How to Make a Freeze Dryer
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- Опубликовано: 28 авг 2024
- How to build a cheap-ish freeze dryer. It can make astronaut ice cream, instant coffee, mre's and all sorts of freeze dried foods.
The freeze drying process turns the water in frozen foods into a gas without it ever being a liquid. This sublimation phase shift maintains the foods structure. While that's cool and all, Freeze dryers are't the most useful things unless you do a lot of camping or long trip without a fridge stuff.
You could easily make it for around $200 starting from nothing
I bought the materials at
Mcmaster.com
amazon.com
and various local stores
dry ice can be purchased at most grocery stores
I found the water bubblier at my local dump
There are many different sorts of design options, this is just a more basic one without much automation.
Various warnings:
Dry ice will give you frost bite if you hold it too long. If your glass bowl is too thin it can shatter/implode and shoot glass all over the place. Change your vacuum pump oil if/when it gets cloudy. Use oil when you drill holes in metal. Isoropanol alcohol is flammable. Don't be stupid.
Music: KOAN - Starlite
The still images aren't mine.
Thanks to Ben Krasnow for the insparation
Consider supporting me and my projects on patreon! / bennbuilds
For those who might find it interesting, the Aztecs used to freeze dry food for storage. They did this by carting their prepared crops up into the mountains, where it was freezing and the air pressure was lower.
The men who collected flowers for the temple would have appreciated that. Reduction in weight and size, just adding water would enable many flowers to be collected 🥔
That wasn't really freeze drying. I know wikipedia mentions it but it isnt the same as freeze drying.
@@unknownkingdom, actually, it is. MY freeze dryer uses vacuum, cold (-50) temps, then warming to freeze dry.
The Aztecs, by carting food up into the mountains, were able to freeze it and take advantage of lower atmospheric temps.
Their method was a fraction as efficient as my Harvest Right freeze dryer, but it did make enough of a difference in the condition of the food to make their efforts worth while.
Merely dehydrating asparagus, for example, makes for some pretty sad end product. Freeze dried asparagus, on the other hand, is completely different in appearance and texture.
@unknownkingdom Yes it is.
Bravo, the first DIY freeze dryer that I found on RUclips that actually freeze dried or at least attempts to. Most people just build vacuum chamber dryers instead of an actual freeze dryer. I think the cold trap should be colder than -30 C, more like -50 C but if you put a dessicant like silica gel in it, you could get away with the higher temps. Of course, the only downside of not condensing all of the water vapour is just wear and tear on the vacuum pump
I reefer watching this In middle school, and now that I am 20 and need one, I remembered the name of the channel. I feel nostalgic rn
Damn!! What a great video. Straight to the point, short but detailed, basically no fluff and functional!
In other words…I'm going to quit complaining about the cost of freeze dried food!
scalenguy05 baba
I love this Ben! I especially love "Freeze dried food will always taste weird"
Awesome!
That last line was perfect.
Wow, who knew it would be so easy to freeze dry your own food! By the way, I'm a rocket scientist...
Who give a care... Just kidding.
Brandon Friend Hahaha! Good one.
😂😂😂😂
Nice presentation. I liked the quick speech- saves me time. Dry ice is expensive. I learned from this vid to spend my dollars on something else. How bout a nice dehydrator and a nice vacuum sealer? Yeah, I think so.
Excellent video. I appreciate the tempo and editing that you have done. Also a great build. I just spent 4 minutes and 24 seconds to find out I do NOT want to freeze dry my own food.
Now you know!
Great video! Love the quick editing and how you move the viewer through the entire process quickly. Makes me want to try freeze drying at home! Thanks!
I wish I could talk that fast. I wouldn’t! You go dude
You don’t have to guess when it’s dry. If you are using a Pirani gauge determine the ultimate vacuum reading you can achieve then monitor pressure when you reach the ultimate vacuum pressure the primary drying is complete. You might need to sit at that pressure for one hour for complete dryness. You can also add a temp gauge to the inside food chamber when the material in the chamber reaches the ambient room temp the drying is complete.
Great work and great editing! Can't say I'm going to build one ... but if I do, I'll be back here to learn.
That is an incredibly thorough and well made video.
I only wish with other instructive videos the people spoke this fast! I personally like it to be right to the point like this and not waste alot of unnecessary talking and time. To the guy that made this: I wouldn't change a damn thing in the future. Very well done sir! Thank you!👌
I strongly agree.
I definitely checked my playback speed part-way through. Ben, you are the Laurelai Gilmore of the making world.
Bwahaha
Good video and right to the point. I don't think I'll be making one anytime soon. Thanks.
Just discovered your channel, and I must say your camerawork, quick presentation methodology and background music makes for some extremely impressive build videos! Keep up the good work!
Thanks!
If you don't have time to make a proper video then don't.
Excellent. And I like the pace of the video. No bullshit.
oh I get it you're the guy that reads those legal disclaimers on television ads
do you think the vapor in the air could damage the pump? otherwise, why would you need any moist trap at all?
My mind just exploded with all the possible use of cryogenic fluids for the cooling bowl ect !
'a little tightening beyond reason' sounds like work lol.
I know this is an old video but I have a couple of questions..
1.does your vac pump have to run the whole time or could you put it on a timer or a pressure switch..
2. What temp did you have to get down to? Could you retrofit an old deep freezer by installing a smaller steel tub in side ?
3. Is 0°F to -10°F cold enough?
You earned my subscription , keep going with those super interesting (and well filmed/edited!) videos.
Thumbs up for “the freeze dried food will keep forever….and always taste weird.” Try some ice cream bars….those are decent freeze-dried. Used to get them as a kid on class visits to the DC Air and Space Museum.
it keep for about 30 years when packed right . Gold.
Dude if only everyone did builds like you
That was great. I think you over did it. Still great. Liked how fast the video went and the end. But I gotta say I love how freeze dryed strawberrys taste
Hey, you're right!
Easy, peasy, Japan-difficult.
This seems very practical.
you are a genius
Great video , just saw how old it is
Damn bro! Nice work! Mcguyver would be proud!
Your going to have to freeze dry a ton of food to make that setup worth while.
KOAN sound is amazing!
youtube doesn't limit videos by time anymore. You can take your time now
but then nobody watches them
Hey, love your video :) i want to build machine like this on my own and i have a 2 questions:
1. how do you prevent water from going directly to the pump from the water trap?
2. how do you know when the process is finish? and you products is completely dried? and when i turn off the pump?
Thank you :)
Thank you! 1: the cold trap gets most of it, but it is not perfect. I also changed the oil after each run.
2: It is mostly just a guess as most items are significantly different. After doing it a few times with one item you will get a good idea of how long to do it for
@@BenNBuilds thank you. what about the drying chamber? is need to be cold? hot? room temperature? how much in C/F ?
@@timamar Did you find out about this?
Shelves need light heating in order to sublimate
That looks cool and is well beyond my technical capability. I don't suppose there is a mad scientist out there that would build for other people lower end freeze drying machines for under $200?
Could you please speak faster? Easier to follow...
Just set the default setting at 2x speed. That way you never have to mess with it 😊
He didn't speak fast enough using the some code to speed it up to 3X
1Howdy1 thank you.... .75 was perfect!
Video Speed Controller extension works wonders for any video played in your browser
Lol
Nice work. I'm looking into building my own freeze dry unit and am wondering what your thoughts are on using a cold plate (similar to a bar system set up) or a copper coil (similar to that used in brewing beer) for the cold trap with either piece in an ice chest stocked with dry ice. Any thoughts on whether that would work?
As long as it gets cold enough and has enough surface area to handle all the water. you may want to test it out before you set it up with feedthroughs, but a lot of commercial freeze driers use cold coils to trap the water
Hi My name is Lauren i am 13 and want to be a food scientist when i grow up. I have experimented with dehydrating and other things but i have not tried freeze drying yet. I want to build my own of course because they are to expensive could you maybe give me a supply list.Thank You.
Well you're 15 now, how's things coming along? I hope you took some initiative and paid more attention to the video, and thus no need for a parts list.
The fact that your lazy ass took 2 years to respond to this kid is fucking ridiculous and sad!
any chance of getting a slightly slowed down version of this without the music? there are points where you talk faster, you get a little quiet, and the music gets a little louder. all are manageable, but when mixed together it makes it hard to follow along
well you made a nice vacuum chamber
Great video. Thanks for posting it. I am looking to do the same thing. I am going to use a 2 inch dewaxing column from bvv for the cold trap. I already had this thing. I bought it right before I quit using butane for extraction, and have yet to use it. The bvv cold trap is 200. It is nice, but I think my 2 inch stainless tri clamp spool with jacket will work just fine. It is 12 inches long, will sit on a tripod stand and have flared hvac fittings on the top and bottom. I will insulated the jacket with those ir space sheet looking stuff. I have a vacuum pump, but I don't think it is strong enough. I can never get my chamber down to lower than -19 in mercury with it. So I guess I will be getting a rotary vane pump, although i hope to not spend an arm and leg for it.
Can I use a 3.5 cfm pump, or should I go for the 5 cfm and something closer to 50 micron full vac? I just don't want to have to get more than one new pump because I sized it wrong. Thanks.
Does the manufacture of this tool still use a refrigerator compressor for cooling?
Hey, not sure why you didn't just order some pre made plexi glass lids for the chambers. They sell them for cheap and they work well.
I had outgassing concerns, but that would probably work fine for most people
wow i wish i knew what you were talking about and how to build it! do you make them for others? thx :)
Hey mate sorry I know this is years on , should I follow your build exactly as you have done it or should I try to improve on it with desiccants? Thanks so much for the work you do!
you could use two vaccuum cleaners in series to get a lot of air out then use the vacuum...
Not low enough pressure
Great innovation without the expense!
I was just curious to know why won't mixing the dry ice and alcohol create the "freeze dried" product? Will the mixture only make it really cold and not dried, or will the mixture not extract the moisture from the items?
Khyiah2012 that wouldn't remove any moisture, it would just freeze the food and cover it in alcohol. You would need to add some sort of desiccant
Your videos are SUPER good!
Just found you Ben. "Subscribe if you want." You are great not boring and I like your brand of snark.
impressive, thank you!
I do not understand why dry ice is used, after all it will bring the temperature down and therefore move the scale for sublimation further to the left and require lower pressure. At room temperature water will evaporate as long as you drop the pressure. In fact I think commercial drive freezers have heating pads to heat the food as it is drying.
Because as the water is pulled out of the food it drops the temperature of the food making it harder for the rest of the water to sublimate....
That is why professional drive freezers use heated plates for the food...
Unless I missed something here...
umm ok, I will just buy one.
lmao, yeah i saw this and i was like........yeah i'm not doing all that.
Honestly for me I don't think I could ever bring myself to spend thousands on one. This contraption he has made, literally saves him and would save anyone else thousands. So if you two just happen to have that much extra money lying around, and can afford to buy non necessities that cost that much - more power to ya. But for the other 90% of the world, making this is a great option.
If you're a man over the age of 25 you should already have most of this stuff, aside from the half inch tap. 300 for the vacuum pump, you can rip the fridge compressor out of some junk, and the taps like 50 bucks. Then the fittings are probably another 75 with the hose. All he really used was a drill and some wrenches. I dont understand how anyone can opt for the 2500 dollar machine over this simple homebrew rig.
are you kidding? a freeze dryer goes for $1500 easy, this is WAAY cheaper, the vacuum pump will run you $150, those pirex dishes wont run more than $20, I think the most expensive parts here is the pump and the aluminum plates, and i dont think you will need that thickness so you can probably get away with something thinner/cheaper. you can definitely use a 1" acrylic plate on the chamber where the fruits are, not on the cooling chamber though since the temp is way to low for the acrylic to be safe.
SICKFREDO The aluminum plates, together, shouldn't cost more than $30-40... By far one of the cheaper parts of this whole setup. But regardless you're correct that this setup should cost a person less than $300 as opposed to a Harvest Right dryer which is actually more than $2000.
Can you please show building one with the freezer parts?
Hi I am looking into building a freeze dryer. Can you maybe send me a parts list? Just so i can make sure i have everything. Thank you.
Will that sealant greese make it's way into the food?
yulius ade, google won't let me reply to your comment.
Yes, the vacuum pump needs to be on the entire time. An extra fan may be necessary so it doesn't overheat. Make sure you do it long enough too, I pumped mine for 18 hours strait. The cold trap stops water vapor from getting into your vacuum pump. It needs to be a lot colder than salt and ice. -35F at least, any less and the water will melt due to the low pressure inside. Also make sure you freeze your food thoroughly before putting it in the chamber
Thank you for your explanation,
so the cold trap isn't affect the result,right?
Actually i pumped it for 20 hours.
my first analysis is my strawberry doesn't freeze in the inside, although i put it in the freezer for 1 night..
Today i will try this again with the slice thin of strawberry and i will let you know the result.
I need your guidance to make this happen, and i really thanks to you..
yulius ade Yulius,
I too am building one, And I'd be very interested in whether you had managed to achieve a result. Also, I don't really see why the vacuum pump needs to be on the entire time, so long as the pressure remains below the triple point. Can anyone explain?
***** Hi Ryan,
I was success to freeze dry a strawberry in a bowl. Now i'm making the bigger machine for production. I think the vacuum pump is turn on for entire time because when the water meets a triple point, the water turn to gas, that gas influence the presure and the preasure is not in triple point, so the vacuum must turn on until the end.
yulius ade that's awesome yulius, I hear berries are tough. As for your response, you are correct, the pressure must be maintained throughout the process. However, this could be done more efficiently with a vacuum gauge, a relay to turn the pump on and off, and a valve to disconnect the pump to the chamber. I.E. when the chamber pressure gets low enough, the valve closes and the pump turns off. when the pressure rises again, then vice versa. I too am curious why that page, which I'd seen before, says a single stage pump will not work. So far I have managed to boil water at room temperature with my sngle stage pump, which means it can go below the triple point. It was my understanding that the second stage simply allowed it to pull harder more easily. any videos of your current setup?
***** Hi Ryan Cook, i still create this machine until now and i still failed, but i didn't give up. I build with big chamber (254 L) and the cold trap (125 L), and 2pcs Vacuum Pump 2stage 1HP. the result is more failed than succed.LoL. Can you give me your email for discussion?
looks really easy, I'm surprised more people don't do this
Could you post a video about the bubbler(?) mentioned at 3:25? This was an overall great vid, but moved to quick at some points. Thanks.
Hi, what is the machine you can use instead of dry ice, I couldn’t understand the name (it was toward the end of the video). Thanks
Could you...
Build one out of a household freezer?
great video, thanks.
Awesome! Love the commentary. Freeze dried berries taste weird!
What is the water bubbler? is it the cooling system on a public drinking fountain (I know those are called bubblers in other parts) . Also, are you cooling the actual food or just the vapor trap?
Was the compressor emptied of oil that it came with?
Woah... You are amazing!
Hi Ben,
I was making a vacuum freeze dryer in home, but the result failed..
my strawberry wasn't dry,,
i have many question for you:
1. is the vacuum pump still on when the process?
2. what is the usage of cold trap?
3. what is the temperature for cold trap? (i just use the ice and salt, is it enough?)
thank you before
Can the dry ice be replaced by a refrigeration unit from a household refrigerator?
Looks like fun making it but... way not worth the trouble, dude.
Great job on the video! You're kinda like a professional ;-)
+Tifdexaler The whole point is the fun, I've only used the thing like 5 times :)
HOw much would you charge to build me one? I have 2 disadvantages: 1). I am a female and 2). I am very disabled. Oh, and 3). I live alone. I want one really bad, but 4). I do not have $1,000's to buy one when I have a '02 minivan that needs work. Thanks.
The materials are almost 1000's and I don't have the time (I would have to charge a TON). Building it yourself is all the fun and a lot cheaper. You might be able to have a friend build it for you, or use someone else's shop. Being female isn't a disadvantage, just go for it!
BenNBuilds The real disadvantage is being severely disabled. Want to sell yours? Have you seen the new ways to make your own electricity?
daschundloverable I'm wondering why you want one so bad. Do you have access to lots of fruit at one point of the year? If so preserving might be a better option, and within your means. Even using a food dehydrator might be an option.
Awesome video!
Can you explain me better how do you get -34ºF in the cooling system? What gas did you use?
Thanks
I just used the standard refrigerant, and -34F wasn't quite cold enough for freeze drying. A refrigerant such as Ethylene is necessary to reach the required temps. ruclips.net/video/mzeRvdnIP-I/видео.html
@@BenNBuilds Would -34F be workable if you ran the system at a slightly higher pressure? The triple point is at 611 Pa, so I would think that 50 to 100 Pa would still be low enough to prevent melting, while making the cold trap easier to build and operate?
How about a DIY spray dryer? Supposedly that is less expensive, at least at the industrial level.
Hi, I don't really understand why the pump must be on for all the time.I red some explanations, and they explain that when the food looses the water, the water vapor rise the pressure aNd the pressure is the key for the process. I don't understand really good. When the food loose the water, we have in the first chamber water vapor and a rised pressure, but the water vapor goes in the second chamber where it become ice, so that we have not anymore gasses but solid and the pressure come back to the first stage.I think that maybe without the vacuum pump always on, the process needs perhaps more time, but it must work. Or not? Do I think wrongly? The pressure rises because there is not anymore vacuum because the water vapor, when it becomes ice, the vacuum is back and with it the pressure.
The water that comes out..is it the fourth phase of water?
3:24 "if you dont have access to dry ice a hacked water bubbler will work. Just wire it so the compressor always runs and it should get to -30f"
.... do u have a video or could u please explain how to do that?
LMFAO - That was great. As for the speed....I just watched a 10 minute video on how to use a metal canning machine - I wanted to scream he was just yammering on. He should watch this video. BenNBuilds could have done that video in 12 seconds.
Awesome work! I soooo want to try doing that!
Do you think that instead of using a cold trap I could get away with pumping the air though a chamber full of silica gel pellets?
You may want to do some tests to make sure they still work under vacuum, but as long as it catches the water you're good
BenNBuilds Thanks for the feedback!
Good point, I hadn't considered what effect vacuum might have on their effectiveness. Someone else on RUclips freeze dried some apples by simply putting them in a jar with some silica packs, vacuum sealing it and leaving it in the freezer for a week, so at least on some level it works, whether it works enough is another matter.
I'm eying a used Robinair 4cfm pump I may be able to snag for $100, if I get it I may start gearing up to try this, I'll let you know of the results.
Andrew Tornadoboy Sounds good! If you see the oil going cloudy fast than it's sucking too much water vapor. This also happens during normal use but it takes longer, if you don't catch the excess water from the food it stays in the vacuum pump oil and can damage stuff (in a rotary-vane type pump)
BenNBuilds Another idea I'm pondering right now is getting an old water cooler and rigging it up with extra heat dissipation before the compressor with things like fans and heat sinks, hoping that maybe that along with bypassing the thermostat and filling the tank with alcohol will get it cool enough to be a cold trap. I'd love to be able to rig it up so as to need as little consumables like dry ice as possible.
Hello Ben! this video is appetizing, makes u want for more...... Can u consider an intern from Ghana?
Im sure someone asked this:
What did it cost to build?
And more importantly, whats the estimated average cost per pound to freeze dry food?
Is the cost of your time, parts, materials, dry ice, etc going to be more than buying the food already preserved?
It cost me about $150 to build.
If you use dry ice for the cold trap it will be way more expensive to run. I used about 10lbs for 18 hours of drying, which is like 10$ every time +checking it every hour. With the hacked water bubblier the only consumable was electricity so it costs less than a dollar to fully dry stuff. If I got a bigger food chamber and fit a pound or two at a time It would get super cheap. If you used it all the time it probly wouldn't take long to break even
A hacked "what" should work instead of dry ice?
what was the chiller you were using if you didn't have access to dry ice?
Nice work BenNBuilds !
I am doing this as a science project but got stuck. The one that lends me the pump said that it should be able to handle water vapor, so i skipped the cold trap (Dry ice is hard to get where i live) and i get below 200 pascal (just checked the pressure shortly because i borrowed the gauge) But as soon as the icecream gets subjected to room temperature, it melts even if the container is connected to the vacuum pump. You mentioned in another comment that the oil catches the water vapour, so maybe it gets oversaturated and then cannot dispose of all the water? The oil have only gone cloudy when air have leaked in.
You may just have to get your ice cream colder before you start. I froze mine past -50F so I had a nice time buffer before sublimation cooling kicked in. If your just pulling it out of the freezer (usually 20F) than that's your problem. Ice cream is meant to be soft and edible at those temperatures. You gotta deep freeze it.
I encourage you to reconsider about the cold trap, Its easy enough to find a water bubblier or something.The pumps really can't handle all the water that is inside ice cream. 5oz of water is way to much for a rotary vane pump to handle. I assume whoever lent it to you didn't know it was intended for freeze drying. The water vapor present in just a couple cubic feet of regular air can be bad.
BenNBuilds The teacher that lends me the pump is actually teaching relatable subjecs to refridgerator maintenance and according to him, there can be water vapor inside the cooling systems so they are built to handle some of that. I am planning to build a cold trap anyway because it adds some security to that the pump will not wreck, and i can also monitor it to see about how much that have left the icecream.
I actually left the icecream subjected to *30C (-22F) under vacuum for 12 hours before i put it in room temperature, and it still melted. I also tried putting it in an icebox with cooling clamps around it so it would not heat up too fast, but it melted anyway. I am starting to think that the standard tubing with the 1/4" vacuum pump fitting may be too small.
Great build
do you think a freezer motor would work as vacuum or would it be too weak ?
They don’t produce a deep enough vacuum to be considered effective. Although they will register as a complete vacuum on a 29” Hg gauge, it won’t reach into the sub 500 micron you need for this type of purpose.
Can you please explain the hack you talked about at 3:27 I cant understand what youre saying and it's the most important part of the video for me please let me know I would appreciate it a ton
Just pull all the guts out and bypass the temp sensor. Replacing the coolant may also be necessary, they don't get cold enough with stock refrigerant. I ended up setting up a two stage system to get down cold enough. ruclips.net/video/mzeRvdnIP-I/видео.html
Where do you get the money to do all of these projects? Along with being able to afford tools and consumables?
Hey BenNBuilds, thanks for this. I'm working on this build and I have a couple questions:
1. What exactly is a water bubbler and where can I find one (wikipedia says it's just a drinking fountain)?
2. What exactly is this hacked water bubbler used for? Is it just used to freeze the food instead of dry ice, or can it somehow be an alternative to dry ice + isopropyl alcohol as part of the freeze dryer moisture trap?
Just one of those office water coolers that take those 5 gallon water tanks. They have small refrigeration loops in them, similar to what cools fridges but smaller.
Its just an alternative to dry ice, but one loop on its own won't get cold enough (you would have to build a cascade with two to reach anything past -30, but that's a fair bit more complicated) so I really just used it as a supplement test less dry ice, but the effect was likely negligible and not worth it as dry ice is pretty cheap.
How much did it all cost?
it's a shame you stopped making videos
Can that chamber be any bigger?
Hi. I am going to build this freeze dryer! But I require some of the details that I am not clear on:
As far as I can understand from the video, you have to drill 3 holes in each aluminium plate. 2 are the same size and one is larger. Can you provide the sizes in mm?
Also you use 2 types of barbs (?) Is it possible to tell exactly what the names of the 2 types are? Can I get them at a hardware?
Where can I purchase a vacuum gauge and pump? Is it easy to get?
Do you have any heating element in the main food chamber?
Thank you!
Shaakira J Go for it!
I drilled and tapped one 1/2" NPT hole in the food chamber plate and two 1/2" NPT holes in the cold trap plate. I also added a 1/4" NPT hole in the food chamber plate for a gauge. The sizes aren't super critical, but I wouldn't go much smaller than 1/2" NPT (~18mm hole).
I used 1" hose witch was a bit big, just go for 3/4 ID it will be a TON cheaper and easier www.pchemlabs.com/subcatagoryb.asp?pid=PVC-Clear-Spring-Reinforced
I just got the hose barbs and adapters off amazon www.amazon.com/dp/B000LNMQTO/ref=biss_dp_t_asn
And an A/C service pump, anything above 3CFM will work www.amazon.com/Arksen-Single-Rotary-Vacuum-Refrigeran/dp/B00E8SXLOC/ref=sr_1_6?ie=UTF8&qid=1425624780&sr=8-6&
To heat the food in the main chamber I used a IR lamp (from the pet store)
Nice Build! What happens if you don't cool it? Wouldn't it suffice to just put in the deep freezer with around -15°C?
Thank you!
Water will be a vapor in a vacuum above -35ish, -50 to be safe. if all the water from your food went into the vacuum pump it would wreck it possibly after just a couple hours of pumping. The water just collects in the pump oil and rusts all the inner components very quickly. The vapor trap stops that from happening only because it's cold enough to freeze the water inside a vacuum
^^? So it would be okay, if i put the food upside down on a gitter? Then it might work?
Dito Not sure what you mean, the food needs to be exposed to vacuum
great vid....you da boss
I need to be able to get to -80c can i do it with this unit ?
Candy works best for freeze drying
What is the dry ice alternative bubbler thing?
what can we use instead of dry ice?
How come the food doesn't need a freeze chamber? I thought it had to be at water freezing temp to sublimate, which is even lower inside a vacuum. You and another person have the same thing going on and I'm confused why the food doesn't need a cold chamber
You just super freeze the food and that usually lasts long enough to keep it in the vacuum chamber ?