Freeze Dryers and Freeze Dried Food (Part 1)

[finishman2000]

lol since my wife says I have every man toy ever invented I already have one.

Temp, water vaper, ice in chamber and vacuum all play a part in the time of cycle. I just wish you could see the temps at certain mp readings. I'm sure the machine is doing it anyway or it would be a simple thing for them to do. it would also allow us to fine tune our freeze time and give us the chance to speed things up.

[peggy w]

I to have found that if it stays in the second stage too long that I need to turn it off, put my trays in the deep freeze and defrost the FDer, when they go back in it is usually really quick finishing.  I add 2 hours freeze time to make sure everything is cold enough to dry properly.

[Rett]

Getting our FD this week! Read all 19 pages of this forum and look forward to applying the valuable lessons learned. Three questions I have since I am new to this and don't really love to cook,

1. Does every thing I FD need to be pre-frozen like fruits,eggs, leftovers or even meat?

2. Can I take prepackaged frozen meals like Lean Cuisine or burritos and take them out of the box or wrapper and put on tray to FD?

3. What is the process for FD raw eggs, are they scrambled first and just poured on the tray? Sorry for the basic questions but I did not see these answered in any of the posts I read. I am excited to get started on this new venture.

[Deryn]

Hello and welcome to the forum, Rett.

 

1) No, you don't have to freeze everything before putting it in the freeze-drier but if you can it will probably do its job faster.

 

2) No reason why you can't do that as far as I know. You don't really even have to remove them from the wrapper but you will have to make a slit so the vapor can escape. You should remove the box though if they are in a box. And remember the height issues with drying anything in a HR drier - 1/2" works best. You can do a bit thicker but it will take longer. In the HR drier, the tray slots on the holder are a bit limiting as there are sensors/heaters on the underside and they are only about 2 inches apart.

 

3) I haven't done raw eggs myself however I believe I read that it is best to scramble them before FD'ing.

Edited January 26, 2015 by Deryn (log)

[JimR]

Third installment of FD’ed foods testing.

Fruit

Apples (fresh, sliced in wedges): Didn’t FD in one cycle. Pieces to large. The pieces that finished on first cycle dry eating very good. Rehydrated good in water (5 mins). Came back like a cooked apple. Should be great in cooking.

I then used a paring, coring, & slicing tool to have slices peeled and  ¼” thick. I even put them in two layers. All FD’ed in one cycle.

Bananas (fresh, sliced ½“): FD’ed good in one cycle. Dry eating very good with strong flavor. Have not rehydrated as the dry eating was great. Should be great in cooking.

Blueberries (frozen, whole): FD’ed good in one cycle. Dry eating had very good flavor. Put them in my cold and hot cereal with good results.

Cantaloupe (Fresh, dices): FD’ed in single cycle. Dry eating good. Have not tried to rehydrate yet. A good dry snack.

Cherries (fresh, whole, pitted); FD‘ed good in one cycle. Dry eating good with a chewy texture (because of the sugar). Have not rehydrated as the dry eating was great. Should be great in cooking.

Also FD’ed frozen cherries from the frozen section of the store. FD’ed very good in one cycle. Put them in my cold and hot cereal with good results.

Cranberries (fresh, whole): Did not FD well. Some of the berries would not FD even after two cycles. The ones that did FD have a very strong and tart flavor. It would be too much work to cut each berry in half, however, it might FD good if you ground the berries and then spread it thinly on the tray. This should be good in cooking.

Grapes (fresh, halved): FD’ed very good in one cycle. Dry eating was very good. Have not rehydrated yet (don‘t know why I would).

Mango (Frozen, ½” pieces): Most pieces FD‘ed good except the larger pieces. Dry eating very good. Put them in my cold and hot cereal with good results.

Pears (fresh, slices): FD’ed very good in one cycle. Dry eating was very good. Have not rehydrated yet.

Pineapple (Frozen, ½” pieces): Most pieces FD‘ed good except the larger pieces. Dry eating very good. Put them in my cold and hot cereal with good results.

FD’ed canned pineapple slices. FD’ed in one cycle. Dry eating was very good. Should be good in cooking. Why FD canned pineapple? Prep is nothing, save almost out of date cans, or you got a good buy on them.

Peaches (Frozen, ½” pieces): Most pieces FD‘ed good except the larger pieces. Dry eating very good. Put them in my cold and hot cereal with good results.

Strawberries (Frozen, ½” pieces): Most pieces FD‘ed good except the larger pieces. Dry eating very good. Put them in my cold and hot cereal with good results.

Misc FD’ed Foods

Broth Paste (Beef & Chicken): We use a broth paste instead of the dry cubes, however, once it is opened it needs to be refrigerated.This is a way to long term storage this staple. Put dollops of paste on tray. FD’ed in one cycle.  

Cheese (Shredded): This was a mozzarella and cheddar mix (pizza) piled ½” thick or a little above the rim of the tray. FD’ed in one cycle. Dry eating very flavorful. Rehydated in water for 10-15 mins, drained, and set for 1 hour. Used it to make homemade pizza. Great for anything the needs melted cheese. You could also use this to make grilled cheese sandwiches.

Have also FD’ed Tillamock Med Cheddar (shedded), parmesan (shedded), shedded Fiesta Mix (Mexican). All FD’ed very well.

Cheese (slices): American and Tillamook Swiss. Placed separated slices 4 high. FD’ed in one cycle. Dry eating good with good cheese flavor. Rehydrated small pieces in water for 10 mins. Still have a little crunch in middle but outside was coming back good. May be try in water longer, drain, and let stand for awhile. Don’t know if FD’ed this is worth it.

Ice Cream (sandwich): Good quality ice cream. Left foil wrapper on but opened. Still felt cool after one cycle. Removed foil wrapper and placed back unto FD’er (which was not turned off) for a 1 hour freezing and 5 hours of additional drying time. Sandwiches were then done. Obviously these are not to be rehydrated, but, are they great dry.

Pumpkin Pie (cooked): My wife cooked a crust less pumpkin pie that has Bisquick in the filling. We cut the pie into ½” thick by 2-3” pieces. They FD’ed on one cycle. Dry eating was very good, however, the pie was very hard, but a great snack. Next time will cut into smaller bite size pieces. Have not tried rehydrating. Might work, might not.

Rice (cooked, white): FD’ed good in single cycle. Have not rehydrated yet. Why FD this? Just a test. Might be useful for instant meals. Should be able to FD flavored rice.

Tomato Paste: For test I put dollops of paste on tray. FD’ed in single cycle. Should be good in cooking. I purchased #10 cans for $4.39. You can use this to make Tomato Paste, Tomato Sauce, Tomato Soup, Tomato Juice.

Milk (1/2 & ½): 1/2" thick ice cubes. Some thicker than 1/2". ALL 1/2" FD'ed in one cycle. The thicker cubes had frozen centers. Rehyrdated well at 1:1. You don’t get the same smooth texture but will be fine for cooking or to add a creamy flavor to dishes.

Milk (Whipping Cream): 1/2" thick ice cubes. Some thicker than 1/2". ALL 1/2" FD'ed in one cycle. The thicker cubes had frozen centers. Rehyrdated well at 1:1. You don’t get the same smooth texture but will be fine for cooking or to add a creamy flavor to dishes.

[finishman2000]

Wow...great post. Thank you very much

[Kerry Beal]

Rehydrated the meatloaf today - added just short of a cup of water to 4 nice slices and left them in the fridge for the day.  Able to sneak it past hubby without his knowledge!  

 

Next thing to try him on will be the rehydrated ragu.  

[Mr. Mike]

Freeze drying raw eggs... I used a pre-scrambled mix..

Here is a HUGE tip... freeze the liq. eggs FLAT first in a freezer... if you fill the tray and put it into the machine unfrozen.. it WILL spill over the edges and make a pretty good mess.

 

One large carton per tray is what you see here... ice build up is HUGE... 3 trays of eggs and something with low moisture (grated cheese) or cooking scrabled eggs and coooking out a lot of the moisture would work better for less ice. 

 

When I do this again.. it'll be 2 trays ea.. liq and cooked eggs.  Should be about right for "typical ice" sidewall build up.

 

Here are some pics of the dried egg mix.. dried, it turns powdery-crystaline.

 

 

Scrambled eggs n cheesy seasoned omlets.

 

 

Eating the cheese omlets is pretty tasty "as is" on the way to work.  Water is needed to wash it all down.

 

Chainging oil.

I drian the entire contents and when it starts to get to the "bottom of the barrel".. I start rocking the pump front to rear to get the "Dregs" out. i.e .chunks.

 

Fill it back up with fresh oil.. bout 1/2 cup ... rock it front to rear and then drain again rocking while draining back n forth (front to rear) to get out MORE dregs.  Repeat until you don't see the dregs come out again.

 

Hope this helps.

 

Mr. Mike

Edited January 28, 2015 by Mr. Mike (log)

[Mr. Mike]

Shredded Cheese Tip:

 

If making anything with shredded cheese.. Sprits cheese hard with a water bottle first to help the rehydration. let stand for a while..-coupla minutes.. sprits as need from there .. otherwise it will stay hard and/or burn in the oven due to being not fully meltable...(if that's a word) lol

 

Mr. Mike

[peggy w]

Thanks for the tip on changing the oil. I was having problems with there being too much nasty stuff left in the oil. I will try it your way when I do my next oil change tomorrow.

[Cowboyartist]

I talked with an engineer at HR and he suggested that when I change oil and flush the pump, to use the used oil to flush.  Use a coffee filter to strain the oil and use it for  the flush.  This way you will not use new oil. 

[Mr. Mike]

TIP: Straining oil:

 

IF you want to strain your oil, using coffee filters is asking for a HUGE mess.  How do I know.  I've fried well over 100 turkeys over the years.. 20 years to be exact.. (I used to teach classes on it before it became really big nationally.)   and I used to strain the oil...

 

Not having anything to hold the filter in place is asking for a oil spill disaster.

 

If you decide to filter your oil, you will want/need to buy one of these devices (See link)  and respective cone filters..  (Tried getting a picture to link.. all were really small jpegs.. this link is better... not pushing this company..... they were the first to have good picture.)  Any good rest. supply or sporting good store that sells turkey fryers.. Academy, Cabelas, etc.. should have this filter frame.

 

http://www.centralrestaurant.com/Fryer-Filter-Cone-Holder-c103p1069.html?gclid=CJ3RiKbitsMCFQisaQod4RoA-w

 

You'll need a pot deeper than the strainer by several inches to allow the oil to strain properly... a turkey fry pot is perfect by the way.

 

To me..strainng any oil is a real pain in the arse....so I don't do it.  It may be viscosity or sediment issue..  soybean oil takes a looong time to filter. even in warm/hot temps.  I may try it for this oil just for the heck of it and report back after this weekend.

 

For others, it may be worth it..... try it and you decide.

 

Mr Mike.

Edited January 28, 2015 by Mr. Mike (log)

[Kerry Beal]

Matt at Harvest Right sent me some pictures of the way they are filtering oil for reuse - will post later.

[Kerry Beal]

Here's what Matt said - 

 

The filter is very simple, but has been working great. You only need 4 things:

 

Quilt Batting

Activated Charcoal: Usually found in pet stores. You need the pellet kinda, not the powder

2 liter soda bottle:

Jar or bucket to catch the clean oil in:

 

Steps to make:

1. Cut 2 liter bottle in half

2. Roll up pieces of the quilt batting as tightly as possible and put it in the neck of the bottle. Put more quilt batting in the bottle to create a bed for the activated charcoal.

3. Pour activated charcoal on top of the quilt batting

4. Add more quilt batting on top of the activated charcoal

5. Put a bucket or jar underneath your filter to catch the oil.

 

[finishman2000]

I would love to see a before and after pic of the filtered oil.

[Pipsqueak]

Hi everyone, some great information here, thanks for everybody's work. I have a couple of comments and a couple of questions. I've had my freeze dryer for about a week and my third batch is running right now. My first batch I ran some strawberries through, quartered they were about 3/4 inch thick. I ran the dry cycle for 8 hours but they weren't quite completely dry. It didn't really matter though because we had them all eaten by the next day. So my question is, do you have any sort of guideline on how to know when the thicker items are finished? Can you tell by the mtorr readout? Or do you just get a feel for it after using it for a while?

I saw in one of the earlier posts somebody mentioned they have a kill - a - watt meter running on their freeze dryer, but I can't Remember who it was. Have you ever checked the power factor when your unit is running? Mine runs about .4 when the heaters are off which seemed pretty low, but I didn't know what to expect.

Anyway, a couple ideas to throw out there and give back to the community a little.

An easy way to check the door seal when you close the door is to shine a flashlight into the edge of the acrylic door. The ring where the seal makes contact will light up and you can see if you have contact all the way around.

One thing I noticed when I had the door seal off was that the surface on the stainless steel cylinder edge was a little rough. I polished it by hand with some microfinishing film to get it smooth all the way around and it seems like it holds the vacuum a little better. The heaters kick in about 6 minutes after the pump comes on.

Has anybody done any reverse engineering on the electronics for this machine? It looks like it's running on an atmega88pa processor. There are 6 pins on the board right next to the processor that may be for a serial connection though I haven't traced them out. If that is the case you could possibly update the firmware on the board. I'm not sure how much support you would get from harvestright on that though. Alternately, somebody could retrofit a unit to an arduino controller and write their own program for it. It would be a fun weekend project.

[Kerry Beal]

The fix I'm interested in considering is a diaphragm pump in place of the oil filled pump so that moisture isn't an issue.  Anyone know if you can get a diaphragm pump that can achieve the vacuum required for the freeze dryer?

[thegrandmammy]

Hi all, my name is Cindy and I also purchased the HR FD in October. We live in Southern Nevada where 8 months of the year we are using a swamp cooler which has proven interesting with the foods I've freeze dried.  I have read all the previous post and must say THANK YOU for the wonderful information and pictures from each of you!  I have completed several fruits, veggies and cooked meats and have yet only had 2 fails which was pineapple and mango, even though I'm sure there are more to come.  Luckily, it was only a tray of each thanks to all of your post on what not to do. My first question, I thought someone posted but can not find it now, about blackberries. Is it best to cut in half or leave whole? Thank so much!

[Kerry Beal]

Welcome Cindy.  I suspect you can leave them whole with no problem.

[Rett]

I ran my first cycle today. A tray of sliced and wedged granny apples, a tray of pears, a tray of precooked meatballs and a tray of precooked breakfast sausage. I also put 2 frozen burritos on the tray. All the apple slices, most of the wedges, all the pears worked but the meatballs, sausage, and burritos had to go back in with the 2nd batch. I put the apples and pears in a mason jar with no oxygen absorber because I knew they would get eaten today. After about an hour the apples started softening up? Anyone know why. The pears still seem dry 3 hours now. The apples were not cold when put in the jar.

I thought the sausage would FD with the default cycle. NO water was in the bucket. Minimal ice in the chamber. I did pre freeze all the trays before adding them to the FDer. I expected to run the meatballs twice since they were frozen and could not cut them in half. I am concerned now why the apples have moistened up in the mason jar. Will oxygen absorber have prevented that. Did not think I needed one since we were eating them today? Any suggestions on what I did wrong

[finishman2000]

if they "softened up" they weren't done in the middle. They thawed and the fd part wicked up the moisture and that is they are soft. high fat foods don't fd well so I'm not surprised that the sausage didn't work out.

[Kerry Beal]

I ran my first cycle today. A tray of sliced and wedged granny apples, a tray of pears, a tray of precooked meatballs and a tray of precooked breakfast sausage. I also put 2 frozen burritos on the tray. All the apple slices, most of the wedges, all the pears worked but the meatballs, sausage, and burritos had to go back in with the 2nd batch. I put the apples and pears in a mason jar with no oxygen absorber because I knew they would get eaten today. After about an hour the apples started softening up? Anyone know why. The pears still seem dry 3 hours now. The apples were not cold when put in the jar.

I thought the sausage would FD with the default cycle. NO water was in the bucket. Minimal ice in the chamber. I did pre freeze all the trays before adding them to the FDer. I expected to run the meatballs twice since they were frozen and could not cut them in half. I am concerned now why the apples have moistened up in the mason jar. Will oxygen absorber have prevented that. Did not think I needed one since we were eating them today? Any suggestions on what I did wrong

[Mr. Mike]

The problem can be from one or two reasons or both.

1. The fruit was not completely dry...even though you thought they were. In this case.. the old adage is true.

It takes just "one bad apple" to ruin the whole bunch. No really. lol.

All food fruit to meat needs to be evenly sliced, cut, layered or pulled for proper and complete drying.

ANYTHING over 3/8" thick will not completely dry as it it too thick to dry in the middle. My rule of thumb is 3/8" max on anything I had this problem with some meat I did that was 1/2+ thick...Dried it to the beeping Completed cycle.. put the meat into a package and overnight..it softened back up. Same thing happened with whole strawberries...I only do thin sliced fruit..if I do any fruit at all.. cycle time takes too long for too little yield IMHO.

OR...

2. When you took out the food it may be dry, but it is still colder than the air on the outside of the machine. i.e. anything colder than the atmosphere temp will start to get a moisture or frost covering on the surface..ever so slightly as it warms up. A principle we should already know about i.e. Sweating glass from cold beverages.

I have had a lot of food "moisten up" or not be as "crisp dry" due to incomplete drying or a little "frost layer" adding an ever so slight bit of moisture back onto the food and re-absorb moisture and get soft in the package. Even if I have vacuum packed it. Fruit-meat.. it doesn't matter.

The biggest piece MUST be as dry as the rest of the product for it to be 'perfectly dry" ..snap those pieces first to test for dryness if in doubt.

Or you may have had those items packed last and it absorbed moisture from the air. It doesn't take much to take the crispness out of the product...promise.

I bet the product was not completely dry is the cause or it took on frost.

Here is how I avoid the "frosting" problem.

TIP: I have everything "ready to pack" as fast as I can as you are working against time for moisture absorption. I have my bags pre-labeled, "flexible funnel" i.e cutting board ready for bag filling, O2 absorbers ready to open, vac sealer on and all ready to go before I take my food out of the machine. When I take the trays out... it's "all elbows" to get it bagged and sealed F-A-S-T.

TIP: I NEVER take out food that is is "cold" from the dryer. If the cycle is "done" i.e. low Torr reading or is says "Completed" and beeping. I am not done with the last "Mr Mike" cycle.

This is what I do:

I will shut the machine off for about 3 minutes, (I don't want to blow out the pump seals on a "Off/On 1 second restart" ) I turn on the machine which restarts the freezing cycle. I turn the freezing time to "0" to start the heating cycle and let the heating cycle run for approximately 30 minutes to "warm" the food/trays back up again.

When I take the trays out of the machine, the food/trays are already warm to hot, it does not take on frost or moisture unlike when its cold and warms up.

Do the "warm up" procedure every time to your food and you shouldn't have a problem with accumulated surface moisture.

An O2 absorbs Oxygen and does not help with moisture..desiccant absorbs moisture.

Hope this helps.

Mr. Mike

Host's note: this topic continues in Freeze Dryers and Freeze Dried Food (Part 2)