In-Oven Tempe Incubator Thermostat
The first thing I'd like to report is an improved system for regulating the temperature in the oven during tempe incubation. If you recall, the system I used to use was just to turn on the oven light to heat the oven to about 90 F, and then turn it off once the tempe started giving off sufficient heat of its own.
I have since constructed a temperature regulatory apparatus using a thermostat and a space heater.
Parts:
AC 110~120V Digital Temperature Controller Thermostat F (Got this from Amazon for $13)
Lasko space heater 5420 (got this at the thrift store for $5, you can use any heating element you want, but this one works quite well for me)
Power cords (cut off of lamps I bought for a couple dollars at the thrift store)
4 wire nuts (I had these sitting around, so I didn't buy them specifically for this project)
Total cost: about $20
Assembly:
Snip and strip the power cords and wire them up according to the diagram that comes with the thermostat. I chose to use the one with independent power cords for the thermostat and for the heater, but they can also be wired in series. I didn't use any solder. I just twisted the wires together in the wire nuts (according to the instructions on the wire nut package).
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| The assembled temperature regulatory apparatus. |
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| The temperature regulatory apparatus. I built this thing in the summer, and I don't have air conditioning, so I think the temperature it's measuring in this picture was literally the ambient temperature in the apartment that day. |
I set the temperature to 87 F, and the hysteresis to 2 F, which means that when the temperature reaches 85 F, the heater turns on until it gets to 87 F. The Lasko heater is super powerful, so it always overshoots to 89 F or so. So my temperature range in the oven during incubation is about 85 - 89 F, which is perfect for tempe. I set the temperature probe right on top of the tempe. One problem I run into is that tempe generates heat while it ferments, and I don't have a cooling mechanism (other than manually opening the oven door). So depending on the batch and how much I'm paying attention, the temperature can get into the 90 - 95 F range. Luckily it hasn't been a serious enough problem to ruin a batch of tempe yet (I've ruined a few batches, but I'm pretty sure it wasn't because of that). One way to solve the overheating problem may be to just leave the oven door cracked open all of the time (the heater is plenty powerful enough to heat the whole room if it has to), another solution may be to rig up a second thermostat with a fan or some kind of cooler, or a door opener.
More Kinds of Lupin Tempe
If you recall from my earlier posts about making tempe, the biggest problem with doing it at home is that hulled beans are hard to come by, and it's a real pain to remove the hulls from lupins or soybeans manually. You can definitely make edible tempe without worrying too much about the hulls, but as a general rule, the fewer the hulls, the tastier the tempe. Lupina LLC was kind enough to sell me some "lupin grits" which are de-hulled and cracked, sweet Lupinus angustifolius from Australia, even though they don't usually sell them. I also bought some California grown sweet Lupinus albus from them to try. |
| Lupin grits (made from Australian sweet Lupinus angustifolius) and whole California sweet Lupinus albus |
2.5 cups of dry lupins (from Lupina LLC)
1 tbsp white vinegar
1 tsp Tempeh Starter (from TempehStarter.com)
Equipment:
Saucepot
Baking tray ( 17.25 x 11.5 x 1 inches)
Plastic wrap
Oven (incubator)
some way to regulate oven temperature
Measuring cups
measuring spoons
big spoon for mixing
sharp knife
Food processor with slicer attachment (if not using previously de-hulled beans)
Process:
1. Soak dry lupins over night (I use a saucepan, the same one I boil them in for step 4)
2. Drain
3. if using hull-on lupins, put them through a food processor to slash open and loosen the hulls (see pictures below)
4. Boil for 10 minutes. Scrape off and discard any hulls and foam that accumulate on the top of the water.
5. Drain while still hot (not rolling but not much cooler than that). Drain off as much water as possible.
6. Wait for 10-20 minutes, stirring occasionally. The point here is to let the hot water evaporate off of the seeds so that they aren't damp any more. The seeds should not be dried out, but they should also not be wet. If they are too dry, the Rhizopus won't grow. If they are too wet, other nasty, bad smelling stuff will grow (if I sound like I speak from experience, it's because I do...).
7. When the beans are no longer wet, and are still warm (but not hot), add the vinegar, mix it around, then add the Tempeh Starter, and mix that around.
8. Spread the mixture out in the pan (if you started with 2.5 cups of dry beans, it should be enough to nicely fill the 17.25 x 11.5 inch baking tray).
9. Cover tray with plastic wrap.
10. Cut slits in plastic wrap.
11. Put tray in incubator at 85 - 90 F for 36-48 hours.
Results:
I think the tempe made from the lupin grits is the best tempe I've ever eaten (though I confess I've never eaten any tempe that I didn't make myself). I eat it pan fried in Canola oil. The tempe from the California lupins is also good, but I think it would be better if those seeds were dehulled better and cut into smaller pieces than I did. Next time I'll try using more extensive processing in the food processor.
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| Processing the California lupins |
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| California lupins ready to boil |
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| A nice big tray of tempe made from California sweet white lupins |
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