Drying is a simple process but extremely delicate, therefore, it is necessary to respect specific precautions in order to obtain a quality product.
After harvesting, the plant material can be directly worked in its fresh state, or in the case one wanted to obtain powder, herbal cuts, or conserve the plant for successive extractions, one must proceed to remove the water of the plant.
Generally, the quantity of water to eliminate through drying corresponds to 70-75% of the weight of the fresh plant.
The plant material is correctly dried when the result contains a quantity of water less than 5% of the weight.
Drying can be done naturally, taking advantage of the natural heat of the air, or artificially, making use of heated, conditioned and dehumidified air.
In natural drying the plants are prepared on some special frames or wooden boxes with some absorbent paper on the bottom, both are covered by a mosquito net to protect the plant from insets and dust.
If whole plants are harvested, they can be bound in clusters and hung from the ceiling.
Ample and well-covered spaces (for example farmyards or courtyards) are necessary that aren’t exposed to direct sunlight: high temperatures would result the degradation of the active thermolabile ingredients or particularly volatile (for example plants rich in essential oils) and then lose the quality of the product.
With the natural drying method, the drying times are much longer (about 10-15 days), depending on the climate conditions.
One can easily run the risk that the herbs in the time of drying go against fermentation phenomena. A drying of this type is not recommended in temperate-humid environments. .
In artificial drying, adaptive solutions are used that considerably change the capacity of the air to remove humidity from the product.
Generally, the air is heated to an appropriate temperature to be able to assure drying in a short time, but at the same time to not deteriorate the quality of the plant. It’s possible to carry out an artificial drying by putting humidifiers in a closed environment or through specific driers (thermostatic oven, overlapped containers, in cells).