Preparing the substrate
Mushrooms are grown from a growth material called 'substrate'. To create the substrate, cassava or yam peels are dried and then milled. Water, lime and rice bran, are added, and the substrate is mixed and heaped into a pile on the ground. It is then left to ferment for 28 days. The compost needs to be turned every 4 days for proper aeration and uniform composting.
Bagging the substrate
Water is added (distributed evenly) to the nutrient rich substrate to the required saturation of 65-70% thus providing everything the mushroom mycelia will need to grow. The substrate is then put into high density polypropylene bags, compressed down and tied with elastic at the top. Cotton is put over the hole to keep the moisture in. The hole will serve as a point of entry for introducing the mushroom spawn.
Sterilising the bags
The bags are placed on a rack in an oil drum with water at the base of the rack. The drum is then heated over a fire. Once steam starts emitting from the tank, it is timed for 2.5-3 hours. The bags are then allowed to cool and then taken to the shaded inoculation room.
Inoculating the bags
The substrate is then ready to receive the mushroom spawns. These are poured into the neck of the substrate bag, and the cotton is replaced on top. The bags are then sent into the incubation room and they remain there until full colonisation of the substrate. The temperature in the room should be 28-30degC max.
Growing the mushroom
After 4-5 weeks in the incubation room the substrate bag turns a white-ish colour and it is ready to open. In contact with the air, the mushroom mycelium begin to grow mushrooms. It will take 24-36 hours for the mushrooms to reach the mature stage when you can then harvest them.
Harvesting the mushroom
Once the mushrooms are fully matured, they are then detached from the substrate and are ready for eating, drying or for sale.
Mushrooms grown from cassava peel substrate have been found, through the Gratitude project, to have high nutritional value. They are rich in protein, carbohydrates, minerals and vitamins, and low in fat.
At the Food Research Institute, staff at the Mushroom Unit are looking at different substrate formulations with sawdust to ensure high yields of mushroom, then finding ways to upscale or optimise the growth conditions. They will then disseminate this information to smallholder farmers.