Ever since we became interested in making charcuterie the issue of the precise way to dry the salami, chorizo, and hams has been a critical part of the plan. When we made the decision to sell our produce commercially, one of the requirements from a food standards point of view was a temperature and humidity controlled environment. We had been using a pantry, which has a surprisingly good record for staying within the limits, however it also contained all of our other food, and cross-contamination ruled it out (it is also too small).
I considered the key requirements:
- had to be a sealed space that was clean, and big enough
- It had to be close enough to the house so I could check it every day
- I had to be able to install bits of heating/cooling/wetting/drying equipment
- We had very little money
I spoke to a few people and got enthusiastic support and some great advice (especially about what would NOT work). Thanks in particular to Neil McNiven from http://www.reuk.co.uk ( a great resource for DIY building), to journalist Tim Hayward (tweets as @timHayward, usually quite entertaining) who introduced me to Andy Mahoney (a cheesemaker tweeting as @handyface). I also got generous advice from local competitor Pete Crumby, the Cotswold Curer.
Practically the only solution was to use our tiny garden shed, 4′ x 4′ and 6′ at the eaves. I started by making it as insulated as possible. Following advice from my mate Robin (an expert in house insulation) I ignored cheap aluminium roll stuff and went for a celotex foam based solution, buying lots of sheets of 2″ thick foam with a reflective surface. I then spent a jolly time fitting these inside the shed, with a ruler, stanley knife, and lots of swearing. I did this in high heat (those three days we had this summer), so as it progressed I was working inside a man-made oven. (Picture below shows first layer nearly complete). Having put in two layers of the foam, and used silvery tape to seal up the insides I was feeling pleased with myself until I noticed I had done nothing to the door. What was needed was not only insulation, but as tight a fit as possible. Cue many more hours of sweating and cursing. Even worse I could only test it by closing it on myself, and looking for light gaps, so I felt even more like an oven ready turkey as I hunched inside in the dark and heat.
Before I stared on the controls, I finished off the interior by fitting 1″ round steel rails across the shed, strong enough to hold the volume of salami, chorizo and hams we were planning on producing during the first year.
Hot and Cold
I put in a thermometer, and tested how well it retained the heat. It would certainly stop things going down to zero when there was snow outside, but overall it would still need a lot of temperature and humidity control. I had spent quite a lot of time researching how I would prevent it over-heating so was dismayed to find that the problem was actually how to keep it warm enough. I realised that most projects were based on a storage “room” that was part of (or leaning against) a house or heated building. My little shed was at the bottom of the garden, no huge heat source to rely on.
There are two ranges that the shed needs to maintain. A temperature range, around 15C (11-18 is OK) and a humidity range, 70% humidity (65-75 is OK). Too hot, and the fat melts (and other nasty things happen). Too cold and the curing stops. Too dry and the outer casing dries and hardens and the inside rots. Too wet and mould goes crazy (we got to learn about this one). I found myself waking up to the mantra “fifteen degrees C, 70 percent “. I also started called the shed “the 3 bears shed”.
Obsessed with solar
I was convinced that the energy required to keep the temperature to this range would be possible using a 12v battery, powered by a solar panel (which I had been using in my greenhouse to power a fan based heat sink, anyone remember the TV series “Its not easy being green” with the mad and wonderful Dick Strawbridge?). So I had a 12v power source and fan, now I needed 12v heater, and a thermostat that would switch it on and off.
Fitting the fan into the wall, and drilling holes for air to come in and go out, was actually quite easy. Maplins provided the 1amp fuses I needed, and the fan worked fine from the 12v battery. Now for the heater.
I bought a cheap (and very nasty) car fan heater, and a rather elegant small 12v powered thermostat. With my mate Jamie we tested the whole circuit, and it worked (we thought). It was duly fitted in the shed and I wandered back the next day to find it had already failed. The car fan heater was not the right heat source, intended only for sporodic bursts of heat. I spent ages on the internet looking for alternative 12v heat sources, but there simply weren’t any. I decided it was time to do some maths. I have an physics A-level from a very long time ago and decided I could work out the total energy needed to raise the heat of the shed by 1C. It seemed that a reasonably powered bulb (80w) should handle the heat rise needed, and a mate Robbie suggested the bulbs used to heat reptile tanks, as they give off only heat and no light. Not trusting my own maths I bought one higher powered than calculated, and then tried to run it off the 12v battery. Nope, no chance. OK – AC/DC (for now)
I now had to run a cable extension from an outside plug socket to the shed, drill a hole through the newly insulated shed wall, and bring in a mains power source. The heat lamp worked a treat, rather too well in fact. Leaving it on for 3 hours raised the temperature to 25C, way too hot. I needed a thermostat but the one I had does not work with mains power. I could not afford another one (yet) but experimented with a timer switch on the plug of the heat lamp, setting it to come on for an hour every 4 hours. After playing with this a little it actually keeps the temperature pretty well within limits. The next problem though is that as soon as the heat lamp comes on, the humidity in the place shoots down. I handled this in the very inelegant but effective way of sitting a frame over the heat lamp, then sitting a tray of water on the frame. (Not quite tidied up version in the picture above). The water heats up when the lamp comes on, absorbing some of the heat which slows down the heating (a good thing) while maintaining the humidity (another good thing). I have a large water bottle in the shed, and top up the tray every 4 days. The bottle lasts a few weeks.So what did I learn?
The shed has been running in its final fitted mode for over a month now and the temperature and humidity seem pretty good. I can improve it by buying a lower rated heat lamp, and a mains powered thermostat. I still want to run the whole thing from solar panels, and will persist in looking for the right components. I already had the shed and reckon I have spent around £450 on its conversion (around £50 wasted). I know I still have to sort out over-heating (should we ever have a hot summer) and have some 12v ideas about doing that.
The real proof though will be in the quality of the charcuterie – as we are about the find out.