Freeze Dryers and Freeze Dried Food (Part 2)

[carolinagirl]

I wanted to share my method for filtering oil.  I didn't come up with this idea, but I have been using it since november and it's perfect.  Been filtering and reusing the same gallon of oil for a couple of months now.  The main part of the filter is a 2 liter soda bottle packed with polyfil, charcoal and more polyfil.  Then I screw a Sawyer mini water filter on the end.  The result is perfectly clear oil. I have backflushed the sawyer once with clean oil and it started running almost like new again.  Here's some pictures. 

[Deryn]

Welcome to eGullet, carolinagirl - and more particularly to our freeze-drying fanatics corner of same!

 

Thanks for the oil filtering idea. I will have to try that. Did you cut off the bottom of that bottle at the top so you could pour the oil in that end? Your picture doesn't quite reach up that far.

[palo]

Is this oil specifically related to freeze drying equipment or could it be used for deep frying oil?

 

p

[Kerry Beal]

It vacuum oil - so probably wouldn't use it for deep frying - but you might be able to clean deep frying oil in a similar fashion.

 

[palo]

Thanks Kerry, one of the main drawbacks of deep-frying is the cost of the oil.

 

p

[carolinagirl]

yes the end is cut off of the bottle.  I let the oil sit overnight so most of the water settles out and then pour in all but the last of it in the catch bucket.  I change my oil every batch and have been filtering and reusing the same gallon for over 3 months. 

[carolinagirl]

This is a really good forum.  When I was  trying to decide if I needed/wanted a freeze dryer, this thread and the part one played a huge factor in deciding.  Very worthwhile information here.  I share a link to these two thread on the FB group I am a member of whenever a person needs help in deciding. 

[Deryn]

I blame Kerry for my having a freeze-dryer! Thank goodness she started this thread - though I suppose if she had waited a year or two I might have a pretty red or aqua one, instead of boring black.

 

Where I am now, out in the Canadian east coast boonies, I can't find activated charcoal or a Sawyer mini anywhere close by, but when I go back down to NC soon I will acquire those so I can make the filter because where I am it is expensive to have heavy gallons of oil shipped in so the longer I can reuse what I have on hand, the better.

 

I gather you are either cycling at least 2 batches of oil then (one in the pump and one being cleaned at any given time) or you are not using your system 24/7 if you let the oil sit for several hours before allowing it to release into the catch jars?

 

I hope you will post here often. I don't use FB but know of the group you are probably talking about and wish sometimes I could at least read it.

[carolinagirl]

I use my freeze dryer 24/7.  As soon as I take the food out, I open the oil to drain it and turn defrost on.  When I come back 15 minutes later, I refill the oil and finish defrosting with a hair dryer.  Within 30 minutes of one batch ending, another has started.  The pump holds about 3 cups of oil and I have a gallon that I keep filtering and using.  That way I have time to let oil settle and then work it's way through the filter.  I takes about half a day for the oil to filter.  Keeping a gallon in use means I am never rushed.  always oil in the jug ready for use, oil settling in the catch pail and oil working through the filter. 

 

I don't know if you have access to Amazon, but that's where I get my sawyer filters.  They are about $18 each.  I have a spare one so if and when my original one clogs, I can just switch them out. 

 

I'll try to post here more often.  Freeze drying has become such a passion.  I no longer cook for two......I cook for 10 or more and freeze dry all the leftovers.  I FD raw eggs when my hens lay faster than I can use them and I am gearing up to have a very large garden this year and will be freeze drying so much of what comes out of it.  I have reduced my dependency on my chest freezers so much in just a few months it amazed me.  I have FD pork, chicken, beef (all home grown) and wild venison.  I am starting to open jars of home canned meat and FD it because I know it will keep longer.  It's just amazing what these machines can do! 

[Kerry Beal]

1 hour ago, carolinagirl said:

This is a really good forum.  When I was  trying to decide if I needed/wanted a freeze dryer, this thread and the part one played a huge factor in deciding.  Very worthwhile information here.  I share a link to these two thread on the FB group I am a member of whenever a person needs help in deciding. 

What can I say - I'm an enabler!

[Deryn]

5 hours ago, carolinagirl said:

 I no longer cook for two......I cook for 10 or more and freeze dry all the leftovers.  I FD raw eggs when my hens lay faster than I can use them and I am gearing up to have a very large garden this year and will be freeze drying so much of what comes out of it.  I have reduced my dependency on my chest freezers so much in just a few months it amazed me.  I have FD pork, chicken, beef (all home grown) and wild venison.  I am starting to open jars of home canned meat and FD it because I know it will keep longer.  It's just amazing what these machines can do! 

 

This is exactly what I need to make myself do. I am a sporadic user rather than a 24/7 one - and I should be the latter. I still (though I am alone now) seem to buy and waste food for 10 (when my freezer is full) because I have not gotten out of the habit of cooking for many at a time - and may never do so. In addition to that, I have to go so far to get many ingredients that I tend to overbuy them and then they go bad before I use them up.

 

I definitely agree though a FD IS the way to go - I haven't used my pressure canner now in quite a while, or even my dehydrators. I have great success with local fish, venison, lobster, crabs, shrimp, etc. and am trying to educate people in this area about (beginning with the basics) what a freeze-dryer is and what it does/what I can do with it - almost hoping they may come to me and ask if I could do a load or two for them. There are so many fisher-people in this area so I thought some might bite but, so far, no takers ... strangely enough, not even any excitement at all .. which I think is kind of sad but I will keep (slowly) trucking along alone with it I guess. I did tell my daughter that when I am gone, she can sell all my kitchen equipment and I was amazed when she said of all the things she knows I have she would like the FD (and my Thermomix).

[carolinagirl]

I think people aren't excited because they really don't understand how FD is different from dehydration.  I know some people keep wanting to call the freeze dryer a dehydrator.  I know most people kind of get a glazed over look when I tell them about it. lol.  It's not until they see and taste the food that they realize it's something very different and very special.  I think it may be a couple more years before people begin to understand.  Most people think you are nuts when you tell them you paid $3500 for a kitchen thing-a-ma-jig.  So I don't bother telling most people.  I don't discuss it on my public facebook page, only in the private groups.  Surprisingly, my 85 year old dad (who is VERY frugal) thought it was an awesome idea.  That surprised me.  I couldn't exactly hide the machine when the whole family came over for Christmas dinner, so I made sure I had some real special treats for people to try.  It's going to take time for this machine to become more main-stream.  And it still might not because of the price.  But I feel good knowing that my delicious home grown meat won't freezer burn and become dog food.  It's safely stored away in mylar. 

[SatelliteDr]

Is there any way to adjust the "tightness" of the locking handle on the HarvestRight plastic door?

 

After four months of nearly continuous use, I happened to be next to the FD when it switched from the freezing mode to drying and the vac pump came on.  The silicone gasket on the door did not seal this time and it was leaking, causing the vac pump to run with a high exhaust flow.  I looked at the door and saw that there was no visible contact seal, so I pressed it closed with my hand and the vac pump was able to make enough progress so that the differential pressure across the door held the seal tight for the rest of the processing.

 

I have already adjusted the hinge side pivots so that there is a small contact seal visible on the left half of the gasket when the door is closed normally, but it looks like the latch side needs to be tighter, too.  I haven't taken the latch apart (yet!) but I don't see any obvious way to adjust it to make a tighter seal.

 

Does anyone know if the latch can be adjusted?

 

In the meantime, I hold two flat washers between the latch bar and the bail as I close and latch the door, and this forces the door to be a bit tighter on the seal.

 

Thanks.

 

Dave

[Deryn]

Hello, SatelliteDr ... and welcome to the eGullet forums.

 

Have you talked to HarvestRight about this problem? I would not adjust the hinge side until I had spoken with them - seems to me I read something about that in the info that came from HR when I first got my FD. But maybe you did and that, and using the washers, were things they told you to do?

 

And have you always followed the suggested procedure to check for a good door seal (using a sheet of paper) before you start up the machine? And do you always make sure you rotate the handle that extra quarter turn so it is really sealed? If you adjusted the hinge side, perhaps that also knocked the whole door out of whack somehow?

Edited May 9, 2016 by Deryn (log)

[SatelliteDr]

Thanks for your prompt response.

 

Yes, I emailed an inquiry to HR right before I posted my initial question on eGullet.  It's the peak of the strawberry season here in northern AL, and berries wait for no one, so I needed some help quickly.

 

HR also responded quickly today via email with a link to their instructional video on door adjustment.  It discusses both hinge- and latch-side adjustments.  Their instructions are very clear and I was very pleased with their design and the fast response to my question.  Here is the link:

 

https://drive.google.com/file/d/0Bw_1ML6nWMC7TkpQSjJiSkQzVzA/view

 

Minimal tools are required and the video shows how to check for proper adjustment.

[Deryn]

Glad you got the answers you needed so quickly. HR has always, in my experience, been very responsive - they have great customer service in my opinion.

 

Good luck with those strawberries. Do hope you continue to post from time to time here on eGullet.

[TXHCMark]

I am new to the FD, got it a couple of weeks ago.  One item I was hoping to FD was a GF elbow pasta, ground beef and Prego sauce for my Daughter.  This may sound odd, but she is iGg responsive to dairy, wheat, soy and peanuts.  Add to that, she is special needs, so preparing food in advance is a big thing for us.  With any travel or such, food is a big logistic item.  

So, I FD'ed one of her cooked meals of the above and it FD'ed fine.  Reconstituted fine too.  However, she noticed it tasted different.  At first, I thought it was her being picky, but it did "loose" something in the process. After reading this forum I saw brief mention that vinegar is "lost" in the process and that Maltodextrin may be added to help preserve the acid, to keep the "twang" in the sauce.

 

Any suggestions?

 

As a side note, this forum and the previous thread (23 pages) are amazing.  I think someone should make a "Mr. Mike is Great" t-shirt.

 

Thanks,

Mark

[TXHCMark]

I saw CarolinaGirl's way of filtering oil.  I thought it was a great idea, as I had a few of those filters around anyway along with the activated char.  Somehow, someway I found myself googling oil filtration and ran across the "TP Oil Filter" invented back in the 50's.  Seems some are using them today with great results in vehicles and other equipment.  So, I grabbed a 2 liter bottle, pulled the cardboard out of the center of a roll of TP, and it fit very tightly in side of the bottle that I cut the bottom off of.  I was initially going to use the water filter as well, but I figured I would run it without just to see how it does.

I gotta say, it does really good.

 

Before - this was a single run of new oil.  I dump all oil every batch.  I plan to filter, then re-use.  Clean oil = happy pump.

 

 

The Setup - there is about 2 inches below the TP.  The TP is compressed a bit where it funnels in.  The oil did slow down when it got to this, but it would just help.  At the moment, I have the bottle taped to the jar to keep it from falling over.  I'll make a stand and probably put a cap with tube that would drain directly into a clean oil jug.

 

After:  sure, it is yellow.  The orig oil has a slight tint.  But all oil changes color when heated.  Nice a translucent.  I see no need to run any other filtering.

 

 

The nice thing about this setup, is when you feel the TP is not moving the oil well enough, toss it all, make a new one.  Oh, I used Charmin as that is what I had handy.  I have read that Scotts 1000 works very well on the vehicle filters.

 

Mark

Edited July 20, 2016 by TXHCMark (log)

[TXHCMark]

I forgot to mention - it catches water.  The current seller of the TP filter (I think it is Franz) notes that water is trapped in the TP.  Seems quite a few people are using it to clean (real term is polish) diesel fuel that has been sitting for some time and has algae and water in it.  I read somewhere each roll can handle about 6 oz of water.

Since the main goal for this is to remove that crud and water, I'll probably replace my setup every month or two.  Lets face it.  Too easy to make another.

 

Mark

[douglai]

I just got my Freeze Dryer from HR. The freezing went fine, but with the drying it has not got below 500 m Tor. It was around 800. I tightened everything, and opened it and cleaned the gasket etc. after 90 min it is down to around 599. It continues to drop some, but now stays around 550. It doesn't ever sound like the motor goes to a hum at all. Appreciate any help. After 2 hours 5 min it has finally dropped below 500. I have 2 trays of bananas, and 2 trays of apricots in.

 

[TXHCMark]

During the normal drying cycle, it will vary between 500-900.  In the final dry, you will see it get down to sub 500.  I think mine has a small leak, but still does a fine job.  I see no lower than 450, however, HR did send a new hose and need to swap it out.  I wouldn't worry just yet.  Different foods affect the pressure too.

[TXHCMark]

After filtering about 1.5 Gal of oil, I the TP filter is working great.  I did see a few drops of water in the bottom of the jar near the end.  Easy enough, I don't pour that back into the jug.

[SatelliteDr]

6 hours ago, douglai said:

I just got my Freeze Dryer from HR. The freezing went fine, but with the drying it has not got below 500 m Tor. It was around 800. I tightened everything, and opened it and cleaned the gasket etc. after 90 min it is down to around 599. It continues to drop some, but now stays around 550. It doesn't ever sound like the motor goes to a hum at all. Appreciate any help. After 2 hours 5 min it has finally dropped below 500. I have 2 trays of bananas, and 2 trays of apricots in.

 

douglai,

 

I had similar problems, but with excellent help and service from HR, our FD is back up and running properly now.

 

We purchased our FD in Jan 2016 and used it successfully, and nearly continuously, until April when we started exhibiting very long batch processing times.  Initially, we could finish a batch in 24-30 hours depending on the type and quantity of food in the batch.  The processing times got longer until they were 50 hours or longer and on several occasions, the food never dried properly.  The freeze stage always performed properly.  My problem was in the drying stage .  I watched the temperature and pressure on the screen and observed symptoms similar to those you described.  In particular, the temperature would be essentially constant at about -20F and the pressure would hover somewhere above 500 mTorr.  As THXCMark pointed out in a separate post, the pressure typically will cycle between 500 and ~900 mTorr during the drying stage.  At first, I suspected a problem with the heaters because they did not come on and therefore, the food didn't dry.  But the problem was that I had a vacuum leak.  The heaters are controlled by the computer (in the HR FD) and are not commanded on until the pressure gets below 500 mTorr.  When they turn on, the ice in the food sublimates, water vapor is captured on the chamber walls as ice, and the pressure rises (as it should).  When a max temperature threshold is reached, the heaters are turned off and the pressure is pulled back down to 500 mTorr and the cycle repeats.  The pressure in my FD was not getting down to the 500 mTorr threshold (due to a vac leak) so the heaters were never switched on by the computer.

 

I had several phone calls with the service department at HR and the techs were all very helpful.  They had me pull the logs from the FD and email them to HR so they could  help diagnose the problem.  The log is a csv file (comma separated value, plain text file) that can be imported into a spreadsheet.  It contains the minute-by-minute details of pressure, temperature, heater status, and the mode in which the FD is operating.  The following table contains the first few rows of the csv file from a successful (nominal) freeze drying session.

TimeStart TimeStamp Pressure Heater Heater State T1 T2 T3 T4 Heater Secs Stage P I D B 006-1 B 006-1 3/12/2016 12:25 3/12/2016 12:25 5000 0 0 76 -- -- -- 0 Drain 0 0 0     1 42441.51806 5000 0 0 76 -- -- -- 0 Freeze 0 0 0     1 42441.51875 5000 0 0 76 -- -- -- 0 Freeze 0 0 0     1 42441.51944 5000 0 0 75 -- -- -- 0 Freeze 0 0 0     1 42441.52014 5000 0 0 75 -- -- -- 0 Freeze 0 0 0     1 42441.52083 5000 0 0 74 -- -- -- 0 Freeze 0 0 0     1 42441.52153 5000 0 0 73 -- -- -- 0 Freeze 0 0 0     1 42441.52222 5000 0 0 71 -- -- -- 0 Freeze 0 0 0       A table of numbers can be pretty dry, but if you plot the data, it looks like this:

These plots have been useful to me to show how well the system is working.  There is a subplot for each of the three stage types.  The total batch time was just over 24 hours with the default 9-hour freeze stage and 7-hour final drying stage .  Pressures are plotted in black and use the scale on the left.  Temperatures are plotted in red and use the scale on the right.  The heater is enabled when the blue line on the bottom of each plot is high.  The heater is actually on when the green line is high.  During the drying stage, note that the heater does not get turned on until the pressure drops to 500 mTorr and it takes about 30 minutes for each temp/pressure cycle during the stage.  Also note that the pressure during the final dry stage typically stays under 500 mTorr.

When I had my vac leak problem, my plots looked like the following:

The freeze stage went fine.  However, during the drying stage the pressure never got below 500, so the heaters never came on and there was no freeze drying happening.  There is no subplot for the final dry stage because the FD never switched over into final dry stage.

During a separate failed attempt to process a batch, the results were as shown in the plot below:

Again, the freeze stage was fine, but the FD took 17 hours to pull the pressure down to 500 when the vac pump turned on at 8AM and there were only three more cycles completed before I turned the FD off because it clearly was not working properly.  These three cycles took an average of about 4 hours each instead of the nominal cycle time of 30 minutes.   I worked through a series of diagnostic steps with the techs at HR to ensure the various vac connections and the hose were not the problem.  HR then suspected that the problem was with my door gasket and a replacement gasket solved the problem.  There was no smoking gun test result that pointed specifically to the gasket as the culprit, but the other tests narrowed down the possible causes.   I installed a new gasket and now I'm getting performance like this:

It's interesting to see that the details are different from the first (nominal) plot, but the overall characteristics, thresholds and times are similar.  (The "bump" in the temperature just after 9PM in the freeze stage was caused because I pre-chilled the empty FD for an hour before I opened the door and inserted the trays of pre-frozen food.)   So, a long story about my problem and its cure ... back to your question.  The problem you described sounds a lot like what is shown in the second plot in which my FD never got down to 500 mTorr due to the vac leak.  My leak was caused by a faulty gasket, but unfortunately, there are several other fittings and components where a leak could occur.  I encourage you to contact HR tech support and work with them to determine how to fix the problem.   BTW, HR emailed me directions for downloading the logs.  There may be different procedures on other HR FDs, but on my FD, I turn off the power, insert a thumb drive into the USB port on the right side of the FD, then turn on the power.  Watch the screen.  When it's finished downloading the logs, you will see the regular screen appear.  You then just remove the thumb drive and move the files to your computer for review.    Good luck.   Dave

[palo]

Sounds like something I might like but what is the initial investment?

As well the process taking 48+ hours seems like a lot of electricity usage.

 

p

[TXHCMark]

Yeah, typically a batch that I have seen is about 30 hours.  Take note, not to overload the machine.  It can only handle so much water before the need of defrosting.  I am trying to minimize my efforts in the process, rather than trim off an hour or two here and there.

SatelliteDr,

I love the graphs.  I was going to try to do this in Excel, but after messing with it, I figured I may try to run it through one of my linux servers tools, like rrdtool.  Would you mind posting what you have done?  We all love pictures.

 

Mark

Edited July 25, 2016 by TXHCMark
type (log)