Adapting a Fridge as a Drying Chamber

[wheels]

There have been many discussions about adapting a fridge as a drying chamber for those of us who don't have access to anywhere else with suitable conditions - this is just my take on the problem:

As i see it, to air-dry meat and particularly salami successfully requires 3 things in the drying chamber:

� The correct temperature
� The correct humidity
� Air circulation

This is how I attempted to solve these issues.

First, acquire a fridge:



(�40 - ebay)

Then to solve the problem of it not running at the temperature I want (10�C to 15�C) I used separate control box to over-ride the fridge's own thermostat:



The capillary thermostat (�16) in this control box is from RS Online, it controls power to the fridge via a relay that ensures electrical isolation and increases it's switching capacity. Probably better is one of the digital fridge thermostats that are often available on ebay - just enter digital fridge thermostat in the ebay search box - seller keefybaby often has them.



This thermostat allows me to control the fridge to within a 3� - 4� band.

Next the problem of humidity. Many of us have checked the humidity of our fridges and rubbed our hands with glee to see that the humidity seems OK for air drying, only to find that when we put meat/sausage into the fridge, the humidity soars.

What I needed was a way of reducing the humidity when it's too high, but of also increasing it if it's too low.

I used a Pfannenberg Hygrostat (�32) from RS online. This can be bought online, but RS also have trade counters around the country (see website for details).



The hygrostat switches the live between to outputs with about a 5% gap in between. It is wired through a control box to keep things tidy.



(OK, I know it's a lousy wiring diagram!)

Ideally, it would switch between a humidifier and dehumidifier, but having looked at the cost I decided to use a mini fogger from Maplin (�15) for humidity. This seemed liked a good idea but in practice sprayed water everywhere! The problem was solved by putting it in a plastic box with a hole at the opposite end to the fogger for the mist (but not spray) to escape.



Excess humidity is controlled by using a 'computer case fan' to extract air from the fridge. They cost a couple of quid from a computer shop/online. Mine's recycled out of an old computer.



The humidity is monitored using an 'Exo Terra' Digital Hygrometer (about �7) from ebay or your local aquatic centre. I will also add one of their thermometers in due course.




To complete the set-up, air vents were drilled in the top of the panel on the opposite side of the fridge to the fan to give an airflow around the meat.

Finishing touches - all the holes have had grommets (Maplin) inserted and the large hole for the fan has been lined with a 'bush' (a slice of plastic pop bottle). The outside of the hole has a grill over it (off an old computer) and it will have an insect screen made from plastic 1.5mm mesh from my local aquatic centre (about �2 per metre). The cables will be tidied using sticky mounts that hold cable ties (Maplin).

I need to cut some dowels for hanging things on, and in due course the two electrical control boxes will be incorporated into one unit.



I've got some pancetta curing at the moment, I need some more meat and want to do more chorizo's next, followed by Lonzino, bresaola and salami.



Oh, and the white polypropylene 'butcher's hooks' are from:

http://www.biltongbox.com/shop/index.ph ... at&catId=9

I'm chuffed with the result, and owe a good few salami's to my mate Malcolm (His business makes 'one off' electrical control boxes - you know, when everyone else says it can't be done - they send for Malcolm - he's virtually retired now but still has all his necessary certificates etc so I'm running legally!)

...and what of the old wooden box from my previous attempts?



...well that's being recycled as a 'fermentation' chamber!

Phil

[Rambling Sid Rumpo]

Hi Phil. I know this is an old post, but am very interested in building a drying chamber that could also be used for fermenting beer. I hope you don't mind, but I have a few questions for you.

Firstly, are you pleased with the finished article? Secondly, is the hygrostat connected to the temperature controller and minifogger to the hygrostat? Thirdly, is the computer fan powered via a transformer?

Thanks

[wheels]

Hi Sid - things have moved on since then. I've gone digital!

http://www.localfoodheroes.co.uk/?e=575

However, let me reiterate what I said to another member on another thread:

"Right - from the start.

Firstly, you are looking for somewhere for air drying with a temperature of around 12 - 15°C (ideally) and with a good relative humidity (RH) of around 70% (ish). It's also good if it has a little bit of air-flow; not much, just a little.

A fridge, or somewhere that needs all sorts of electrical devices, should not be the first choice (in my opinion). Do you have a cellar, pantry, outbuilding etc that has these conditions or near to them? You can check with a normal thermometer and a cheap hygrometer - these are cheap on ebay (search for hygrometer) - something like this (not a recommendation - just an example).

If you can't find anywhere that's even near the target figures, then you could consider adapting a fridge or freezer. The minimum in this case will be to control the temperature - one of the temperature controllers from Forttex or a similar one from ebay will do this.

Hopefully that's all you'll need to do.

I guess we're best to leave further adaptions until you've done the above. There's no point going into things at this stage that may be unneccesary.

If you have any problem/questions just post them back here."

Phil

[Rambling Sid Rumpo]

Thanks for the swift reply Phil. I thought that if I was going to build a fridge for drying meat, I might as well try to build one I could use for brewing beer in during unseasonable weather and also get cold enough to make lager in once I get around to it. As a member of a beer making forum, I was hoping to sort the info I need for beer there, the info I need for meat here and then to run the final plans in their entirety past both forums for a final check. Many people who build fermentation fridges for beer use the ATC 800, ATC 800+ or TC 10 from Fortex or their generic equivilent.

Anyway, I do have a cellar, but being mid-terrace and Edwardian, it's not and never will impervious to rodents, so was going to use heavy guage, fine wire mesh and insect screen in any vent/fan holes etc. This has just reminded me that the air in the cellar can be fairly musty, so was thinking I might use a piece of ducting between the computer fan (if used) and an airvent in an outside wall, again with heavy guage, fine wire mesh and insect screen.

So, first things first:

1. Obtain a fridge without a freezer compartment.
2. Use a hygrometer and thermometer to check the relative humidity and temperature of the fridge with, say, some pancetta drying in it, because as you said "Many of us have checked the humidity of our fridges and rubbed our hands with glee to see that the humidity seems OK for air drying, only to find that when we put meat/sausage into the fridge, the humidity soars".
3. If the levels are within those you gave, nothing else needs to be done apart, maybe from a computer fan if airflow is needed as I won't be able to leave the fridge door open.

Does this sound like a good first step? Thanks again.

[wheels]

Mmm... Beer!

Given the dual useage, I'd go ahead and get a digital thermostat. As they're only a few quid different in price, I'd go for one of the 'cool AND heat' variety. By using a fridge and a small heat source you can have total control over the environment for your beer/meat. You could also use it with a slow-cooker for sous-vide and a variety of other uses.

Yes, I'd defer doing anything about humidity until you've run trials of the set-up.

Personally, I'd pursue using the cellar. It seems to me that all you'd need to do would be create an 'old fashioned meat-safe' with some mesh. Were you thinking of something like this mesh?

http://www.ebay.co.uk/itm/280757846429

I'm guessing that rats and such like would find it fairly unpalatable!

Hopefully some other members will comment with their experiences - I know we've some pretty keen brewers around.

Phil

[Rambling Sid Rumpo]

Hi Phil. Thanks for the continued advice. I really would like to give the meat safe a go, but we're a bit limited for space in the cellar and as we've had some furry visitors in the cellar before, I don't really want to encourage them any further. To be honest, I'm more worried about attracting rodents that anything attacking my meat.

As for the insect mesh, thanks for the link, but I think I might be able to get enough plastic fly screen for maybe even enough rodent-proof mesh to go with it.

Anyway, I'm going to clear enough space in the cellar over the next few days, get a wanted ad on Freecycle and Freegle to try to score a free fridge and buy a hygrometer.

Thanks again Phil.

[NCPaul]

I am in a similar position of wanting to use a refrigerator for both beer and meat curing. I know that I can ferment pilsners at 52 F which is at the low end for meat curing, but what would happen to the meat curing when I started to drop the temperature to lagering temps (40 F)? Would it simply be too hard to keep the RH up high enough to prevent case hardening? Can I only overlap these two when the meat curing would finish during early beer fermentation? I'll keep them seperate for the time being until I am at least successful at the meat curing once.

[Rambling Sid Rumpo]

Hi NC Paul. Although I've not experience of using a fridge for either beer or meat, I'd say not to do both at the same time in case the beer became infected by any moulds on the meat. However, if you use an airlock, you may be fine. Have you ever visited http://www.jimsbeerkit.co.uk/ ? - Moderators please feel free to remove link if I am in violation of terms.

[wheels]

That link's fine Sid.

[NCPaul]

I made the change over from beer



to sausage



Wish me luck (I'll need it).

[wheels]

Wow! Beer AND Sausage. Doubly blessed!

[Yannis]

Sausages and beer

Good luck Paul !!!!

[Cedaronics]

Phil

As I'm new to this area of food processing, I need to try to understand the process of curing. Can I ask, therefore:

If you had one humidistat unit that could control the humidifying AND de-humidifying within a fridge (or larder, or room, whatever), would that be sufficient to achieve your aims?

Or is temperature control important too?

I have a humidifying unit that can have plugged into it some sort of extractor fan (230v) and on the other hand a mister - assuming such a thing is available.

Can I also ask, is 82% humidity a desirable figure? Does it need to maintain this humidity for the life of the entire curing process?

Thanks for reading.

Tim

[wheels]

Phil

As I'm new to this area of food processing, I need to try to understand the process of curing. Can I ask, therefore:

If you had one humidistat unit that could control the humidifying AND de-humidifying within a fridge (or larder, or room, whatever), would that be sufficient to achieve your aims?

Yes, one unit would then take care of any humidity problems. It may also be that only one unit is required in a situation where humidity is constant - too high, or too low.

Or is temperature control important too?

Temperature control is very important - aim for 12 - 15°C

I have a humidifying unit that can have plugged into it some sort of extractor fan (230v) and on the other hand a mister - assuming such a thing is available.

Can I also ask, is 82% humidity a desirable figure? Does it need to maintain this humidity for the life of the entire curing process?

Ideally, the humidity of the chamber should be lowered in line with the reduction of water activity in the product. It is very difficult to achieve this - not least because of the cost of a water activity meter! A humidity of around 75% is generally considered to be 'about right'.

Hopefully, other members will add their opinions/advice.

Phil