GROWING GOURMET - Anto2ni.it

ag resembles those still widely in use by Asian
cultivators. (See Figure 115). In 1963 several
similar patents were awarded in London
(#985,763; 1,366,777 and 1,512,050). R.
Kitamura and H. Masubagashi recieved a patent
(#4,311,477) for a specialized mushroom culture
bag in 1982. *
About a dozen bags are currently available
to mushroom cultivators, some borrowed from
the hospital supply industry. Cellophane deserves
re-examination since it is made from
wood cellulose and is completely biodegradable.
If problems with seam integrity, tensile
strength, and heat tolerance could be improved,
spawn bags made of this environmentally
friendly material could eliminate the widespread
use of throw-away plastics. An
advantage of cellophane-like materials is that
the mushroom mycelium eventually consumes
the very bag in which it has been incubated.
Autoclavable bags are inoculated with Grain
Masters and are Second or Third Generation.
Agar-to-grain inoculation from petri dish cultures
to bags is awkward and impractical unless
liquid inoculation techniques are employed.
(These techniques are fully described later on.)
Bags are filled with pre-moistened grain, with
the lips folded closed. Some spawn producers
use spring-activated clothespins, paper clips,
plastic tape, to hold the folds closed. I prefer to
simply press the bags together with flaps
folded. As the bags are sterilized, the contents
exceed the boiling point of water, and gases are
released. If the bags are sealed before loading,
explosions or "blow-outs"—holes where live
steam has vented—are likely.
In the standard 18 x 8 x 5 inch gussetted
* Other patents, too numerous to list here were also
awarded. Many re-designed the seam, the filtration
media, and/or sometimes the wording to qualify for a
new variation.
GENERATING GRAIN SPAWN 141
autoclavable spawn bag featuring a 1 inch filter
patch, no more than 3500 grams of dry
grain should be used. *
941 pressure cooker can process 50 lbs. of
dry rye grain in one run. However, the pressure
cooker—with its tightly packed
contents—should be kept at 15+ psi for 4-5
hours to insure even and full sterilization.
If the grain is first boiled or simmered in hot
water before filling, even moisture absorption is
assured. Excess water collecting at the bottom of
the bags often leads to disaster. If this water is reabsorbed
back into the media by frequent shaking
orby turning the bags so that the excessively moist
grain is on top, the cultural environment is soon
re-balanced in favor of mycelial growth. Standing
water, at any stage in the mushroom cultivation
process, encourages competitors. Many spawn
producers add 20-3 0 grams of calcium sulfate to
the grain, when dry, to help keep the kernels separated
after autoclaving.
After sterilization, 2 hours at 15 -18 psi if the
bags are separated or 4-5 hours if the bags are
tightly packed, the bags are removed and allowed
to cool in the pure windstream coming
from the laminar flow bench. An alternative is
to allow the grain bags to cool within the pressure
vessel, provided it is of the type that holds
a vacuum. The vacuum is then "broken" by allowing
clean-room air to be sucked in. If the
pressure cooker does not hold a vacuum, then
it should cool within the sterile laboratory to
preserve sterility. In either case, I place a presterilized
cotton towel, soaked in alcohol, over
the vent cock to act as a filter. For equalizing the
pressure in a larger autoclave, air passes directly
through a microporous filter into the vessel's
* Please see formulas on page 130. Spawn incubation
bags are available from suppliers listed in Appendix
IV: Resource Directory.
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