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[Modernist Cuisine] Sous vide tenderizing stage and enzymatic activity


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Hi Henrik,

 

I think that you are actually talking about an optional second stage, not a first stage. If you have more than one sous vide bath, you can first cook your food for just a few seconds in a very hot bath, and then put the food in a bath just above the desired core temperature of your food. Optionally, you can put the food in a 45-50 C bath in between.

 

This optional in-between-bath does have some advantages. From page 247 of volume two: "These two enzymes are present in animal muscle. The enzymes break down the protein structures that form parts of the connective tissue within the muscle. In the live animal, their function is part of the natural cell replacement cycle that allows muscles to grow. After slaughter, the enzymatic activity drops, but does not completely stop. Calpains, in particular, continue tenderizing meat, which is why the tenderness of some cuts of beef improve with aging. When these enzymes are activated by the heat of a 45-50C bath, they go to work again, breaking down the connective protein bonds in the muscle, tenderizing it. Note that this is different from converting collagen to gelatin, though both processes have the result of producing more tender meat." You might also want to check out 3·76.

 

Hope that helps!

 

Judy

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Judy Wilson

Editorial Assistant

Modernist Cuisine

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  • 1 year later...

I guess the first very hot step is to kill surface pathogens.  At what temperatures do the enzymes break down and at what temperature are they the most active?

It's almost never bad to feed someone.

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Has anyone experimented much with this? I'm curious about the effect on flavors. I've been trying to research effects of enzymatic activity on dry aging flavor and have found surprisingly little ... most of the literature is about texture. One source I found suggests that enzyme activity at 60°C can actually encourage off-flavors in beef. But I don't know anything about the circumstances or methodology of the study.

Notes from the underbelly

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Ok, I dug a little deeper. This study finds that calpains and cathespins break down proteins into smaller peptides. This increases tenderness and "mildness" but does not increase the beefy flavors we associate with aging. However, these new peptides are then broken down into smaller free amino acids by amino peptidases, in particular ones categorized as C, H, and P. These free amino acids are the flavor bombs.

 

Another study finds alanyl and arginyl aminopeptidases (RAP) to be important flavor compound creators in dry-cured meats. I don't know if these enzymes are relevant or not to dry aging (or sous-vide "warm aging").

 

This study on dry cured ham (abstract only) found a correlation between bitterness and cathespin levels (bitterness also correlated with a lot of other factors). Lower bitterness levels correlated with higher amino peptidase levels.

 

This study (based in part on Baldwin's work) sites a food science book that found prolonged cooking at 49°C to improve tenderness significantly, but that it introduces "somewhat undesirable flavors." This would be consistent with the study above. By 55°C, many of the enzymes are inactive, but collagenase keeps doing its thing.

 

Here's what I've found, mostly by attempting to interpret biology papers that were tackling entirely unrelated questions (translation: don't trust this).

 

Aminopeptidases C, H, and P

C: maximum 40°C?
H: maximum 60-70°C?
P: maximum 80°C?

 

alanyl and arginyl aminopeptidases (RAP)
stable up to 45°C?
most active -1°C to 19°C?

 

 

Thoughts so far:

-prolonged "warm aging" at 40°C may be a better bet than 50°C, because of the off-flavors reported by a few sources, and because it's in the range where more of the aminopeptides are active.

 

Is there a biologist in the house who can comment?

Edited by paulraphael (log)

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  • 5 weeks later...

I just made SV'd short ribs for the first time, and holy wow did they exceed my expectations. I thought this was going to take a few trials to get right.

When I warm up the rest of them I'll try to take some pics.

 

The ribs are pink, juicy, and fork-tender. I didn't use a knife on them at all. the meat fell off the bone when I unbagged them, but held its shape and could be cut into little blocks.

 

The meat itself was pedestrian stuff from the local supermarket ... black canyon angus, which seems a couple of notches up from bargain basement. It was $6-something a pound in NYC.

 

I browned them lightly, packaged in ziplocks with the deglazing liquid and a bit of stock, and then blanched each bag for a minute in simmering water. Then I pre-cooked in a 40°C/104°F water bath for 3.5 hours to speed up enzymatic reactions, and then turned up to 60C/140F for the remainder of the 72 hours.

 

I made sauce from a beef coulis, which was made from ground shin meat and browned bones and mirepoix vegetables sous-vided with some beef stock, thickened with a bit of xanthan and lambda carrageenan (the stock was pressure cooked from roasted oxtail and ground shin and chuck and all the usual other stuff). The sauce had reduced red wine and shallots, porcini mushrooms, a bit of port, and thyme and rosemary.

 

I cooked pearl onions on the side, sv. with a little beef stock.

 

This is only one trial, so no way to say for sure. I think the pre-cook at 40°C does a lot of tenderizing, and may even enhance flavors. Many of the relevant enzymes become inactive above 40 or 45C.

Edited by paulraphael (log)

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I've looked at a bunch of research on this. Partly I was trying to see if anything could enhance aged flavors and not just tenderness. I found some reports that pre-cooking at 50C can produce off-flavors. This correlates with the peak activity of a tenderizing enzyme called cathespin.

 

Here's a summary of what I found. The question marks mean I had to interpret research papers that were trying to answer unrelated questions. I'm not a biologist, so please don't consider this the final word on anything.

 

Tenderizing enzymes:

 

Calpain
most active: 40°C / 104°F

 

Cathepsin
most active: 50°C / 122°F (may introduce off-flavors)

 

Collagenase
most active: 60°C / 140°F

 

Flavor-molecule producing enzymes:

 

Aminopeptidases C, H, and P
C: maximum 40°C?
H: maximum 60-70°C?
P: maximum 80°C?

 

alanyl and arginyl aminopeptidases (RAP)
stable up to 45°C?
most active -1°C to 19°C?

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Notes from the underbelly

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I've looked at a bunch of research on this. Partly I was trying to see if anything could enhance aged flavors and not just tenderness. I found some reports that pre-cooking at 50C can produce off-flavors. This correlates with the peak activity of a tenderizing enzyme called cathespin.

 

Here's a summary of what I found. The question marks mean I had to interpret research papers that were trying to answer unrelated questions. I'm not a biologist, so please don't consider this the final word on anything.

 

Tenderizing enzymes:

 

Calpain

most active: 40°C / 104°F

 

Cathepsin

most active: 50°C / 122°F (may introduce off-flavors)

 

Collagenase

most active: 60°C / 140°F

 

Flavor-molecule producing enzymes:

 

Aminopeptidases C, H, and P

C: maximum 40°C?

H: maximum 60-70°C?

P: maximum 80°C?

 

alanyl and arginyl aminopeptidases (RAP)

stable up to 45°C?

most active -1°C to 19°C?

Could you please supply the references for the above temperatures?  Were the enzymes all from mammals?

 

Some are way higher than the temperature that enzymes would function at in a living cow.

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I'm looking forward to the references, too; there's a lot of information that I'd like to get in more depth. I just reviewed the transcript of a lecture given by Dan Souza of ATK during last fall's edX course. He noted that calpains and cathepsins are particularly important enzymes in breaking down proteins, and that they're active but slow at lower temperatures (e.g. dry-aging in a refrigerator); the rate of reaction goes up with temperature until the shutoff point. In other words, they are active in living mammals but not at the rate a cook might prefer. Specifically, he said cathepsins, which break apart a range of proteins and work on collagen as well, work better as temperature rises but deactivate at 122F. The upshot of the strategy is to tenderize meat by raising its internal temperature to 115F (allowing for a 7F margin of error) and holding it there for some time, to allow the enzymes to do their work.

He mentioned calpains as the other of the two most important enzymes and noted that they work on the proteins that hold a muscle fiber in place within a particular muscle; however, I can't find in the transcript where he specified their shutoff temperature. Judging by paulraphael's information above, he may not have thought them as worthy of keeping active as the cathepsins.

Edited to add: I'm not trying to contradict paulraphael's "peak activity at 122F" statement; Souza specified it as the shutoff temperature, but I suspect rounding for convenience in one source or another. It's also possible that Souza meant 122F is the maximum temperature at which cathepsin is still active, although that isn't what he said.

Nancy Smith, aka "Smithy"
HosteG Forumsnsmith@egstaff.org

"Every day should be filled with something delicious, because life is too short not to spoil yourself. " -- Ling (with permission)

"There comes a time in every project when you have to shoot the engineer and start production." -- author unknown

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Could you please supply the references for the above temperatures?  Were the enzymes all from mammals?

 

Some are way higher than the temperature that enzymes would function at in a living cow.

 

We should keep in mind that a living cow would have no use for being tenderised or having its flavour enhanced while walking around (I was going to say 'while moooving', but restrained myself, manfully).

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Leslie Craven, aka "lesliec"
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After a good dinner one can forgive anybody, even one's own relatives ~ Oscar Wilde

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Please, I'm more than open to information that contradicts what I've posted. I've looked all over, and can find very little study on these enzymes in the food science arena.

 

There's quite a bit on the top three, and it was a couple of food science sources that reported the off-flavors from cooking at 50C (presumably from cathepsin).

 

The MC crew has recommended pre-cooking at 45C, but they don't explain their reasoning. They may just be splitting the difference between the active temperatures of calpain and cathespin. And they don't discuss the possibility of flavor development during aging.

 

The most interesting paper I found is on aminopesidases. It finds that that these enzymes break down the products of calpains and cathespins into smaller, more flavorful molecules. 

 

I found a bunch of non-food science papers on these various aminopepsidases; they give the temperature ranges I cited above. 

 

I decided to go with a pre-cook of 40°C in order to 1) reduce the potentially bad flavor products from cathespin, which is most active at 50C, and 2) to avoid overheating alanyl and arginyl aminopeptidases and aminopepsidase C, and 3) to maximize the effects of calpain.

 

This is a completely amateur hypothesis at this point. But I can say with 100% non-scientific enthusiasm that these ribs that were pre-cooked at 40°C were amazing. There was no control group (if I'd been more ambitious than hungry it would have been easy to do two groups of ribs; one with and one without the precook, and everything else equal).

 

Beware of the dangers of these precooks. The enzymes in question thrive at the same temperatures as all varieties of pathogens and spoilage bacteria. I recommend pre-searing and / or blanching in the sous-vide bag, and keeping the time in this temperature range under 4 hours.

 

I only have one circulator, so considering the time it would take to bring the water from 40C to 60C, I limited the pre-cook to 3.5 hours.

Edited by paulraphael (log)
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Notes from the underbelly

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I'm looking forward to the references, too; there's a lot of information that I'd like to get in more depth. I just reviewed the transcript of a lecture given by Dan Souza of ATK during last fall's edX course. He noted that calpains and cathepsins are particularly important enzymes in breaking down proteins, and that they're active but slow at lower temperatures (e.g. dry-aging in a refrigerator); the rate of reaction goes up with temperature until the shutoff point. In other words, they are active in living mammals but not at the rate a cook might prefer. Specifically, he said cathepsins, which break apart a range of proteins and work on collagen as well, work better as temperature rises but deactivate at 122F. The upshot of the strategy is to tenderize meat by raising its internal temperature to 115F (allowing for a 7F margin of error) and holding it there for some time, to allow the enzymes to do their work.

I'd be interested in seeing this source. One question is if the peak activity point is very close to the deactivation point.

 

In practice, even though we don't know the mechanisms with certainty, we know that pre-cooking at 45C and 50C accelerate tenderizing. This strongly suggests some kind of enzymatic active activity, because chemical breakdown of collagen is much slower in this range than at cooking temperatures.

 

One thing that's difficult with this kind of amateur research is knowing when you're oversimplifying. This google book chapter talks about cathespins as a whole family of enzymes. The ones listed are active above 50C, but I can't tell you if those are the ones we care about.

Edited by paulraphael (log)

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I'd be interested in seeing this source. One question is if the peak activity point is very close to the deactivation point.

In practice, even though we don't know the mechanisms with certainty, we know that pre-cooking at 45C and 50C accelerate tenderizing. This strongly suggests some kind of enzymatic active activity, because chemical breakdown of collagen is much slower in this range than at cooking temperatures.

With regard to the peak activity point: I haven't seen a graph, but I got the idea from the video that it's more nearly a steady rise with a very abrupt drop at the deactivation temperature. A graph would be good, wouldn't it?

I don't know whether these links will work, or for how long. I know the lecture videos were posted to YouTube, but so far I've only accessed them via login to the edX course. That said, I know they've archived the lectures and homework.

Here's a link to the ATK video on steak: https://courses.edx.org/courses/HarvardX/SPU27x/2013_Oct/courseware/d13e7aef954441bd8f2d58dc70df5518/e7c1eb5c84604d15bb130956eb5831b1/

Here's a link to the transcript: https://courses.edx.org/c4x/HarvardX/SPU27x/asset/ATK.txt

Please let me know whether these are accessible; the "https" at the beginning makes me wonder. There may be a more direct link of which I'm not yet aware.

Nancy Smith, aka "Smithy"
HosteG Forumsnsmith@egstaff.org

"Every day should be filled with something delicious, because life is too short not to spoil yourself. " -- Ling (with permission)

"There comes a time in every project when you have to shoot the engineer and start production." -- author unknown

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the text ref works fine  the video requires a log in

 

that might  be free, Ill check later.

 

many thanks for allthe above in info

Enrollment in edX is free, but that's a bit of work just to watch the video. So far I haven't found the equivalent video online, but maybe it's out there. (I'm not subscribed to ATK, so I couldn't examine all that came up in my search.) Thanks for the information that the text link works without a login.

Nancy Smith, aka "Smithy"
HosteG Forumsnsmith@egstaff.org

"Every day should be filled with something delicious, because life is too short not to spoil yourself. " -- Ling (with permission)

"There comes a time in every project when you have to shoot the engineer and start production." -- author unknown

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