Freeze Dryers and Freeze Dried Food (Part 1)

[Kerry Beal]

I'm a bit of a food geek - I've got a lab background and often fall back on familiar lab equipment for various projects that I'm playing with.  I have an extensive collection of graduated cylinders, beakers, flasks, thermometers, refractometers...  

 

Back in 2006 I purchased a used lab vacuum microwave from e-bay - cost me somewhere in the range of a hundred bucks.  Never did get it to work the way I had hoped though.

 

I've been watching freeze driers on e-bay for about 10 years - seriously considered a couple of them - but they were rather huge - would have taken up the better part of the garage.  They were also 220 V.  I have 220 in my chocolate room - but there is a limit to the number of things I can plug in there.  Also some had been used to freeze dry dead animals - which I didn't think would provide me with a food safe unit!

 

Back in early August Ninagluck posted about a Sosa product called Airbag - it's pork skin granules that you use as breading.  That got me started looking at freeze driers again.

 

I discovered that a company in Utah was making a home unit - 110V - about the size of a small freezer.  Well - conveniently Chocolot lives in Utah and it just so happened she was heading to the area the day after I contacted her - so off she went to check this out for me.  She was sent home with some samples of things they had dried that she then dipped in chocolate and returned to them.  

 

Pictures arrived - contacts were made - and the rest is history.  Chocolot has been back there several times - getting the fellows who manufacture the units to freeze dry different products that she wants to play with.  Bet it won't be long before she has one too!

 

It arrived on Wednesday - hubby took it down to his workshop and unpacked it.  I had to wait until Friday to grab a cart from Uline to put it on - 'cause after hubby saw it he decided the cart I had earmarked for it was not suitable!  Today finally he adjusted the door which had gone off a little in transport, hooked up the vacuum pump, pulled out the drain hose from it's hiding spot.  There are a couple more things he needs to do with it before he will release it into my care.  So with any luck by tomorrow afternoon I can start on my first project. 

 

 

Hubby working on the vacuum pump.

 

 

 

The innards.

 

 

The trays.

 

In the next post I'm going to explain a bit about the theory of freeze drying - but I'm hoping this thread will serve as a bit of a journal of my experiments - and I hope others might jump in if they get bitten as badly as me.  I think it would be a good place to talk about commercial freeze dried products as well.  

 

 

[Kerry Beal]

So a little of the theory of freeze drying.

 

The product is first frozen to a low enough temperature that when heat is applied the liquid in the product will sublimate (i.e. go from solid to gas) rather than melt (i.e. go from solid to liquid).  This can only happen if the warming occurs in at a lower atmospheric pressure - hence the vacuum pump.  

 

The unit also contains a condenser - so that the water that has been removed from the food can be removed without getting into the pump oil of the vacuum.

 

Once the frozen water is sublimated, more heat is applied to bring the moisture content down to between 1 and 4%.

 

The finished product needs to be sealed to prevent humidity from softening it.  A mylar bag with an oxygen absorber will allow you to keep the product for 25 years or more.  Often the product is sealed in number 10 cans - again with oxygen absorbers.  If you seal in a vacuum bag, oxygen will eventually leak though the bag after a couple of years and the product will degrade.

 

I've got a list as long as my arm of things that I want to try - but first I have to figure out what I'll do for my first run.  I do have some bananas that are getting just the way I like them - spotty and brown.  One objection I've had to freeze dried bananas I've purchased is that they aren't as ripe as I'd like.  

 

I also have a whole bunch of purees taking up a lot of space in 3  freezers - if I could FD these it would go a long way towards the clean out they seriously need.  

 

 

 

 

[Beth Wilson]

Oh Kerry!  I am so looking forward to following this thread! 

 

I love freeze dried fruit in chocolates and can't wait to see what you come up with.

[Kerry Beal]

I suspect the chocolate will benefit most from my new toy!

[Beth Wilson]

Can you freeze dry other things like caramel or brownies???  Just thinking of things I love in chocolates :-)

[Lisa Shock]

The removed water may be interesting, think of, say, ice cubes made from the water out of fruit. It may not be strongly flavored, but could still be useful.

[Kerry Beal]

Can you freeze dry other things like caramel or brownies???  Just thinking of things I love in chocolates :-)

Caramel for sure - I have some from Sosa that I use now.  Don't see why brownies would't work.

[dcarch]

The removed water may be interesting, think of, say, ice cubes made from the water out of fruit. It may not be strongly flavored, but could still be useful.

 

The water removed will be pure water. Like distilled water.

 

With the freeze dry setup, you will be able to make the most flavorful bouillon cubes.

 

 

dcarch

[Kerry Beal]

The removed water may be interesting, think of, say, ice cubes made from the water out of fruit. It may not be strongly flavored, but could still be useful.

Trouble is the removed water will have frozen on the inside wall of the unit and then will be melted off and collected in a bucket.  Given that I'll probably FD a combination of raw and cooked stuff, and that bacteria freeze dry quite nicely and don't die I might not collect the liquid.    

[Kerry Beal]

The water removed will be pure water. Like distilled water.

 

With the freeze dry setup, you will be able to make the most flavorful bouillon cubes.

 

 

dcarch

Here's an idea I've had.  Sous vide a steak, FD the steak, FD the osmasome separately.  Keep track of the starting weight of the steak.  Package the steak along with some of the FD'd osmasome and mark with the weight of water that was removed and needs to be added back.  

[FauxPas]

My head exploded a bit reading this thread. You are not a timid cook, that is for sure! Even if I had the space and the discretionary income, I am not sure I would do all that you do, but Wowser, I do love reading about it!!!! 

[lordratner]

Do you, by chance, require a second husband?

[Kerry Beal]

My head exploded a bit reading this thread. You are not a timid cook, that is for sure! Even if I had the space and the discretionary income, I am not sure I would do all that you do, but Wowser, I do love reading about it!!!! 

She with the most toys when she dies - wins!  

[Kerry Beal]

Do you, by chance, require a second husband?

I did laugh out loud when I read this!  While I love to have people to feed - one husband is is quite enough.  Thanks for the offer though.

[Kerry Beal]

So - went to start things up this am - realize that there are supposed to be 2 knobs on the right side of the machine - one to adjust the freezing time, the other to adjust the vacuum time.  Second knob MIA.  It's back in the shop getting the side taken off to see if the knob is in there somewhere.

 

The top knob did get broken off in the unpacking I was told and had to be replaced.  

[Shelby]

Now you can make freeze dried ice cream like the astronauts take with them 

 

I'm following this with great interest.

[dcarch]

For a source of heating the frozen food inside the vacuum chamber, I wonder if Peltier junction devices would make sense.

 

Peltier devices generate heat and cooling at the same time to keep the chamber cold.

 

dcarch

[Kerry Beal]

Look like I'm out of business until I hear back from the manufacturer. I probably could run it cause the default is 5 hours - however it's back in the shop and I suspect I won't get it back until it's back together.

[Kerry Beal]

For a source of heating the frozen food inside the vacuum chamber, I wonder if Peltier junction devices would make sense.

 

Peltier devices generate heat and cooling at the same time to keep the chamber cold.

 

dcarch

Pretty sure the cooling isn't Peltier (compressor) - but the heaters might be.  Didn't take a really close look at them.

[Kerry Beal]

Now you can make freeze dried ice cream like the astronauts take with them 

 

I'm following this with great interest.

Got a bunch of ice cream sandwiches waiting, and waiting, and waiting...

[thegreatdane]

Wow, what an adventuresome person you are! How do you plan to use the freeze dried products with chocolate? Recently, I received samples from a company and have tried freeze dried in white chocolate. Too sweet, but the colors were cool. Ganache may be a great way to use them. I'm also thinking about price.

[MelissaH]

I'm a bit of a food geek

Um, Kerry? I think this might just be the biggest understatement ever on eG! Nonetheless, I envy you, and look forward to seeing what you do with your new toy!

[Kerry Beal]

Wow, what an adventuresome person you are! How do you plan to use the freeze dried products with chocolate? Recently, I received samples from a company and have tried freeze dried in white chocolate. Too sweet, but the colors were cool. Ganache may be a great way to use them. I'm also thinking about price.

I already use a lot of freeze dried stuff with chocolate.  I use chunks of freeze dried fruit, coffee, toffee in bark.  I add freeze dried fruit powders to boost the flavour of ganaches.  

 

What I might do new is to make some centres then freeze dry them, then enrobe in chocolate.  For sure I'll enrobe the ice cream sandwiches and freeze dried ice cream.  

 

I've had freeze dried whole strawberries panned in white chocolate before - panned fruits will be one thing for sure.  

[curls]

Got a bunch of ice cream sandwiches waiting, and waiting, and waiting...

Shelby beat me to it, I also wanted to know if you could make freeze dried ice cream. Looking forward to your reports on your experiments!

Hope your freeze drier is working soon.

Edited September 7, 2014 by curls (log)

[dcarch]

Dumb dumb dumb idea, OK?

 

Sushi fish are first flash frozen. I wonder what they would taste like if you dry the fish before they are thawed. The fish would be still very fresh, but crunchy and airy, and can be kept fresh for a long time.

 

Canned sushi! Mail order sushi! --------- Possibilities, possibilities!

 

I told you this is a dumb idea.

 

 

dcarch