977 replies to this topic

[joesan]

Maybe it was unique in the particular piece of ribeye I got but it definitely has these major seperations. I am not sure how I could explain it. Maybe I can post a picture for you to see. Do you understand what I am talking about?

Sygyzy - Perhaps these separations that you experienced were do to some over-zealous mechanical meat tenderizing. Some suppliers will mechanically puncture the tougher cuts of meat with blades (similar to the hand jaccards that many of us use) to make them more tender. If this is done over-zealously then the meat can break down into these "major separations". When done properly you wouldn't notice it at all.

[Qwerty]

I doubt anyone would attempt to mech. tenderize a ribeye steak. More than likely you just got a cut from the chuck end of the rib primal, which has many many individual muscles that are held together with layers of fat and connective tissue. The number of muscles diminishes near the loin end, so you probably just got one of the first steaks from the chuck end. Next time, specify a center cut ribeye steak and that might help.

I hope I made sense.

[Digijam]

Brisket has a lot of collagen -- that is why it is so tough if you don't braise it -- and why it takes  long time to cook even by traditional methods (it takes about 18 to 20 hrs for my smoker to get a brisket up to temp). At low temperatures like 135 and 147F, the collagen takes a lot longer to gelatinize than at higher temps (collagen breaks down a lot faster above about 170F -- I think that is about where it speeds up a lot). I have done 26, 36, and 48 hr SV brisket. At 48 hrs, the brisket at 135F was fork tender but also nice and meaty and held together -- not stringy at all. The meat was a nice bright pink, too - at 147F the meat was pinkish gray. At 26 hrs, the brisket was tasty but not as tender as I wanted. 36 hours wasn't as tender either but edible.

I suppose results will vary with the quality and marbling of the brisket. The French Laundry does theirs at 147F for 48 hrs.  But I found 147F to yield a result dryer than I hoped for.

Low and slow is definitely the way to go, although I've also had good success with salt beef brisket for 48 hours at around 152F. This was with particularly well marbled and capped brisket, though, so I wanted a good compromise between protein preservation and fat rendering. And several days of brining probably helped with the juicyness.

[MikeTMD]

I had a few questions about the brisket experiment...

At one point, there is a third muscle that is not exactly deckle and not exactly ribeye (it happens to be one of the best pieces of meat on a cow, and I'd appreciate if anyone could tell me the exact name of that torpedo shaped muscle).  So, your cut could have incorporated all three muscles with extraneous fat inbetween all of the cuts.

Thanks for any answers.

cookingkid,

You may find this interesting( and save $70 on NAMP Meat Byers Guide - LOL):


http://bovine.unl.ed...74527&crossec=H


I think you are talking about Delmonico Steak - but see for yourself, please.

JIC, here is the picture:




There are few other good references (with pictures):


http://www.inspectio.../beeboe1e.shtml

http://www.beeffoods...nfo.aspx?Code=7

Hope this helps.

Edited by MikeTMD, 08 May 2008 - 10:50 AM.

[MikeTMD]

I had a strange experience recently with SV Ribeye....

During cooking, the steak sort of split into multiple steaks. I realized after that ribeyes are probably not the best steaks to SV with. They are naturally "split" at various points. Cooking only made these splits more pronounced. I thought for a few minutes about whether or not I wanted to eat this. I was concerned about potential bacteria problems but I figured this was the same as putting steak in hot water. It's not as bad as having a bag expand while SV cooking, which would indicate bacterial growth. Right?

Any feedback would be appreciated.

sygyzy,

The results you got are not unusual, and in fact could be quite desirable, although the broken seal doesn't make for the best SV experience ( we all have seen it happened , though).

First, you could always double-bag whatever it is you are SV'ing ( in fact Heston Blumenthal recommends it for pork bellies: https://www.nespress...046_0051_en.pdf ).

Also, generally we are trying to DISSOLVE connective tissue WITHIN a muscle ( which is what makes it tender, vs. conventional cooking methods - where high cooking temps make collagen fibers SHRINK. Needless to say, all connective tissue elements, including the outer fibers that connect different muscles get the same treatment and dissolve equally. With addition of proteolytic substances ( the ones that break down proteins) , such as garlic, vinegar or alcohol, connective tissue breaks down quicker and easier - which is why we all love to marinate meat cuts before cooking.

I agree with you on the choice of cuts for SV: single muscle cuts , like eye of ribeye, flat iron steak, tenderloin, strip, brisket, hanging tender are ideal, whereas T-bone Steak, Porterhouse and Ribeye would not have the same appeal, as they would on the grill - they would simply fall apart.

Again and again, I would point out that temp control and full vacuum are essential: former to assure uniform cooking, the latter would allow low temp to do its job ( remember: a liquid in a vacuum environment has a lower boiling point than when the liquid is at atmospheric pressure, a liquid in a high pressure environment has a higher boiling point than when the liquid is at atmospheric pressure.)

Hope this helps.

Edited by MikeTMD, 08 May 2008 - 11:04 AM.

[e_monster]

I agree with you on the choice of cuts for SV: single muscle cuts , like eye of ribeye, flat iron steak, tenderloin, strip, brisket, hanging tender are ideal, whereas T-bone Steak, Porterhouse and Ribeye would not have the same appeal, as they would on the grill - they would simply fall apart.

Again and again, I would point out that temp control and full vacuum are essential: former to assure uniform cooking, the latter would allow low temp to do its job ( remember: low pressure raises boiling point of water among other things)

I disagree with Mike about the Ribeye. Ribeye can be absolutely amazing cooked sous vide and quite different from grilling if using a good cut of meat and remembering that you are only cooking to bring it up to temp--there is no reason to subject the ribeye to long cooking times -- you aren't trying to tenderize it -- you are trying to get a uniform texture -- medium rare, for instance, all the way throughy. A ribeye cooked at 130F for an hour and then seared for 20 seconds a side in a VERY hot pan is a wonderful treat. I have never had one fall apart.

Contrary to Mike's statement low pressure does not raise the boiling point. Also (as noted below) the influence of pressure on temperature isn't relevant -- because everything is at atmospheric pressure when cooking in bags:

1) Low pressure REDUCES the boiling point a liquid. It DOES NOT raise the boiling point of water. (This is also irrelevant to sous vide cooking as noted in #2). Boiling point increases with pressure which is why a pressure cooker reduces cooking times when compared to steaming at atmospheric pressure.
2) when you are cooking things that have been vacuum sealed in a bag they are not under low-pressure. They are at atmospheric pressure. They are at the same pressure they would be at if they weren't in a bag because the walls of the bag collapse as air is pumped out. (To have low pressure inside of a container, you need to have a rigid container that does not collapse when the air is pumped out.)

[MikeTMD]

A ribeye cooked at 130F for an hour and then seared for 20 seconds a side in a VERY hot pan is a wonderful treat. I have never had one fall apart.

e-monster,

I completely agree with your approach to Ribeye SV: that is exactly how I would do it. My comment was in reference to longer SV times, which is what makes it fall apart.

... when you are cooking things that have been vacuum sealed in a bag they are not under low-pressure. They are at atmospheric pressure. They are at the same pressure they would be at if they weren't in a bag because the walls of the bag collapse as air is pumped out.  (To have low pressure inside of a container, you need to have a rigid container that does not collapse when the air is pumped out.)

This is where I can't agree with you: vacuum sealed bags are BELOW atmospheric pressure, which is why they collapse when vacuum is applied.
Vacuum/low-pressure decrease boiling point - just like you said, which is exactly what we are looking for in SV applications.

Edited by MikeTMD, 08 May 2008 - 11:35 AM.

[dougal]

...
Again and again, I would point out that temp control and full vacuum are essential ...

And again and again, I've wondered just what you might be meaning by "full vacuum"...

e_monster may have misread your post regarding pressure and boiling point, BUT
- he's quite right that the pressure in a non-rigid s-v bag is going to be at atmospheric pressure (or actually just slightly above atmospheric pressure because of being submerged below the waterbath surface).
The flexible bag collapses until pressure is equalised inside and out. Being flexible, and stretchy too, the bag cannot resist the external pressure of the atmosphere. It would be different with a rigid box or bottle. But its a flexy, slightly stetchy bag. And atmospheric pressure is pretty strong about 14.5 pound pressing on every single square inch. The bag doesn't stand a chance!
- and boiling point is irrelevant to s-v cooking. (Because pressure - and so boiling point - isn't changed, as above.)

However, it does seem to be important that the bag doesn't float to the surface, and that the bag should be well collapsed around the food, so that the waterbath is in good thermal contact with the food - as far as possible on all sides.
So "well evacuated" makes sense, but "full vacuum" or even "low pressure" really don't.

"Vacuum" sealing and "sous vide" aren't scientifically correct descriptions. Just as "convection" is a pretty inaccurate description for an oven with a fan ...

Edited by dougal, 08 May 2008 - 11:52 AM.

[slkinsey]

Mike, I'm afraid you are incorrect about the items inside a vacuum sealed bag being below atmospheric presure.

Think about it: What is atmospheric pressure?

Atmospheric pressure can be simply described as approximately the hydrostatic pressure caused by the weight of the atmosphere. A more simple way of putting it is that atmospheric pressure is the combined weight of the air above us "pressing down."

If you reduce gravity, weight is reduced and atmospheric pressure goes down. When elevation increases the mass of air molecules above is reduced, and atmospheric pressure goes down. If climactic conditions create a "low pressure condition" the mass of air molecules above is reduced, and pressure goes down (the opposite is true for a "high pressure condition").

So, what happens with respect to pressure when we put a piece of beef in a bag and suck all the extra air out of the bag? Nothing, really. The mass of air molecules "pressing down" on the steak through the bag is exactly the same as the mass of air molecules "pressing down" on the steak before it was in the bag. In both conditions, the steak is under regular atmospheric pressure.

If we would like for the steak to be under reduced pressure, we must put the steak into a rigid container and evacuate the air from the rigid container. At this point, the mass of air molecules "pressing down" on the steak is very small, and the steak is under less-than-atmospheric pressure.

Another way to think about it is this: Suppose you took the steak in the vacuum-sealed bag and put it at the bottom of the ocean. Would the steak be at low pressure or high pressure? Now, suppose you took the steak in the vacuum-evacuated rigid container and put it at the bottom of the ocean. Would that steak be at low pressure or high pressure? (Answer: steak #1 = high pressure; steak #2 = low pressure.)

[MikeTMD]

And again and again, I've wondered just what you might be meaning by "full vacuum"... 

The flexible bag collapses until pressure is equalised inside and out. Being flexible, and stretchy too, the bag cannot resist the external pressure of the atmosphere. It would be different with a rigid box or bottle. But its a flexy, slightly stetchy bag. And atmospheric pressure is pretty strong about 14.5 pound pressing on every single square inch. The bag doesn't stand a chance!

My dearest dougal,

Full vacuum, just like absolute zero temps are impossible, although we try to approach them as much as we could - and I completely agree with you about that.

When the pressure outside the bag and inside the bag are equal - the bag wouldn't collapse ( just like when gravity and lift are equal an object would be in flight), when the pressure inside the bag is approaching zero - the bag inevitable collapses (it's not cooking - it's physics, really). Would you agree with me on that?

- and boiling point is irrelevant to s-v cooking. (Because pressure - and so boiling point - isn't changed, as above.)

I'll get back to you on that tonight, OK?

[pounce]

I thought we already beat this one to death up thread...

http://forums.egulle...dpost&p=1524333

[slkinsey]

When the pressure outside the bag and inside the bag are equal - the bag wouldn't collapse ( just like when gravity and lift are equal an object would be in flight), when the pressure inside the bag is approaching zero - the bag inevitable collapses (it's not cooking - it's physics, really). Would you agree with me on that?

The bag only collapses because there is a temporary pressure disequilibrium. Once the bag collapses (which happens almost instantly), the inside and outside of the bag are in pressure equilibrium. This is only relevant with respect to a chamber sealer. For edge-sealer type machines, the inside and outside are always at pressure equilibrium.

Perhaps these graphics can explain.

Here is a piece of meat inside of a bag. The bag is full of air. You can see by the air molecules that the inside and outside of the bag are at pressure equilibrium and the meat is under regular atmospheric pressure.

Now we have sucked most of the air out of the bag in a chamber vacuum and sealed the bag. The graphic below shows the conditions right after the chamber is opened. As you can see, the inside of the bag is at lower pressure than the outside of the bag (illustrated by showing that there are far fewer air molecules per square inch inside the bag compared to outside the bag). There is pressure disequilibrium, and the meat is not under regular atmospheric pressure (note that the pressure arrow is not touching the meat).

A split second later, the flexible bag material has responded to the pressure disequilibrium by bending under the atmospheric pressure. As a result, the bag is much smaller now, and close to the exterior of the meat. The external atmospheric pressure will continue to crush the bag material towards the meat until such time as the inside of the bag and the outside of the bag are at pressure equilibrium (illustrated by showing that the number of air molecules per square inch are the same inside and outside the bag). The meat inside the bag is now at regular atmospheric pressure.

What if you remove 100% of the air from the bag? Well, much the same thing happens. You go from this situation when the chamber is opened:

To this situation a split second later:

The only difference is that there is a small amount of air remaining in the bag in the first example, and no air remaining in the bag in the second example. In both cases, the steak is under regular atmospheric pressure once the bag collapses.


The only way to have the steak under low pressure after the chamber is opened is to have the steak inside a rigid container. If the walls of the chamber cannot contract, then there can be no pressure equilibrium and the steak will remain under lower pressure. You end up with this situation:

[smashz]

I currently smoke a brisket for a beef duo on the menu, but I haven't thought about the sous vide idea for it.  In other words, I just smoke until it's done.  Anyway, what would the optimal cooking temperature be for the sv of a brisket?  It is not a collagen rich cut, as far as I'm concerned, so would you do like e_monster recommends and go for a lower temperature, but not as long of a time, like maybe for 18 to 20 hours?  In other words, why such extended water time?  What is the benefit of 48 hours, or another way of putting it, what is the gastronomic difference between the brisket at 24 hours and 48 hours?  Is is just to be on the safe side?  By the way, I'm thinking of a brisket flat or some call it brisket nose off.

As several people have slipped in ahead of this, brisket is collagen rich; that's why it makes such a magical transformation when smoking or braising.

I was looking for several basic things in the experiment:
- Is a 2-hour smoke then SV enough to impart smoke flavor? YES
- Is the SV result better than the smoked result under set conditions? YES
- Do the conditions chosen give great results? NO. (But certainly not terrible)

I chose WAG conditions with the reasoning that because brisket is tough and benefits from long and low, but the lower temperatures for a better cut of meat did not feel right, I'd need to go higher. Thus, 146F. Why 48 hrs? It seemed long enough. But, given the result (tougher and drier than I'd like, more gray than pink) and comments, I suspect that it was high enough to contract the muscle (squeezing out too much water), negating the benefits of collagen breakdown. So, as mentioned above by several posters, I'll try it again at a lower temperature, probably for 2 or 3 different times.

[sygyzy]

sygyzy,

The results you got are not unusual, and in fact could be quite desirable, although the broken seal doesn't make for the best SV experience ( we all have seen it happened , though).

Does anyone know why this happens? I know Food Saver says you can put their bags in boiling water so the 130-140 F water shouldn't have mattered.

[e_monster]

I have used the FoodSaver hundreds of times and have never had a good seal break BUT it is possible to create a less than optimal seal if you aren't paying close attention and either get the area where the seal will be too wet OR have a tiny tiny little wrinkle that keeps the bag from being sealed well. I think if you inspect the seal after it is done, you won't have any problems.

When vac-packing moist foods, it is possible to have an improperly sealed bag without realizing it. It is also possible to have a little wrinkle that interferes with sealing. A few weeks ago, I was a little careless and vac-packed a porkloin with a wee bit of marinade. The seal seemed fine (i.e. the bag shrunk down and didn't expand when the FoodSaver was opened. I put the bag in the fridge and when I took it out half an hour later, the bag was no longer tight around the food. Upon close inspection, there was a small area where the bag had not really sealed well. It was pretty obvious when I looked at it.

sygyzy,

The results you got are not unusual, and in fact could be quite desirable, although the broken seal doesn't make for the best SV experience ( we all have seen it happened , though).

Does anyone know why this happens? I know Food Saver says you can put their bags in boiling water so the 130-140 F water shouldn't have mattered.

[MikeTMD]

- and boiling point is irrelevant to s-v cooking. (Because pressure - and so boiling point - isn't changed, as above.)

OK, I just want to get done with this issue.

Vacuum in SV is needed for the following reasons:

1. To remove oxygen, and as such to prevent change in color, tast, smell, texture and taste caused by oxygenation.

2. To preserve shape of a "substrate" inside a SV bag - pressure INSIDE the bag is approaching zero, pressure ON the bag is full atmospheric pressure.

3. To prevent evaporation/loss, and as such product shrinkage - important because boiling point of water is lower under vacuum/near vacuum conditions.

There are some other secondary considerations as well.

For anyone still in doubt I would recommend to check "Sous-Vide"by Roca and Bregues, or wait for "Under Pressure" to pop-up at Barnes&Nobles.

Edited by MikeTMD, 09 May 2008 - 03:02 PM.

[pounce]

Since it seems like you are getting your info from the books you own could you cite the page references?

[MikeTMD]

More practical application:

I cooked Hanging Tenders at 64C, for 90 minutes.

I used an immersion circulator and Cryovac sealed tenders:



Meat was very tender, and retained a slight "gamey" taste:



Finished in clarified butter, with salt and spices - temp/time settings would be applicable for any medium-rare single muscle application, in my opinion.

This is what the final dish looked like:

Edited by MikeTMD, 09 May 2008 - 09:53 AM.

[e_monster]

2. To preserve shape of a "substrate" inside a SV bag - pressure INSIDE the bag is approaching zero, pressure ON the bag is full atmospheric pressure.

Hi Mike,

I am fairly certain that your assertion about the pressure is mistaken.

As long as the bag is exposed to atmospheric pressure, the pressure is the same inside and outside the bag. If the bag is exposed to atmospheric pressure, the contents are at atmospheric pressure. It is that simple. If you were dealing with a rigid container, the inside and outside would be at different pressures. But that isn't the case.

If you have a cookbook that says otherwise, then the author is mistaken. Perhaps you are mis-reading the text.

--e

Edited by e_monster, 09 May 2008 - 03:53 PM.

[ChefCrash]

As long as the bag is exposed to atmospheric pressure, the pressure is the same inside and outside the bag. If the bag is exposed to atmospheric pressure, the contents are at atmospheric pressure. It is that simple. If you were dealing with a rigid container, the inside and outside would be at different pressures. But that isn't the case.

May we entertain the idea that cellular structures (along with veins and capillaries) of proteins and vegetation, are semi rigid (elastic)?

[slkinsey]

There are effects that are possible only with machines that can pull high inches of mercury. But they're not the effects that you're generally talking about. Having a super-strong vacuum machine is really not so important once you're actually cooking the food in the water bath. Rather, the interesting things that a strong machine are things like pressure "cooking" tender greens, compressing vegetables and fruits, sucking the air out of certain vegetables and fruits so that they "vacuum infuse" a liquid once the pressure is released, etc.

1. To remove oxygen, and as such to prevent change in color, tast, smell, texture and taste caused by oxygenation.

This can be important for long cooking times. However, the bar is significantly lower than "total vacuum." Semipro bag sealers such as these can pull 28 inches of mercury, which is more than enough if you're concerned about oxidation. Air is only around 20% oxygen by volume. I wouldn't recommend cooking short ribs for 48 hours inside of a ziplock bag. But even a cheap FoodSaver whould be able to reduce the air in the bag to less than 3 to 5 cubic centimeters (this is a worst-case scenario). That's simply not enough oxygen to make a huge difference.

2. To preserve shape of a "substrate" inside a SV bag - pressure INSIDE the bag is approaching zero, pressure ON the bag is full atmospheric pressure.

Mike, you still misunderstand. So long as the bag is able to shrink to the point at which the inside of the bag and the outside of the bag are at pressure equilibrium (which will happen 100% of the time under normal conditions), the pressure inside the bag is normal atmospheric pressure. In actuality, once it goes into the water bath, the contents of the bag are under slightly higher than normal atmospheric pressure due to the weight of the water above the bag.

As for preserving the shape of the food that is bring cooked, it is necessary to pull a reasonably strong vacuum before the bag is sealed, but nothing beyond the capabilities of a FoodSaver. Before I got my current semiprofessional bag sealer, I was able to do things like deboning and rolling up salmon steaks into a puck-shaped "salmon fillet mignon" -- and never had any difficulties with anything keeping its shape.

3. To prevent evaporation/loss, and as such product shrinkage - important because boiling point of water is lower under vacuum/near vacuum conditions.

This statement reflects several misunderstandings on your part.

First, as I explained at a level I think would be understandable to a seventh-graded, the contents of the bag are not under lower pressure once the bag collapses. This happens instantly when the chamber is opened, or simultaneously with the air being evacuated from the bag when it is an edge-sealer machine.

Second, as a result of the fact that the contents of the bag are not under less than 14.7 pounds per square inch of pressure ("normal" sea-level atmospheric pressure). But, let's say that it is under less than 14.7 PSI. How low do you suppose the pressure would have to be in order for the boiling point of water to be lowered to a temperature that would be significant to us? For the most part, we're cooking in the neighborhood of 60C. Water boils at 60.8C when it is at 3 PSI. Simple physics suggests that there is no way a steak inside of a collapsed bag and submerged under several inches of water is anywhere near as low as 3 PSI.

Third, evaporation is not a significant issue when one is cooking in a closed bag significantly under the boiling point of water. Other factors, such as water loss due to contraction of muscle fibers, etc. are the primary reasons for water loss in sous vide cooking.

Edited by slkinsey, 10 May 2008 - 09:20 AM.

[slkinsey]

As long as the bag is exposed to atmospheric pressure, the pressure is the same inside and outside the bag. If the bag is exposed to atmospheric pressure, the contents are at atmospheric pressure. It is that simple. If you were dealing with a rigid container, the inside and outside would be at different pressures. But that isn't the case.

May we entertain the idea that cellular structures (along with veins and capillaries) of proteins and vegetation, are semi rigid (elastic)?

That would only be germane to this fork of the discussion if one were somehow able to lower the pressure inside the cells, veins and capillaries only, such that the walls of the cells, veins and capillaries represented the boundary between higher pressure on the outside and lower pressure on the inside without collapsing.

As others have pointed out, the only way to have the food under less than 14.7 PSI is to put the food inside a rigid container and lower the pressure inside the container. In this case, following your idea that the cellular structures (along with veins and capillaries) of proteins and vegetation are semi rigid and thus somehow able to maintain pressure disequilibrium, the pressure inside these cells and inside these veins and capillaries would be higher than the pressure inside the chamber.

[MikeTMD]

make sure you know what you're talking about before you start telling people to seek out a seventh-grate physics text book. I've got access to several of the most important physicists and physical chemists of the latter half of the 20th century.  If you like, I could put the question to them and post their answers here. . .

slkinsey, thank you for your reply and input, among many other things it cools things down a bit.

Later today I would post references to support the statements I made above, and hopefully put this issue to rest. The physics and mechanics of SV process are important, although personally I am more interested in practical applications, such as temp/time, taste/texture experiences, etc. After all, this is a epicurean blog, although I am sure physicists have at least one of their own. :-)

Edited by MikeTMD, 09 May 2008 - 03:05 PM.

[slkinsey]

Mike, we're happy to have you share your experiences, and especially for you to share whatever you may have gleaned from books. But when you're making statements that are based on, e.g., Juan Roca's book -- especially statements which a reasonably informed person might hold to be incorrect from a scientific standpoint -- perhaps it would help to give context to your assertions if you would post the passages on which your assertions are based. This way other participants here can have some basis either to understand or critique your basis for making those assertions.

The deal about pressure inside the bag once the bag has been sealed and collapsed, I believe must be based on a simple misunderstanding on your part. Perhaps this based on something you read in one of these books -- we have no way of knowing if you don't post the basis of your assertions and simply continue to assert that you are correct and everyone else is wrong.

My own academic background is not as important in this case as the academic background of the parents who raised me. Both are chemists and my father is a noted physical chemist (member of the National Academy, festscrift edition of the Journal of Physical Chemistry, etc.) So not only did I literally grow up hearing about many of these basic principles (and really, the stuff we're discussing here is quite elementary) but I have a good basis for educating myself as to the topics that interest me and, perhaps most importantly, can count any number of famous scientists among family friends I could potentially ask to explain these things. My experience, however, is that things like this are at a basic-enough level that a simple query to a parent for support of my understanding or further explanation is sufficient.

Edited by slkinsey, 10 May 2008 - 10:11 AM.

[MikeTMD]

Since it seems like you are getting your info from the books you own could you cite the page references?

Absolutely. The following references are from "Sous-vide Cuisine", Joan Roca/Salvador Brugués, Montagud Editores S.A.

Original title: La Cocina al Vacio
First published in 2003 by Montagud Editores, S.A.
©Third English edition: Montagud Editores, S.A. 2007

©Joan Roca and Salvador Brugués
©Francesc Guillamet
©Michael Debbane
©Montagud Editores, S.A.

Copyright Registration: B-26942-2007
ISBN: 978-84-7212-112-6

Chapter 3. Sous-vide Cooking , p.51

“We can broadly define cooking sous-vide as heating the food previously sealed in an airtight and heat-resistant container whose atmosphere has been modified ( a vacuum has been produced,, with or without elements such as gases, liquids, etc.).”

Chapter 3. Sous-vide Cooking , p.76

“ In the vacuum, the atmospheric pressure acting on the packaged product causes the water to vaporize before it would in the conventional cooking, in which pressure does not have as great of an impact on the final result (this means that the food will experience the effects of water vaporization at lower temperatures, along with all consequent modifications). This is therefore a very important fact that distinguishes sous-vide cooking from traditional methods.”

“ Pressure is one of the fundamental principles on which sous-vide is based, since it what allows a vacuum-sealed product to cook at low temperatures. Nonetheless, it remains a subject seldom studied by cooks-even though they have an inkling of its vast possibilities, the still don’t use it as a fundamental principle when cooking or intentionally seeking positive alteration of foods.”

Chapter 3, Sous-vide Cooking/ Technical Fundamentals p.84

“Our aim is to discover the why and how of the sous-vide cooking system through the analysis of the following parameters:
- Oxygen-free atmosphere
- Airtight containers and effect on pressure
- The time/temperature relationship

THE OXYGEN-FREE ATMOSPHERE
In this section we study a factor that plays a crucial role in cooking foods and, as a result, in their final quality… One of these potential alterations, … ,is oxidation, a reaction that occurs when oxygen bonds with other elements in food. Let us remember that these alterations manifest themselves in changes in color, odor, flavor, in its organic properties, etc.

When we cook sous-vide, and thus without oxygen, we prevent these reactions.4
… Another area affect by a lack of oxygen is enzymatic reactions, because the enzymes’ behavior is inhibited."

Bottom of the page, left corner, light grey font:

“4. The majority of food reactions are hydrolysis or oxidation; therefore, these reactions must be slowed to preserve or improve preparations. One way of doing this is to eliminate one of the reactants ( in this case oxygen).”

Chapter 3, Sous-vide Cooking/ Technical Fundamentals p.85

“AIRTIGHT CONTAINERS AND THE EFFECTS OF PRESSURE
COOKING SOUS-VIDE WITH THE EFFECT OF PRESSURE

Pressure has a fundamental effect on foods and provides a series of advantages in preparation that would be difficult to attain by traditional methods. The bag in this case acts as a second skin or direct protection for the ingredient ( especially in the case of shrink bags) and subjects it to constant pressure.

The main functions of the airtight containers are:
1. To support or hold the ingredient’s natural structure so that it does not break apart (e.g., foie gras).
2. To exert equal pressure over the entire surface of the ingredient. This evens out the cooking time for many ingredients (e.g., asparagus).
3. To prevent changes in weight from the ingredient drying out during cooking, thanks to the airtight container and the use of low temperatures.
4. To stop aromas from volatilizing, thereby enriching the preparation. The container helps to lock in the ingredient’s natural flavors; in fact, it serves the purpose of closing pores. This also occurs in cooking by concentration, but here there is no need to apply high temperatures that could denature or alter the ingredient’s initial flavor.”

“Sealing in shrink bags: guaranteed pressure” (highlighted in grey, upper left corner ,p.85)

“ All vacuum-packaged foods are subject to exterior pressure due to the absence of air in the bag. Sous-vide preparation sometimes requires the product to remain under pressure during the cooking process. Certain ingredients subjected to high temperatures during sous-vide cooking do release water vapor due to the heating of their own water.6 The bag then undergoes some interior pressure, causing it to lose some of the effect we are looking for.”

Middle of the page, footnote, highlighted in grey:

”6. In sous-vide conditions, water vapor forms at much lower temperatures than in normal atmospheric pressure conditions.”

I don’t know if a definition of vacuum is even needed at this point, but according to The American Heritage® Dictionary of the English Language (Fourth Edition copyright ©2000 by Houghton Mifflin Company. Updated in 2003. Published by Houghton Mifflin Company. All rights reserved.):

vac•u•um (v k y - m, -y m, -y m)
n. pl. vac•u•ums or vac•u•a (-y - )
1.
a. Absence of matter.
b. A space empty of matter.
c. A space relatively empty of matter.
d. A space in which the pressure is significantly lower than atmospheric pressure.

I hope this answers most of the questions we have discussed this week.

Edited by MikeTMD, 10 May 2008 - 08:35 AM.

[Qwerty]

OK, I apologize for asking this question, but I don't think I have the inclination to read all 60+ pages of this topic for an answer...

Has someone compiled a table/chart of time/temps. I'm not really looking for a table that charts the bath temp. and then states how long the heat will take to penetrate the various thickness of the proteins...I'm looking for something along the lines of a compiled table of recommended time/temps for various proteins and veg. For example, chicken breast @ 147F for 2 hrs, salmon at 135F for 1 hour, etc, eggs at 140 for 3 hours. Maybe some info on times to effectively kill bacteria (like, chicken is OK at 148F, but you have to cook it for 4 hours to kill the germs).

I understand that a lot of the results are subjective, and of course some people want steak cooked at higher temps, etc. I am about to pursue in earnest setting up a home sous vide setup and would like some starting points.

I'm not asking anyone to compile a list for me, but if one exists out there or in the thread that would be great.

Thanks guys.

[mhkhung]

So I made Sous Vide (the first time) chicken last Saturday to serve my guests in one of the dinner courses. 1 piece of breast and 1 piece of leg in 61C bath for about 3 hours (basically started cooking at 4 and serve straight for the course at around 7).

The chicken is "perfect". Good enough that I forgot I made a sauce for it.. :)

But, over the discussion, we figured what's wrong with Sous Vide cooking.. (My guests and us have both ate at a number of restaurants that use Sous Vide.. including the FL)

Our conclusion is that the food cooked in Sous Vide lacks "passion". It doesn't vary depends on the weather of day, the difference in the heat of the stove and the skill/execution of the chefs.

At the end of the day, it's like food mass produced from a factory..

- M

[Quiltguy]

OK, I apologize for asking this question, but I don't think I have the inclination to read all 60+ pages of this topic for an answer...

Has someone compiled a table/chart of time/temps.

A Short Guide to Sous-Vide Cooking

Edited by Quiltguy, 10 May 2008 - 06:23 AM.

[slkinsey]

Hi Mike. Thanks for posting the quotes from Roca. I can see how some of that stuff may be confusing.

Some quick thoughts below...

As to the stuff on Page 76: I believe Roca must be talking about cooking food in a rigid container rather than a flexible container. As I and others have mentioned, it is possible to go under 14.7 psi in a rigid container -- it's just not possible in a container as flexible as a bag, because the container deforms until there is pressure equilibrium.

As to the stuff on Page 84: Roca is correct that removing most of the oxygen can have an important effect. However, we should understand that even if we remove all the air from the bag, we have not removed all the oxygen from the cooking environment -- there is still oxygen in the meat itself. So the question is not whether we have removed all of the oxygen, because this is impossible. The question is how much oxygen we have removed. When we are considering vacuum machines of different strengths, there is a question as to whether the difference in the oxygen removed is large enough to make a significant difference on a chemical basis. My strong suspicion is that, so long as the vacuum machine is reasonably strong (say >25" Hg), there is not going to be a significant difference. More on this later.

As to the stuff on Page 85: No one disagrees that sous vide bags support the ingredient's structure, help to exert equal pressure over the entire surface of the ingredient, help to prevent drying due to moisture loss (also significantly due to cooking at lower temperatures) and help to prevent aroma/flavor loss due to volatization.

The question is how strong the vacuum machine has to be in order to accomplish these things. Certainly, a stronger machine may create a situation in which the bag material presses against the food more evenly, but this doesn't necessarily argue for a zillion dollar machine. As I have pointed out, I've been able to compress and support salmon steaks rolled up into a "salmon fillet mignon" very well with a run of the mill FoodSaver. For sure there are likely some effects that would be done better with a stronger machine (e.g., an extremely delicate food that does not want to cohere).

Please take note: As you can see in the passages you quoted, when Roca talks about pressure, he is talking about the bag pressing on the food inside. This directly contradicts your earlier assertions that the contents of the bag are under less-than-normal pressure. Indeed, physics tells us that the bag is pressing inwards on the food with exactly the same force that is being applied externally on the bag. In this case, it is 14.7 psi when the bag is not in the water bath (normal atmospheric pressure), and slightly more than 14.7 psi when the bag is in the water bath (where pressure is higher due to the weight of the water).

As to the "highlighted in gray" material on Page 85: This is true if the food is inside a rigid container. If it is in a bag, it is not true.



I have a proposal: Let's come up with a series of questions about pressure and oxidation reactions as they apply to sous vide cooking. We'll agree on a list of questions, and I will send them to this guy, who I hope we can agree has a level of expertise that should provide for a definitive resolution to these questions. He is familiar with sous vide cooking, having had several examples prepared by me.

Here are a few questions I propose:

1. A piece of steak is sealed inside an impermeable flexible plastic bag in a zero-atmosphere environment. The bag is exposed to normal atmospheric pressure, and the bag deforms to tightly cover the meat. Is the meat now under (1) normal atmospheric pressure; or (2) less than normal atmospheric pressure?

2. Let's suppose that the bag is sealed inside an environment that is somewhat less than zero-atmosphere. Let's say that the machine is capable of 25" Hg, so there is a tiny bit of air left inside the bag. Is this difference likely to have any significant effect as to oxidation reactions when the food is cooked at 60C?

[MikeTMD]

As to the stuff on Page 76:  I believe Roca must be talking about cooking food in a rigid container rather than a flexible container.  As I and others have mentioned, it is possible to go under 14.7 psi in a rigid container -- it's just not possible in a container as flexible as a bag, because the container deforms until there is pressure equilibrium.

Although R&B mention rigid containers in the book (specifically - jars), virtually all of their SV cooking ( "direct" and "indirect", according to their classification) is done in various types of flexible bags, and as such, those containers are the primary subject of their research and conclusions.

As to the stuff on Page 85:  No one disagrees that sous vide bags support the
ingredient's structure, help to exert equal pressure over the entire surface of the ingredient, help to prevent drying due to moisture loss (also significantly due to cooking at lower temperatures) and help to prevent aroma/flavor loss due to volatization.

There was some heavy criticism of the points above, which is why I had to quote this particular paragraph.

...As you can see in the passages you quoted, when Roca talks about pressure, he is talking about the bag pressing on the food inside.  This directly contradicts your earlier assertions that the contents of the bag are under less-than-normal pressure. 

The contents of the bag are under vacuum, which is by definition less than atmospheric pressure.

As to the "highlighted in gray" material on Page 85: This is true if the food is inside a rigid container.  If it is in a bag, it is not true.

R&B are quite clear on this one - the title of the highlighted text box is “Sealing in shrink bags: guaranteed pressure”.


The theory of SV is interesting and important, indeed. Personally, I would like to concentrate on SV recipes, techniques and experiences, at this time.

Edited by MikeTMD, 10 May 2008 - 12:32 PM.