GROWING GOURMET - Anto2ni.it

130 GENERATING GRAIN SPAWN
determine the moisture content of any given formula,
weigh 100 grams of the grain, dry it out,
and re-weigh the remaining mass. (This can
easily be determined by drying out the moistened
grain in an oven for at 300° F. (150° C.)
for 8 hours. The difference in weight is the water
lost, or the percentage moisture.) Now water is
added to achieve atargeted moisture content. Once
cooked, a sample of grain is taken and oven dried.
To check the proposed formula, just take the
mass of the lost water divided by the total mass
of dried grain and the lost water. This will give
you a moisture percentage. Remember, moisture
percentage is the mass of water divided by
total mass, lost water included. This is not a ratio
of water to dry mass, but a percentage of
water over total mass. (This is a common mistake
amongst certain schools of Shiitake
growers and wood lot managers.) Once a targeted
moisture content is achieved, spawn
growers rely on volumetric scoops customized
to the new formula for ease of handling.
Grain Formulas for Spawn Production
16 oz. Mineral Spring Bottles
100 grams rye (approx. 125 ml.)
150 ml. water
.5 grams gypsum
(60% moisture*)
Gallon or 4 Liter Jars
800 grams rye
600 ml. water
4 grams gypsum
(43% moisture*)
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Quart or
Liter Jars
200 grams rye
200 ml. water
1 gram gypsum
(50 % moisture*)
2 1/2 Gallon
10 Liter Jars
2200 grams rye
1500 ml. water
8 grams gypsum
(40% moisture*)
Since grain comes to the consumer with an
inherent moisture content of 8-15%, less water
is added than might be expected to achieve the
right moisture content for spawn production.
Each cultivator may want to adjust the following
proportions of water to grain to best fithis needs.
Keep in mind that one liter (1000 ml.) of water
weighs 1 kilogram (1000 g.). A quart is
almost a liter and for the purposes of the mushroom
cultivator can be used interchangeably.
(The amount of grain within each vessel is specified
in the following formulas.A variation of only
5-7% between the two volumes is not statistically
significant.) Gypsum is added to help keep the
kernels separated after sterilization and to provide
calcium and sulphur, basic elements
promoting mushroom metabolism. (See Stoller,
1962; Leatham and Stahlman,1989.)
A delicate balance between the mass of grain
and added water must be preserved to promote
the highest quality spawn. As the spawn container
is increased in volume, slightly less water
1/2 Gallon or
2 Liter Jars
480 grams rye
400 ml. water
2 grams gypsum
(45 % moisture*)
Standard Spawn
Bags (17.5 x 8.25 x 4.75 inches)
3300 grams rye
1400 ml. water
12 grams gypsum
(38% moisture*)
* These moisture contents are not meant to be taken literally. The natural moisture content inherent within "dry"
grain can affect absolute moisture by 15% or more. Properly dried grain should have 8-12% ambient
moisture. With the slightest increase above this level, bacteria
proliferate, requiring that the sterilization cycle
be extended.
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