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Growing mushrooms commercially
is a difficult and unique process, which Denny’s team
of expert growers has taken many years to perfect.
The basic process consists of manufacturing a suitable growing
medium or compost, adding spawn (seed) to it and then caring
for it by providing ideal environmental conditions, until mushrooms
appear, grow, and are ready for harvesting. These processes
are described in more detail below. |
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The
growing medium or compost takes about 2 weeks to prepare and
consists primarily of wheat, maize, cotton and nitrogen supplements.
Because mushrooms don’t contain chlorophyll, they are
not reliant on sunlight for their nutrients, but obtain them
from the organic matter in the compost.
Mushrooms, unlike most plants, don’t grow from seeds,
but from microscopic spores. (Plants which grow from spores
are known as fungi). Spores are collected from mature mushrooms
in the sterile environment of a laboratory and are then applied
to grains of rye to produce spawn (which is the mushroom grower’s
equivalent of seed). The spawn is mixed into the compost which
is then transferred to specialised indoor growing rooms where
it is placed in layers about 150 mm thick on specially designed
shelves. |
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The
growing rooms are fully environmentally controlled, making the
cultivation of mushrooms completely independent of weather or
seasonal climatic conditions. Temperature, humidity and fresh
air flows are precisely controlled by computer to ensure that
optimal conditions are provided for mushroom growth. A temperature
of about 20oC together with very high humidity, a regular supply
of fresh clean air and plenty of water make Denny mushrooms
the most pampered mushrooms in Africa !
After about two to three weeks, the spawn has grown through
the compost which is then covered with a network of lacy white
filaments called mycelium, which is like the roots of the mushrooms.
At this stage a layer of pasteurised casing soil (which can
be peat or clay) is spread over the compost to act as a reservoir
from which the growing mushrooms will draw their moisture. The
mycelium grows through this layer and eventually forms tiny
white pin heads on the surface. These pins continue to grow,
becoming the mushrooms. Once the pins have formed into small
mushrooms, they magically double in size every 24 hours until
they are of a suitable size for picking.
Denny mushrooms are freshly picked every day and are packed,
refrigerated and distributed in refrigerated trucks to various
retail outlets, restaurants and food manufacturers. |
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It takes
approximately four weeks to harvest a crop of Denny mushrooms,
after which the growing room is emptied and sterilised with
steam before being refilled with compost for the next crop.
The whole process is then repeated taking about eight weeks
in total for each crop. By having many growing rooms that are
at different stages of growth at any one time, Denny is able
to provide a steady flow of high quality mushrooms to consumers
every day of the year. |
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(A video tape of the process
is available from Denny at a cost of R40,00. A limited number
of videos are available at no charge to bona fide educational
institutions) |
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