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Drying cupboard

 
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tahir



Joined: 28 Oct 2004
Posts: 44269
Location: Essex
PostPosted: Thu Aug 18, 11 10:13 am    Post subject: Drying cupboard  Reply with quote    

We will have solar hot water, we'll also have a lot of surplus fresh produce, so I was thinking of putting an extra loop of copper from the solar system into a double height kitchen unit racked out with wire trays as a dehydrator. Is this a sensible idea? Any ideas on how I might do it?

Treacodactyl
Downsizer Moderator


Joined: 28 Oct 2004
Posts: 25697
Location: Jumping on the bandwagon of opportunism
PostPosted: Thu Aug 18, 11 10:17 am    Post subject: Reply with quote    

You've got the heat but how will you get rid of the moisture?

tahir



Joined: 28 Oct 2004
Posts: 44269
Location: Essex
PostPosted: Thu Aug 18, 11 10:20 am    Post subject: Reply with quote    

If we had a mesh strip at the top of the cupboard, would convection take care of it?

Went



Joined: 19 Mar 2006
Posts: 6968

PostPosted: Thu Aug 18, 11 10:23 am    Post subject: Reply with quote    

Interested to follow this and see how you do it...

tahir



Joined: 28 Oct 2004
Posts: 44269
Location: Essex
PostPosted: Thu Aug 18, 11 11:58 am    Post subject: Reply with quote    

Just had a word with our engineer, he says the best way to deal with this is to have a separate thermostat and timer for this loop and a duct into the MVHR to get the airflow and remove the warm air.

The question he asked was what kind of evaporation rate are we expecting to achieve. Any ideas???

Andrea



Joined: 02 May 2005
Posts: 2260
Location: Portugal
PostPosted: Thu Aug 18, 11 1:01 pm    Post subject: Reply with quote    

OH has also had the idea of combining the two, but it hasn't progressed beyond and idea yet. I'm very interested to see how you get on.

cassy



Joined: 04 Feb 2008
Posts: 1047
Location: South West Scotland
PostPosted: Thu Aug 18, 11 2:02 pm    Post subject: Reply with quote    

I've just been working out the area needed in our dehydrator (Excalibur) to dry each kilo of fruit/veg. It varies a lot -

(random examples, pieces close together but not touching)
shallots 0.98 m2/kg
cucumber 2.17
gooseberries 2.28
kale 0.11

Once you know what weight of produce will be in the drying cupboard (when full) and it's moisture content (fruit and veg seems to be between 80 and 90%), I think you could work out the evaporation by deciding how quickly you want to dry it / what time period you want to the lose the water over. It seems that the quicker the better so long as that doesn't mean increasing the temperature.

In our dehydrator -
shallots took 3h at 145 degF
kale took 1h 13mins at 140 degF
gooseberries took 13h 20mins at 135 degF (sugary fruit takes longer than veg)
The temperatures were taken from Mary Bell's Complete Dehydrator Cookbook.

So, if your cupboard had 3m2 of drying space, you could fit in 2.9kg of shallots (moisture content 88%). If you wanted to dry them in 3 hours, the evaporation rate would be 0.86 litres/hour. Or 0.19 litres/hour for the same weight of gooseberries dried over 13 hours.

I hope that helps but it feels a bit "how long is a piece of string", sorry.

tahir



Joined: 28 Oct 2004
Posts: 44269
Location: Essex
PostPosted: Thu Aug 18, 11 4:52 pm    Post subject: Reply with quote    

Thanks Cassy most useful

Mutton



Joined: 09 May 2009
Posts: 1508

PostPosted: Sat Aug 20, 11 5:56 pm    Post subject: Reply with quote    

Looked at Mary Bell's Complete Dehydrator Cookbook on Amazon and it had mixed reviews. Implication is that is purely for an electric power dehydrator. Is that the case?

We are working towards solar hot water, been thinking about drying cupboards, but had not thought to combine the two (duh!). It will be several years before we build anything, but knowing where we need to leave the space is also good.

Cassy - electric dehydrators. How much do they cost to run? How does that compare to bottling? How long lasting are the results?

Mustang



Joined: 15 Jul 2005
Posts: 768
Location: Sunny Suffolk
PostPosted: Sat Aug 20, 11 6:24 pm    Post subject: Reply with quote    

cassy wrote:

cucumber 2.17


What do you do with the dehydrated cucumber?

cassy



Joined: 04 Feb 2008
Posts: 1047
Location: South West Scotland
PostPosted: Mon Aug 22, 11 10:37 am    Post subject: Reply with quote    

Mutton wrote:
Looked at Mary Bell's Complete Dehydrator Cookbook on Amazon and it had mixed reviews. Implication is that is purely for an electric power dehydrator. Is that the case?

Yes, but the discussion of dehydrators is only a small part of the book. The interesting (for me) part is applicable to any drying method i.e. water content of fruit, veg and herbs, how to prepare them for drying, making leathers, what to do with dried produce etc.
Mutton wrote:
How much do they cost to run?

We're off-grid and using summer PV ("excess" that's not needed for battery charging) but here are some figures from the electricity monitor so you can work out what it would cost you.

Herbs at 95 degF - 6 hours at 0.09 kilowatts per hour
Gooseberries at 135 degF - 12 hours at 0.11 kW/h
Kale at 140 degF - 1 h 13 mins at 0.36 kW/h
Shallots at 145 degF - 3 h at 0.39 kW/h

The only drawback for us is that I'll have to stop using it soon as we start to produce less electricity so I probably won't be able to dry apples for example without storing them till next spring. It's our first season with the PV and with the dehydrator so it'll be interesting to see how much I can get done in a season.

Mutton wrote:
How does that compare to bottling?

Haven't tried bottling yet so can't compare but for example, at the moment if I make jam I have to use bottled gas and add bought in sugar, so for us, drying is a cheaper, less time consuming method of preservation with a more flexible end product - you can eat dried fruit as it is, rehydrate it, add it to cooking food but jam is just jam. Dried veg takes up very little room in jars and should be as convenient to add to dishes as frozen veg, without taking up freezer space (and using electricity in winter when we might not have enough as well as the risk of defrosting and losing all our produce).

Mutton wrote:
How long lasting are the results?

Dried foods, stored properly as supposed to last for a long time. Most of the books recommend using up the produce within the year, before the next harvest. We've only started drying stuff this summer, so no long term info but Bloke Off The Telly had been drying for years, he'd be able to tell you more about use by dates.

cassy



Joined: 04 Feb 2008
Posts: 1047
Location: South West Scotland
PostPosted: Mon Aug 22, 11 10:47 am    Post subject: Reply with quote    

Mustang wrote:
What do you do with the dehydrated cucumber?

It's surprisingly salty, like dried celery is. I've just made it for the first time and it's nice as it is, like vegetable crisps but I suppose you could put it in a cooked dish, in a winter sandwich, crumbled on top of a winter salad. It'll add a bit of variety in the depths of winter.

tahir



Joined: 28 Oct 2004
Posts: 44269
Location: Essex
PostPosted: Mon Aug 22, 11 11:29 am    Post subject: Reply with quote    

Cassy you should do an article on your experiences. (Says he who's never submitted an article on anything )

dpack



Joined: 02 Jul 2005
Posts: 35398
Location: yes
PostPosted: Mon Aug 22, 11 11:42 am    Post subject: Reply with quote    

for meat a temp of 70 c or above for part of the drying should be used to kill bugs

for each kilo of wet food there will be about 500 to 700 ml of water vapour

recon a small fan and a thermostatic controlled booster heater might be good features

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