Dehydrating foodstuffs with the Anova Precision Oven (APO)

[TdeV]

I've been posting questions in the APO topic and the Food Dehydration topic, so I thought to join them together. Here's some history of various discussions:

 

Now I have a total of 5 racks for my APO: 2 original and 3 are Hamilton Houseware's 12" x 17" cooking racks which fit the APO perfectly (a recommendation from @palo who said "They fit perfectly, smoothly slide in and out of the grooves and are rigid enough that there is no concern of them popping out of the grooves").  Via Amazon, here for Canada and Australia and here for the US. For the two racks which came with the APO whose rungs are too wide to support drying food, I got Silpat P52 baking mats which have tiny holes in them; this was a recommendation by @JoNorvelleWalker, and do the job perfectly.

 

3 Fruit Leather sheets from Bright Kitchen.

 

The only APO published recipe comes from Scott Heimendinger (Anova) for dehydrating apple chips where he only uses heat on the bottom of the oven. Dehydrating multiple racks means some goo drops to the bottom of the oven which produces jam on the heating element. Does putting the tray over the lower heating element reduce the oven's efficiency? Should the heat source be changed to the rear element? Here's my request on the subject but no answers yet.

 

Resources and recipes:

Mary T Bell: Complete Dehydrator Cookbook (eG-friendly Amazon.com link) and Food Drying With an Attitude (eG-friendly Amazon.com link)

@Okanagancook recommended this https://www.excaliburdehydrator-recipes.com/

 

The APO door needs to be propped open to dehydrate foodstuffs. I have learned that a chopstick (~1/4") is enough space and a skewer (~1/8") is not enough. With the latter (skewer), I opened the oven in the morning (after 12 hours) and all surfaces on the door were full of water and the zucchini were still soft and wet.

 

Here's a discussion of my experiment with marinated zucchini.

 

 

 

Edited August 21 by TdeV
Edited to update links (log)

[TdeV]

@kayb  @Okanagancook @andiesenjiand Everyone,

 

Do you seed roma tomatoes or any other kind of tomato before dehydrating?

 

It seems Mary T Bell recommended drying herbs (in this case basil) at a lower temperature (90°F/32°C) to keep more of the essential oils. My Anova Oven (with the door cracked open) has been at this for 18 hours and the basil is drier but not dry, i.e. still limp. Should I change strategy?

 

Mary Bell also recommends taking all the fat out of ground meat with paper towels, removing all the fatty tissue from other meats and fish, as well as using zero fat yogurt, methinks because, in longterm shelf life, anything with fat might go rancid. I'm not planning on (ever) doing any backpacking with dehydrated foods, so do I need to adhere to these rules?

 

[TdeV]

Also, has anyone cooked beans (e.g. Rancho Gordo) and then dehydrated them?

[kayb]

3 hours ago, TdeV said:

@kayb  @Okanagancook @andiesenjiand Everyone,

 

Do you seed roma tomatoes or any other kind of tomato before dehydrating?

 

It seems Mary T Bell recommended drying herbs (in this case basil) at a lower temperature (90°F/32°C) to keep more of the essential oils. My Anova Oven (with the door cracked open) has been at this for 18 hours and the basil is drier but not dry, i.e. still limp. Should I change strategy?

 

Mary Bell also recommends taking all the fat out of ground meat with paper towels, removing all the fatty tissue from other meats and fish, as well as using zero fat yogurt, methinks because, in longterm shelf life, anything with fat might go rancid. I'm not planning on (ever) doing any backpacking with dehydrated foods, so do I need to adhere to these rules?

 

 

No, I don't seed. I slice the Romas crossways, cherry or grape tomatoes in halves or quarters, depending on size, sprinkle with salt, drizzle with olive oil, and go. Have taken a flyer at drying herbs (sage), and it seemed to work OK.

 

On the tomatoes, if I'm doing a lot, as I slice I lay on paper towel covered racks and salt them there, to let them drain a bit, then move to the dehydrator trays. On my cheapie Ambiano, a round plastic model, I think it may have taken between 24 and 36 hours. Don't recall how long the herbs took.

 

55 minutes ago, TdeV said:

Also, has anyone cooked beans (e.g. Rancho Gordo) and then dehydrated them?

 

Never tried. I've soaked chickpeas, then dried off with a towel, tossed in olive oil and seasoned, and roasted them (200 or so for 3-4 hours), though. Nice snack.

[cyalexa]

On 8/7/2021 at 2:22 PM, TdeV said:

The only APO published recipe comes from Scott Heimendinger (Anova) for dehydrating apple chips where he only uses heat on the bottom of the oven. Dehydrating multiple racks means some goo drops to the bottom of the oven which produces jam on the heating element. Does putting the tray over the lower heating element reduce the oven's efficiency? Should the heat source be changed to the rear element? Here's my request on the subject but no answers yet.

 

In the spreadsheet posted by @JasonsCookingAdventures, plums are dehydrated in a Miele combi-oven using the convection setting. I'm going to try the rear element when I dehydrate figs in my APO. Hopefully that makes propping the door open unnecessary. 

[TdeV]

@cyalexa, so far I have found no difference (in the time required to dehydrate food) between turning on the bottom element or the rear (convection) element. I would like to suggest, however, that propping open the door will speed up getting rid of the moisture. (But I don't know that for a fact, as I have not tested it).

[TdeV]

Addendum: I actually have dehydrated quite a few fruit and veg this summer and fall. I have lots of handwritten notes, so I will try to focus on writing up my experiences. And I've certainly got some photos.

 

 

Edited November 14, 2021 by TdeV
Spelling (log)

[TdeV]

Perhaps one of my most interesting dehydrate/rehydrate discoveries is peppers, including green bell peppers. (Sorry @rotuts).  When dehydrated, much volume is lost. The rehydrated pepper doesn't rehydrate fully and, even after a bit of cooking, is still quite leathery, so it doesn't disappear like a regular pepper would. Also when using the dried peppers, I have a tendency to throw quite a bit (1/3 to 2/3 cup) into the beans or soup or stew. This results in a very strong bell pepper flavour which I find very tasty!

 

In a full Instant Pot I might also add 1+ tablespoon of dried poblano pepper.

 

Yesterday at the farmers' market I bought 3 pounds (1.4 kilo) green bell peppers and a quart (litre) of small colourful bell peppers. This created 3 trays of green bell pepper and 1 tray of colourful bell pepper.

 

 

Fresh, the colourful pepper tray had about half the volume of one tray of green bell pepper (which was also cut into twice larger dice). This is the tray after it had dried overnight. 

 

 

This 600 ml jar contains all of the dehydrated green bell pepper. It's about 2/3 full (couple dessicant packs in there).

So that's 1.4 kilo = 400 ml. You can see there is quite a significant reduction!

 

 

 

 

Edited November 22, 2021 by TdeV
Clarity (log)

[TdeV]

Voilà, done!

 

[JoNorvelleWalker]

1 hour ago, TdeV said:

Voilà, done!

 

 

Beautiful!

 

[TdeV]

 

4-12 oz packets of fresh cranberries (from Wisconsin) were processed according to Spruceeats' advice (boiling water, then tossing and soaking with 1 cup sugar syrup) (link).

 

The process of pouring boiling water on them, leaving to soak, then stirring now and again, meant that the berries were very unevenly "cooked." Many of the berries did not collapse. This necessitated my poking every darn one with a knife. Does anyone have a shortcut for this? Photo above is the dividing line between already- and not-yet-poked.

 

Cranberries were placed on a purée sheet (with a lip) because they were rolling everywhere. Spruceeats said to keep 1/2" space surrounding each cranberry. Ha ha ha ha! I'm thinking they might collapse by tomorrow, then I can transfer them to Silpat sheet.

 

 

Here they are as they went in the APO at noon today (Thanksgiving).

 

 

Does anyone have experience dehydrating cranberries? How have you handled the uneven cooking?

 

Did you find it was worth the trouble?

 

 

 

Edited November 25, 2021 by TdeV
Clarity (log)

[TdeV]

This is half of today's capture of fresh strawberries from the farmers' market. I also got rhubarb (which I will also dehydrate) and broccoli raab (which I will not). 126°F (52°C) for 6-8 hours. If the berries are not dry tonight, I'll plan to freeze them semi-dry on the morrow.

 

 

 

 

[TdeV]

This afternoon I have been reading The Ultimate Dehydrator Cookbook by Tammy Gangloff (eG-friendly Amazon.com link). I've now got a list of more than a dozen items which I *should* have dehydrated by now!

[TdeV]

These are all the strawberries after ~7 hours. They're dry on the outside but still fairly squishy. Went back into the APO this morning.

 

 

 

Following the Gangloff book, the rhubarb was dipped in boiling water for 75 seconds. This rhubarb is mostly green. It's okay to eat, yes?

 

 

 

And, there's still room, so I threw in these tired bananas. I put a heaping tablespoon of citric acid into a bowl, then dipped in the bananas.

 

 

These photos are not mounting the same way I see them, but I don't know why.

 

[TdeV]

No picture, sorry, I just thought to mention my disaster.

 

Friday I had a pretty ripe cantaloupe, part of which got used as melon + prosciutto appetizer, balance sliced into 1/" - 3/4" slices which rested on the Silpat mats until about 6 p.m. whereupon the trays were added to the APO at 125°F/52°C.

 

Next morning I opened the oven, to see if they were dry (almost, but not yet) and decided to eat the one I'd squished. Turning it over, I saw it was covered with black mould. So I turned over the rest. Almost all with mouldy spots. Sadly, all the pieces were tossed in the trash.

 

Which was a shame. The one I ate had a lot of flavour with a whisper of sweetness.

 

Good idea, faulty execution. What I should have done was a bath with a splash of lemon juice or acetic acid.

[ElsieD]

I would like to dehydrate some jalapeno peppers.  I have never dehydrated anything before.  Since I want the seeds as well, I'm guessing I would deseed them, chop the flesh up and take the seeds off the stem ot whatever you call it.  These would get separated from the stem so they are loose.  Since they will be in small bits I'd have to dehydrate them on a 1/4 sheet pan.  Does this sound right?  I guess I would use the app setting to dehydrate them, leaving the oven door slightly ajar.  Any advice?

 

 

[Senior Sea Kayaker]

19 minutes ago, ElsieD said:

I would like to dehydrate some jalapeno peppers.  I have never dehydrated anything before.  Since I want the seeds as well, I'm guessing I would deseed them, chop the flesh up and take the seeds off the stem ot whatever you call it.  These would get separated from the stem so they are loose.  Since they will be in small bits I'd have to dehydrate them on a 1/4 sheet pan.  Does this sound right?  I guess I would use the app setting to dehydrate them, leaving the oven door slightly ajar.  Any advice?

 

 

 

A lot of advice from years of dehydrating ingredients and meals for backcountry trips

My first question is why do you wish to dehydrate the jalapenos. It isn't the best preservation method unless you have to carry them for a week or two in summer temps and there are drawbacks with respect to flavour that's an accepted trade off.

I would simply freeze them whole and when needed defrost and use as you would. Texture would be the same as rehydrated peppers and would taste better.

Just my $0.02.

 

[TdeV]

@ElsieD, one thing I like about dehydrated peppers is that they retain more structure than fresh bell or chile peppers. IMHO, fresh peppers go from crunch to mush very quickly, less so with dehydrated peppers.

[ElsieD]

Thank you both.  I have a tendency to buy a bunch of jalapeños use 1, and the rest turn to mush.  I thought dehydrating them would solve the waste problem.  Mostly what I use them for (I presently have some from Penzey's) is for John's grilled cheese sandwiches.  I just pull my little bag out of the cupboard, sprinkle some on top of the cheese and grill them.  He's happy with them.   Maybe instead of dehydrating them I should just finely chopped and freeze them?  Maybe I could dehydrate some non-green bell pepper because I use them also.  I keep Scotch Bonnets, Habaneros, and some oeruvial peppers in the freezer but those I don't put on sandwich

He's.  They get turned into hot sauce.

[DesertTinker]

@ElsieD Here’s another option and I think it would be a good option for your use. The dried peppers end up more leathery than hard/crunchy. But they also do very well added to wet cooked dishes. I only have this one reference to it in home use. If you search for it on the internet,  it seems to only be referenced in a commercial context. From HPBooks  “How To Dry Foods” by Deanna DeLong, published 1979. I’ve used the method for bell peppers of all colors successfully, the advantages being reduced freezer space used and quicker better rehydration. The conditioning referred to is an easy internet search away “conditioning dehydrated food”

 

[JoNorvelleWalker]

https://forums.egullet.org/topic/149399-freeze-dryers-and-freeze-dried-food-part-1/

 

[ElsieD]

I have another, totally different question.  My sister is coming to visit next week and since she lives right near peach country, is bringing a nice big basket of ripe peaches for me.  One way I would like to preserve some of them is by dehydrating some.  I would do this in the APO, I don't have a dehydrator.  Has anyone done this?  If you have, I would appreciate receiving your guidance.  I also plan to freeze some which I have done before.

[Senior Sea Kayaker]

I'd like to add that when dehydrating many fruits it's a good practice to give them a quick dunk in acidified water (lemon, lime....) to prevent browning during the dehydrating process (and improves the flavour).

Commercial producers of dried fruit generally go with the addition of sodium bisulfate but for home dehydrating I would go with acidified water or even diluted unsweetened pineapple juice.

Just my $0.02 as I've owned an American Harvester Dehydrator and have used it pretty extensively.

 

[ElsieD]

When my peaches arrive, I plan to cut them into eights and dehydrate them.  After cutting, I'll dunk them in acidified water.  Do I need to dry them before dehydrating?  I don't plan to peel them as I will be freezing after dehydrating and I found that in the past when I've frozen fresh peaches, a quick rinse under the tap and the skin comes right off.  I have 5 oven racks, but only 2 silpats with holes in them.  Can I use the perforated pan that came with the oven?  I'll do them at 126F, rear circulation, the oven door open a crack.  I'll expect that it will take 8 to 12xhours.  How much will they shrink?  By about half?  I want to be able to reconstitute them, not have them turn into powder.

 

Does that sound about right?  I appreciate all the help?

 

Elsie

[Senior Sea Kayaker]

@ElsieD

Your plan sounds good.

You don't need to dry your peaches unless you're concerned about any liquid dripping onto the oven bottom.

Going through my notes and my dehydrator manual the recommended temp for fruit is 40 C. / 105 F. so if you can get your oven that low it may not be necessary to leave the door open. They'll be done when the peaches are 'leathery' but still pliable (think dried apple slices).

They'll most likely exhibit a shrinkage of 50 to 70 % (dependent on the initial water content).

Hope this is helpful and please report on your results.