Substrate pasteurisation drum (200 L)
A 200-litre drum for steam pasteurising straw and maize cobs before spawning. Removes the weed seeds and mould that would otherwise take over your crop.
KES 9,500 each
Pasteurisation is not cleaning. You are not trying to make the substrate sterile, you are trying to kill the weed seeds, mould spores and bacteria that would out-compete your mushroom, while leaving the nutrients the mushroom needs. That is why it is a temperature and a duration rather than a clean-down.
A 200-litre drum is the size most small and mid-size growers start with. Message us on WhatsApp before you buy and we will confirm the drum material, whether it is insulated, and whether the 200 litres is a dry or a filled capacity, because those three details decide how you size your batch..
What it is for
Raw straw, maize cobs, wheat straw and similar material arrive carrying whatever was living in the soil they were cut from. Mixed in with spawn, they usually win: you open a bag two weeks later to find mould instead of mushrooms. Pasteurisation gets the substrate warm enough, for long enough, to kill those competitors.
How to use it
- Chop or shred the substrate into roughly 5cm pieces. Long straw does not heat evenly and comes out cold in the middle.
- Wet it thoroughly before it goes in. Dry straw steams unevenly and the whole point is even heat.
- Fill the drum no more than about three-quarters full, so there is room for the steam to move.
- Heat with steam or with the substrate heated in hot water. Bring the centre of the mass to 60 to 65C and hold it there for 1 to 2 hours.
- Let it cool to below 30C before you add spawn. Spawn mixed into material hotter than this dies, and you have wasted both.
- Drain, and mix in the spawn.
Keeping the temperature between about 60 and 70C is the part people get wrong. Hotter than about 80C for too long cooks the nutrients out of the substrate, and it will not support a crop.
Common mistakes
- Overfilling. A full drum cannot heat evenly, and you get hot outside and cold inside.
- Chopping too coarse. Long pieces are the single most common reason a pasteurisation fails to heat through.
- Adding spawn too early. Above about 30C you are killing the spawn.
- Washing the substrate. Washed straw is clean and also empty. It has the nutrients washed out of it.
- Under-insulating in a cold climate. Holding 60C for two hours in a hot room is a different problem from holding it in a cold one, and the drum is often bought for the second while planned for the first.
Common questions
What temperature do you pasteurise substrate at?
60 to 65C in the centre of the mass, held for 1 to 2 hours. Above about 70C for too long cooks the nutrients out and the substrate will not support a crop.
Do I have to chop the straw before pasteurising?
Yes, into roughly 5cm pieces. Long straw heats unevenly and comes out cold in the middle, which is the most common reason a batch fails to pasteurise properly.
How full should the drum be?
About three-quarters full. A full drum cannot heat evenly, so you get hot material at the edge and cold material in the middle.
Can I use this drum for other substrate?
Yes. It suits straw, maize cobs and similar agricultural waste. It is a heat vessel, so anything you are pasteurising in a bag can be pasteurised in it.
Do I need this drum for a small setup?
For a handful of bags a large pot and a thermometer will do the same job. The drum earns its price once you are pasteurising substrate in bag quantities, where doing it in batches by hand starts to cost more in time than the drum costs in money.