump. I don't know what the price difference is, but the service from Fresh Meals Solutions is generally regarded as exemplary.
Bob
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It all went down brilliantly, darling son loved measuring all the spices out (using new gram scale that arrived yesterday) and wolfed down his plateful. The lamb shanks were spot on (after 48h at 62C), probably one of the most successful SV things we've made so far.
MC is a truly remarkable book, can't wait to make more from it.
I'm really glad to see you and your 5-year old using metric measurements in these recipes. Even the UK has gone metric for some time now, as well as Canada, leaving only the US consumer to fumble around with demonstrably inaccurate volume-based teaspoons, tablespoons. and cups, as well as ounces, pounds, etc.
The rest of the world is passing us by, and our antiquated measurement system is at least part of the problem.
Wake up, people! It isn't all that hard. If a 5 year old can do it, why can't you! And cookbook authors, PLEASE get with the times!
Bob
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I have no experience with the Sous Vide Professional, but I have two of the PolyScience 7306 units with the stainless steel protective cage, which I absolutely love. I opted for that model over the SVP because of the hard water in my area, and the thought that the SVP would be difficult to clean.
I had a local sheet metal worker make a stainless steel box to hold the PolyScience plus the standard Cambro tank, and I have insulated it with some foam-core between the Cambro tank and the outer shell.
In addition, I also have a number of the Sous Vide Magic units, which I use in combination with with several different size rice cookers, as well as with the Fresh Meals Magic circulator and tank.
As I am about to present a 10-course tasting menu and Modernist Cuisine class in Santa Fe, with lots of sous vide, hydrocolloids, etc., we will probably use all of this equipment, in addition to demonstrating their use.
Bob
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I've never noticed any significant difference, but I normally go straight from the freezer to the SV bath, in some cases as long as 2 years after sealing the meat.
However, if you want to start an interesting food fight, consider the keeping quality of long term frozen storage, which benefits from as complete a removal of as much oxygen as possible, vs. the claims by Dave Arnold (which I've never been able to duplicate or confirm), that a 99% vacuum on a chamber vacuum somehow hurts the texture of the meat.
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For my up-coming class in Modernist Cuisine, I want to make some mushroom gnocchi using reverse spherification, served in a clear oxtail consommé as per MC 2-376.
However, the recipe calls for Super methylcellulose SGA150, and I only have the F50 from WillPowder, and I'm wondering whether I can substitute one for the other.
I've posted a note to a rather stale thread on methylcellulose at but if anyone has tried that recipe or has any advice, I'd like to know.
Bob
Sous vide, liquid nitrogen, and deep frying
in Cooking
Posted
The only recipe I found was for the sous vide burger. It wasn't obvious, at least when I started this, that similar times would apply to a steak, a leg of lamb, or whatever. At this point, I think it probably would, but I haven't tried anything else yet. That's why IO'm hoping that others can contribute.