Sous Vide: Recipes, Techniques & Equipment (Part 5)

[nathanm]

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Has anyone tried a turkey, chicken or regular burger with SV?

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Isn't any sort of sv 'burger' (or other ground/minced meat product) a rather bad idea from the food hygiene standpoint?

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I would say not really, provided to achieve proper 5/6d reduction times maintaining an intact surface isn't really a concern. in fact given adequate temp and time, a sv burger would be considerably safer then a regular grilled burger.

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How does that work for Clostridium botulinum?

Isn't that the major worry (in terms of seriousness of outcome) with any 'comminuted meat' product in a low oxygen, non-acid, environment at these 'warm' temperatures? And where the centre is not going to benefit from post-sv searing?

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My understanding is that botulism needs time to germinate and produce nasty toxins. I don't think you should cook and hold burgers or any ground meat, but if you grind some beef, make a burger, cook the burger and then eat the burger in the time it takes you to do this, I can't see it being a problem but I am not a micro-biologist.

Also its not like you have to cook burgers low and slow, you just want to bring them to temp, they are already plenty tender.

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My understanding of botulism was similar - that you need a long time in a zero oxygen enviroment for it to grow and produce toxins... the FDA shows in the food code how long you can keep pasteurized ROP products at different temperatures.... From what I understand, if you do cook-chill, you can keep stuff at refrigerator temps (34F) or lower for a max. of 30 days (according to 3-502-12D(2)(e)(i))

So, theoretically, you can cook your burger to 55C for a time long enough to pasteurize depending on thickness, and then chill them down and refrigerate for a month - then just take out and sear on the grill to bring back to temp whenever you're ready... If you want to cook at lower temp. (for a really rare burger), I don't see why you couldn't do it, just so long as your burger wasn't 4" thick so that it would sit in the danger zone for too long.... then eat right away - can't store in the refrig. since it's not pasteurized....

Am I reading this correctly? Someone please correct me if I'm misunderstanding this....

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Various pathogens die at different temperatures. The standards set by USDA FSIS (food saftey inspection service) and FDA (food and drug administration) are based on their overall judgement as to what people ought to do as a general rule.

Their general rule starts at 130F/54.4C, and is based on research on Salmonella. However, Salmonella can be killed at much lower temperatures - there are scientific papers documenting Salmonella down to 120F/48C. The times for 120F/48C are much longer, and yes you can extrapolate them from the existing curves. You could also extrapolate to 122F or 125F.

I have asked USDA / FDA officials why they start at 130F/54.4C instead of lower. The answer is basically that the standard was set for pre-cooked ready-to-eat roast beef (i.e. sold packaged in grocery stores). The industrial food companies that make it asked for 130F, because for that product they didn't need it lower. Nobody asked for lower temperatures. Once the standard had been set for that, then the FDA adopted it as a recommendation for other cases. There is no strong scientific logic at work here.

So if you care about Salmonella, then there is strong scientific evidence that you can cook below 130F/54.4C if you cook for a long enough time.

Other pathogens can survive at higher temperatures. Listeria is one, Clostridium perfringens is another. However, the general judgement is that the rule for Salmonella ought to be enough.

It would be nice if general rules came with a gurantee, but they don't. If you have a horribly contaminated piece of meat, cooking it to the general rule - at any temperature - might not be enough.

Conversely if you have uncontaminated meat, you can eat it raw. Carpaccio and steak tartare are delicious and with quality ingredients are MUCH safer than many things we do every day - like ride in an automobile.

Ground meat is OK if you cook it so that the core temperature reaches the appropriate tempertaures for the appropriate amount of time as given by the rules/tables.

Botulism is much feared, but it only comes from storing the food in a vacuum long enough to germinate. If you eat the food immediately after cooking, you do NOT need to worry about botulism. So it only applies to cook-chill sous vide.

The lower the storage temperature the longer you can store it. at 34F/1C you can store a month. At 41F/5C a week. Again these are general guidelines, which match FDA 2005 Food Code.

Edited April 25, 2009 by nathanm (log)

[nathanm]

blackp, I am working with Frank Hsu at Fresh Meals Solutions (source of the Sous Vide Magic) to put together a guide to tuning the SVM. I was all set to fire up my data logging thermometer tonight, as a matter of fact, but I realized I first have to find a USB to serial port adapter -- I no longer have a computer with an old-fashioned serial port.

Here are my initial suggestions, but they are primarily based on my experience with the large 10 liter rice cooker, instead of my 1.8 or 1.2 liter Tiger and Ikeda units.

First, forget the Autotune function -- it seems to come up with some rather bizarre settings, at least for the large pot, even after running all night.

Instead, first determine an approximately optimum P (proportional) setting, with I=0 and D=0.  I would try the settings in the instruction book first, and then experiment from there.

At least initially, start at ambient temperature, and record and plot the temperature of the bath (preferably using an external thermometer with 0.1 degree resolution) every 30 seconds for say 20 minutes.

If the overshoot is too great, the P value is probably too low.  As a result, the SVM is putting out full power until the unit is close to the set point temperature, and at that point the trapped heat makes the device go into overshoot, even after the power is essentially off.  Then, because rice cookers are well insulated, it takes a long time to drop back down.

On the other hand, if there is relatively little overshoot, but it takes forever to come up to temperature, the P value is probably too high.  I don't know that I would cut it in half -- that might be too much -- but cut it substantially.  It should then go into overshoot mode, and by increasing or decreasing by 1/2 of the difference each time, you should be able to optimize the P value fairly quickly.

(Of course, one good way to simplify this entire process is to add preheated water of approximately the right temperature to the pot to start with!)

If the final result, once everything has stabilized, is an undershoot, then you may need to adjust the I value.  So far, with the large pot, I haven't found the need to do this yet, but if you check out "PID controller tuning" on Wikipedia, you will find some suggestions.

I THINK that the best way to do this is to apply a massive increase to the I value, in which case the system probably ought to start oscillating -- swinging back and forth slowly from a minimum to a maximum and back.  Once that happens, record the period, i.e., the amount of time in seconds between two successive minima or maxima, then divide by two,  set the I value to that., and experiment from there.

I'm not even close to determining an optimal way to set the D value, mainly because the amount of food I add to the water bath is small compared to the 10 liter mass of water, and things stabilize fairly quickly.  But my plan is to take a set of "Blue Ice" bricks from the freezer one at a time, drop them in the water, plot the response, and tweak accordingly.

If Douglas Baldwin or other mathematician or process control engineer can suggest improvements to this procedure, I would certainly welcome their insights.

Once we get some better data for a number of different cookers, Frank has promised to post the results on his web site.

BTW, I assume, with no personal experience to back me up, that using a circulator, an electric turkey fryer, or similar device that has the heating element directly in the water along with a circulator would simplify this process, except perhaps for optimizing the response if you drop in some colder food all at once.

Note added:  I've just been informed that the topic re sous vide thermometer accuracy has been relegated to the Kitchen Equipment section, at http://forums.egullet.org/index.php?showtopic=123336.  (Why, I don't know.)  In addition to tuning your PID controller, you really need to confirm the accuracy of the controller, so please reference that thread.

Bob

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I don't think physics class would help that much.

Changing the PID parameters is known as "PID tuning". It is a huge topic - I just found 289,000 hits in a Google search, including YouTube videos etc. There are dozens of books on PID on Amazon (and I have them all). It is not brain surgery, but it is an involved topic.

Autotuning controllers do this for you automatically, which is very convienent.

There are two kinds. The cheap kind has an autotune button or mode. As discussed in other posts it works best when the temperature is already stable. To use it, you read the manual, then put it in the mode and it will tune itself.

Autotuning requires that the system perform some tests and determine how long it takes to heat up and so forth. It can sometimes be fooled as the post above suggests.

The newer, and a bit more expensive self-tuning PID controllers will do automatic tuning at all times - instead of an autotune button, it just always watches what is going on and adjusts itself. In general these are much better, and when I use a PID controller I try to get one of these. However, I don't think that is the kind they use on SVM.

Different PID manufacturers have their own terminology for the automatic tuning - some claim they use "fuzzy logic", others use a different term.

In the case of immersion circulators or water baths, the manufacturer sets the PID parameters and you should never need to change them.

Edited April 25, 2009 by nathanm (log)

[nathanm]

Doug Baldwin's great sous-vide pages mention that eggs can be pasteurized at 135F by cooking for 1 hr 15 min or more. Anyone  have any idea what the time to pasteurize would be at 131F and 133F? I tried to find some good data on the web but found that a lot of the pages (even from the food industry) wave their hands around and act like 140F is the minimum temp at which salmonella is killed.

I found one paper that confirmed that 131F was sufficient but I wasn't able to determine from the paper the time required to pasteurize against salmonella in eggs at that temp. (Apparently the substrate makes a difference in how long it takes to kill the salmonella).

I'd love to be able to pasteurize eggs when I am cooking at 131F and 133F.

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That is an interesting question, I'm not sure why most studies do not consider anything less than 135F/57C in eggs or poultry; . For an educated guess, we can use the D-values for Salmonella enteritidis of 4.5 min at 58C and 6.0 min at 57C in [J Appl Microbio 83 (1997) 438--444]. These D-values give a z-value of 8C (1/log_10(6.0/4.5)). Therefore, at 131F/55C it would take 6.5*6.0*10^((57-55)/8) + 35 = 105 min and at 133F/56C it would take 6.5*6.0*10^((57-56)/8) + 35 = 87 min (where the study found that the egg took 24--35 min to come up to temp).

From Table 4 of the survey article [J Food Sci 71 (2006) R23--R30] (which includes many studies at 55C, 57.5C, 58C, ..., 70C for Salmonella spp in poultry), I compute a D-value of 4.8 min at 60C with a z-value of 6.46C. Thus, a 6.5D destruction of Salmonella spp is: 6.5*10^(9.97- 0.1548*55) + 35 = 220 min at 131F/55C and 6.5*10^(9.97- 0.1548*56) + 35 = 165 min at 133F/56C. However, since Salmonella enteritidis (which is the strain found in eggs) is a less thermally resistant strain than the Salmonella senftenberg containing `cocktail' used in most the studies, the times in the previous paragraph should be sufficient.

Edit: Added extra detail.

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Amazingly enough there is no US government standard time and temperature for whole-egg pasteruization. I have asked pointedly and they can't find any, in part because of a bureacratic issue as to whether it should be set by FDA or USDA.

The typical recommendation from both USDA and academic papers for whole egg pasteurization is 5D, rather than 6.5D. You might ask why, and I have done so without getting a good answer. In general the answer to these things is usually an arbitrary decision somebody made.

In fact, there are so many arbitary decisions, and outright errors, in the FDA code that it is almost amusing. My book will have a big discussion of this.

Typically the adacemic egg science literature is interested in shortening processing time, so they recommend the highest temperature they can use without denaturing the proteins in the egg (which would mean it wouldn't whip well etc.).

As Douglas says, it takes about 25 min for an egg to reach core temperature (and this does not depend very much on temperature within this range). After that if you hold for the same times as the normal 6.5D table you will be more than fine.

The standard 6.5D table is 112 minutes at 130F/54.4C.

So, if you want 6.5D you should do 112 + 25 = 137 minutes (2 hours and 17 minutes) total cooking time at 55C/131F

Or you want to do 5D, you could reduce the times to 25+ 86 = 111 min (1 hour 51 minutes) at 55C/131F

Edited April 25, 2009 by nathanm (log)

[nathanm]

I've actually been thinking about doing something similar, along the lines of the SV burgers....  someone PLEASE let me know if this is a little crazy, or just not practical...

Anyway, I've been thinking about doing a bolognese sauce and, separately, meatballs by SV at say 55 or 60C for long time (i.e. 24 hours, ,etc)... or what about either 67 or 83C for 8 hours or so??  I gather that a really good bolognese needs to simmer for a long time to get a really great mouthfeel.. so I figured why not do the same thing you'd do with tenderizing a chuck steak, but to ground meat? 

Similarly with meatballs - I've had way too many meatballs made the conventional way where the meat was gray and really tight... either from simmering too hard, or not long enough... I figured, even if the connective tissue int eh meat is ground up, it's still there...  if you cook it long enough to convert it to gelatin, wouldn't that make a melt-in-your-mouth product???

Any thoughts???

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The reason to cook a sauce that long is to leach gelatine from the meat into the sauce, which adds richness and mouthfeel. You don't really need to tenderize ground beef, because it is ground. It might make some difference, but it could also fall apart.

Traditional bolognese sauce used cubed meat which did need to get tender.

[e_monster]

blackp, I am working with Frank Hsu at Fresh Meals Solutions (source of the Sous Vide Magic) to put together a guide to tuning the SVM. ....

First, forget the Autotune function -- it seems to come up with some rather bizarre settings, at least for the large pot, even after running all night.

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Does autotune on that unit come up with bizarre settings that work or bizarre settings that don't work?

The Auber instruments auto-tune has worked perfectly for me --although it can take 6 to 8 hours -- because it can take a long time for the water to cool down between the auto-tune cycles. The results I have gotten have worked great although they may have seemed 'bizarre' in the sense that they aren't what I would have guessed they would be.

If the SVM's auto-tune is worthless, that seems like a serious design flaw.

For future reference for the group, it would be interesting to know if other people also have problems using the auto-tune with the SVM machine.

In any case, it is worth trying.

p.s. Thanks Doug and Nathan for the additional info on egg pasteurization.

Edited April 25, 2009 by e_monster (log)

[nathanm]

This is an important point - the amount of time it takes to autotune can be very long because it must go through a couple cycles of heating and cooling to measure overshoot and time response.

If you change the set up (different heating element, different volume) you must retune.

That is another reason to prefer continuously tuning PID controllers....

[Robert Jueneman]

Nathan, thank you for your always informative posts.

When I initially ran the autotune function on my SVM 1500A overnight with a 1500 watt, 10 liter commercial rice cooker, the resulting parameters were P=15, I=998, and D=499. Now, that means that it is going to put out full power until it is within 1.5F of the target temperature, and then integrate and differentiate the results to the max. Because the results were so far to the extreme, I simply discounted them as not realistic, and didn't actually try them.

I was about to re-enter those values and try them, but I can't! The maximum setting I can enter manually for the I value is 900, and the maximum setting for D is 300. Strange.

I'm about to go buy a USB to RS-232 adapter for my data logging thermometer -- the Belkin unit I have won't work with my Vista laptop because of driver issues(??), and running XP under VMWare on my Mac Pro is too much bother. But I should be able to automate some of this testing this weekend.

BTW, to the best of my knowledge, the Sous Vide Magic and the Auber units are identical except for the name, although there may be internal differences.

e_monster, when you calibrated your Auber unit, what type of rice cooker were you using, and how large was it?

[Robert Jueneman]

Cooking Vegetables

I think I have a reasonably good understanding of the science of meat cooking, the opposing forces at work, and why sous vide gets such great results.

But I really don't understand what happens when you cook a vegetable, and what the time/temperature relationship is.

Why do some vegetables require 185 or even 195F, while others are best at 165F (at least according to Thomas Keller).

How long would it take to "bake" a sous vide potato in a 131F bath? Would it work at all? I assume the same issues regarding pathogens would still apply, as they do in meat?

[tomdarch]

A quick, minimally informed response: cooking veggies is quite different than cooking meats. In meats (and eggs) a lot of the "cooking" is denaturing proteins, and otherwise breaking down connective tissues. In veggie cooking, you're breaking down very different components. I'm sure that proteins play some role, but to a much lesser degree. The vegetable tissue is also the "bones" of the plant, so they are very different than animal muscle/connective tissue. I remember that pectin is one of those components, but I can't remember if it's "cook temperature" is above or below 85C. The idea is that you are breaking down some components, but leaving others in tact. I suspect that "exploding" cell walls is also a factor, but I'm not sure specifically how. There are also a complex set of chemical reactions that happen when different vegetables are cooked, and sous vide can control which of these do or don't happen. Lastly, cooking in a bag prevents a lot of flavors and nutrients from being diluted out into the cooking water.

Because the "cooking" of vegetables is so complex, it makes sense that you would see different temperatures ranging from 165F/74C to 195F/90.5C. It's a question of what's in the particular veggie and what do you want to do to it? (I wish I knew exactly....)

Vacuum "compression" is a whole different, and interesting, set of issues.

So far, I have done potatoes and carrots (around 85C - roughly, because I was "tending" a pot on the stove) for about 45 minutes. The were roughly 1cm cubes, bagged with butter, salt and pepper. The result was definitely "cooked", and consistently cooked all the way through. But unlike fully boiled veggies, there was still a small amount of crunch. This was unlike a rapidly blanched carrot, which may be overcooked on the outside and still semi-raw in the middle. It was a good, interesting way to cook veggies, but not mind-blowing. I'm planning on trying parsnips next...

Here's an article by the Ideas in Food folks about sous vide veggies:

http://www.popsci.com/diy/article/2009-01/shades-green

[e_monster]

When I initially ran the autotune function on my SVM 1500A overnight with a 1500 watt, 10 liter commercial rice cooker, the resulting parameters were P=15, I=998, and D=499.  Now, that means that it is going to put out full power until it is within 1.5F of the target temperature, and then integrate and differentiate the results to the max.  Because the results were so far to the extreme, I simply discounted them as not realistic, and didn't actually try them.

I was about to re-enter those values and try them, but I can't!  The maximum setting I can enter manually for the I value is 900, and the maximum setting for D is 300.  Strange.

.......

BTW, to the best of my knowledge, the Sous Vide Magic and the Auber units are identical except for the name, although there may be internal differences.

e_monster, when you calibrated your Auber unit, what type of rice cooker were you using, and how large was it?

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This was with a 22 quart Hamilton Beach tabletop roaster -- which is almost a worst case device for these PIDs because of the huge latency in heating due to the double-walled nature. So, I was pretty pleased that it came up with rock solid settings. (There is a small amount of initial overshoot that settles down quickly). Oh, for auto-tune I used room temperature tap water -- in normal use, I start with water that is already about 130F.

Even if the numbers looked weird to you -- it would be interesting to know if they worked. In my opinion, it is worth trying the settings because you might be pleasantly surprised.

The numbers I got were weird but they worked. They were similar to what you got (different P but the I and D values were the same -- which are the maximum allowed values). I suspect that there are different settings that may also work and look less weird -- but they worked for me so I was a happy camper.

The settings it came up with I couldn't re-enter by hand -- so I re auto-tuned and it came up with the same results. This was before I wrote to Auber to find out why I couldn't enter them manually. If I have to re-enter them again, I will take the advice offered by Auber which I provide below because others may also find it helpful.

Suyi is responding to a message in which I mentioned that auto-tune came up with settings that worked well but couldn't be entered by hand.

We limit the I to 900 because the controller can't display more than 999. In addition, when the I>600, the integration function is not really meaningful when we use a cycle rate of 2 second. The difference between 900 and 998 is very little. What you can try is set I=0. That will remove the I function. If that is not as good, reduce the P by 50% each time. We found using PD instead of PID also works better for large cookers. Based on the PID control theory (developed in 1940 but still the most commonly used), the D should normally about 1/4 of I. That is why the D is also limited

[blackp]

Oh dear. The more I read the more I know for sure that I don't know!

I'm wondering if I am being over cautious or am I correct in attempting to get the tuning of my SVM PID stable before cooking anything for a long time?

With a few hours to kill yesterday and still waiting for the data logger to arrive I filled the 12litre Tiger to about 9 litres - which is about 6cm or 2.5 inches below the top allowing for the addition of some food with a margin for error. (BTW anyone who says the Tiger JNO-(A/B)360 is 12l is correct, but you couldn't fill it with 12 litres of water and put any food in it as well).

The water was from the hot tap and was about 60C when added to the Tiger.

I allowed the Tiger to stabilise for about 45 minutes so that any error from the "cold" Tiger and the hot water would be minimalised.

When I powered up the SVM and Tiger the starting temp of the water was 49.6C. From that point I kept the lid closed through the whole sampling process. My intention was to wait until the temp stabilised and then to add a fake food load and watch the impact. Unfortunately I didn't get to that part of the experiment as getting to the target went beyond my bed time ;-)

After power-up I became a human data logger recording the temp from a thermocouple thermometer (not the SVM readout) every minute for the next 3 hours. (Memo to self: wait for data logger to arrive before attempting this experiment again!). After 3 hours I needed to get dinner happening so I set the kitchen timer for 5 minutes and recorded 5 minute intervals for the next 5 hours.

See Chart:

What I found that disturbs me was the massive initial overrun and the fact that the target temp was not achieved until about 7.5 hours after starting the experiment.

Also I cannot explain the oscillation between 58C and 56C before the temp finally reduced to near the target of 54C.

When I get some more time I'm going to try reducing the power to 50% as the Tiger is 1610W in it's 240V model.

I was going to cook some beef short ribs for 48 hours. Should I wait until I've stabilised the SVM or is it pretty safe to just give it a go?

Thanks,

Peter.

[blackp]

Given the "odd" outcome I wondered if anything was not right with my last experiment, so I ran a smaller one tonight.

Here are the results:

The only difference was that in experiment 1 I had attached the 2 temp sensors (one for the SVM and one for my thermometer) to a wire cake rack with rubber bands to keep them low in the water but off the surface. Maybe the cake rack itself gained temperature from the metal container of the rice cooker - who knows?

In test 2 I used a weight to hold the wires of the sensors down but did not let it touch the sensors themselves. The only other difference I can identify was that the ambient temp was 2C lower than the last attempt.

The difference is substantial - and a big improvement without changing any parameters.

When I get time I will play with settings to see what difference they make.

PB

[nathanm]

I am not sure why the difference between tests. Ambient temperature is ceratinly part of it.

In both tests you are getting a very strong overshoot, which lasts for a long time. This is not right and is something that proper tuning parameters should eliminate. You should not get this level of overshoot.

If you put an aquarium air pump and bubbler in to stir the water it will help. The air will be ambient temperature so that cools the bath down and will help reduce the overshoot. It will also stir the water around. This is only a partial solution because it looks like your PID parameters do need improving.

[slkinsey]

The newer, and a bit more expensive self-tuning PID controllers will do automatic tuning at all times - instead of an autotune button, it just always watches what is going on and adjusts itself.  In general these are much better, and when I use a PID controller I try to get one of these.  However, I don't think that is the kind they use on SVM.

Any brand recommendations?

[mtigges]

I have an equipment question, but at 80 plus pages, the discussion does not yield good enough resolution on searches. So, my apologies if this generates a little extra noise.

I'm going to step in to SV with one of the Auber units. My question though concerns the vessel that I'll be using for immersion. According to this link: aubers equipment recomendations my available option is not optimum.

I have one of these:

http://www.amazon.com/Rival-SCVI600B-SS-Cr...40932689&sr=1-1

I bought it because the pot can go on the stove top. I love it.

While it does have an integrated circuit board, it is nothing more than a timer and a digital readout of the time left, or heating setting. I'm quite certain the switch is mechanical. I would have absolutely no qualms about pulling the cord out while the unit is set to low or hi. It won't remember the time, but in this case I don't care.

Aubers pdf (linked above) says that if it has a digital readout it's not appropriate for use. I have a suspicion that that's just a CYA statement. So, I'm petitioning those here for whatever experience they have with similar units.

I would even consider a little surgery on the unit to install a plug to bypass ICB that I can use with the PID when used in sv. So any advice from people who have done this something similar very welcome. I'm reticent to get another tool (rice cooker) because I have enough clutter as it is.

All opinions welcome.

Thank you.

[slkinsey]

That's a pretty small vessel for cooking sous vide, especially with no circulator. 6 quarts is only 1.5 gallons (346 square inches) of volume. How much do you envision cooking in there?

[dougal]

...

While it does have an integrated circuit board, it is nothing more than a timer and a digital readout of the time left, or heating setting.  I'm quite certain the switch is mechanical.  I would have absolutely no qualms about pulling the cord out while the unit is set to low or hi.  It won't remember the time, but in this case I don't care.

...

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The absolute essential is that it remembers the heat setting - or defaults to something you can work with.

The external PID will be "pulling the plug" every couple of seconds or so ...

PS - also important is that powering on/off rapidly should NEVER confuse the "integrated circuit board" - like thinking 'time left is now zero, so I'm switching off'.

Simple is what's needed!

Edited April 28, 2009 by dougal (log)

[e_monster]

Given the "odd" outcome I wondered if anything was not right with my last experiment, so I ran a smaller one tonight.

Have you tried running the auto-tune mode? At the risk of seeming like a broken record, I recommend trying it -- you have nothing to lose and it might find settings that work. It may take 6 to 12 hours for the tuning to be completed. The worst that will happen is that you will end up with settings that don't work -- but I think it is worth a try and I think it is likely to work (based on my experience).

[Robert Jueneman]

blackp, you now understand why I broke down and ordered the data logger accessory for my thermometer!

Using a 10 liter, 1500 watt commercial rice cooker that is similar to yours, for Celsius measurements with the SVM 1500B I'm using P=100, I=0, D=0. With those settings, beginning at ambient, I find that things stabilize very nicely within 20 minutes, with no more than about 1.5C overshoot.

With the SVM 1500A or 1500C, which offers 1 degree resolution, I use Fahrenheit for the improved precision. However, the SVM 1500B offers 0.1 degree resolution (Celsius only), so I've been using that for better control when cooking meat.

With the above settings, the 1500B stabilizes at 0.2C lower than the set point, and never budges from there. Both the SVM and the reference thermometer agree at that point.

Of course the easiest thing to do would be to simply change the set point, bu I thought I would try adding a little I value to see if I could tweak it a bit. I tried I=250, but after waiting for an hour noticed that the cooker was in the Warm position, rather than Cook. Stupid human!

As I understand it, the fact that you are showing oscillations is a strong indication that the I value is too high. I read somewhere that if that occurs, you should set the I value to one half of the cycle time in seconds. If I can read your time line correctly, the period is about 4.2 minutes, so I=125 might be a reasonable starting point to try.

But first, I would try I=0.

This assumes you are not likely to add more than 1 or 2 kg of meat to the pot, or not more than 20% of the mass of water, in which case the water itself is going to do a pretty good job of integrating over time. Now, if you were adding that much to a small 1.2 liter rice cooker, that would be a completely different story, and then you would probably need a D value, but I haven't played with that yet.

I've heard people say that the sensor should be touching the bottom of the unit, but I'm not sure I would agree. It would seem to make more sense to measure the water, rather than the bottom of the pot, which is almost surely going to be fluctuating every time it turns on or off and now you've got some crazy feedback going on.

As far as cooking short ribs and other meat such as brisket or chuck for 48 hours, I think you should wait until things stabilize, or add some cold water if necessary. The long time is to dissolve the collagen, but an hour or even a half-hour (depending on the thickness) will be enough to cook it to medium, rather than medium rare or rare.

Edited April 28, 2009 by Robert Jueneman (log)

[mtigges]

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While it does have an integrated circuit board, it is nothing more than a timer and a digital readout of the time left, or heating setting.  I'm quite certain the switch is mechanical.  I would have absolutely no qualms about pulling the cord out while the unit is set to low or hi.  It won't remember the time, but in this case I don't care.

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The absolute essential is that it remembers the heat setting - or defaults to something you can work with.

The external PID will be "pulling the plug" every couple of seconds or so ...

PS - also important is that powering on/off rapidly should NEVER confuse the "integrated circuit board" - like thinking 'time left is now zero, so I'm switching off'.

Simple is what's needed!

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There is a mechanical switch with four settings off, low, high, timer. For this application I would leave it on high. I'm fairly certain that the ICB is run off a relay to engage the display and the timer if necessary. If I unplug, and power back on while leaving that switch in either low or high it fires.

My only concern is if the cycling will damage the ICB.

[mtigges]

That's a pretty small vessel for cooking sous vide, especially with no circulator.  6 quarts is only 1.5 gallons (346 square inches) of volume.  How much do you envision cooking in there?

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Note that the smaller the vessel the lower the need for circulation.

The pot has excellent insulation properties. Astounding actually. When I make stock, I bring it to a boil on the stove, and then place the pot in the slow cookers base. The liquid continuous to boil for at least 15 seconds after turning off the flame on the stove.

I have no doubt that this vessel will have very small temperature differentials throughout the liquid. The element in the base is below the unit allowing for natural convection and it has an excellent heavy lid.

Water to food ratio in my machine would be significantly higher than at the restaurant at which we ate on Friday. I had a very good view of their set up and it never wavered more than one degree and they're almost constantly fishing out packages, and adding new ones. Not that the transgressions of others should provide rationale for me.

To answer your question about quantities of food. Not very much. My true desire is 48 hour shortribs. Probably only cooking for myself as my wife finds the waste of plastic distasteful. So I see myself cooking duck breast, small pieces of fish, beef and pork & chicken, when she plays badminton and leaves me to my own devices.

[howsmatt]

That's a pretty small vessel for cooking sous vide, especially with no circulator.  6 quarts is only 1.5 gallons (346 square inches) of volume.  How much do you envision cooking in there?

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Note that the smaller the vessel the lower the need for circulation.

The pot has excellent insulation properties. Astounding actually.

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I started my SV cooking with a similar device. The problem is exactly what you stated, too much insulation-therefore harder for the PID to adjust quickly and lose temp when it overshoots. I suspect that like me you will soon want to do a few more items and certainly larger ones. If you have to wait 48 hours for short ribs, may as well cook 2 batches and freeze one for later. I don't think you could even fit one of the american cut short ribs that I buy.

I went out and bought this http://www.blackanddeckerappliances.com/product-304.html

Cost $30 Can at walmart (although I'm sure your wife won't like walmart shopping either).

The rice cooker works great with the PID settings. I also bought an 18 quart cooker which is good too but obviously slower up and down in temp.

Best of luck.

[mtigges]

That's a pretty small vessel for cooking sous vide, especially with no circulator.  6 quarts is only 1.5 gallons (346 square inches) of volume.  How much do you envision cooking in there?

←

Note that the smaller the vessel the lower the need for circulation.

The pot has excellent insulation properties. Astounding actually.

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I started my SV cooking with a similar device. The problem is exactly what you stated, too much insulation-therefore harder for the PID to adjust quickly and lose temp when it overshoots. I suspect that like me you will soon want to do a few more items and certainly larger ones. If you have to wait 48 hours for short ribs, may as well cook 2 batches and freeze one for later. I don't think you could even fit one of the american cut short ribs that I buy.

I'm pretty sure you had your pid set incorrectly. The point of it (over a thermostat) is that it slows it's approach to target. Overshoot should not be an issue if you have it set correctly. Admittedly, it can be tricky to set well. Especially with a slow cooker whose electric elements will still contain and impart energy when switched off. This is an interesting consideration that hadn't occurred to me.

Did your unit have a printed circuit board relayed to a mechanical switch? If so did the cycling damage the electronics?

I went out and bought this  http://www.blackanddeckerappliances.com/product-304.html

The rice cooker works great with the PID settings.  I also bought an 18 quart cooker which is good too but obviously slower up and down in temp.

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28 cups to fill it to the brim? That's only one quart more (15%) in volume than mine. It's not that much difference.

The last time I braised short ribs I think I put about dozen 3" english style in there. What the hell kind of cows do you have?

[slkinsey]

Surely you don't think they started out three inches long?

A full beef short rib is more like ten inches long. Let's say an inch wide and an inch and a half thick (both measurements being on the small side of normal) and you've got fifteen cubic inches per short rib. A dozen of those equals 180 cubic inches. 28 cups is around 400 cubic inches, so that leaves only 220 cubic inches (around 15 cups) of water to regulate the heat. And this is without any forced circulation, so there are hotspot issues of concern with this food-to-water ratio as well.

[mtigges]

I don't think so. Conductively, the difference between the meat and the water is very small. The thermal sink should be nearly identical. It matters for when you're bringing the meat up to temperature for sure, but for 48 hours to melt gelatin? Irrelevant.

Regardless, as I said, I only plan to cook for myself.