GROWING GOURMET - Anto2ni.it

154 GENERATING
GRAIN SPAWN
kept in a refrigerator in the same space as mushrooms
are stored. The mushroom spores can
become a vehicle of contaminationbacteria and
other fungi directly into the stored spawn.
Spoiling mushrooms are often covered with the
very contaminants so dreaded in the laboratory
environment.
Another problem with refrigeration rooms is
that the cooling of spawn causes condensation
within the spawn containers.
Free water, in the
form of condensation,
should always be viewed
with concern by the cultivator. Contaminants
proliferate within the water droplets and are efficiently
spread by them. Bacteria, in particular,
reproduce feverishly in free water environments,
even at cool temperatures. Further,
refrigeration blowers and cooling elements attract
and collect dustparticles, which inevitably
must be cleaned. The force of the air blasting
from the cooling elements covers the outer surfaces
of the bags with contaminant particles that
are easilytransferred by anyone handling them.
Most often, the filter media, designed to limit
airborne contamination, become the sites of
black and green mold growth. In time, they can
penetrate from the outside into the interior environment
of the spawn containers.
If refrigeration is your only alternative, then, by
definition, you have missed the best opportunity:
to use the spawn at its peak of vitality. Nevertheless,
every spawn producer faces this dilemma. So,
if you have to refrigerate your spawn, the following
precautions are suggested.
1. Treat the refrigeration room as if it were a
clean-room. Analyze all potential contamination
vectors. Install a HEPA filter if necessary.
Make sure floors and walls are kept clean by
frequently washing with a 10%bleach solution.
2 Rotate your spawn! Only similarly aged
spawn should be kept together.
3 .When refrigerating spawn, use bags, not jars.
4. Inspect the stored spawn once a week for
visible signs of contamination,
especially at the
location of the microporous filter patches. (Although
spores may not pass through the
filtration material, mold mycelia can.)
5. Maintain a low relative humidity. The humidity
should never exceed 60%, and should
ideally be kept in the 40-50% range.
6. Minimize any material which could become
a platform for mold growth, particularly
wood, cardboard, and other paper products.
Lastly, some species are more receptive to
cold storage than others. Some of the tropical
species die upon exposure to cold temperatures.
(Volvariella volvacea is one notable example.)
The cold-weather Oyster strains (Pleurotus
ostreatus and allies) can be shocked into fruiting
upon placement into a cold room. One
commonly sees Oyster mushrooms fruiting
frantically in containers which were otherwise
hermetically sealed. The force of fruiting, the
bursting forth of mushrooms within the spawn
containers, can actually cause enough stress to
split plastic seams, unscrew lids on bottles, and
force apart filter membranes.
With the rapid-cycle spawn techniques described
in this book, cold storage of spawn is
not necessary and is not recommended. Cold
storage is an option widely utilized by the
Agaricus industry, an industry historically
fractured into specialty companies. When inventories
exceed demand, spawn is kept for as
long as possible under refrigeration. Often the
consumer, not knowing better, becomes the
victim of a spawn producer's over-production.
If the spawn fails, the excuse heard, more often
than not, is that the spawn was mishandled
by the purchaser. This type of business relationship
is intrinsically
and is yet
another reason why mushroom farms should
generate their own spawn.
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