160 replies to this topic

[rotuts]

I love the perfect poached egg, as everybody does.

I havent started with them yet

that being said, once we decide on the SV temp that suits us:

can a dozen eggs be done, cooled, placed in the refrig and very carefully brought up to temp later?

Id love to know how to do this!

cheers!

[Scout_21]

I rather enjoyed these instruction from Wylie Dufresne...though the first temp is in C and the second is in F. I made these a few weeks ago on a Saturday for a nice breakfast on Sunday but didn't want to deal with cooking the eggs while prepping the hollandaise and canadian bacon and I thought they were wonderful...and I never even cracked an egg to check on their texture. I would recommend cracking them into a bowl first after reheating to clean them up a bit before platting like he says in the article. I'd be happy to hear other people's successes or failures.

How to Cook an Egg, By Wylie Dufresne

Edited by Scout_21, 23 March 2011 - 02:24 PM.

[rotuts]

Whooooooooooooo!

thanks for your Time!

Im On the Way!

[vengroff]

I love sous vide eggs and until recently always used the slow cooking method. But I’ve been experimenting with 75°C water and have had some very good results. The most critical thing to know about the faster method is that when the center reaches the target temperature it is still moving up pretty rapidly, so pulling the eggs out at exactly the right time is critical. There are other factors that matter a lot too, like whether you use a circulating or non-circulating bath, and some that are far less critical, like the exact starting temperature of the eggs from the refrigerator.

I actually modified my iPad sous-vide dashboard a little bit to make the rising temperature effect really clear. Here’s a screen shot of the dashboard configured for an egg of 150mm circumference and 75°C water.



First, notice that in the graph the core temperature (the thick dark line) is still rising rapidly at the end of the cooking time. This means that if you leave the eggs in for an extra minute or so, their temperature will rise quite a bit relative to your actual goal. This is very much in contrast with the more common sous-vide approach that produces a nice soft landing at the target temperature by using a bath only 0.5-1.0°C warmer.

Exactly how fast the temperature will be rising at the end of the cooking time is given by the number 1.46°C/min., which tells us that if we leave the egg in an extra minute the core temperature will rise quite significantly.

In contrast, consider the lower temperature approach shown here:



In this case, the core temperature curve has the more classic shape where it slows down a lot as it reaches the target temperature. In this case, it is rising at only 0.13°C per minute. For larger eggs, this number will be even smaller. For large cuts of meat, like beef tenderloins, this number can be well below 0.1°C/min. at the point the meat reaches temperature.

If we look at what other factors can affect the outcome of eggs, we find that one of the most significant has to do with the type of equipment used. In the examples above, I had my dashboard set for a Polyscience Sous Vide Professional. If I switch to the Sous Vide Supreme, which does not have a powerful circulator, and go back to the 75°C method, things take longer because without circulation the water does not transfer heat to the food as efficiently.



The difference in time between the two machines is 2:40, which at a rate of approximately between 1.2 and 1.4°C/min. means a significant temperature difference. If I used the Sous Vide Supreme numbers for the Sous Vide Professional or vice-versa I would not get the results I hoped for. It is thus critical that I use times tailored to my specific machine.

Another factor that we might think would make a big difference is the initial temperature of the eggs. However, this does not make nearly as big a difference as the machine or the exact cooking time in the 75°C case. In the example below, I raised the initial temperature of the eggs from 5°C to 8°C and the cooking time was only reduced by 16 seconds. So food safety issues aside, you don’t have to worry much about your refrigerator not being adequately cold.



Finally, just as a test case to make sure my calculations are not off the rails, I duplicated some Douglas Baldwin’s table scenarios and got results to within a matter of seconds. For example, here is the case from his table for a 150mm circumference egg in 75°C water with a custom circulator somewhat more powerful than my Sous Vide Pro (h=200 W/m^2-K vs. 155 for the technically minded):



Douglas’ table says 17:10 for this case, whereas my dashboard says 17:12. I’m happy with this, as there are probably subtle differences in how we handle some of the technical details of the simulation that could account for a difference this small.

I was originally planning to just use this dashboard to fill in some gaps in the tables, but I’ve since found that by playing around with it I have gained a much better understanding of the dynamics of sous-vide cooking and what factors have the greatest influence over the quality of the results. I certainly expect to cook even better eggs in the future as a result.

[PedroG]

vengroff,
that's awesome!
Would you mind programming this for a common Windows-PC (Excel-sheet)? Or a Windows-Mobile-PDA?
Thanks
Pedro

[technophile50]

What about starting with a fixed volume of water at 100 deg C in an insulated (styrofoam?) container, to which you add an egg from the fridge, where the combined masses equilibrate to the desired yolk temperature (64C), but the gradient while it's coming to equilibrium firms up the white?

[lstrelau]

Vengroff, can't wait til this shows up on iTunes for my iPhone!

[vengroff]

Would you mind programming this for a common Windows-PC (Excel-sheet)? Or a Windows-Mobile-PDA?

Windows Phone could be an option in the future, but Excel is probably not. The style of simulation required doesn't lend itself well to a spreadsheet. It isn't just a series of formulas, but rather an iterative process where for each of a large number of very short time intervals from the time the food enters the water until it is done you have to solve a relatively large set of equations. I'm sure it could be done with some clever VBA, but it's not really the sort of thing Excel was built for.

Vengroff, can't wait til this shows up on iTunes for my iPhone!

I've got a small number of bugs to work through but I'll probably submit it to Apple in the next couple of weeks. We'll see from there how long the approval process takes. Initially it will be for the iPad, but I will also try to rework the UI for the iPhone.

Thanks to both of you for the support.

[vengroff]

What about starting with a fixed volume of water at 100 deg C in an insulated (styrofoam?) container, to which you add an egg from the fridge, where the combined masses equilibrate to the desired yolk temperature (64C), but the gradient while it's coming to equilibrium firms up the white?

I haven't seen exactly this proposal before, but I have certainly seen people advocate putting the eggs in cold water, bringing it to a boil, then immediately shutting it off and holding it for some number of minutes. The Joy of Cooking, for example, advocates this technique.

I suspect it is possible to come up with more than one water temperature over time curve that generates the kind of gradient you described to cook the white, then drops the water temperature to allow just the right amount of heat to reach the center of the yolk. If it can be done with a quantity of water at a fixed initial temperature in a well insulated vessel as you describe, that would be even better.

I have contemplated the non-constant water temperature approach for a number of applications, but I have never followed through. Mainly it's because I think it would require something more sophisticated than an off-the-shelf PID to control properly.

[yosemit3]

Has anyone tried to sous vide the eggs at the temp for their desired yolk consistency, then chill. Later, place them in a hotter bath, for a derived time to set the whites to the desired stage. I'm assuming there would be a small delay in the heat transfer from the white to the yolk. Then one could shock the egg in a cooler bath to protect the yolk. If one pasteurized the eggs in the first step, then you could store them, and reheat in an under 145F (serving temp) bath to serve any time. A lot of fiddling and variables, but may be worth the effort.
Disclaimer: I have several heated and chilled baths.

[rotuts]

I love the 'personally perfect poached egg'

SV eggs have the advantage as you pick the 'yolk temp' you love and then can SV a couple of dozen and you are set for a while.

"fresh eggs" where you get them and talk to the chicken are best as the albumen is very 'tight' these eggs will not work for anything that requires whipped eggs whites. they cannot be whipped correctly as they are too tight.

these eggs are best for SV but hard to find. in the Old Days one water poached the eggs and that solved the problem as the albumen that had stretched out was left in the water.

some say after you SV, you take a very short time in really hot water to set the white. havent tried this.

my SV eggs have a small amount of 'water' in them when I break them on toast. it might be water that entered the egg ( 60 min is a long time!) or albumen that had not set. i dont mind this on my toast. it softens it and allows me to use less butter I love butter but if you use it as a condiment you will have at least a few months more to enjoy SV before you Croak!

Try to find true fresh eggs. Still warm, Fresh form the Hen.! I have a source and will report back

Edited by rotuts, 03 April 2011 - 12:41 PM.

[PedroG]

I did it again (four eggs of 143mm circumference, 75°C / 16 minutes), see upthread. The result was perfect, but one of the eggs must have had a slight crack that had gone unnoticed. It was just a little bit of egg-white that escaped, but what a mess! Cleaning the polycarbonate container and the FreshMealsMagic took me considerably more than half an hour. In the future I will do eggs only in my SVM-controlled stockpot without a circulating pump so eventual cleaning would be easier.

[DocDougherty]

Vengroff,
Great work. Reminds me of Nathanm's original approach using Mathematica. I trust you are solving Gauss in 3-D with an appropriate step size, so perhaps it would be possible to expose the heat transfer coefficient as an input variable so that those of us with Lauda circulators can adjust the model to accommodate variable pump speeds (or for other complications that make it different from your assumptions about the equipment).
Doc

[vengroff]

Vengroff,
Great work. Reminds me of Nathanm's original approach using Mathematica. I trust you are solving Gauss in 3-D with an appropriate step size, so perhaps it would be possible to expose the heat transfer coefficient as an input variable so that those of us with Lauda circulators can adjust the model to accommodate variable pump speeds (or for other complications that make it different from your assumptions about the equipment).
Doc

Thanks, Doc. I do provide an advanced customization screen that allows you to override all relevant input variables. You can use that to set the surface heat transfer coefficient as you wish between 50 and 1200 W/m^2-K. That being said, most users will rely on the built-in values tied to particular equipment that are chosen from the main setup menu. These include 95 W/m^2-K (Sous Vide Supreme), 155 W/m^2-K (Sous Vide Professional), and fixed values of 200, 300, and 600 (the values I most commonly see in the literature). If you happen to know the coefficients for the Lauda machine you have, please let me know and I'll be happy to add them. If you know them for the different pump speeds, so much the better.

The app is in beta now and should be publicly available in the app store soon.

[DocDougherty]

What about starting with a fixed volume of water at 100 deg C in an insulated (styrofoam?) container, to which you add an egg from the fridge, where the combined masses equilibrate to the desired yolk temperature (64C), but the gradient while it's coming to equilibrium firms up the white?

That is a very clever notion. And I am tempted to immediately start an inductive experiment, but a little back of the envelope analysis says that it is quite sensitive to losses (conduction, container mass and Cp, convection and radiation, etc). Making the approximation that Cp for an egg is 1.0, egg mass is 60 gm (large egg), the sensitivity to the mass of 100°C water is something around 0.5°C of final egg temperature per gram of water, not including anything for the as yet unspecified losses or their dependency on T(water) or T(egg) or ambient conditions, or container specifics. So while it should work, the degree of precision may be a little tough to deliver.

But I am going to try it anyway using a wide-mouth thermos liner and a double air gap for insulation and an initial assumption that the losses are about 20% of the total heat.

Doc

[DocDougherty]

A couple of eggless trials to calibrate the thermal losses showed that they are more like 65% of the energy required to cook the egg and are dominated by heating up the container (in this case a 16 oz widemouth thermos liner) followed by conductive losses through the cap/seal.

Because cooking time is quite long if you want to wait until everything gets to equilibrium, adding more hot water and stopping at a pre-calculated time seems likely to be an improvement.

Two runs with eggs uncovered and then confirmed/quantified a major temperature stratification issue. With a 60gm egg, 198gm of boiling water, and after 25 min of undisturbed cooking time there was almost 10°C of temperature difference between the top and the bottom of the water column (61.5°C at the bottom and 71.2°C at the top). A needle probe showed 66.8°C in the geometric center of the egg so the yolk should have been (over)cooked. But when it was sectioned through the center, the top half of the yolk was solid (the top was marked with a permanent marker) and the lower half was liquid. On average the egg was cooked.

So if this is going to work, there will need to be a mechanism to circulate the water (or the egg), and it will require some empirical modeling of the loss mechanisms which are a substantial fraction of the total energy required, and there will likely still be a desire to add a time component to get the precision. It might be possible to build the model that is well enough calibrated that a combination of end point water temperature and elapsed time correctly estimates the internal egg temperature.

Another approach would be to drop an egg into a water bath at a higher temperature and transfer it to a lower temperature bath after a fixed period of time, letting the heat propagate both in and out to finish cooking the yolk and to stop cooking the white. While it is still a 3-D problem, a 1-D approximation along with a calibration term might be good enough to deliver what you want.

Doc

[rotuts]

Re: cracks

as Pedro has suggested, from time to time I get a thin crack in my """SV""" eggs.

in the Dark Ages when i cooked mu eggs Darklleyy I understood that there was a small air sac at the base (the less round end) and if you used a Push-Pin that released the air that was there as the heat expanded it ..... so the eggs did not crack at those temps.

I thought of doing this with my """""SV""""" eggs then re thought that as I cool them water might enter and leave them less desirable and may not '''pastureized'''

so I just eat them!

eggs are enough to get anybody that loves egg into SV !!

not the same as those fried eggs with the crispy edges!~

Eggs for All!

[mgaretz]

vengroff - did your iPad app ever come out? I couldn't locate it in the app store.

Edited by mgaretz, 23 June 2011 - 09:07 PM.

[Intellidepth]

vengroff - searched under 'sous vide' for your app in the store, couldn't locate it yet. I only have an iphone so keen for the alternative user interface :) What a brilliant concept.

[jaymer]

I looked at Douglas' pdf on egg cooking times.
I have to think that if a tiny .5 cm difference in circumference requires a 40-50 sec increase in cooking time (for example), then there's got to be an even greater difference in cooking 2 eggs or 8 eggs since the 8 cold eggs will greatly (i say greatly, but I have not measured it) drop the water bath temp initially.

Am i missing something? (like maybe I didn't read the entire thread)
Is the table for 1 egg at a time?
Whats the formula for scaling to multiple eggs?

For me personally, I'm looking for runny yellow - like Kyhmos @ 40 min
http://blog.khymos.o...rt-2/#more-2897


thx
jaymer...

[PedroG]

Douglas' tables are for any number of eggs, if your water bath is not very small.
8 eggs may be about 500g.
In my PID tuning experiment (last post in the old SV topic), throwing an ice-brick of 560g/-20°C into a 15L water bath at 55°C resulted in a temperature drop of just 0.2°C for less than 2 minutes, so the temperature drop from 8 eggs (500g/5°C) will be negligible, at least with a well tuned system.

[Robert Jueneman]

Douglas' tables are for the classic single temperature model, as opposed to the more recent 6X egg technique that Martin Lerch and other have discussed (including myself, at http://freshmealssol...n&Itemid=100088).

But what happens if something other than chicken eggs are used, say quail eggs, or perhaps duck eggs?

Duck eggs are about the same size as chicken eggs, but on the only time I tried them, I got vastly different results, so perhaps the different species protein matters.

And for quail eggs, there is both a different species, and a considerably different size, and perhaps a difference in the ratio of white to yolk, as well.

Before I waste time experimenting with them, has anyone already done this?

Bob

[shar999]

Received my machine today. I've spent the past week trying to read all the pages of the sous vide threads. It's overwhelming.
My question is: Eggs....can I place them in a zip loc bag without a vacuum to cook in case one breaks. If I can, do I have to fill the bag with some of the water?

[mgaretz]

Received my machine today. I've spent the past week trying to read all the pages of the sous vide threads. It's overwhelming.
My question is: Eggs....can I place them in a zip loc bag without a vacuum to cook in case one breaks. If I can, do I have to fill the bag with some of the water?

You could, by why bother? If one breaks, it isn't a big deal. Maybe a little more effort to clean up afterwards, but I have yet to break one, and I'm guessing it's more effort to bag them. Yes, you'd have to fill the bags with water and get as much air out as possible.

Think about this, do you bag eggs now to hard/soft boil them and they're out of the shells to begin with in regular poaching.

[vengroff]

Received my machine today. I've spent the past week trying to read all the pages of the sous vide threads. It's overwhelming.
My question is: Eggs....can I place them in a zip loc bag without a vacuum to cook in case one breaks. If I can, do I have to fill the bag with some of the water?

I would not recommend this, and I would definitely not put the eggs in bags filled with water. In general, you want the water to circulate freely around your food as it cooks. If there is water in a bag with the food then that water is not circulating around the bath back to the heating element.

I would not worry too much, though. I cook eggs regularly and breakage has never been a problem.

[Robert Jueneman]

Received my machine today. I've spent the past week trying to read all the pages of the sous vide threads. It's overwhelming.
My question is: Eggs....can I place them in a zip loc bag without a vacuum to cook in case one breaks. If I can, do I have to fill the bag with some of the water?

I would not recommend this, and I would definitely not put the eggs in bags filled with water. In general, you want the water to circulate freely around your food as it cooks. If there is water in a bag with the food then that water is not circulating around the bath back to the heating element.

I would not worry too much, though. I cook eggs regularly and breakage has never been a problem.

Vengroff, as one Chief Scientist/Amateur Cook to another, I have to strongly disagree with you. In my experience, as well a PedroG's, egg cracking is a quite common problem, and if you are using any kind of a circulator, a real PITA to clean up afterwards. I certainly don't want to ruin an expensive circulator for a minor inconvenience!

If the bag containing the eggs is filled with just enough water to cover the eggs in a single layer, and importantly, the water that you use is already up to temperature (having been extracted from the bath), any temperature differential is likely to be minimal. Your could of course test this by sealing a thermocouple inside the bag, using the Archimedes principle, and I confess that I haven't done so, but if it was more than 0.5 degree F I would be quite surprised -- astonished, in fact.

Bob

[PedroG]

Received my machine today. I've spent the past week trying to read all the pages of the sous vide threads. It's overwhelming.
My question is: Eggs....can I place them in a zip loc bag without a vacuum to cook in case one breaks. If I can, do I have to fill the bag with some of the water?

I would not recommend this, and I would definitely not put the eggs in bags filled with water. In general, you want the water to circulate freely around your food as it cooks. If there is water in a bag with the food then that water is not circulating around the bath back to the heating element.

I would not worry too much, though. I cook eggs regularly and breakage has never been a problem.

Vengroff, as one Chief Scientist/Amateur Cook to another, I have to strongly disagree with you. In my experience, as well a PedroG's, egg cracking is a quite common problem, and if you are using any kind of a circulator, a real PITA to clean up afterwards. I certainly don't want to ruin an expensive circulator for a minor inconvenience!

If the bag containing the eggs is filled with just enough water to cover the eggs in a single layer, and importantly, the water that you use is already up to temperature (having been extracted from the bath), any temperature differential is likely to be minimal. Your could of course test this by sealing a thermocouple inside the bag, using the Archimedes principle, and I confess that I haven't done so, but if it was more than 0.5 degree F I would be quite surprised -- astonished, in fact.

Bob

I totally agree with Bob:

Finagle's corollary to Murphy's Law says: Anything that can go wrong, will -- at the worst possible moment. (i.e. in a SV bath most difficult to clean).

Cleaning a SVS after breaking an egg may not be a very big deal, but in an FMM or IC you may need to use a professional grill-cleaning-solution containing sodium hydroxide to clean the mess. I did my last SV eggs in a skewer-suspended ziploc bag partly filled with hot water from the SV bath to displace the air, and the outcome was the same as with naked eggs in the bath.

[mgaretz]

Guess I am used to my SVS which cleans easy if necessary.

[blackp]

Guess I am used to my SVS which cleans easy if necessary.

It will clean easily, but has no chance of maintaining a constant temperature throughout the tank as well as a "stirred" bath. An impeller, pump or air circulation system will make sure that no matter where your eggs lie they will be at the same temperature. A square/oblong tank with a heater underneath cannot possibly have a consistent temperature without some form of stirring.

I agree with Pedro and Bob - Murphy does exist and a zip lock bag is a simple way to make sure that any eggshell fractures do not become a clean up problem.

Edited by blackp, 17 November 2011 - 01:28 AM.

[rotuts]

after refining my technique Ive never had a cracked egg:

the egg cracks when the inner air pocket at the flatter end expands too quickly: a cold egg from the refrig into the hot SV solution might do it.

I either bring the eggs to room temp either by placing them in a hot water (tap) bath for a few minutes or bring to room temp slower.
\
you may notice if you try this tiny bubbles come out of the egg on the entire surface. this was a concern for me as when cooling i assumed the water went back into the egg.

but maybe not.

anyway, no more cracked eggs.