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Anna N

Cooking vacuum-packed vegetables in the microwave

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Anna N   

over here weedy explained how he cooked carrots under vacuum (sous vide) in the microwave. He explained that it was a technique used by Chef Michael Voltaggio. I was fascinated and had to follow up. I found a Youtube video and attempted to replicate the results myself. Like Chef Michael I bagged the carrots with some butter, vacuum sealed the bag and put them in the microwave.I watched carefully until the bag ballooned and then turned off the microwave.

The carrots were barely this side of raw. I was not in the least surprised. I have often cooked carrots in the microwave and know that they take longer than barely 2 minutes it took for this bag to balloon. Nevertheless it obviously worked for weedy who says he cooked them for about three minutes and he was not perturbed that the bag burst.

I am still interested in solving this mystery of why it works for others and not for me.

According to the chef this can work for many vegetables. He even suggests you can use this technique to pre-cook vegetables and store them in the refrigerator until service. This requires that the bag remain intact I would think. I can see many uses for such a technique and would like to figure out how to make it work.

With a topic devoted to this subject perhaps we can continue the conversation.

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rotuts   

i have not seen the video.  is it possible that your goal is the burst bag as an end point ?

 

wonder at what pressure the bag bursts :  I micro pressure cooker for a short period of time ?

 

keeping the energy  ( water vapor ) in the bag rather than boiling off into the Micro ?

 

not such a good time here for fresh veg, but ill give it a go when I spot something

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Anna N   

i have not seen the video.  is it possible that your goal is the burst bag as an end point ?

 

wonder at what pressure the bag bursts :  I micro pressure cooker for a short period of time ?

 

keeping the energy  ( water vapor ) in the bag rather than boiling off into the Micro ?

 

not such a good time here for fresh veg, but ill give it a go when I spot something

rotuts

The video is in the original subject which I linked to. The aim is not to burst the bag but to stop just prior to that.

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cdh   

What good does a vacuum bag treatment do to the process that just sealing them in, say, a bowl under cling film doesn't do?  You're steaming them in their own steam either way...

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What good does a vacuum bag treatment do to the process that just sealing them in, say, a bowl under cling film doesn't do? You're steaming them in their own steam either way...

I was thinking the same thing.

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FeChef   

Alot of times i under cook meats sous vide. Not really under cook, but under the temp of my liking. I do this with the intention of reheating at a higher temp or in this case, to microware the frozen vacuum sealed bags. One of the benefits i found was flipping the bag every 30 seconds in the microwave for 1# prevent the bag from exploding and 2# let the meats juices hydrate the meat and prevent drying it out. Works very well, especially thin sliced roast pork.


Edited by FeChef (log)

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Anna N   

What good does a vacuum bag treatment do to the process that just sealing them in, say, a bowl under cling film doesn't do?  You're steaming them in their own steam either way...

So the point I'm trying to get across (watch the video) it's not that there are no other ways to cook vegetables in the microwave. Of course there are. But if you can cook them quickly in a sealed environment, chill them in icewater, and toss them into the fridge still in their sealed bag, then you have a very convenient ingredient at hand. Steaming them in a bowl will simply not get you the same thing.

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rotuts   

saw the vid.  very interesting.

 

if the bag expands, to just a second less than an explosion, you have a mini-pressure cooker

 

the temp in the bag at  just less than explosion would be directly related to the tensile strength of the bag

 

this has to be part of the effect id guess.  them temp however briefly has to be above 212.

 

Im also guessing the veg in question are very fresh ie natural moisture and the right diameter to relate to the

 

plastic tensile strength.  a flimsy bag   ( zip loc say ) might work very differently than a 3.5 mil or 4 mil bag

 

but its a nice thing to fiddle around with, they do state that the unbroken bag returns on cooling to its original shape

 

and volume.

 

and the chill/refrig feature keeps everything in the bag which Id guess you can reheat to serving temp

 

in hot water.

 

now to find some 'fresh' veg, not wooden winter  little logs. those probably have lost some of their

 

'native' water, so there would be less interstitial water for the microwave to heat up providing the

 

cooking energy inside the veg.

 

if this would work for me, it would dramatically change my Vegetable Eating Habits.

 

I like a lot of veg, but get quite lazy making them as a separate item.

 

these would be 'ready to go' after the chill/refrig if I could get the timing right !

 

Ill check my shots, see if they are up to date, so that I can venture into Whole Foods for a few

 

experimental items.

 

might even look into TJ's frozen case, hoping that what's in there was frozen 'fresh'

 

PS  looking at the vid again, Im guessing that the bag they used seemed fairly 'stiff'

 

ie was thicker version of an SV bag compared to Foodsaver or ZipLock


Edited by rotuts (log)

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rotuts   

rather than start a different thread, Ill ask this here, as it might be a potential component to MicroSV :

 

in the vid Im guessing the bag in question is relatively thick compared to all the various bags people use for SV.

 

Im also guessing that they used a chamber vacuum system, not a simple vacuum system.  note the circulator

 

they showed off:

 

so the question is : does anyone know if chamber vac'd veg at the low low vacuum that you can get in these machines

 

( ie boiling water at room temp ) damage the cellular structure of the veg on a cell-by-cell basis ?

 

cooking veg is really damaging the cellulose structure of the veg which makes it tender

 

unlike meat-protein cooking.

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btbyrd   

From what I've gleaned from Modernist Cuisine and Dave Arnold's discussions of the topic, there's no appreciable loss of texture when sealing root vegetables sous vide. Softer-fleshed veg can experience some damage if you hold them at vacuum for extended periods, and that's what makes compression and vacuum infusion possible. The softening that vegetables undergo through cooking is primarily a result of pectin breakdown rather than physical violence done to the cellulose.

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rotuts   

thank you very much

 

tomorrow Ill look up pectin breakdown in MC

 

any pointers to Dave Arnold's discussions would also be appreciatred.

 

thanks again.

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btbyrd   

I don't have any specific pointers to the Dave Arnold comments, because I think most of his discussion of the issue was on the Cooking Issues podcast rather than their blog. Their blog does have a really nice discussion of the effects of vacuum level on meat texture.

 

With respect to plant matter and softening, plants are largely composed of cellulose, starch, and pectin. Starches start to swell and gelatinize around 70C, and pectin starts to hydrolyze around 85C, which is why this is the magic number for SV vegetables. Cellulose is indigestible and doesn't begin to break down until it reaches much, much higher temperatures than you'd ever reach in cooking.

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ElsieD   

Great topic, Anna! I plan on getting some carrots today so I can try this. I wonder if you can do the same thing with beets or if the bag would burst before they cooked through? I guess there is only one way to find out.

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dcarch   

1. Food inside a vacuum bag is not under vacuum using a Foodsaver type of "vacuum" machine. It is just airless.

 

2. Food is subjected to vacuum inside a chamber vacuum machine. Once it is outside the machine, it is no longer under vacuum, even it is in a sealed bag.

 

3. There is very little pressure inside a hot blown up bag. Plastic is soft when it is hot.

 

4. IMHO, cooking inside a sealed "vacuum" bag in a microwave is not that much different than cooking in a container inside a microwave.

 

dcarch

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rotuts   

""  There is very little pressure inside a hot blown up bag  ""

 

likely to be true.  but it has to be more than 1 ATM.

 

too bad we don't know how much more, as a curiosity perhaps

 

thicker bag w good seal :  more pressure in the bag.

 

has to add something, 

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dcarch   

""  There is very little pressure inside a hot blown up bag  ""

 

likely to be true.  but it has to be more than 1 ATM.

 

too bad we don't know how much more, as a curiosity perhaps

 

thicker bag w good seal :  more pressure in the bag.

 

has to add something, 

 

It is very much a function of the total surface area of the bag.

 

If you use a very large bag, put it under a big truck, you can actually lift up the truck by simply blowing with your mouth. 

 

A big tractor trailer can be lifted up with a leaf blower and air ballons.

 

 

Similarly, a huge sports arena air structure is supported by only a few small fans. Very little pressure is needed.

 

dcarch


Edited by dcarch (log)

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rotuts   

Soooooooooooo, the had to use a leafblower for that truck  ...

 

seeme the LB was Cropped out

 

:biggrin:

 

would have been impressive if some guy was blowing through a staw, id say

 

:laugh:

 

more than one ATM of pressure in those Blue Bags, any way you look at it.


Edited by rotuts (log)

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dcarch   

"----more than one ATM of pressure in those Blue Bags, any way you look at it."

 

Estimating the total surface area of the balloons = 60,000 sq. in.

 

Estimating the truck weight = 60,000 lbs

 

All you need is 1 lb / sq. in. to lift the truck.

 

A pressure cooker works with 15 lb/sq. in.

 

ATM = 14 lbs/sq. in.?

 

dcarch


Edited by dcarch (log)

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cdh   

So the lesson here is that the surface area of the inflated bag is important, and that if Anna's bags are exploding, then making the bag bigger would lessen the likelihood of that happening?


Edited by cdh (log)

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rotuts   
cdh

 

excellent point.  you would need a bit more water for the steam, but i like your thinking.

 

I was thinking smaller, but will keep your ideas in mind once i find some 'fresh' carrots, you know w tops on them.

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btbyrd   

When water converts to steam, its volume increases by more than 700 times. I don't think using a bigger bag will do much to solve the problem.

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cdh   

I'll presume there is some reason that just using a water bath to cook carrots and butter in a sealed bag won't work for the intended purpose?  I know from her posts previously that Anna has at least one immersion circulator readily to hand, so is the microwave substitution just to save time and turn a hour at 180F in the bath into 2.5 minutes in the nuker? Or is there some other benefit here too? 


Edited by cdh (log)

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btbyrd   

Something that hasn't come up in this discussion is using different wattages and power settings on the microwave. It may be that Anna's carrots came out raw compared to the ones prepared by the Voltagios because her microwave was using different power settings. With the exception of broccoli, I seldom cook vegetables in the microwave but I've found that I get better results using lower power settings. My theory is that because these settings cook the vegetable more slowly, it allows the vegetable to become softer by the time it starts to give off a significant amount of steam. I occasionally use the microwave on full power to finish off SV carrots if they haven't really finished cooking in the water bath. This is a great way to compensate for timing errors if you're trying to serve SV veg a la minute.

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btbyrd   

MC@H lists their "best bets" for cooking vegetables in the microwave on p.347. All of their recipes use an 1100W microwave oven at full power. What's interesting is that their main microwaved vegetable dish, Sichuan Bok Choy, uses the same times as the recipe in the full version of Modernist Cuisine (p.3-313) but that recipe called for "full power" of 800W. There are also a number of variations in how the bok choy is packaged; there are 2 pictures of this in MC@H -- one in the recipe (which uses Ziploc bags) -- and one in the section explaining how microwaves work (which features vacuum-sealed bok choy). And in "Strategies for Using a Microwave Oven" in the full version (p.2-185) they have a picture of the bok choy on a plate under plastic wrap. So from what I can gather, it really doesn't much matter how you package food that's cooked in the microwave.


Edited by btbyrd (log)

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