Sous Vide: Recipes, Techniques & Equipment, 2011

[dcarch]

To test circulation:

Put a few drops of ink, or food coloring in the tank and see how quickly the ink gets evenly distributed.

dcarch

[jmolinari]

I've taken the plunge and ordered a Sous Vide Supreme. Has anyone used sous vide to pasteurize eggs instead of cooking them? I'm thinking that the proper amount of time and the correct temperature should work. (I'm talking about really pasteurizing the entire egg, not just the shell.)

If i remember correctly Modernist Cuisine calls for ~2 hours at 131 deg. for pasteurizing eggs. I did it with my circulator, but just to be on the safe side i used 132 (circulators and thermometers have measurement error..thought it would be good to be just a touch higher, and i don't know if they'll ever pasteurize below 131...i forget what the tables in MC list), which partially cooked the whites, they not look hazed. they're fine for cooking with, but not clear and perfect like the purchased pasteurized eggs.

As I understand it, the purchased pasteurized eggs only have the shells pasteurized and not the internals. That gets rid of near all the risk, but I figured if I have the equipment, why not remove all of the risk?

Did you try to whip them? My primary interest is in using them to make mousse.

I'm pretty sure they're fully pasteurized not just the shell. At least the ones I get.

Haven't tried whipping them. Sorry.

Edited June 21, 2011 by jmolinari (log)

[DouglasBaldwin]

I've taken the plunge and ordered a Sous Vide Supreme. Has anyone used sous vide to pasteurize eggs instead of cooking them? I'm thinking that the proper amount of time and the correct temperature should work. (I'm talking about really pasteurizing the entire egg, not just the shell.)

If i remember correctly Modernist Cuisine calls for ~2 hours at 131 deg. for pasteurizing eggs. I did it with my circulator, but just to be on the safe side i used 132 (circulators and thermometers have measurement error..thought it would be good to be just a touch higher, and i don't know if they'll ever pasteurize below 131...i forget what the tables in MC list), which partially cooked the whites, they not look hazed. they're fine for cooking with, but not clear and perfect like the purchased pasteurized eggs.

I talk about pasteurized in-shell eggs in my guide. I don't know how Nathan et al. got 2 hours at 131˚F (55˚C) since I haven't seen any z-values* for Salmonella enteritidis in intact eggs reported in the scientific literature. I recommend 1 hr 15 min at 135°F (57°C) based on experimental measurements at that temperature by Schuman et al. (1997). Note that the egg whites will be milky at this temperature and will take more effort to whip to the same volume.

* The classical model for pasteurization gives a D- and a z-value for a particular pathogen in a particular medium -- in this case, Salmonella enteritidis in intact eggs: the D-value is measured at a specific temperature and tells how much time is required to reduce the pathogen by a factor ten; the z-value is measured in temperature and tells you how many degrees you need to increase (decrease) the temperature to decrease (increase) the D-value by a factor ten. Without known the z-value for Salmonella enteritidis in intact eggs, I don't know how to compute the pasteurization time for intact eggs at different temperatures.

J. D. Schuman, B. W. Sheldon, J. M. Vandepopuliere, and H. R. Ball, Jr. Immersion heat treatments for inactivation of Salmonella enteritidis with intact eggs. Journal of Applied Microbiology, 83:438–444, 1997.

[rotuts]

Neil: in my set ups with various bubblers the temp of the water is fairly uniform up to the 38 QT coleman cooler

do you need an immersion circulator for a much larger volume of water or another purpose?

just curious

[dougal]

... the D-value is measured at a specific temperature and tells how much time is required to reduce the pathogen by a factor ten; the z-value is measured in temperature and tells you how many degrees you need to increase (decrease) the temperature to decrease (increase) the D-value by a factor ten. Without known the z-value for Salmonella enteritidis in intact eggs, I don't know how to compute the pasteurization time for intact eggs at different temperatures.

...

Douglas, two questions if I may.

1/ Is it possible to estimate (put probable bounds on) that z-factor and thus give any approximate idea of the sort of time that might be required at 55C?

2/ The 'pasteurisation' time would be a minimum time, wouldn't it? Would there be any problem in going (considerably) over it? I'm thinking that since many folks would often be running their bath for a couple of days continuously at or about 55C, if there was space to tuck in some eggs, as long as you weren't in any hurry to make the mayonnaise for your grandmother, you should be fine, shouldn't you? But I'd have guessed (and its only a guess) that there wouldn't be much point leaving them in beyond about the eight hour mark.

[rotuts]

since eggs are one of todays topics I thought Id ask:

having noticed that putting cold eggs in the warm water bath tinny bubbles come out all over the egg. this is not just in the bottom "air sac"

Im guessing that as the eggs warm some air from inside the eggs expands and comes out

as they cool in cold water would water be going back inside? would this be the etiology of the "watery whites" with SV eggs?

dont know if the shell is water impermeable

what do the SV egg experts think?

[DouglasBaldwin]

Douglas, two questions if I may.

1/ Is it possible to estimate (put probable bounds on) that z-factor and thus give any approximate idea of the sort of time that might be required at 55C?

2/ The 'pasteurisation' time would be a minimum time, wouldn't it? Would there be any problem in going (considerably) over it? I'm thinking that since many folks would often be running their bath for a couple of days continuously at or about 55C, if there was space to tuck in some eggs, as long as you weren't in any hurry to make the mayonnaise for your grandmother, you should be fine, shouldn't you? But I'd have guessed (and its only a guess) that there wouldn't be much point leaving them in beyond about the eight hour mark.

(1) Yes, I could probably determine a worst-case z-value and then compute a lower bound for pasteurization of intact eggs at 131˚F (55˚C). I don't have time to do that today, but I'll try to get to it soon and let you know.

(2) From a pathogen destruction perspective, you can hold it for as long as you like at 131˚F (55˚C). I don't know if the proteins will eventually denature at that temperature and change the yolk's or white's texture. I used to think that yolk texture was only a function of temperature until Martin Lersch's Khymos blog post on April 23rd where he discusses a paper by César Vega and Ruben Mercadé-Prieto that shows that yolk texture is a function of both temperature and time. The lowest their graph goes is 140˚F (60˚C), so I don't know how long it'll take (if at all) for the yolk to change texture at 131˚F (55˚C).

[jmolinari]

... the D-value is measured at a specific temperature and tells how much time is required to reduce the pathogen by a factor ten; the z-value is measured in temperature and tells you how many degrees you need to increase (decrease) the temperature to decrease (increase) the D-value by a factor ten. Without known the z-value for Salmonella enteritidis in intact eggs, I don't know how to compute the pasteurization time for intact eggs at different temperatures.

...

Douglas, two questions if I may.

1/ Is it possible to estimate (put probable bounds on) that z-factor and thus give any approximate idea of the sort of time that might be required at 55C?

2/ The 'pasteurisation' time would be a minimum time, wouldn't it? Would there be any problem in going (considerably) over it? I'm thinking that since many folks would often be running their bath for a couple of days continuously at or about 55C, if there was space to tuck in some eggs, as long as you weren't in any hurry to make the mayonnaise for your grandmother, you should be fine, shouldn't you? But I'd have guessed (and its only a guess) that there wouldn't be much point leaving them in beyond about the eight hour mark.

That's what i'm thinking. Can we use the D and Z values for the highest fat chicken that has been tested (so it would be closer to a fatty yolk) and then add a safety factor of 2, 3 or whatever to calculate pasteurization at 131?

Maybe Nathan was able to pull data sheets/records for the validated process that the shell egg pasteurization companies?

[DouglasBaldwin]

That's what i'm thinking. Can we use the D and Z values for the highest fat chicken that has been tested (so it would be closer to a fatty yolk) and then add a safety factor of 2, 3 or whatever to calculate pasteurization at 131?

Maybe Nathan was able to pull data sheets/records for the validated process that the shell egg pasteurization companies?

No, it's not quite that easy. First, egg yolk is about 26% fat, so 12% fat poultry meat probably isn't a good reference. Two, the cocktail of Salmonella species for those experiments may not have even include Salmonella enteritidis. I'll let the board know if I find something useful in the literature.

[dougal]

Thanks in anticipation!

[PedroG]

Visualizing convection currents

To test circulation:

Put a few drops of ink, or food coloring in the tank and see how quickly the ink gets evenly distributed.

dcarch

This may work, but for repeated visualization you have to add another few drops of ink again and again until the water gets too dark.

I tried various corpuscles to continuously visualize convection currents: plastic snippets, short threads of cotton or Nylon, grains and seeds, all were either too heavy or too light; finally, with ground quinoa I succeeded, although it was not floating in perfect equilibrium.

I used my FreshMealsMagic (2000W) in its transparent polycarbonate container without bubbling. While heating at full power, natural convection current was easily visible, but during steady state at 55°C (heating at about 110W), no significant convection current was visible. I turned the bubbler on for a few seconds to show the quinoa corpuscles moving; after stopping the bubbler movement subsided. My suspicion is that if 110W does not induce significant convection current, in a well insulated rice cooker or stock pot with a heat loss of less than 50W, there will be even less, i.e. practically no convection current.

The videos are now on Youtube (in my earlier post of 10 July 2010 they were on www.mydrive.ch which requested login).

[HowardLi]

Visualizing convection currents

To test circulation:

Put a few drops of ink, or food coloring in the tank and see how quickly the ink gets evenly distributed.

dcarch

This may work, but for repeated visualization you have to add another few drops of ink again and again until the water gets too dark.

I tried various corpuscles to continuously visualize convection currents: plastic snippets, short threads of cotton or Nylon, grains and seeds, all were either too heavy or too light; finally, with ground quinoa I succeeded, although it was not floating in perfect equilibrium.

I used my FreshMealsMagic (2000W) in its transparent polycarbonate container without bubbling. While heating at full power, natural convection current was easily visible, but during steady state at 55°C (heating at about 110W), no significant convection current was visible. I turned the bubbler on for a few seconds to show the quinoa corpuscles moving; after stopping the bubbler movement subsided. My suspicion is that if 110W does not induce significant convection current, in a well insulated rice cooker or stock pot with a heat loss of less than 50W, there will be even less, i.e. practically no convection current.

The videos are now on Youtube (in my earlier post of 10 July 2010 they were on www.mydrive.ch which requested login).

On the other hand, steady-state heating will require much less fluid velocity in order to maintain the "same" uniformity.

[mgaretz]

That's what i'm thinking. Can we use the D and Z values for the highest fat chicken that has been tested (so it would be closer to a fatty yolk) and then add a safety factor of 2, 3 or whatever to calculate pasteurization at 131?

Maybe Nathan was able to pull data sheets/records for the validated process that the shell egg pasteurization companies?

No, it's not quite that easy. First, egg yolk is about 26% fat, so 12% fat poultry meat probably isn't a good reference. Two, the cocktail of Salmonella species for those experiments may not have even include Salmonella enteritidis. I'll let the board know if I find something useful in the literature.

Wow! Thanks Douglas.

Edited June 22, 2011 by mgaretz (log)

[PedroG]

Visualizing convection currents

To test circulation:

Put a few drops of ink, or food coloring in the tank and see how quickly the ink gets evenly distributed.

dcarch

This may work, but for repeated visualization you have to add another few drops of ink again and again until the water gets too dark.

I tried various corpuscles to continuously visualize convection currents: plastic snippets, short threads of cotton or Nylon, grains and seeds, all were either too heavy or too light; finally, with ground quinoa I succeeded, although it was not floating in perfect equilibrium.

I used my FreshMealsMagic (2000W) in its transparent polycarbonate container without bubbling. While heating at full power, natural convection current was easily visible, but during steady state at 55°C (heating at about 110W), no significant convection current was visible. I turned the bubbler on for a few seconds to show the quinoa corpuscles moving; after stopping the bubbler movement subsided. My suspicion is that if 110W does not induce significant convection current, in a well insulated rice cooker or stock pot with a heat loss of less than 50W, there will be even less, i.e. practically no convection current.

The videos are now on Youtube (in my earlier post of 10 July 2010 they were on www.mydrive.ch which requested login).

On the other hand, steady-state heating will require much less fluid velocity in order to maintain the "same" uniformity.

Yes, for a water bath without adding cold food. Forced circulation does make a difference in surface heat transfer coefficient, as Douglas Baldwin posted upthread. And poor circulation increases thermal inertia of the system, which would call for different PID settings. My SVM/FMM usually is stable ±0.04°C during LTLT cooking. One day stability had deteriorated to ±0.1°C or even worse, until I noticed that the silicon tube of the bubbler was kinked (at first I did not notice the missing bubbling, as the bubble wrap insulating the polycarbonate container obstructs vision).

[e_monster]

I'm pretty sure they're fully pasteurized not just the shell. At least the ones I get.

Haven't tried whipping them. Sorry.

You are correct. If an egg is marked as pasteurized it is supposed to be pasteurized through-and-through. At least that is the case in California.

The shells of all commercial eggs are essentially sterilized in the shell by washing the eggs in a mild bleach solution from what I understand. If they didn't do this, merely handling egg shells and egg cartons would spread salmonella as eggs are pretty (for lack of a better word) icky coming out of the chicken.

The reason for pasteurizing is to pasteurize the interior since some small number of eggs have salmonella inside.

Best,

Edward

[e_monster]

since eggs are one of todays topics I thought Id ask:

having noticed that putting cold eggs in the warm water bath tinny bubbles come out all over the egg. this is not just in the bottom "air sac"

Im guessing that as the eggs warm some air from inside the eggs expands and comes out

as they cool in cold water would water be going back inside? would this be the etiology of the "watery whites" with SV eggs?

dont know if the shell is water impermeable

what do the SV egg experts think?

The watery part of the whites is because some of the proteins in the whites don't set at the temperature of the 'ideal' yolk. I remove the eggs from the bath before they cool-- depending on how I am using the eggs, I sometimes leave the water stuff -- but if I am serving eggs to strangers, I drain it.

I need to buy Douglas' book and try his technique.

Interestingly (and this touches on something Doug mentioned earlier). The yolks are much more time-sensitive than the whites. You can cook eggs over night at 145F and the yolk will be quite a bit more set than if cooked for 90 minutes. On the other hand, the whites are the same.

I did some experiments with multi-temperature cooking (moving the eggs between baths. But it was clear that it was going to take a lot more experimentation than I had time for to get it right -- so that the yolk is a barely set gel and the whites tender and lightly set.

Doug: is this the state that the eggs will be in when using your method?

[HowardLi]

What happens to a whole bird if it gets SVed right in the bath, i.e. direct contact with the water?

[dcarch]

What happens to a whole bird if it gets SVed right in the bath, i.e. direct contact with the water?

You get chicken soup?

dcarch

[HowardLi]

But what happens to the chicken?

[dcarch]

But what happens to the chicken?

Actually you get very delicious simple poached chicken, similar to what you can get from a Chinese store, plain poached chicken done to perfection, with dipping sauce.

dcarch

[mgaretz]

My SV Supreme arrived yesterday - for a quick trial I did some "poached" eggs using Douglas Baldwin's basic instructions - 148F for 45 minutes. The whites were just a tad runny but perfectly acceptable and better yet, my wife loved them.

When I told her we were having the eggs for dinner (served over leftover 3-bean vegetarian chili) she was very happy but she was a bit taken back when I brought the eggs, still in the shell, to the table. "You don't mean poached eggs, you mean soft-boiled eggs," she said. "Nope. Poached." "But they're still in the shell. Poached eggs are made in water," she explained. I cracked one and poured it out onto my chili and she was amazed.

Tomorrow night - sirloin!

[Smokalicious]

Martin Lersch posted perfect egg yolks part 2, a follow up post to that mentioned by NathanM upthread. He addresses the egg white issue by cooling the eggs to room temp before giving them a 3 minute boil. Result - perfect yolk and perfectly set whites. I've been using this method for a while and no longer have to decide what to do with leftover eggs. There are none!

BTW, the chart from perfect egg yolks part 1 is a great tool. I have used several time/temperature combinations and the results are always on the mark. My favorite is 63C for 75 minutes

Dave

[rotuts]

the reply's above re chicken in the SV bath gave me an Idea Ill try at some point:

chinese stock ck. or other is cooked at a lower temp than 'simmer' for a long time. it gives the broth an meat a very delicate flavor

why not take some Ck on the bone, add water, salt and white pepper and some green onions and a few slices of ginger and put that in a bag. a long bag if you can make one and carefully seal and then poach in the SV bath say 140 or so maybe a little more 145? for 12 - 24 hours.

stain the "stock" remove the chicken meat and "chinese chicken soup"

I think the key is the lower temp for a longer time

anyone already doing this?

what a fine idea. since you are not heating up the kitchen if you use insulated coolers this can be done in the heat of the summer too!

you can add a bag of stock anytime you are SV other things if your cooler is large enough for almost no further energy waste.

on further thought, if you are unable to seal so much water, why not get an extra clean ice cube tray and make fresh icecubes and quickly put those in with the chicken/herbs and seal that.

locally chicken thighs go on sale for 99 cents from time to time. plan to make this soon: chop up the thighs carefully with a cleaver to inclease the surface area make sure to rinse off any blood etc

Edited June 25, 2011 by rotuts (log)

[Borgstrom]

I took the Ideas in Food: Sous Vide 2.0 class at Le Sanctuaire today. During the class, Alex mentioned you'll get better results if you chill & retherm SV-cooked foods rather than just use directly from the SV cooking bath. I always thought the chill/retherm steps were just to stop cooking and reheat food prior to service, usually in a commercial setting. Does anyone have experience with this? Will you get better results with a chill/retherm cycle even for items that will be used immediately? Perhaps time for another experiment...

[gfweb]

I took the Ideas in Food: Sous Vide 2.0 class at Le Sanctuaire today. During the class, Alex mentioned you'll get better results if you chill & retherm SV-cooked foods rather than just use directly from the SV cooking bath. I

Why is this? Did they explain?