Medicinal and Aromatic Crops

Post-harvest processing

Inspection and sorting

• Raw medicinal plant materials should be inspected and sorted prior to primary processing. The inspection may include:
• Visual inspection for cross-contamination by untargeted medicinal plants and/or plant parts;
• Visual inspection for foreign matter;
• Organoleptic evaluation, such as: appearance, damage, size, colour, odour, and possibly taste.

Primary processing
Appropriate measures of primary processing are dependent on the individual materials. These processes should be carried out in conformity with national and/or regional quality standards, regulations and norms. In some cases, purchasers may request that specific protocols are followed. These protocols should also comply with national and/or regional regulatory requirements that apply in the producer and the purchaser countries. As far as possible, standard operating procedures should be followed. If modifications are made, they should be justified by adequate test data demonstrating that the quality of the medicinal plant material is not diminished. Harvested or collected raw medicinal plant materials should be promptly unloaded and unpacked upon arrival at the processing facility. Prior to processing, the medicinal plant materials should be protected from rain, moisture and any other conditions that might cause deterioration. Medicinal plant materials should be exposed to direct sunlight only where there is a specific need for this mode of drying.

Medicinal plant materials that are to be used in the fresh state should be harvested/collected and delivered as quickly as possible to the processing facility in order to prevent microbial fermentation and thermal degradation. The materials may be stored under refrigeration, in jars, in sandboxes, or using enzymatic and other appropriate conservation measures immediately following harvest/collection and during transit to the end-user. The use of preservatives should be avoided. If used, they should confirm to national and/or regional regulations for growers/collectors and end-users. Medicinal plant materials that are to be employed fresh should be stored under refrigeration, in jars, in sandboxes, or using enzymatic or other appropriate conservation measures, and transported to the end-user in the most expeditious manner possible. The use of preservatives should be avoided. If used, this should be documented and they should confirm to national and/or regional regulatory requirements in both the source country and the end-user country.

All medicinal plant materials should be inspected during the primary-processing stages of production, and any substandard products or foreign matter should be eliminated mechanically or by hand. For example, dried medicinal plant materials should be inspected, sieved or winnowed to remove discoloured, mouldy or damaged materials, as well as soil, stones and other foreign matter. Mechanical devices such as sieves should be regularly cleaned and maintained. All processed medicinal plant materials should be protected from contamination and decomposition as well as from insects, rodents, birds and other pests, and from livestock and domestic animals.

Drying
When medicinal plant materials are prepared for use in dry form, the moisture content of the material should be kept as low as possible in order to reduce damage from mould and other microbial infestation. Information on the appropriate moisture content for particular medicinal plant materials may be available from pharmacopoeias or other authoritative monographs. Medicinal plants can be dried in a number of ways: in the open air (shaded from direct sunlight); placed in thin layers on drying frames, wire-screened rooms or buildings; by direct sunlight, if appropriate; in drying ovens/rooms and solar dryers; by indirect fire; baking; lyophilization; microwave; or infrared devices. When possible, temperature and humidity should be controlled to avoid damage to the active chemical constituents. The method and temperature used for drying may have a considerable impact on the quality of the resulting medicinal plant materials. For example, shade drying is preferred to maintain or minimize loss of colour of leaves and flowers; and lower temperatures should be employed in the case of medicinal plant materials containing volatile substances.
The drying conditions should be recorded. In the case of natural drying in the open air, medicinal plant materials should be spread out in thin layers on drying frames and stirred or turned frequently. In order to secure adequate air circulation, the drying frames should be located at a sufficient height above the ground. Efforts should be made to achieve uniform drying of medicinal plant materials and so avoid mould formation. Drying medicinal plant material directly on bare ground should be avoided. If a concrete or cement surface is used, medicinal plant materials should be laid on a tarpaulin or other appropriate cloth or sheeting. Insects, rodents, birds and other pests, and livestock and domestic animals should be kept away from drying sites. For indoor drying, the duration of drying, drying temperature, humidity and other conditions should be determined on the basis of the plant part concerned (root, leaf, stem, bark, flower, etc.) and any volatile natural constituents, such as essential oils. If possible, the source of heat for direct drying (fire) should be limited to butane, propane or natural gas, and temperatures should be kept below 60 °C. If other sources of fire are used, contact between those materials, smoke and medicinal plant material should be avoided.

Specific processing
Some medicinal plant materials require specific processing to: improve the purity of the plant part being employed; reduce drying time; prevent damage from mould, other microorganisms and insects; detoxify indigenous toxic ingredients; and enhance therapeutic efficacy. Common specific processing practices include pre-selection, peeling the skins of roots and rhizomes, boiling in water, steaming, soaking, pickling, distillation, fumigation, roasting, natural fermentation, treatment with lime and chopping.

Processing procedures involving the formation of certain shapes, bundling and special drying may also have an impact on the quality of the medicinal plant materials. Antimicrobial treatments of medicinal plant materials (raw or processed) by various methods, including irradiation, must be declared and the materials must be labelled as required. Only suitably trained staff using approved equipment should carry out such applications, and they should be conducted in accordance with standard operating procedures and national and/or regional regulations in both the grower/collector country and the end-user country. Maximum residue limits, as stipulated by national and/or regional authorities, should be respected.

Processing facilities
The following elements should be considered when establishing a quality assurance system and be adapted to the different steps of production and production sites.

Location
Facilities should preferably be located in areas that are free from objectionable odours, smoke, dust or other contaminants, and are not subject to flooding.

Roadways and areas used by wheeled vehicles
Roadways and areas serving the establishment, within its boundaries or in the immediate vicinity, should have a hard paved surface suitable for wheeled vehicles. There should be adequate drainage, and provision should be made for cleaning.

Buildings
Buildings should be of sound construction and maintained in good repair. Dirty areas, such as those used for drying and milling, must be isolated from clean areas, preferably in separate buildings. All construction materials should be such that they do not transmit any undesirable substance to medicinal plant materials. Once construction is completed, construction materials should not emit toxic vapours. The use of materials that cannot be adequately cleaned and disinfected, such as wood, should be avoided unless they would clearly not be a source of contamination.

Buildings should be designed to provide adequate working space and storage room to allow for satisfactory performance of all operations;

• facilitate efficient and hygienic operations by allowing a regulated flow in processing from the arrival of the raw medicinal plant materials at the premises to the dispatch of the processed medicinal plant materials;
• permit appropriate control of temperature and humidity;
• permit the separation by partition or other means of processes that may cause cross contamination, especially to isolate dirty areas (drying and milling) from clean areas;
• permit control of access to different sections, where appropriate;
• permit easy and adequate cleaning and facilitate proper supervision of hygiene;
• prevent the entry of environmental contaminants such as smoke, dust, etc.;
• prevent the entrance and harbouring of pests, livestock and domesticated animals;
• where appropriate, prevent direct sunlight from entering a particular section.

Medicinal plant material handling areas

• Floors, where appropriate, should be of waterproof, non-absorbent, washable, non slip and non-toxic material, without crevices, and should be easy to clean and disinfect. Where appropriate, floors should slope sufficiently for liquids to drain into trapped outlets.
• Walls, where appropriate, should be covered with waterproof, non-absorbent and washable materials, sealed and free from insects, and should be light coloured. Up to a height appropriate for handling operations, they should be smooth and without crevices, and should be easy to clean and disinfect. Where appropriate, angles between walls, between walls and floors, and between walls and ceilings should also be sealed and covered to facilitate cleaning.
• Ceilings should be designed, constructed and finished so as to prevent the accumulation of dirt and minimize condensation, mould development and flaking, and should be easy to clean.
• Windows and other openings should be constructed so as to avoid accumulation of dirt, and those that open should be fitted with insect-proof screens. Screens should be easily removable for cleaning and kept in good repair. Internal window sills, if present, should be sloped to prevent use as shelves.
• Doors should have smooth, non-absorbent surfaces and, where appropriate, be self closing and close-fitting.
• Stairs, lift cages and auxiliary structures such as platforms, ladders and chutes should be situated and constructed so as not to cause contamination to medicinal plant materials. Chutes should be constructed with inspection and cleaning hatches.
• Overhead structures and fittings should be installed in such a manner as to avoid contamination of medicinal plant materials (both raw and processed) by condensation and drip, and should be protected to prevent contamination in case of breakage. They should not hamper cleaning operations. They should be insulated, where appropriate, and be designed and finished so as to prevent the accumulation of dirt and to minimize condensation, mould development and flaking. They should be easy to clean.
• Living quarters, food preparation and eating areas, changing facilities, toilets and areas where animals are kept should be completely separated from and should not open directly onto medicinal plant material handling areas.

Water supply
An ample supply of water, under adequate pressure and at suitable temperature, should be available with appropriate facilities for its storage, where necessary, and distribution, and with proper protection against contamination.

• Ice should be made from potable water; it should be manufactured, handled and stored so as to protect it against contamination.
• Steam used in direct contact with medicinal plant materials or surfaces in contact with medicinal plant materials should contain no substances that may be hazardous to health or may contaminate the medicinal plant materials.
• Non-potable water used for steam production, refrigeration, fire control and other similar purposes not connected with processing should be carried in completely separate pipes, identifiable preferably by colour, and with no cross-connection with or back siphonage into the system carrying potable water.
• Potable water should be used for washing and wet sterilization procedures.

Effluent and waste disposal
Facilities should have an effective effluent and waste disposal system, which should at all times be maintained in good order and repair. All effluent pipes (including sewage systems) should be large enough to carry peak loads and should be constructed so as to avoid contamination of potable water supplies.

Changing facilities and toilets
Adequate, suitable and conveniently located changing facilities and toilets should be provided. Toilets should be designed so as to ensure hygienic removal of waste matter. These areas should be well lit, ventilated and, where appropriate, heated. Hand-washing facilities with warm or hot and cold water, a suitable hand-cleaning preparation and hygienic means of drying should be provided adjacent to toilets and located so that employees have to pass them when returning to the processing area. Elbow-operated taps are desirable and, where hot and cold water is available, mixer taps should be fitted. If paper towels are supplied, a sufficient number of towel dispensers and waste receptacles should be provided near to each washing facility. Notices should be posted directing personnel to wash their hands after using the toilet.

Hand-washing facilities in processing areas
Adequate and conveniently located facilities for hand-washing and a hygienic means of drying should be provided whenever the process demands. Where appropriate, facilities for hand disinfection should also be provided. Warm or hot and cold water and a suitable hand-cleaning preparation should be provided. Elbow-operated taps are desirable and, where hot and cold water is available, mixer taps should be fitted. If paper towels are supplied, a sufficient number of towel dispensers and waste receptacles should be provided adjacent to each washing facility. The facilities should be furnished with properly trapped waste pipes leading to drains.

Disinfection facilities
Where appropriate, adequate facilities for cleaning and disinfection of working implements and equipment should be provided. These facilities should be constructed of corrosion-resistant materials, should be easy to clean, and should be fitted with hot and cold water supplies.

Lighting
Adequate natural or artificial lighting should be fitted throughout the facility. Where appropriate, the lighting should not alter colours and the intensity should be not less than:

• 540 lux at all inspection points
• 220 lux in work rooms
• 110 lux in other areas.
Lighting fixtures and light bulbs suspended over medicinal plant materials at any stage of processing should be of a safety type and protected to prevent contamination of the medicinal plant materials in case of breakage.

Ventilation
Adequate ventilation should be provided to prevent excessive heat, steam condensation and dust and to remove contaminated air. Air should never flow from a dirty area to a clean area. Ventilator openings should be provided with a screen or other protective enclosure of non-corrosive material. Screens should be easily removable for cleaning.

Storage of waste and unusable materials
Facilities should be provided for the storage of waste and unusable materials prior to removal from the premises. These facilities should be designed so as to prevent access to the waste or unusable materials by pests and to avoid contamination of medicinal plant materials, potable water, equipment and buildings of the premises. Clearly marked waste bins should be provided and emptied daily.

Bulk packaging and labeling
Processed medicinal plant materials should be packaged as quickly as possible to prevent deterioration of the product and to protect against unnecessary exposure to potential pest attacks and other sources of contamination. Continuous in-process quality control measures should be implemented to eliminate substandard materials, contaminants and foreign matter prior to and during the final stages of packaging.

Processed medicinal plant materials should be packaged in clean, dry boxes, sacks, bags or other containers in accordance with standard operating procedures and national and/or regional regulations of the producer and the end-user countries. Materials used for packaging should be non-polluting, clean, dry and in undamaged condition and should conform to the quality requirements for the medicinal plant materials concerned. Fragile medicinal plant materials should be packaged in rigid containers. Whenever possible, the packaging used should be agreed upon between supplier and buyer. Reusable packaging material such as jute sacks and mesh bags should be well cleaned (disinfected) and thoroughly dried prior to reuse, so as to avoid contamination by previous contents. All packaging materials should be stored in a clean and dry place that is free from pests and inaccessible to livestock, domestic animals and other sources of contamination.

A label affixed to the packaging should clearly indicate the scientific name of the medicinal plant, the plant part, the place of origin (cultivation or collection site), the cultivation or collection date and the names of the grower/collector and the processor, and quantitative information. The label should also contain information indicating quality approval and comply with other national and/or regional labeling requirements. The label should bear a number that clearly identifies the production batch. Additional information about the production and quality parameters of the medicinal plant materials may be added in a separate certificate, which is clearly linked to the package carrying the same batch number. Records should be kept of batch packaging, and should include the product name, place of origin, batch number, weight, assignment number and date. The records should be retained for a period of three years or as required by national and/or regional authorities.

Storage and transportation
Conveyances used for transporting bulk medicinal plant materials from the place of production to storage for processing should be cleaned between loads. Bulk transport, such as ship or rail cars, should be cleaned and, where appropriate, well ventilated to remove moisture from medicinal plant materials and to prevent condensation. Organically grown medicinal plant materials should be stored and transported separately or in a manner that ensures their integrity.
Appropriate security measures should be applied to the storage and transport of medicinal plant materials that are potentially toxic or poisonous. Whenever required and when possible, fresh medicinal plant materials should be stored at appropriate low temperatures, ideally at 2-8oC; frozen products should be stored at less than -20oC. Fumigation against pest infestation should be carried out only when necessary, and should be carried out by licensed or trained personnel. Only registered chemical agents authorized by the regulatory authorities of the source country and the countries of intended end-use should be used. All fumigation, fumigation agents, and dates of application should be documented. When freezing or saturated steam is used for pest control, the humidity of the materials should be checked after treatment.