Problem sealing liquids in chamber vac machine...

[hotponyshoes]

Hi,

New guy here so I am hoping I have put this in the correct place!

I will pop a post in 'introductions' in a bit to give the full history but a quick intro is:

 

I have been trying out sousvide with the ziploc/water displacement method then cooking in a large cast pot on an induction hob with a diy PID controller. Was working ok but I wanted better results. So, I have upgraded to a 30litre stirred lab bath and a commercial chamber vac packng machine. I ordered a selection of vac bags which arrived yesterday so I spent the evening messing about.

 

I first bagged a steak (bit of butter and a garlic clove) which 'looked' to bag up fine and set that cooking.

I then tried a watermelon infusion but when I placed this in the chamber the liquid started to 'boil', the bag swelled up in the machine. Swelled more as the vacuum increased and when it had finished it left me with a sealed pouch that was 'loose' at best. I would say about 20% was still air. After messing about with both plain and embossed bags, and the position of the bag in the chamber I was not getting any improvement. 

I then tried sticking the sealed bag in the freezer for an hour or so (it was not going to freeze fully though as I had vodka in it)

This did not help.

My machine starts the cycle when the lid is closed and runs for 10secs. I found that by not quite shutting the lid properly for the first 5 seconds I could prevent the liquid 'boiling' in the bag and stop the bag swelling up. My best end result with the watermelon is to get 99%> of the air out but there is still no compression on the bag which is what I was after.

 

I then decided to check the vacuum (the gauge is reading just under -1 at the end of a cycle. I put a glass of Ice water in and sure enough it boils up so the vacuum side of things is fine.

 

I then tried 2 salmon fillets, These had a good dash of olive oil in the bag (oil was at room temp).

Again, About halfway through the cycle the oil started to boil and the bag started to swell, (but not as much as the water melon one) When sealed off and the chamber re-compressed it did shrink back down but I would still say it felt 'loose' 

The fillets would not move around in the bag and I could not see much air but there were places where the bag was not completly in contact with the fish.

When cooked these places were full of white pectin where the places that were in contact were nice and clear pink.

 

Finally, I had opened a big box of peppercorns and filled my mill up so I decided to vacuum pac the rest of these.

I put them in a plain bag and they sealed up very tightly. It is not possible to move any of the peppercorns around in the bag and it looks like proper commercial packing.

 

After packng the peppercorns I realise that the steak may have been a bit loose as I didin't really know what to expect when I packed it. I have since tried coke cans, books etc and the cans are being crushed and the books are ending up with bag contact on all sides.

 

Why am I having problems with liquids? Packing liquids was the main reason for getting a chamber vac.

On my machine the sealer bar is across the front of the chamber and 'pops up' againsd a strip on the lid to seal at the end of the cycle. I thought the adjustment may be out and it was holding the bag shut but you can fit a pencil in the gap and close the lid so that looks ok. I also tried embossed bags and they are just the same.

10secs is the shortest program (although you can change the program) but it does have 40second programs. Would a longer program suck out all the vapour that is coming from the gassing?

If so is it a good idea to be drawing that vapour into my pump? Or should I be looking for shorter cycles to prevent gassing in the first place?

I though about raising the front of the maching to help the gas out of the bags but I don't think that will be any good for the oil in the pump?

 

Thanks in advance for any ideas!!

Edited November 18, 2015 by hotponyshoes (log)

[AlaMoi]

the "boiling point" of water / liquids decreases under vacuum.  if you are "boiling" ice water that is one super vacuum machine, and that is the problem. 

 

to much of a good thing - including "nothing" aka "vacuum" is not always better.

 

the point of the "vacuum" bit is simply to remove excess "free air" - it would appear your set-up is going way way far overboard.
 

[Okanagancook]

Yes, you have too much vacuum.  You will have to play around with the settings.  First I would reduce the settings you were using to half, then try again.  You don't want the liquid to boil up, but just before it does that.  Also depends on how hard a vacuum you need.  When I package sauces, I just want to exclude most of the air for freezing but if I am sous viding a stew or solid pieces of meat I want a little stronger seal so the bag doesn't float.  The liquids need to be cold also.  So, just experiment unless someone else has something more definitive.

[daveb]

Nothing definitive here but wonder if it's more too fast a vac rather too much vac.  My VacMaster VP-112 goes to -.9 (just under -1) and does fine (except the time I tried to seal sauce right out of the VMix.  You'll only do that ONCE ).  It takes 30 seconds to get there.  The bag does appear swollen until seal is complete then it compresses around the product as it should.  A 10 second vac seems almost violent in it's speed.

 

For salmon; a pellicle will form when cooked unless the fish has been brined prior.  Don't think yours was a function of the sealer but rather fish cooked well but not brined.  Overcooked salmon will cook off the pellicle.

 

Your peppercorns mirrors my results when bagging leftover walnuts yesterday.  Bagged tight and commercial like sealing.