Comments on: Boring but useful technical post: vacuum machines affect the texture of your meat. The International Culinary Center's Tech 'N Stuff Blog Thu, 09 Jan 2014 18:17:16 +0000 hourly 1 By: davearnold Tue, 10 May 2011 03:27:04 +0000 Howdy Robert,
Interesting test. I have run the vac test many times –It is part of the sous-vide low-temperature class we teach at the FCI. We almost always get the same vacuum effects time after time. I wonder if your cooking times are so long that they are masking the effect (which would be interesting). In tests we ran for cooking turkey ( longer cooking times tend to approximate the effect we see at high vacuums. Those pieces of chicken should cook relatively quickly –on the order of 20-30 minutes. Thoughts?

By: RobertJueneman Sat, 07 May 2011 13:48:43 +0000 Hi, Dave,

I finally got around to repeating the same tests that blackp conducted, with essentially the same results:

I purchased a tray of “chicken tenders” (cut from a chicken breast to a remarkably uniform size). I then weighed and cut each one to be as close to 50 grams as my scale would allow (+ or – one gram, or 2% accuracy).

One was vacuum packed at 99.9% + 30 seconds. Another was vacuum packed at 99.9+30, then opened and repacked at 70%. A third was packed at 95%, and a fourth at 80%.

All four were cooked SV for 2 hours at 63C, immediately afterwards.

After cooking them, I opened and weighed each piece. Each weighed 46g, except for the one which was packed at 99.9% + 30 seconds, which weighed 44g.

I didn’t bother to photograph the pieces, because I couldn’t detect any visible differences at all.

As far as the organoleptic quality (taste, smell, visual appearance, mouth feel), I couldn’t tell any significant difference. To the extent that there was any, the piece that was vacuum packed at 99.9+30 tasted somewhat less dry and more juicy than the others, despite the fact that it lost 2g more in juice! Go figure!

My wife ate the remains of the test in an chicken sandwich, and liked it. I also cooked the rest of the package, put it in an ice bath until dinner, then grilled it on on my cast iron plancha and made a grilled chicken Caesar salad with roasted caperberries. Quite good!

As a result, I have to say that n my experience, at least for very short vacuum times, there doesn’t seem to be any significant difference between the different vacuum levels, and if anything, the higher vacuum settings seems to work as well or better, regardless of which way the water swirls going down the drain.

Now, would things change if we packed the same chicken pieces in the same different vacuum levels, and then froze them for say a couple of months in that condition? TBD — more research is required.

But somehow, your results and ours don’t agree with each other, and it isn’t yet obvious why.

On the CO2 issue, I’m seriously thinking about buying the gas fill adapter for my minipack MSV-31X, but I would welcome any comments from anyone about long-term taste effects.

By: PedroG Sun, 01 May 2011 01:02:23 +0000 I mean squeezing as much air as possible out of the bag to be sealed in the chamber sealer by placing it between two sealed bags of water acting as cushions, thus reducing the residual air volume when sealing at 80% vacuum.

By: davearnold Sun, 01 May 2011 00:03:43 +0000 What gel system are you using? Alginate? If so, which one and at what percentage. What calcium are you using and at what percentage?

By: davearnold Sun, 01 May 2011 00:01:19 +0000 You mean instead of sealing underwater?

By: davearnold Sat, 30 Apr 2011 17:18:11 +0000 I’d mainly agree. Ziploc and water is the easiest for me. I wish i had a sealer that could work underwater.

By: PedroG Fri, 29 Apr 2011 09:34:52 +0000 Just another idea:
Use a sealed bag of water to weigh down the bag to be sealed and eventually a second sealed bag of water below the bag to be sealed, thus displacing as much air as possible out of the bag before sealing.

By: PedroG Wed, 27 Apr 2011 08:41:43 +0000 The vacuum level dilemma with chamber sealers for sous vide cooking:

Edge sealers suck all air out of the bag before sealing, tightly fitting the bag to the food; so even with low vacuum levels, there is virtually no air left in the bag, except for some surface irregularities of the food to which the plastic may not have been snugly fitted. Maximum vacuum levels achieved by edge sealers (80-90%) will not damage food by cold boiling and/or compression.

In contrast, chamber sealers suck the air out of the bag and its surrounding, then seal, and the bag will only be fitted tightly to the food after releasing the vacuum from the chamber. To fit the bag snugly to the food, vacuum levels of 99% to 99.9% are applied. These vacuum levels may damage delicate food like fish or poultry. Reducing the vacuum level in a chamber sealer to e.g. 80% may leave some air in the bag causing floating and poor heat transmission: if the initial air volume between food and bag was e.g. 200ml, after sealing in an 80% vacuum there will be 40ml of air (that’s a jigger!) left in the bag.

If there is no edge sealer at hand for sealing delicate food, a Ziploc bag may be preferable to the chamber sealer. Another solution might be to weigh down the bag within the vacuum chamber with a rectangle cut out of a stab protection apron, so it fits as snugly as possible to the food before sealing and releasing the vacuum.

By: richard Mon, 25 Apr 2011 01:23:08 +0000 hi dave I need help on different subject. Im trying to make a spherical margarita .Utilizing reverse spherification was wondering if u had done it before or new someone who could help me out. i keep getting too thin a membrane around the gel or if not i get too thick a membrane. any help or info would be greatly appreciated

By: davearnold Fri, 22 Apr 2011 17:32:21 +0000 Hello Robert,

“The conventional wisdom is that once you release the vacuum, the air pressure on the exterior of the bag neutralizes whatever vacuum might exist inside the bag. I’m not nearly so sure. Obviously in the case of watermelon, there is a considerable compression effect, and although meat doesn’t have vacuoles like plants do, the sudden shock (for those of us without a soft air release) might at the very least cause some bruising.”

I believe this is essentially correct. Meat, with the exception of blood vessels/capillaries/interstitial spaces acts pretty much like an incompressible solid and after any initial damage or shock cause by the bag hitting/deforming the food seems unaffected. In fact, this “lack of effect” is the principle behind the repeated vacuuming of fruits when doing texture modification. The first time the bag hits the fruit the evacuated voids near the surface of the fruit are compressed. The next time you vacuum the fruit and let the bag hit again, those previously compressed voids are incompressible and the next layer of voids is compressed…and so on.

“In addition, if subcutaneous boiling takes place during the vacuum stage, it might cause some of the cells to rupture, setting the stage for future leakage. Then, I believe, when the food is raised to cooking temperature while still in the bag and in an evacuated state, more leakage will occur.”

I believe this is also essentially correct. Although any rupturing should cause leakage whether or not the food remains in the bag. The effect is similar to cell rupture caused by repeated freeze-thaw cycles.

“One way to resolve this might be to decrease the vacuum to the point where water would not boil, even at the cooking temperature. At 60C, that would only be 70%, at least for water. What the boiling point is for meat juices is yet another question that would need to be resolved. I am assuming the boiling point is raised, but I don’t know that for a fact.”

I do not believe this is true. Once the bag has equilibrated with environment, the food essentially feels no force –there is no boiling in the bag. The only exception is when foods containing internal uncrushed voids are heated, but the amount of water vapor (from boiling/evaporation) that would be required to bring the partial pressure of water in the bag up to atmospheric would be miniscule.

“And if all this weren’t difficult enough, there is the question of whether introducing say 20% CO2 after the vacuum process would help the long term storage issues.”

it would certainly enhance microbial safety. You would have to evacuate the bag prior to cooking. I’d be worried there might be some residual taste.

For me the real question is: why does the level of vacuum something is cooked under inherently affect the texture of the meat? I don’t believe it has anything to do with cell rupture/boiling (that isn’t inherent… it is temperature dependent –although the effect of texture destruction due to vacuum boiling is something I sincerely believe in). I am willing to be proven wrong on the temperature thing, but remain unconvinced.