Sous Vide: Recipes, Techniques & Equipment, 2011

[PedroG]

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Guys,

I'm currently starting to design a sous-vide cooking appliance. This thread has been a great source of both inspiration and information, so I'd like to ask you all to help with the design process by answering a couple of questions. I hope I'm not out of order, but I think this thread is possibly the biggest collection of sous-vide cooks in the whole internet, and you're exactly the people I'd like to design a better sous-vide machine for. When I get further down the project I'll share sketches and prototypes, and hopefully any knowledge I've picked up along the way. Please feel free to add any comments.

1- What kind of sous-vide gear do you have (and how much did you pay for it)?

1. SVM 1500D plus FMM 2. SVM 1500D + VEGA stockpot 9L 400W

2- How regularly do you use it?

2-3x/week

3- How much food do you usually cook at once?

mostly 1 cut of 300-800g, sometimes up to 4 cuts

4- What annoys you in the process of cooking sous-vide?

nothing

5- Would you make any improvements to your gear?

NO. Bath should be tall to allow all bags to be suspended in vertical position. 1500-2000W power is nice for fast ramping up. Heater/bath-system should have minimal thermal inertia for easy PID-tuning. Autotuning should give useful PID-settings. The optimal system should be streamlined like a SVS and as versatile and stable as a SVM/FMM

Thanks a lot!

[dcarch]

Something for you guys to consider:

Heat sink/cooling fans for laptops are very cheap on eBay. Typically that device incorporates heatpipe technology. As you know heatpipe can tranfer thermal energy very efficiently.

You can easily salvage the heatpipes from those cooling fans.

Would it be a good idea to stick a few of those heatpipes into the meat when you have a very thick chunk of cold meat such as roast?

dcarch

[nickrey]

I'd avoid that one unless they were made specifically for cooking. One of the liquids used in some of them is mercury. No point poisoning yourself to get better heat conduction in your food.

[dcarch]

I understand what you are talking about. But I think mercury as the latent heat transfer agent is used only for very high temperature heat pipe applications. Laptop CPUs operate at very low temperature therefore will not be using mercury.

The CPU heat pipe is very well constructed and it is unlikely to leak. If it does leak it will suck in liquid not expel liquid because it is always under vacuum.

I agree. One should always be careful with food.

Dcarch

[Anna N]

OK so I know I must be particularly obtuse on this one but I have wanted to ask this question for ages:

I was taught that the best way to deal with frozen meat for safety and quality reasons was to thaw it slowly in the refrigerator or in frequent changes of cold water. With sous-vide one can take vacuum-sealed meat directly from the freezer and pop it into "hot" water. In fact Doug Baldwin has a table to accommodate meat going from the freezer to "done" with no thawing. What am I missing? (I have done it on more than one occasion without any problems - I just need to understand the science behind it.) Thank you.

[nickrey]

I'm pretty sure it relates to time in the "danger zone." If you thaw it slowly in the fridge, it never reaches the danger zone. If you thaw it in the sous vide set up, the thermal conductivity means that it passes through the danger zone sufficiently quickly so as not to do damage. The heating process through thermal conductivity is what Douglas has modelled in his equations and tables.

Thawing it in cold water with many changes is a way of maintaining a temperature differential between the meat and the water so it thaws comparatively quickly. To my mind, this would be potentially the most dangerous option of the three, particularly if you were not cooking it straight away and needed to rechill it.

[rotuts]

as above is correct: if you want to do it safely and save a little energy: thaw in the refrig. you are cooling the refirg. sl. it is still cold.

then place in your SV apparatus. you use a little less electricity not doing the thaw there.

(Still working on those asparagus. have them and will report!)

[e_monster]

I'd be concerned with whatever the metal is that is used for the heat pipe. If it wasn't intended for being used for food preparation, the metal could be some sort of alloy that leaches metal into the food.

Best,

E

I understand what you are talking about. But I think mercury as the latent heat transfer agent is used only for very high temperature heat pipe applications. Laptop CPUs operate at very low temperature therefore will not be using mercury.

The CPU heat pipe is very well constructed and it is unlikely to leak. If it does leak it will suck in liquid not expel liquid because it is always under vacuum.

I agree. One should always be careful with food.

Dcarch

[DouglasBaldwin]

Hi Anna,

I'll first address your question about the safety of cooking from frozen, then how it affects quality, and a brief comment on thawing.

There is nothing inherently unsafe about cooking from frozen -- even conventionally -- so long as you measure the core temperature and verify that it's been pasteurized. In general, it takes about 50% longer to heat from frozen than it does from thawed. (Indeed, there was an active thread awhile ago on cooking frozen roasts in the oven.)

So why does almost no one recommend cooking from frozen? Because very few cooks (outside of eGullet, of course) use a thermometer when cooking and so tend to under-cook frozen food. Also, many cooks are impatient, crank up the oven, and burn the outside before the core has even thawed -- I bet you've gone to at least one Thanksgiving dinner where the turkey was golden brown and frozen in the middle (I certainly have ). I think it's natural to cook from frozen sous vide because you don't have to worry about overcooking the surface while the core thaws and then comes up to temperature.

The main problem with cooking from frozen sous vide is that it's very hard to accurately compute how long it'll take to heat the core to your desired temperature. That's why I've never posted pasteurization from frozen tables, because I'm just not satisfied with the agreement of my numerical calculations with my empirical measurements. I implemented several numerical algorithms but none of them met my expectations and it's far enough from my area of expertise (nonlinear wave phenomena) that I haven't had the time or inclination to revisit the calculations I did back in late 2008. (The only cook from frozen time in my cookbook is for a chicken breast in a 140°F/60°C water bath and I determined the 3 hour cooking time directly from a series of empirical measurements of chicken breasts that I froze a needle temperature probe in.)

Now, there is a small difference in texture from cooking sous vide from frozen compared with cooking from thawed. This difference in texture isn't necessarily bad; indeed, sometimes I prefer the texture of cooked from frozen. My hypothesis is that this difference is caused by the proteins near the surface denaturing and being supported by the frozen core and then the denaturing of the core eventually being supported by the denatured proteins that surrounds it -- not unlike the slightly different texture of meat near a bone. But that's just a guess and the difference in texture is slight.

So why is thawing in the fridge or in cold water recommended? Well, Nick hit it on the nose with concerns about the ``danger zone''. A lot of home cooks just plunk frozen food on the counter to thaw and the problem with this is that the surface may well reach room temperature before the core is thawed and so allow bacteria on the surface to multiply rapidly. Both thawing in the fridge or in exchanges of cold water greatly reduce the growth of surface pathogens. To get an idea of how quickly different pathogens multiply to dangerous levels at near refrigerator temperatures, check out Table A-2 (Time/Temperature Guidance for Controlling Pathogen Growth and Toxin Formation in Seafoods) in the FDA's Fish and Fisheries Products Hazards and Controls Guidance, 3rd Ed.

[Anna N]

Hi Anna,

I'll first address your question about the safety of cooking from frozen, then how it affects quality, and a brief comment on thawing.

Thank you, Doug and others. I think I better understand now. Anna N

[PedroG]

Hi Anna,

just to illustrate what Douglas explained, see the graphs in my wikiGullet article, and the discussion in a late topic.

The difficulty in calculating cooking/pasteurizing times from frozen is caused by the chaotic behavior of heat conductivity during phase change (i.e. the transition from ice to water).

We always refer to danger zone and pathogens but not to spoilage germs. I quote from my above-mentioned article: "Thawing in cold water (0°C) would shorten the time in the "danger zone" but prolong the time in the "spoilage zone", as spoilage bacteria begin to multiply at 23°F/–5°C."

[dcarch]

I'd be concerned with whatever the metal is that is used for the heat pipe. If it wasn't intended for being used for food preparation, the metal could be some sort of alloy that leaches metal into the food.

Best,

E

I understand what you are talking about. But I think mercury as the latent heat transfer agent is used only for very high temperature heat pipe applications. Laptop CPUs operate at very low temperature therefore will not be using mercury.

The CPU heat pipe is very well constructed and it is unlikely to leak. If it does leak it will suck in liquid not expel liquid because it is always under vacuum.

I agree. One should always be careful with food.

Dcarch

Good point. The material appears to be pure copper, the same material as drinking water piping.

Of course it can easily be tinned.

dcarch

[lstrelau]

Would you REALLY want to put copper (assuming that these heat pipes are pure copper rather than some other alloy) into direct contact with food? Possibly if there was absolutely no acidic component in the food but even then I expect you would get a chemical reaction between the copper and the meat (yummy - green corrosion stains in my steak!!). Aside from copper being toxic and the colour unfortunate, the taste would be dreadful too. Copper plumbing pipe is one thing but not combined with food and heat and moisture.

Maybe stainless steel rods (albeit not such a good conductor) or maybe annodized aluminum but frankly doesn't sound worth it to me.

[Anna N]

Hi Anna,

just to illustrate what Douglas explained, see the graphs in my wikiGullet article, and the discussion in a late topic.

The difficulty in calculating cooking/pasteurizing times from frozen is caused by the chaotic behavior of heat conductivity during phase change (i.e. the transition from ice to water).

We always refer to danger zone and pathogens but not to spoilage germs. I quote from my above-mentioned article: "Thawing in cold water (0°C) would shorten the time in the "danger zone" but prolong the time in the "spoilage zone", as spoilage bacteria begin to multiply at 23°F/–5°C."

Thank you Pedro. I think I am slowly beginning to grasp it.

[dcarch]

Would you REALLY want to put copper (assuming that these heat pipes are pure copper rather than some other alloy) into direct contact with food? Possibly if there was absolutely no acidic component in the food but even then I expect you would get a chemical reaction between the copper and the meat (yummy - green corrosion stains in my steak!!). Aside from copper being toxic and the colour unfortunate, the taste would be dreadful too. Copper plumbing pipe is one thing but not combined with food and heat and moisture.

Maybe stainless steel rods (albeit not such a good conductor) or maybe annodized aluminum but frankly doesn't sound worth it to me.

I understand your concerns, but consider the following:

The amount of copper which will get into your body is dependent on the following:

1. Frequency of the use of copper cookware.

2. Surface area of cookware in contact with food. The larger the contact area, the more copper may leach into food.

3. Degree of agitation of the contact point between copper and food. The more agitation, the more leaching of copper may happen.

4. Acidity of food. Copper may react with acid food.

I believe that the copper heat pipe as shown does not meet any of the above four conditions. In any case, a small amount of copper is required for good health, that tiny amount of copper, if in fact present, may just be good for your health.

I think it is a good idea to beat eggs in a copper bowl, lots of stirring with metal to metal scrapping and exposure to large surface area.

As I said, most of the piping for potable water is in fact copper. On the average, most people drink large quantities of water from copper pipes everyday for over 70 years (life expectance). I am not sure drinking water is not somewhat acid with chlorine and fluorine and acid rain.

Having said all these, my experimental heating pins using heat pipes are actually tin coated. I think for SV, it will make a few hours of difference of cooking time to equalize cold temperature of a very thick piece of meat right from the refrigerator.

dcarch

[paulpegg]

Would you REALLY want to put copper (assuming that these heat pipes are pure copper rather than some other alloy) into direct contact with food? Possibly if there was absolutely no acidic component in the food but even then I expect you would get a chemical reaction between the copper and the meat (yummy - green corrosion stains in my steak!!). Aside from copper being toxic and the colour unfortunate, the taste would be dreadful too. Copper plumbing pipe is one thing but not combined with food and heat and moisture.

Maybe stainless steel rods (albeit not such a good conductor) or maybe annodized aluminum but frankly doesn't sound worth it to me.

I understand your concerns, but consider the following:

The amount of copper which will get into your body is dependent on the following:

1. Frequency of the use of copper cookware.

2. Surface area of cookware in contact with food. The larger the contact area, the more copper may leach into food.

3. Degree of agitation of the contact point between copper and food. The more agitation, the more leaching of copper may happen.

4. Acidity of food. Copper may react with acid food.

I believe that the copper heat pipe as shown does not meet any of the above four conditions. In any case, a small amount of copper is required for good health, that tiny amount of copper, if in fact present, may just be good for your health.

I think it is a good idea to beat eggs in a copper bowl, lots of stirring with metal to metal scrapping and exposure to large surface area.

As I said, most of the piping for potable water is in fact copper. On the average, most people drink large quantities of water from copper pipes everyday for over 70 years (life expectance). I am not sure drinking water is not somewhat acid with chlorine and fluorine and acid rain.

Having said all these, my experimental heating pins using heat pipes are actually tin coated. I think for SV, it will make a few hours of difference of cooking time to equalize cold temperature of a very thick piece of meat right from the refrigerator.

dcarch

I think the opportunity to introduce pathogens into the meat far outweighs the potential reduction in cooking time by perhaps only a few minutes. I doubt that it would reduce the time by hours since those same BTU's still have to make their way out to the water and the mass of the heat tube is insignificant relative to the entire mass to be heated. you are not providing any benefit to the process and complicating a very simple cooking method by introducing an indeterminate variable.

[dcarch]

Would you REALLY want to put copper (assuming that these heat pipes are pure copper rather than some other alloy) into direct contact with food? Possibly if there was absolutely no acidic component in the food but even then I expect you would get a chemical reaction between the copper and the meat (yummy - green corrosion stains in my steak!!). Aside from copper being toxic and the colour unfortunate, the taste would be dreadful too. Copper plumbing pipe is one thing but not combined with food and heat and moisture.

Maybe stainless steel rods (albeit not such a good conductor) or maybe annodized aluminum but frankly doesn't sound worth it to me.

I understand your concerns, but consider the following:

The amount of copper which will get into your body is dependent on the following:

1. Frequency of the use of copper cookware.

2. Surface area of cookware in contact with food. The larger the contact area, the more copper may leach into food.

3. Degree of agitation of the contact point between copper and food. The more agitation, the more leaching of copper may happen.

4. Acidity of food. Copper may react with acid food.

I believe that the copper heat pipe as shown does not meet any of the above four conditions. In any case, a small amount of copper is required for good health, that tiny amount of copper, if in fact present, may just be good for your health.

I think it is a good idea to beat eggs in a copper bowl, lots of stirring with metal to metal scrapping and exposure to large surface area.

As I said, most of the piping for potable water is in fact copper. On the average, most people drink large quantities of water from copper pipes everyday for over 70 years (life expectance). I am not sure drinking water is not somewhat acid with chlorine and fluorine and acid rain.

Having said all these, my experimental heating pins using heat pipes are actually tin coated. I think for SV, it will make a few hours of difference of cooking time to equalize cold temperature of a very thick piece of meat right from the refrigerator.

dcarch

I think the opportunity to introduce pathogens into the meat far outweighs the potential reduction in cooking time by perhaps only a few minutes. I doubt that it would reduce the time by hours since those same BTU's still have to make their way out to the water and the mass of the heat tube is insignificant relative to the entire mass to be heated. you are not providing any benefit to the process and complicating a very simple cooking method by introducing an indeterminate variable.

I don’t have any data to show. As I remember, it takes close to half an hour of resting time for the interior temperature to get to rare temperature after you roast the beef in a high temperature oven. I would think it takes more than a few minutes in the SV bath.

I will agree with you that the possible use of additional implements to accelerate the heating of interior of large pieces of meat is not for everyone. I have a feeling that SV cooking is at the moment, for many people who are adventuresome, and with a willingness to try for perfection in cooking, and this new technology of using heat pipe may be of interest to them. There are many who configure their own system with PID controllers, pump, bubblers, heating coils, etc.

While I can agree with you that the using heat pipe can increase the possibility of introduction of pathogens, but for a well informed user of SV methods, that doesn’t not appear to be as an overwhelming challenge to maintain sanitary conditions.

dcarch

[lstrelau]

While I can see where some sort of metallic heat sink could help speed up the cooking process wouldn't you have to have a number of probes inserted to have significant effect on the process and then when you slice the meat you would have all these funny holes in it? Tinned copper is perhaps better than straight copper, though wonder if there would be any taste residue. You could probably find some surgical steel implements (there are canulas and other medical instruments that would be perfect for your purpose (google something called a urethral sound) Once you get over cringing at the thought of these things used for their intended medical purpose they could work as heat sinks with no risk of metal contamination of food. Though I realize stainless steel isn't as good a conductor as copper.

With SV there are still people (like my good friends who are staunch foodies but traditionalists) who find cooking in plastic bags suspect enough (their concern about leaching of nasty stuff). I can only imagine their reaction to copper pipes cooked with their roast

What about butterflying the roast and then meat gluing it together again (or just have smaller slices?

[dcarch]

While I can see where some sort of metallic heat sink could help speed up the cooking process wouldn't you have to have a number of probes inserted to have significant effect on the process and then when you slice the meat you would have all these funny holes in it? ----------

The idea is this device called "heat pipe". It uses an interesting principle (latent heat, phase change) to conduct heat very efficiently. It conducts more BTUs than pure metal. That's why they use it in critical heat transfer needs in computers and other applications such as nuclear power cells and space crafts.

It is very intriging that this high-tech device can be had at such low cost in the surplus market.

dcarch

[dougal]

...

Having said all these, my experimental heating pins using heat pipes are actually tin coated. ...

I wouldn't guess that it was food-safe tin.

Have you?

Remember that in electronics assembly parlance to "tin" just means to coat with solder. Which, unless documented otherwise, I would treat as distinctly food un-safe, because of the non-tin constituents of the alloy.

'Tinning' electronic components is not the same as 'tinning' copper cookware.

Have you had the things chemically analysed, or re-tinned by a cookware service business?

Heat pipes are fun, but really not needed in this application.

And those fins will either rip sv bags or trap air, causing unwanted floatation and oxidation, assisting spoilage.

Sorry - creative concept, but not needed, and adding WAY too many concerns.

[nickrey]

Get meat a bit faster versus a whole heap of unknowns that could very well be toxic ... We've all tried to warn you subtly but let me be a bit more forceful: Don't do it, it is not worth it.

[dcarch]

“Get meat a bit faster versus a whole heap of unknowns that could very well be toxic ... We've all tried to warn you subtly but let me be a bit more forceful: Don't do it, it is not worth it.”

Very good advices to be careful when it comes to food stuff. Don’t hunt for mushrooms if you are not a 200% expert in the area of mycology. You will be suicidal to eat Fugu if you do not have years in training in the preparation.

However,

I am not entirely convinced that rendering the small copper pins food-safe can be so imposible.

I am not convinced that for a few experienced sous vide cooking practitioners, to maintain sanitary conditions for a few pins is so overwhelming.

I am not convinced that it is meaningless to take advantage of the incredible thermal transfer capability of heat pipes, for instance, in the situation when you have to cook an ice cold chunk of 4” thick roast to raise the temperature of the interior of the meat as quickly as possible to control and optimize the cooking time..

I do agree that safety in any kind of cooking is important, and I appreciate the advices for caution. We have come a long way to convince people that sous vide cooking should not be made illegal.

No doubt driving a car is extremely dangerous and I don’t blame those people who will not drive a car.

dcarch

[PedroG]

According to Nathan's table you can cook a 150mm slab at 65°C bath temperature for 3h53' to a core temperature of 50.5°C which during rest time of 58' will rise to a final core temperature of 54.4°C, and you are still safe without the heat pipe thing which I suggested rather for fun as a theoretical possibiliy and not meaning you really should do that.

[prospectbake]

I've scanned the previous pages of this thread, so hopefully I'm not repeating a question. I have access to a molecular biology lab, and can obtain new equipment-such as an immersion circulator, other than being more compact is anyone aware of any advantages the sous-vide professional has? I would think it's very similar, just marketed to the food industry.

Thank you!

[dcarch]

According to Nathan's table you can cook a 150mm slab at 65°C bath temperature for 3h53' to a core temperature of 50.5°C which during rest time of 58' will rise to a final core temperature of 54.4°C, and you are still safe without the heat pipe thing which I suggested rather for fun as a theoretical possibiliy and not meaning you really should do that.

You have discribed the exact purpose of my post for the heat pipe idea.

I have been using heat pipes for a while with a great deal of success, including using them for baking big cold turkeys. I only decided to post the idea mostly because one poster was asking what would be a best designed sous vide cooker. I thought may be makers of kitchen gadgets and sous vide cookers can see this post and perhaps would be interested in looking into this high-tech device and realize that they can be made inexpensively for kitchen use.

dcarch