GROWING GOURMET - Anto2ni.it

Figure 149. Newly constructed, screened floor racks
which allow the passage of steam underneath the
mass of bulk material being pasteurized.
centers of densely packed Phase II steam
chambers remain below 1000 F. (38° C.) for
several hours, lagging behind the hot outer
shell, and suddenly race upwards. If steam output
from the boilers is not reduced in time, the
entire mass continues to heat at an uncontrollable
rate. Without the cold core, which in
effect is a heat sink, to deflect the spiralling increase
in temperature, thermal momentum
continues for an hour or two beyond the time
steam injection is shut off. The minimum recommended
time for steam pasteurization is two
hours above 160° F (71°C.).
A common oversight in steaming a mass of
straw or compost is the failure to chart, every
30 minutes, the temperature profile of the
mass. By measuring and charting, trend analysis
is possible. If the climb in temperature is not
anticipated, and reduced at the right time, the
CULTIVATING GOURMET MUSHROOMS 187
thermal momentum of the hot outer shell not
only overwhelms the ever-shrinking cold core,
but causes the entire mass to skyrocket to
200°+ F. (930 C.), a temperature above which
disaster awaits. Above this temperature plateau,
non-competitive, beneficial organisms
are killed, and the substrate becomes an open
habitat for many competitors which would otherwise
be held in abeyance.
When the steam output from the boiler
is turned off, the Phase II box should be
immediately positive-pressurized with contaminant-free
alt By forcing air through a
HEPA filter and ducting the air directly into
the Phase II chamber, contaminants are prevented
from being sucked in as the mass
cools. For a steam box measuring 10 ft. x 10
ft. x 10 ft., a 1/8 HP blower pushing 200 CFM
through a 12 in. x 12 in. x 6 in. HEPA filter
(99.99 % @ .3p) adequately positive-pressur-
Figure 150. inside a iarge Phase 11 chamber.
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