Suggestions For a Freeze Dryer

[marcus hampton]

I'm interested in getting a freeze dryer for business use. I am wondering what is a good size and what features it should have. I know they are expensive but what else do I need to know. Is there a good brand or a brand to avoid? Is there anyway to save money?

[Jerry Adams]

I wonder if you could jury rig something. Conventional freezer with some sort of vacuum chamber inside. I wonder how much vacuum you'de need?

[marcus hampton]

I'm hoping for a machine that is fairly portable and reliable. I already know how to make a freeze dryer with dry ice and a Styrofoam cooler, but I need a freeze drier for business use. I found a 4.5 liter dryer but I'm not sure if that's big enough. Maybe this should be in the gear section or something.

Jerry, here's the cut and paste if you are serious about jury rigging something.
http://www.ehow.com/how_5732031_make-freeze-dryer.html

[Jerry Adams]

That's weird, all they do is put dry ice and the food you want freeze dried in a styrofoam cooler, no vacuum, I thought feeze dried food uses a vacuum

Doesn't seem like that would dry the food

Dry ice is like -100 F which is way colder than any freezer

[Jerry Adams]

wikipedia says a freeze drier has both a freezer and a vacuum

freezer has to be like -60 F so regular freezer with it's refrigerant won't work

wikipedia says freeze drier is expensive

I think you'de have to use it a lot to make it worth while

[Dale Wambaugh]

The freezers used for tissue research run -80F. You should see how fast they frost up!

They make small vacuum containers for Seal-A-Meal machines– a liter or two.

There are commercial vacuum pumps used for evacuating air conditioning equipment. You could probably crush a container with one.

Interesting idea to freeze dry vs air dehydrating.

[marcus hampton]

Jerry Wikipedia is correct. I was wanting to spend around $3,000 but now it's looking like I may be spending over $6,000. I'm not sure but, they may also need to be serviced and repaired, similar to industrial deep fryers.

[Jerry Adams]

wikipedia says first you do a few millibars for a few days. Way below Daisy Seal a Meal but not ridiculously low

then do microbars to get rid of adsorbed water. That is more difficult

[Sarah Kirkconnell]

Before you buy anything find out what the FDA rules are…..while Wa state has a cottage rule now for small food companies you can only bring in a tiny amount of money, and still must be health dept approved. I know there are people who skirt the rules, but well…….

[marcus hampton]

Hi Sarah. Thanks for your comment. I'm not worried about the logistics because we have help from someone who already makes jam at the Fire Hall in our tiny town. She sells them in stores. I have my food handlers card and I am not expecting much trouble meeting regulations, except expense.

I am just wondering what a good type and size of freeze dryer would be. Maybe I should just get a countertop model to start with.

BTW: I love your vegan dry cheese mix. I recently found out that was your recipe I've been using for years.

[Sarah Kirkconnell]

Yeah, having access to a local 3 sink kitchen for prep makes it soooo much easier!

[Ian]

I just read through the eHow link and I'm a bit confused with the instructions

"Place the lid on the styrofoam cooler and let it sit for about 30 minutes. Check the items that are being freeze-dried to see if they are frozen solid, if not put the lid back on the cooler and continue to check the items every 5 minutes. When the food items are frozen solid they should be removed and placed in a normal freezer until they are ready to be used. If the items have been vacuum-sealed prior to freeze-drying, they do not have to be placed in a normal freezer but can be stored in a pantry or food closet"

Seems a little bass ackwards. If I just flash freeze it but don't vacuum out the moisture, then don't I just end up with frozen whatevers? If I vacuum seal it before hand, then the moisture won't escape.

Seems like vacuum sealing it after freezing it might be the better way to go? Anyone try this?

[David Thomas]

That eHow link is goofy. It is not about how to freeze-dry, but how to flash-freeze. And rather expensively at that, since you'd need to buy dry ice for all the items you freeze.

To freeze dry, you need a serious freezer and a serious vacuum pump, one that pulls a greater vacuum than the vapor pressure of water at the temperature of the freezer. Here's a chart:

Converting Pascals to God-given units of psi: a harder vacuum than 100 pascal x 0.000145 psi/pascal = 0.0145 psi would be needed at -20C. Half that much pressure at -30C and approximately half as much for each additional 10C lower temperature.

Once you've started to sublime moisture out of the food, you'll be cooling the food further until the food absorbs more heat from its environment.

[Ian]

Thanks David.

This looks interesting.

Edit: correction. It looked interesting until I re watched the video and realized that it took him 14 hours of feeding it dry ice to freeze dry that food. No thanks I'll stick with my dehydrator.

[Bob Shaver]

The place where I worked we vacuumed dried apples and apple pieces, like French fry shaped. We first dried the apples down to 23% moisture (leathery), then spread them on a tray about 4' by 4', 2 inches deep, and put about 30 trays in the vacuum on shelves. The shelves were hollow and hot water circulated inside the shelves. Then we'd shut the doors on the vacuum, and pull a vacuum while heating. The heat combined with the vacuum puffed the apples up, and when they came out they were dry and brittle, at about 4% moisture. They snapped if you tried to bend them. Very tasty.

I suppose freeze drying would be similar but take longer to sublimate off the water.

[Yak Attack]

Sorry to revive such an old thread.

OP, if you’re still interested in one of these here’s a company that’s selling them. I’ve read a handful of posts on other forums from people who have gotten one, and so far they’re all positive.

They had a Black Friday special for $650 off the price of the stainless machine, so a friend and I decided to jump and split one. I can’t speak for it personally yet, ours should be here next week.

harvestright.com

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