Heaven on Earth Project


The spores needed for tempeh production are often available in, or can be ordered through health food stores. Instructions are available with these satchels. The following technique was developed by the author using self grown spores. Production of these spores is currently discontinued. If it is too difficult to obtain commercially prepared spores it is worth experimenting with home production.

Another method of obtaining spores is possible using commercial tempeh but may require some experimental trial and error to perfect. Ambient temperature, humidity, freshness and non-contamination of the commercial tempeh are the main factors which influence the procedure. Crumble a 2 cm cube of non-pasteurised (live culture) tempeh into small pieces onto a large leaf such as comfrey or flat spinach.. Lightly press the tempeh into the furry side of the leaf and cover this with another leaf so that the tempeh is sandwiched between. Lightly fold a newspaper around these leaves and clip it with staples or paper clips so that it forms a loose, but closed envelope. Hang this envelope over a warm spot. The leaves should dehydrate within a few days. In this time the tempeh should have sporulated showing a black or grey colour. Leave hanging until the leaf and the tempeh is completely crumble dry. When making fresh tempeh finely crumble some of the leaves into bean mixture using the otherwise normal procedure. Crushing some of the leaf in a mortar and pestle and mixing with s few teaspoons of soy or other flour will make it easier to use when mixing with the cooked beans. Try small batches to begin with and determine the strength of the starter. Welcome to microbiology

When the spores begin to vegetate and spread white mycelia throughout the soy beans, a lot of heat is produced which can cause over-heating and spoilage of the tempeh if care is not taken to cool the batch. For this reason 2 kg of soy beans is probably a convenient and manageable sized production run until you are acquainted with some of the problems that are likely to arise. Tempeh production is not difficult but it requires attention to detail. Confidence is achieved after a few production runs.

If you are unable to solve particular problems with production write to the author for suggestions.


1. Thermometer which includes a scale between 25 and 40 degrees Centigrade.

2. Zip-lock plastic bags about 25 cm X 25 cm in size (a larger version of the spore satchel). If you have a plastic bag heat-sealer, any type of plastic bag will do provided it is clean and hasn't been used for other purposes which could contaminate the bag.

3. Incubator. An old refrigerator or any enclosed space which can be maintained at around 30 degrees Centigrade will do. You will need to have enough wire racks to be able to spread out all the bags of beans with space between them.

4. Heating system for the incubator. A room space- heater with thermostatic control will do. Do not use a room heater which does not have an operational thermostat - overheating and fire could result. If you intend using an inflammable (cardboard or wood) box for the incubator, care must be taken that the room heater or other heating system does not cause fire. Whatever heating system you use, make sure you have tried it and tested its ability to maintain the temperature around 30 degrees before you begin incubating your first tempeh batch. Tinkering at production stage can cause failure of the batch.


1. Process 2 kg of soy beans through a grain mill which is adjusted to split the bean in half. If a lot of fine bean grit is produced during milling, sift it off because it may make the tempeh block too dense for oxygen to penetrate into the centre during incubation. The main reason for milling the beans before soaking them is to loosen and remove the hull from the beans. If you do not have a grain mill, you can use a more manual method of de-hulling described in step 3. Soak these beans over night (12 - 18 hours) in about 6 litres of warm water - at about 40 degrees Centigrade. After this begins to cool a natural fermentation process will cause the beans and the water to acidify slightly which will enhance the growth of the spores when they are added to the cooked beans.

2. Tempeh spores need oxygen to grow so the plastic bags must be perforated to allow oxygen to enter them. Take about 4 or 5 bags at a time and with a pin or a needle, pierce a hole all the way through every 1 cm along the width and 1 cm along the breadth of the bags. The entire surface area of the bags should be regularly perforated every centimetre. If you intend to continue with tempeh production it will be worth the effort to construct a special tool which will make perforating easier. The diagram below is an example of a simple to make perforating tool.

3. After the beans are soaked they need to be de- hulled. The tempeh mycelia cannot penetrate the hull so unless all or most of them are removed, production of tempeh will not be successful. You can do this a number of ways but one is simply stirring and scooping the hulls off the surface of the soaking water with a wire gauze scoop. You may have to add more water to achieve this. If you did not split the beans through a grain mill before soaking, you will have to rub them between your hands which will free the hulls and then scoop them off as above. 2 Kg of beans will take about 15 minutes of rubbing. This requires considerable effort but it is essential that at least 80-90% of the beans are de- hulled before cooking. Provided the hulls are split most of those remaining on the beans will become separated during the cooking stage.

4. Prepare the incubator so that it has stabilised in temperature by the time you are ready to incubate the bags of inoculated beans.

5. Boil or pressure cook the de-hulled beans in enough of their soaking water to just cover them. Pressure cooking will take about 1/2 hour, but if simmering allow to cook until they are tender through out. You will need more water for simmering. This will probably take at last one hour. Do not over-cook by making the beans mushy. They will soften more during the incubation period, but if they are under-cooked they will cause early sporulation of the mycelia and will not make a good batch of tempeh. While the beans are simmering, scoop off any hulls which float to the surface. It is possible to use this stage of production to remove the hulls, but the beans should have been rubbed before cooking to loosen the hulls.

6. After the beans are cooked, pour off the cooking water (this makes a good soup stock) and spread the beans over a clean dry cloth, or towel or a fine wire gauze to allow them to cool and dry. They should be free of all surface moisture before you inoculate them with the spores in the TEMPEH STARTER satchel.

8. When the cooked beans are cool and have no surface moisture, place them into a clean dry bowl and then sprinkle the contents of the TEMPEH STARTER satchel (or leaf produced spores) over them. With a clean mixing spoon, gently turn the beans in the bowl to spread the spores evenly over all the beans. Mix gently but thoroughly for at least five minutes it ensure an even distribution of the spores. If you have over-cooked the beans, they may begin to break up and become mushy at this stage. Ideally, they should retain their shape so that oxygen can easily penetrate the mass of beans in the perforated bag.

9. After coating the beans with the spores, package them into the perforated bags. 200 gm of beans will make the bag about 2 cm thick which allows for oxygen to easily reach the centre of the bean mass and to allow heat to disperse once growth begins.

10 Spread the beans evenly in the bag and place each bag on a wire rack inside the incubator. Leave at least 1 cm space between each bag and do not place one bag on another. This will prevent oxygen penetration and heat build up which is likely to lead to spoilage. If you have to layer the bags in tiers of racks, make sure there is at least 5 cm of space between tiers and some space between the edge of the tier and the walls of the incubator.

If you are using a room heater to warm the incubator, position it so that it doesn't blow hot air directly over some bags. You may have to use some deflector to prevent this, and if so, make sure it wont cause over heating of the heater, or cause fire. All this should have been tried and tested before you are ready to load your first batch.

A bowl of water placed in the incubator is not essential but will allow the air inside to remain reasonably moist during incubation.

11. Place the thermometer onto the highest tier and close the incubator. There will likely be no visible activity until after about 12 hours. It will probably be useful to schedule the beginning of incubation so that the first 12 hours is up sometime in the morning otherwise you will have to be getting out of bed to regulate the final hours of production.

Depending of the efficiency of the incubator and other factors growth of the mycelia should beginto appear between 12 and 18 hours from the start of incubation. Under some conditions, no growth activity will be noticeable for about 24 hours. In this case the whole incubation period can extend to over 36 hours. If there is no activity after this time or there is a strong ammonia presence, something has almost certainly gone wrong.

Once sweating inside the bags is noticeable check the temperature is not too high. If it begins to go above 35 degrees open the door of the incubator a little to allow the hot air to escape. Most space heaters have a non-heating setting on their controls. If you have such a heater, switch to this phase once the temperature begins to climb. There will be enough (maybe more than enough) heat liberated by the fermentation to maintain the temperature once growth becomes evident. The temperature may climb to 40 degrees but if it begins to go higher, allow more cooling by increasing ventilation.

12. The tempeh should be removed and allowed to cool once there is a solid white cake. It should not be crumbly and there should be no spaces evident between the beans. There may be some grey or black spots appearing around the pin holes in the bag. This is only spore growth in the areas where there is most oxygen and it does not indicate spoilage.

All the bags might not grow at the same rate. Remove those that are ready and replace the slowest bags in their spot. It is sometimes useful to invert the bags so that both sides have plenty of oxygen. The sides of the bags which face one another between the tiers may become hotter because of the restricted air circulation. Inverting the bags may improve growth.

Once cooled, place each bag into a separate non- perforated plastic bag and refrigerate. If you are keeping the tempeh for more than a few weeks, it will be worth freezing the packs. Deep frozen it should last indefinitely.

Take a careful note of all the characteristics you notice during your production runs. This will help you sort out problems which may arise in future batches.