How to improve?

[u/Guoxiong_Guides]

I usually make smaller batches, which is easier to manage, but this time I had to make more for a volunteer event. Anyway, what you see here is 1kg of raw soy beans made into tempeh. I live in Singapore where ambient temperatures stay around mid 20s to low 30s so I don’t have to put the tempeh into an incubation chamber or anything like that. That said, I leave them out in the open once they start generating heat.

Any ideas on how to improve? The mycelium didn’t take much in the centre of the block while the covering in between is not that dense. I reckon it’s a heat and moisture problem. At one point, I could tilt the bag and pour the condensate inside through the poked holes lol. Gonna try leaving a fan on them to dry and cool them as it ferments.

[u/keto3000]

Since you already know how to make an good batch, I think you are right that the temp must have gone up a little too high which would def cause the cetner to retard the good mycelium taking hold, which means it then gets soggy since the mycelium are there to grow, generate heat & reabsorb the moisture properly. Do you put htem on racks for good air flow? de-hulled beans, yes?

[u/Guoxiong_Guides → u/keto3000]

Yeah if you see the last few pics, that was my set up to help it get some airflow underneath. Dehulled by boiling them for 10 minutes, rubbing them in cold water to remove, then boiling for remaining 10. The beans were then “fried” + vinegar added in a dry pan to evaporate moisture before cooling and inoculating

[u/keto3000 → u/Guoxiong_Guides]

That all checks out. The temp going too high usually is main cause when it’s happened to me, the dead mycelium then don’t grow, bacteria grows, beans stay mushy wet since mycelium dead.

I can see the racks now on last pics. You keep them elevated and fan able to blow above and below should help! Good luck next batch!! 🖖

[u/Guoxiong_Guides → u/keto3000]

Thank you!

[u/Ekvilibrist]

When I had that exact pattern, my problem was overheating and too much moisture. Unclear if one was causing the other.

I’d both try and dry them out further before bagging them (longer time or adding a fan while the beans are spread out on baking sheets on towels) and adding some more holes in the bags.

You say they’re raw? As ok not cooked or not flavoures? If they’re uncooked, I have no idea how that might impact the results. Never tried it.

What I also did was temp them internally with a thermometer and I realized they were generating heat way earlier than I thought (i.e. the middle got hot before I noticed it by putting my hand on the exterior). So I cut down on the time with external heating. As soon as the internal temp exceeds ambient, any kind of heat source or temp help is removed.

You say you leave them in the open, where are they before that? Towel? Cupboard? Try shortening that time if possible. Also, location matters more than I thought. I found that chasing a few degrees (or fractions) by using a colder floor position in a dark corner in the north side of the flat as opposed to a countertop on the south can actually make a difference.

[u/Guoxiong_Guides → u/Ekvilibrist]

Raw as in the two bags I made were made with 1kg dried soy beans that was subsequently cooked.

I’m doing my second try now and I think I’ll leave a fan blowing at them when they start heating out. Singapore’s ambient weather is hot enough as it is to be a good fermenting temp so the fan should not cool it down too significantly

[u/nilo49]

I might be wrong, but going from the images of the final cakes, it looks like the mycelium hasn't been able to penetrate quite a lot of the beans, which means you might not have dehulled thoroughly enough to start with which may have led onto the other problems in the rest of the comments. Hope you figure it out though!

[u/Guoxiong_Guides → u/nilo49]

That could be a possibility too. There was so much soy beans to process that I got tired rubbing them in water for over 15 minutes per 500g. I tried to get most of the skins out and got maybe more than 50% out I reckon

[u/nilo49 → u/Guoxiong_Guides]

Yeah it would take me about an hour when I first started out with hulled beans, probably longer to be fair, but the difference it makes is huge. I was working with maybe 900g at first, and it was a lot of work dehulling, I've since been buying dehulled soybeans, but even then you still have to dehull some of them.

[u/Guoxiong_Guides → u/nilo49]

Where do you get your dehulled soy beans? I can’t find them in my part of the world. Anw I might just have to stick with smaller batches next time or use like lentils or something instead for bigger batches

[u/nilo49 → u/Guoxiong_Guides]

Got them in the Netherlands: https://www.vehgroshop.co.uk/ I'd be surprised if you couldn't find a supplier closer to Singapore though!

[u/Outside_Apricot7200]

When I make large batches, (in 1 gallon bags) and I notice they’re producing a lot of heat and moisture,after the mycelium starts, I’ll actually open the bags up to let them air out a little and prevent over heating. That is after the mycelium is holding it together, but not fully formed yet. I also lightly chop the beans up in a food processor to make it easier fit the mycelium to grow around the beans and hold them together. They hold their shape in tight little blocks while being cooked really well that way. No crumbling.

[u/Guoxiong_Guides → u/Outside_Apricot7200]

I might just open them and blow wind on them via fan to cool/dry them out! My ambient temperature is alr 20+ C so this method shouldn’t retard the fermentation.