Primary processing of medicinal plant materials.

When preparing raw materials for drying, their compliance with the requirements of the RD for this type of raw material is checked .

Raw materials are sorted, viewed for the presence of affected, dirty objects. They shorten the stems, flower stalks, cut the petioles of the leaves, remove the stalks. Stems, thin roots, dead parts are cut off from underground organs. At the roots of the dandelion, cut off the root collar.

The underground organs of plants are washed, except for the roots of marshmallow, licorice and ginseng.

Large rhizomes and roots are cut into pieces along or across and dried.

Juicy fruits are also dried, laying out in a draft for 2-3 days.

At the same time, the raw material loses up to 50% of water, otherwise the fruits may burst during drying.

Ginseng roots are blanched before drying. they retain the ability to germinate for a long time. Treated with steam or hot water.

When processed for 5-10 minutes, starch gelatinization does not occur – a “white ginseng root” is obtained, when processed for 15-20 minutes, gelatinization occurs and the roots acquire a horn-like texture – “red ginseng root”.

Drying of medicinal plant materials

This is a method of preserving medicinal raw materials, ensuring the safety of biologically active substances, creating a more convenient marketable condition for transportation and storage.

This is the process of removing (dehydrating) liquid from plant material. The collected medicinal raw material contains, as a rule, 70-90%, and dried – 10-15 (20)% moisture.

The choice of method and mode of drying depends on:

1) on the amount of water in the raw material;

2) from the morphological and analytical structure of raw materials;

3) on the physicochemical properties of active substances and the state of enzymatic systems.

Most types of medicinal plant raw materials are used in medicine in dried form. Only a few species are processed fresh immediately after collection.

Biochemical processes

in the collected raw materials at first they flow, as in a living plant, i.e. synthesis of biologically active substances prevails.

Then, as dehydration progresses, the metabolic processes shift towards decay, which leads to a decrease in the content of biologically active substances in the raw material.

If the drying is carried out at a temperature that does not denature the enzymes, then the lysis reactions continue during the entire drying process.

However, in some cases, the processes occurring in the drying raw materials, on the contrary, lead to an increase in the content of active substances.

Thus, the accumulation of essential oils, cardiac glycosides in May lily of the valley and cannabis kendyr was noted.

The optimal drying mode should be based on experimental data on the effect of drying and its methods on the content of certain groups of biologically active substances.

In some cases, drying is preceded by drying of the collected raw materials, i.e. keeping raw materials at normal temperature under a canopy. Sometimes the drying procedure increases the content of active substances or speeds up the process of subsequent dehydration.

Moisture is in the plant in a free and bound state.

Free moisture retains all the properties of pure water:

– mobility,

– activity,

– the ability to evaporate and freeze,

– dissolve various substances.

Related –

(chemically, adsorption, capillary, osmotically)

– to some extent loses these properties,

– Harder to evaporate and freeze

– less active

– reactivity.

Bound moisture is removed from raw materials much more difficult than free moisture.

The duration of the drying process and the performance of drying plants are influenced by:

– morphological features of raw materials,

– its initial humidity,

is the total surface area of the material to be dried,

– as well as humidity,

– temperature and speed of movement of the coolant.

Currently used methods for drying medicinal plant materials are divided into two groups:

Without artificial heating:

a) air-shadow, carried out in the open air, but in the shade, under sheds, in attics, in special drying sheds and air dryers;

b) sunny, outdoors or in solar dryers; with artificial heating, or thermal.

Air-shadow drying is used for drying leaves, herbs and flowers.

In the simplest cases, raw materials for drying are laid out under sheds or in special drying sheds. However, it is preferable to carry out drying in specially equipped air dryers or in attics.

Air dryers are equipped with racks with frames, on which a rare fabric or metal mesh is stretched. Drying in air dryers, drying sheds and attics is slower than outdoors under sheds, but provides better quality raw materials.

Solar drying is used in areas with a hot dry climate, mainly for bark, roots, rhizomes and other underground organs, which, as a rule, are almost not damaged under the influence of solar radiation.

Especially “shown” solar drying for raw materials containing tannins. However, it should be noted that the content of some alkaloids decreases when raw materials are dried in the sun (scopolia, ragwort).

Due to the damaging effect of sunlight on pigments, it is recommended to dry leaves, flowers and herbs only in the shade.

The advantages of the solar drying method include faster dehydration than air-shadow drying.

Both during air-shadow and solar drying, in order to avoid moistening of the raw material at night, it must be removed indoors or covered with a dense cloth.

Thermal drying is used for drying various morphological groups of raw materials. It provides fast dehydration and can be used in all weather conditions and in all harvesting areas.

Artificial drying can be convective, contact and sublimation.

Convective drying is carried out in batch or continuous dryers. Numerous designs of dryers can be divided into dryers of stationary and portable types.

During convective drying , the raw material is washed by a stream of heated dry air, and the device of the dryer can be different. There are chamber dryers, fire dryers and multi-tiered belt dryers.

Stationary dryers are usually installed on farms where medicinal plants are cultivated, or at large procurement points.

They consist of a drying chamber equipped with racks with frames on which fabric or metal mesh is stretched and a boiler plant isolated from the drying chamber.

Dryers are heated by water, steam or flue gases.

Dryers by design can be continuous or intermittent.

Portable dryers are designed for drying mainly “wild” medicinal raw materials. Collapsible portable dryers are convenient for transportation and allow you to organize the drying of raw materials directly in the harvest area. Individual assemblers for heat drying use ovens and heated plates.

During contact drying , the raw material comes into contact with a heated surface.

In freeze drying , moisture is removed by freezing under vacuum.

Radiation drying is carried out with the help of infrared rays, which have a high penetrating power and can significantly reduce the dehydration process. This method is used in the laboratory. The experiment proved the effectiveness of using microwave ovens for drying medicinal plant raw materials.

The optimal drying mode is given in the instructions for harvesting and drying specific types of medicinal plant materials.

General drying rules:

1) raw materials containing essential oils should be dried at a temperature


With a rather thick layer of 10-15 cm to prevent the essential oil from evaporating; drying should be delayed in time, because. at this time, the biosynthesis and accumulation of essential oil continues.

temperature range:

– if the essential oil is localized in exogenous essential oil formations – ° = 25-30 ° С;

– if the essential oil is localized endogenously – t°= 35-40° С;

– if aromatic compounds predominate in the composition of the essential oil – up to 45 ° C.

2) raw materials containing glycosides are dried at a temperature of 50-60 °C. within an hour, dried at a lower t °. High t ° is necessary for the inactivation of enzymes. This mode allows you to quickly inactivate enzymes that destroy glycosides.

3) if the raw material contains cardiac glycosides , then the initial t ° of drying is increased to 60-70 ° C. Raw materials of lily of the valley and adonis in fine weather can be dried in the air-shadow method. Their enzymatic systems are not very active.

4) if the raw material is underground organs of plants containing polysaccharides , then it cannot be dried quickly at high temperature, because caramelization of the surface layer may occur, but moisture will remain inside and rotting will begin. This applies to the raw materials of dandelion and elecampane.

Rhizomes and roots of elecampane containing sesquiterpene lactones along with essential oil are recommended to be dried at a temperature of 50 °C.

5) raw materials containing alkaloids are dried at temperatures up to 50 °C;

6) raw materials containing ascorbic acid are dried at a temperature

80-90 °C. Rose hips (contain ascorbic acid or vitamin C ), begin to dry at t ° = 80-90 ° C, dry at a lower temperature. At such a high temperature, denaturation of enzymes occurs.

7) if the morphological group of the raw material is buds , then they are dried “in the cold”, with heat drying the buds bloom.

It has been established that in the roots of barberry, the grass of the yellow machka, the motherwort, the fruits of hawthorn, the roots of ginseng, the grass of the May lily of the valley, the content of active substances is higher at a temperature regime within 60-90 ° C than when drying the same types of raw materials according to general rules.

With all drying methods, medicinal raw materials, with the exception of essential oil, are laid out in a thin layer and regularly turned over, while, however, they tend not to increase the degree of grinding.

On the basis of experimental studies, weight loss during drying was established for various morphological groups of medicinal raw materials:

– kidneys – 65-70%;

– flowers, buds – 70-80%;

– leaves – 55-90%;

– herbs – 65-90%;

– roots and rhizomes – 60-80%;

– bark – 50-70%;

– tubers – 50-70%;

– fruits – 30-60%;

– seeds – 20-40%.

Drying is considered complete when the roots, rhizomes, bark, stems do not bend when bent, but break; leaves and flowers are ground into powder;

juicy fruits do not stick together in lumps, but crumble when pressed.

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