Spawn is a living product !
The storage lifespan of spawn depends on:
- the strain
- the storage temperature
- the way it is stored
1. The strain:
Strains with slowly growing mycelium have the longest shelf-life. In order of appearance, the signs of the ageing process are:
- the mycelium becomes more compact
- formation of skins, crusts and lumps
- production of colored fluid with an unpleasant odor
- autolysis of the mycelium and disintegration of the spawn.
In stages (1) and (2) the mycelium is perfectly useable, although it is less crumbly than totally fresh spawn. Since the autolysis (=self-destruction) of the cells begins at the end of stage (3), it is recommended to use the mycelium before that time. In stage (4) the mycelium is dying and should be eliminated.
2. The storage temperature:
The ideal storage temperature for most strains of spawn is 0 to 2°C. At this temperature the spawn can be kept for 2 to 4 months.
Exceptions to this rule:
Another exception are spawn plugs (dowels): they keep much longer, at the same temperature of 0 to 2°C. Depending on the strain, plugs can be kept for 8 months to 1 year.
3. The spawn storage method:
To prevent overheating, never store complete pallets in the cold storage unit. Place the boxes on shelves, or stack them in an alternating manner like bricks, always being sure to leave ± 10 cm space for air flow between the boxes. If spawn for Oyster Mushrooms or other exothermic species has to be stored for longer periods, then the sacks should be taken out of the boxes and put separately on shelves in the cold storage unit.
On a daily basis, the cold storage unit should be opened for ventilation. Good air circulation is very important for uniform refrigeration and spawn survival.
- Upon arrival: at Mycelia’s the bags of spawn are individually refrigerated at 0°C and packaged for shipment at the last moment. The temperature of the spawn on the pallets is measured just before shipment and indicated on the shipping bill (CMR). In order be sure that the shipping was correctly carried out, and to have evidence in case of dispute, the temperature should be measured again upon arrival, and indicated on the same CMR.
- We advise against ordering spawn which is to be stored months before use. The extra shipping costs will be largely compensated by the extra yield and/or the lower production risk.
- Each package of spawn carries an identification label on which strain number, line and inoculation data are specified. Please keep these references in your production records to allow traceability whenever necessary.
It is recommended to test aged spawn on a petri dish before use. See testing spawn quality.