Persistent Contamination in Tempeh

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Persistent Contamination in Tempeh

Postby gkowash on Wed Nov 09, 2016 9:11 pm


The majority of my attempted batches of tempeh have fallen victim to contamination. They look great for the first couple days, but inevitably the wet slimy patches appear and begin taking over. I believe it's some kind of Bacillus bacteria.

Here's my procedure:

~~I soak two cups of beans overnight, then boil them for around 45 minutes.
~~After draining, I return them to the pot over low/medium-low heat and stir to evaporate the excess water.
~~I then transfer them to a food processor and chop them roughly. I've never had success with any hulling methods so I leave them in.
~~I pour them into a bowl, mix in two tablespoons of vinegar, and thoroughly distribute the starter (from Cultures for Health) throughout the beans.
~~I scoop the mixture into ziplock bags punctured with many small holes and place them in my incubator, covered with a towel.
~~I let the incubator cycle between 29 and 32 C (sometimes 30-32), until they begin putting out their own heat, around 16-24 hours.
~~I turn off the incubator and leave them inside, checking on their progress 2-3 times a day until they're done, or, more likely, showing signs of contamination.

The food processor, bowls, utensils, bags, and my hands are thoroughly washed with soap and warm water shortly before use. I've used bleach on occasion, but I'm under the impression that it's typically not necessary.

I have ideas for how to proceed with this, like washing everything with bleach, soaking or cooking the beans with vinegar, and using pre-hulled beans. I'd greatly appreciate it, though, if anyone can offer suggestions or point out some glaring flaw in my procedure. Fresh tempeh is one of my favourite foods, and I'd love to start having success with it. Thank you so much!
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Joined: Sat Nov 05, 2016 1:28 pm

Re: Persistent Contamination in Tempeh

Postby Tibor on Thu Nov 10, 2016 12:52 am

I see a few places that things could be questionable. The food processor, how you dried the beans , the punctured zip locks and how long the process took you. Moisture in tempeh making is critical but too much will do what you describe.
There is most definitely a learning curve to making delicious tempeh. Black eye pea and garbanzo are my favorites.
I add the vinegar to the water when I boil the beans ,not afterwards.From my experience and from what I have read, you want to split the bean into it's halves from the hull .By using a food processor ,you end up with more mash which could hold more moisture. Also,I believe, when you inoculate you have a lot more surface to cover. Separating all the hull is not critical, as long as you dry the beans to the moisture level needed to inoculate. I use clean large kitchen towels, first toss around with one and then transfer to a second one. I sterilize my bowl, my utensils and the pyrex bread pans I use to make the tempeh in.I've never used bleach.
The zip lock way has never appealed to me and how it's punctured and how it gets circulation is critical. Using a pan ,there is lots of air space and a cover with just the right amount of holes for circulation and keeping in enough moisture for the spores to produce the lovely nutty smelling white carpet covering and impregnating the half beans. My tempeh is done in 24 -32 hours at 86-92 degrees with even dispersed heat.
I know people have success with zip locks but it's plastic and a petroleum product. I've used Cultures for Heath's spores and they are pretty good.
I hope this helps. Good luck !
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Re: Persistent Contamination in Tempeh

Postby gkowash on Thu Nov 17, 2016 1:04 am

Thank you, I really appreciate your thorough feedback!

I have a new batch which is nearly done--it looks and smells perfect. I skipped the food processor step by doing my best to hull the beans by hand. Instead of adding the vinegar at the end, I mixed it into the cooking water. And finally, the plastic bags have been superceded by a nice big pyrex dish.

Throwing away block after block of spoiled tempeh was really starting to dash my hopes, so this most recent batch is quite a relief. I'm incredibly happy to be having success with this. Thank you so much for your help!
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Joined: Sat Nov 05, 2016 1:28 pm

Re: Persistent Contamination in Tempeh

Postby bjdmytro on Sat Feb 24, 2018 2:15 pm

Do you have any pictures to help troubleshoot? When I've had this problem, it often has to do with the moisture content of the substrate being too high. The thickness of the cakes, air circulation, temperature extremes, length of fermentation, etc. can all contribute. Also, I find that without a little air circulation, I tend to get a buildup of CO2 in the incubator or hot spots in the cakes that kill the mold and create dead slimy spots in the middle of the cakes. Some people discourage air circulation because they think it will dry the cakes out, but I have better success when I go on the dryer side of things, so long as I am fermenting in plastic bags with little holes.

You also have to make variations based on your climate. I have to adapt different techniques for the different seasons. Further, I keep the temperature under close monitor using a reasonably priced thermostat: Inkbird Itc-308 Digital Temperature Controller Outlet Thermostat, 2-stage, 1100w, w/ Sensor
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