herbs conservation and cooperation

7/29/2019 Herbs Conservation and Cooperation

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Herbs In Africa

Conservation andCooperationThese articles havebeen published inScience In Africawww.scienceinafrica.co.za

A series of articles which outline the basic requirements, for small scale, sustainable

cultivation, and processing techniques, for rural communities.

By Ivor HughesTo give to each Nation its own type of medicine, the

theoracam best suited to it, as it behooves, for I can well realize that myprescriptions may turn out to be ineffectual among the foreign Nations,and that foreign recipes may turn out to be ineffetual in our Nation. That isto say that I write for Europe, and I do not know whether Asia and Africamay profit from it.

Paracelsus (1493 - 1541)

Even in the face of adversity and injustice, the Africanpeoples have been fecund. This is evidenced by large African populations in

North America, the Carribean and the United Kingdom. These groupings of Afropeoples, represent a very large, and lucrative market for indigenous remedies.

However before these markets can be tapped, a continuity of supply must beassured. That continuity cannot be achieved by the wild harvesting of medicinalplants. Such procedures end in the extinction of countless species.

On the other hand, the large-scale mono-cropping of medicinal species, whichneed inputs of artificial fertilisers, and large scale spraying of dangerous andexpensive biocides is not a sustainable practice. The results of those policiesare clearly visible in the form of a destabilised weather pattern, and a degradedenvironment. Inevitably, wide-spread famine and disease is the result indeveloping nations. Most of these problems are caused by first world economic

criteria applied to every nation across the board. Science in the service of multi-national corporations, becomes malignant rather than benign.

In a short series of articles it is intended to outline the basic requirements, forsmall scale, sustainable cultivation, and processing techniques, for ruralcommunities. No large inputs of capital expenditure and inappropriatetechnology are required. In other words, what is required, is the willingcooperation of small communities and the application of appropriate technology.This means tapping the Natural Science knowledge that is passed from
http://www.scienceinafrica.co.za/http://www.scienceinafrica.co.za/http://www.herbdatanz.com/HerbsInAfrica4.htmlhttp://www.scienceinafrica.co.za/http://www.scienceinafrica.co.za/http://www.herbdatanz.com/HerbsInAfrica4.html


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generation to generation. Forget about large scale corporate financial muscle.No Westernised company that tries to use Afro-ethnic knowledge can have thecredibility of the real deal !

Appropriate Technology

In a community that does not have access to corporatepower, water, and sewage disposal, the technology offered by first worldcountries is obviously not appropriate to the situation. Appropriate technology ina zero situation, is people, land, a shovel, and seeds, and a need to ensure thecontinuity of the community. From that point on, any community may bootstraptheir way into a viable situation without resorting to the money lender/debt trap.The technology is Solar or Helio technology. From the power of the Sun, and thepower of Nature, all is possible. This, without disturbing that cooperativeessence, of the structure of life on our planet.

Business is Business

Cooperation within small communities to meet commongoals is a natural process. However any community that wishes to engage incommercial activities outside the boundaries of the community will need aframework in order to interact with larger scale commercial activity.

Free legal advice and assistance for communities may be accessed via theGlobal Cooperative Movement. The cooperative structure not only defines theindividuals rights, duties and rewards but also allows them a legally recognisedbusiness framework. Within this framework they can trade across nationalborders. However what is appropriate, is that any budding community must firsttrade within their natural boundaries. That means that their first markets stemfrom the healer within the community. In other words everyone must cooperatein common cause.

Market Scope

The herb grower has a degree of flexibility and marketoptions which are unmatched by any other branch of agriculture or horticulture,the options may be divided into 4 main categories:

1. Food and flavours.2. Cosmetics, perfumes and Toiletries.3. Natural Medicines.4. Industrial intermediates eg Dyes, tanning agents, insecticides and

craft materials.

It will be understood that those categories are further sub-dividable and when combined with the number of herb species traded then theoptions are diverse. However to access the options the grower must be able toprocess the crop.

By employing one or more of the following techniques the grower mayconsiderably value-add the primary product:


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The Process

Dehydration - (Removal of water)Distillation - (Steam, Water, Separation)Extraction - (Use of solvents)Compounding - (Manufacturing combination products)

The techniques are simple and usually no morecomplicated than those methods employed in a domestic kitchen.

The Technology

The technology required fits the following criteria:

It can be owner constructedIt can be owner maintainedIt has low construction and maintenance costsIt has a low environmental impact.

Much of the technological hardware equates to scaled updomestic kitchen apparatus.

Crop Yields and Economic Potential

Crops yields are subject to many variables eg:;

In addition, the drying ratio between root, leaf and flowerwill vary from species to species, nonetheless the grower needs a general guideupon which to provide a forecast of economical potential.

The following table was compiled across a number of seasons and can be usedto represent fair average yields for forecast purposes.

Tinctures and Extracts


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The tinctures and extracts are the basis of many diverseproducts

Types of Extract

The base form of all extracts is liquid and is classified into

types as follows;

A. The Liquid Extract is the strongest type of plant liquid made, its ratio of theplant material to solvent is 1:1, i.e., 1 gram crude drug represents 1 ml of theliquid extract. For technical reasons it may only be further concentrated byevaporation of the solvent. Occasionally a 1:2 preparation, i.e., 1 g crude drugequals 2 ml liquid is called an extract, this is incorrect and leads toconfusion.When the term extract is used here, it means a 1:1 preparation.

B. The Tincture is the most common form of plant liquid. An official definition ofa tincture is that it has a drug/solvent ratio of 1:4 and that the solvent be aminimum 45% by volume.There are some difficulties with that definition because

there are strong tinctures, i.e., 1:2 or 1:3 or they may go from 1:5 through 1:10.International protocol on potent plant drugs, e.g., Belladonna, Digitalis,Strophanthus etc. is agreed upon 1:10. The international protocol wasestablished for obvious reasons. Preparations above 1:10 are little more; thanpreserved concentrated infusions.

C. The Essential Oils represent a fraction of 1% of the total plant constituentsand are not representative of a plant's therapeutic range. They are undoubtedlythe finest natural bactericide, that because of their potency can be dangerous inthe wrong hands.Therefore if taken internally they can be extremely toxic and ifused without dilution externally, the result will be damage to dermal or mucoustissue.

D. The Expressed Plant Juices enjoyed popularity in the early years of the 20thcentury but were gradually abandoned because of their limitations. They arebrisk and vigorous in action; this may be attributed to the live enzyme contentand as such bear comparison with fresh fruit and vegetable juices, howeverstrict dosage restraints must be adopted otherwise harm may result. Thepreserved juices are problematical.

E. The Concentrated Infusions and Decoctions are prepared with water as thesolvent. If taken in that form they are classed as recentium (recent) oralternatively they are preserved with alcohol 20%.

They are the basis of pills and ointments.

F. The Pasty or Dry Extracts are prepared from liquid extracts by evaporation.They must be prepared with extreme care lest irremediable damage occurs.There are three types;(1) Soft. (2) Semi-soft. (3) Dry.

Methods of Preparation for the Extracts


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Dry Yield Converted to Liquid Yield

On the assumption of 100 kg of dried material, a liquid

extract will yield 100 litres of extract.

On the same amount of dried material, a 1 in 4 tincture will yield 400 litres oftincture. A Homeopathic mother tincture is 1 in 10. (There are a few oddexceptions). Therefore, the original 100 kg of dried material will yield 1000 litresof the mother tincture. It may be seen that the original 100 kg of dried materialhas suddenly started to be commercially viable.

An average consumer-ready bottle of a tincture or extract has a volume of 15ml. Accordingly, 1 litre will yield on average 65 x 15ml bottles (allowing forevaporation during the bottling process). The bottles may be filled with nothingmore than the usual type of spirits dispenser found in hotels and public houses

Appropriate technology is all around us. Grow slowly, but think big..

Dehydration

Dehydration as an art is very old, the origins of which are lost in time. As ascience it is relatively young being less than 100 years old. As a process it isfundamental to most herb growing operations.

The drying phase is the point at which an otherwise satisfactory crop may beruined or its economic value considerably reduced and yet it is the one processwhich is most often botched with some quite appalling materials appearing inthe market place.

The Benefits of Dehydration

The ownership of a dehydrator confers upon the herb grower a degree ofmarket flexibility which is unmatched by any other branch of horticulture. Someof the benefits are as follows:


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The crop is stabilised and may be stored for up to nine months.No necessity to sell the crop onto a glutted market.The crop bulk is reduced with good savings on transport.The crop is greatly increased in value.

The marketing options are considerably expanded.

The Aim Of Dehydration

Good dehydration practice seeks to preserve the herb metabolites in as near totheir natural state as possible. Therefore the water content of the material mustbe quickly and efficiently reduced to a level where biochemical reactions ceaseand micro-organisms are unable to function. The temperatures employed mustbe so regulated that the metabolite and cosmetic integrity of the material is notdamaged, therefore the grower must not only have knowledge of dehydrationtheory and the apparatus employed but must also understand the characteristics

of the material upon which they work.

The Living Herb

As living entities herbs are incredibly complex. A single cell with the addition ofa few basic elements can manufacture in seconds a dazzling array of intricatecompounds, even one of which could take a modern research laboratory manyyears of painstaking work to reproduce, if indeed they could be reproduced atall. It is well that we remember that the chemical expertise demonstrated by asingle blade of grass is as yet beyond our knowledge.

Photosynthesis

The word 'photosynthesis', means literally, 'made from light' and by that ultimatetransmutation the green plant may be seen as the supreme planetaryalchemist. The green plant alone has mastered the secret of the transmutationof sunlight, water and carbon dioxide into food. All life forms are dependant onthe power of the leaf.

There are certain kinds of bacteria that are classed as autotrophs ie, able tosynthesize food from inorganic molecules such as hydrogen sulphide; howeverthe hydrogen sulphide which is used instead of water, is produced from thebreakdown of green plant protein by sulphide bacteria, so they too aredependent on the green plant for life. In that respect they may be seen as thebacterial equivalent of the fungus.

Primary and Secondary Compounds

Primary compounds such as carbohydrates, proteins, lipids and nucleic acidsare to be found in all living organisms, whereas the natural distribution of thesecondary compounds such as alkaloids and glycosides etc, is somewhat moresporadic, however the secondary compounds are produced in great variety bythe green plants. Several thousand of them have been identified, what is


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surprising is that they have been synthesized from just 6 major chemical groups,yet they are able to elicit all known pharmacological responses.

General Plant Metabolism

Metabolism is the term applied to thesum total of chemical activity that occurswithin the plant. Herbs like humans must eat,drink, respire, reproduce and die. Water asthe arbiter of life performs the same functionwithin the herb as does the blood streamwithin the human system. The plant is able toexercise a high degree of control of the waterthroughout its system. When the weather ishot and water plentiful, its rate oftranspiration is rapid. Experiments haveshown the metabolic rate of an organism isconsiderably increased by a rise in thetemperature, the rate of many reactionsbeing doubled by a 10C rise.

The evaporation effect of transpiration iscooling therefore the plant is able to modifyits internal temperature and reduce itsmetabolic rate. When the weather is hot andwater is short, the plant is able to reduce its

rate of transpiration and within limits control its metabolic rate.

The herbs, stem and upper surface of itsleaves are covered in much the same way as human skin with thousands of tiny

pores called stomata (pl.). the stoma may be opened or closed by 2 sickleshaped guard cells, which line the edges of the stoma.

The guard cells are activated by internal or environmental cues or a combinationof both. The stomata allow the exchange of gas and vapours between the plantand the atmosphere.

The skin or epidermis that surround the stomata secretes a waxy cuticle thatinhibits the evaporation of water from the epidermal area of the leaf. For thatreason around 95% of the plants respiration and transpiration is via the stomata,however in young or partially developed leaves, or for shade loving plants, thenthe cuticular exchange of gas or vapours could be as high as 50%.

The stomata are normally open during daylight hours and closed at night,however they will also close if the plant is in anyway damaged or subjected toenvironmental stress.

Water vapour on being discharged from the stomata will linger around the plantand form what is known as the boundary layer. The depth of the boundary layer


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will vary from specie to specie and will only form in still air, a light air movementbeing sufficient to disperse it.

Enzymes, the plant chemists

Enzymes are classed as complex proteins and nearly all chemical reactions

that occur within a living organism are ordered by enzymes.Enzymes are sensitive to temperature (thermolabile), with many beingdestroyed at temperatures in excess of 70C. The minimum temperature atwhich enzyme activity will cease is 0C or freezing point. The optimumtemperature at which enzyme activity is at its greatest is 30C.The temperatures given are not absolute for it is not only the degree oftemperature that is important but also the duration.

As previously stated, metabolism is the sum total of chemical reactions withinthe plant. Metabolism is of two orders;Anabolic ~ which is a constructive process involving the building up of complexmolecules from simpler structures.Catabolic ~ which is akin to a destructive process in which complex moleculesare broken down into their component parts.

Harvesting shock initiates intense biochemical activity, the dynamic equilibriumof the herb is disrupted as the enzymes commence to fire in random order.

Anabolic reactions cease and the catabolic reactions predominate as the herbstarts to die. During that process, the important secondary compounds aresystematically reduced to primary compounds and from there they decomposeto the original elemental state.Therefore from harvesting onwards the herbs potency, or lack of it, is a functionof time, with up to 35% of the herbs pharmacological activity reduced in 12hours, however this biochemical activity must be mediated by water. Removethe water and the biochemical activity will cease.

Dehydration Times and Temperatures.

The water content of the freshly harvested herb must be swiftly and efficientlyreduced to 8 or 9% of its total, at which point enzyme activity will cease, theherbal material may then be considered stable.Heat is necessary for the evaporation of water, however the method, the degreeand the duration of the heat applied is of prime importance in the production of aquality crop. Many of the herbs secondary compounds are thermolabile(Decompose) when exposed to excessively high temperatures, conversely lowtemperatures are equally destructive because the extended drying timepromotes excessive enzyme activity. As a general rule drying times in excess of

10 hours are detrimental.

Dehydration, Basic Information

Differing species of herb exhibit differing characteristics not only in shape andform but also in the structural composition of its parts, eg soft, hard, fleshy,dense, fibrous, waxy, thick, thin etc; all of which may be considerably modifiedby geo-climatic factors which will vary from site to site, therefore it is not


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possible to raise the treatment of any specie to the level of dogma. Gooddehydration practice is as much an art as it is a science and because of theconsiderable number of variables involved it has not been possible to reduce thepractice to a series of tidy mathematical equations. The human mind can weighand judge imponderables, then arrive at a working solution, therein lies the art.Therefore the operator of dehydration equipment must temper the science with

observation and experience.

Part three in a series of articles which outline the basic requirements, forsmall scale, sustainable cultivation, and processing techniques, for rural

communities continues.

Extracting with SolventsApart from the crude drugs, the base materials of compounding, are its solventsand carriers. The solvents are alcohol (ethanol) and distilled water. The carriersare solutions, emulsions, mucilages, syrups, water and alcohol. An essentialpart of some carrier substances are the fixed oils and waxes. By far, the most

important substance is alcohol, without it, a complete extraction of herbconstituents is not possible.

Solvents used for Extraction PurposesFrom the standpoint of pharmacy, the purpose of a solvent is to remove from asolid, either in part or in its entirety, such substances that may be rendered to aliquid. In chemistry the solvent is known as the 'SOLUTION' and the extractedmaterial as the "SOLUTE'. In pharmacy the solvent used for extraction isreferred to as the "MENSTRUUM'. When the material has been extracted, themenstruum is known as the "VEHICLE' or "CARRIER" of the extracted material.

The use of solvents allows quite precise manipulation of herbal material andwithout their use, herbal therapeutics would not have advanced far beyond aprimitive art. Solvents of various kinds are in widespread use throughout

industry and many households, in the form of stain removers and ovencleaners, etc. Solvents differ widely from each other, not only in differing boilingpoints, but how they act or react with substances in which they come in contact.In order to maintain the synergy of herbal preparations, it is vitally important thatthe plant compounds do not decompose, dissociate or complex when in contactwith a solvent.

Solvents used for Herbal PreparationsThe majority of solvents are toxic to a greater or lesser degree. It should also beremembered that it is not possible to remove all traces of a solvent from anextracted substance. There are no perfect solvents, each one has itsdrawbacks. When considering the suitability of a solvent it should meet thefollowing criteria;

1~ It should display low toxicity to higher life forms.2~ It should not cause the extract to complex or dissociate.3~ It should be preservative in action.4~ It should promote rapid physiologic absorption of the extract.5~ It should be easily evaporated at a low heat.

Alcohol (Ethanol) will meet all of the above criteria.Alcohol

The alcohol of the British Pharmacopoeia, is a 95% mixture of ethanol andwater, which is obtained by the distillation of fermented sugars or by synthesis. It


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is a clear, colorless, volatile liquid. It has a burning taste, with a characteristicodor and boils around 78C. It is miscible with water in all proportions, however,when mixing with water, a contraction of volume and a rise in temperatureoccurs. The mixture must cool to 20C before it is adjusted to its final volume.Its Specific Gravity (SG) at 20/20C (atmosphere 20C - liquid 20C), is0.8119, for practical purposes we can say 0.800, its molecular formula is

C H OH.

Synthetic alcohol can be manufactured by various chemical routes, fromdifferent starting substances including ethylene, ethyl amine or ethyl iodide. Themost common starting substance is ethylene which is converted to ethanol inthe presence of water and sulphuric acid.

The alcohol produced by such methods is cheaper, and therefore, attractive.On analysis, its formula is C H OH. The physiological effects are manifestlydifferent to those of alcohol produced by fermentation methods. What isproduced is determined by the strain of the yeast and the material (substrata)upon which the yeast must work. The perfumers preference, is for a grainbased alcohol to produce the ethereal and elusive top notes of fine perfumes.

Whereas, for the herbal pharmacist, a fruit or herb based alcohol is the preferredsolvent.

Alcohol from CarbohydrateThe carbohydrates are found as complexes in all higher plants, those that occurin the lower plants, such as the ferns, mosses and their allies, are substantiallythe same, therefore, with the correct treatment, we may use them asfermentation substrata, with or without, the addition of sucrose. Remember thatcarbohydrate synthesis in plants is photosynthesis. This is an important pointfor the Spagyric Pharmacist, because the alcohol used to extract a plant, ismade from the same species. The following table may be used as a rule ofthumb to estimate the amount of plant material required, to produce a givenamount of alcohol.

The rule is; that all such plant parts must be treated with amylase to convert thecarbohydrate to fermentable sugars. We may see from the above table, that theleaf part of the plant contains the least amount of carbohydrate.

EnzymesThe conversion of sugars by yeast to alcohol, is performed by enzymes; over adozen have been identified; the total of which is called the ?ZYMASECOMPLEX', all of which are involved in the fermentation process.


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Not all of thefunctions are understood. The most important enzymes, from the alcoholproduction point of view, may be summarized as follows.It should be understood, that the clear cut divisions between substances andsugars that are shown in table only indicate the major type of sugar to be foundin a plant, for they will undoubtedly contain a complex of sugars.

Production RoutesHoney, Malt or Molasses may be treated as mono-saccharide. Commence the

process at the 2nd treatment.

Remember the amylase, like yeast is heat sensitive, therefore, a poly-saccharide liquid should be allowed to cool to 25C before adding the amylase.To test if the starch has been converted to sugars, half fill a test tube with theliquid and add 1 or 2 drops of tincture of iodine. If the starch is present it will beindicated by a purple/black color change. If a significant change is noted, leave

the ferment liquid for a few hours longer to allow the amylase to complete itstask. If the color change is persistent, add more amylase. When thefermentation has ceased the resulting liquid is then distilled.

DistillationDistillation is an ancient technique known to many cultures. Western sciencehistorians usually credit its discovery to the Arabs in the 11th or 12th century

AD. However translations of far older Indian and Chinese medical documentsmention products that would need spirits of wine to produce. Therefore would itbe reasonable to assume the technique arrived in Arabia from points East and


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then percolated into Europe, via Spain, which then, were strongly influenced byArab culture.

It is a fact that all of our technology is no more than a shadowy reflection of anatural process, e.g., distillation is a micro emulation of the planetary rain cycle.The essential process involves a reversible change of state, i.e., Liquid

-->,Vapor-->, Liquid

A liquid is subjected to heat to produce a vapor. The vapor is then rapidlycooled to produce a liquid. The apparatus used in a laboratory is known as adistillation train.

Fractional DistillationFractional distillation is another technique which is used to separate thedifferent components of a mixture. Separation may also be achieved by simpledistillation, but the technique is discontinuous and can become tedious.Whereas the fractional technique is a continuous process that conserves timeand energy.

In herbology, the major use to which the technique is put, is for the fractional

distillation of ethanol. However, for more advanced work, fractional distillationunder reduced pressure may be used for certain of the perfume oils. And for theproduction of granulated extracts.The preparation of ethanol, employing the simple distillation technique, will oncondensation produce a liquid which contains some 60 to 70 % water,depending on the care taken. Water evaporates at all temperatures above 0Cand water vapor will be carried over with the ethanol.

The collected distillate must then be redistilled a number of times to free theethanol from as much of the water as possible. Traditionally the old herbologistswould distill seven times. However, by employing a fractional column, highstrength ethanol may be produced in a single distillation. From the 95% alcoholwe produce the purified or rectified spirit of the Pharmacopeia, which is 90%alcohol freed from impurities and fusel oils; the diluting medium is doubledistilled water.

Introduction


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The techniques for the preservation of foods, along with the manufacture ofstone and bone tools, must rank amongst the very earliest of humankind'stechnological achievements.

Combination smoking and sun drying, was a common technique of hunter-gatherer cultures, which still finds widespread usage today. Strips of lean meat

(jerky orbiltong) maybe quickly andefficientlypreserved insitu, bysmoking andsun drying.The process ofhaymaking intemperateclimates, issun drying on

a large scale.

The sun dryingof medicinal plants, or parts, is an extremely destructive process, during which,up to 85% of the plants bio-activity may be lost in a 12 hour period. Comparethat with warm air drying, where the economic loss may be reduced to 35%, orwith skill, to as little as 15% within the same period of time.The Production of Warm Air - Simple Drying Shed.In the early days of large scale herbal cultivation, such sheds werecommonplace. The introduced innovations were the provision of heated air anddrying racks which replaced the bunching and hanging of the herbs undercover.For the first time the commercial herb grower had a modicum of control over hismain production process. The gains were considerable. The grower could planharvesting and dehydration schedules and operate on a 24 hour basis at peakharvesting times. Temperature control was rudimentary and relied upon theopening and closing of convection vents and doors, and the damping controlson the combustion stoves. Ergonomically they left much to be desired and thecrop dried in an uneven manner. This necessitated much turning and moving ofthe harvested material. Today the technology has advanced considerably andmany high-tech solutions are available. However many of those solutions arenot appropriate to the needs of small scale community production.

Appropriate Dehydrator Technology.Solar Vertical Stack Dryer. New Zealand 1984. The photograph is of my first,owner built solar dehydrator, which Ioperated across 3 seasons. The

sheathing was weather treatedplywood. The solar air heatingpanel to the front of the apparatuswas constructed from scavengedmaterials. The solar heat collectingplate was made from corrugatedroofing iron, painted matt black. Itoperated on the principle of warm airconvection. I was able, during


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sunny weather, to heat the drying chamber to 40C. That was usually, onaverage, 15C above ambient temperature. Crude temperature control wasachieved by means of an adjustable, ambient air flap, opposite, and at thesame height as the solar air inlet. The stack, which stands above the dryingchamber, houses two cheap plastic domestic bathroom convection fans toassist the warm moisture laden air to be vented to the atmosphere. The fans

are powered by warm air convection and not electricity. The shape of the dryingchamber roof and the narrowing of the stack was intended to increase the airvelocity needed, to carry the vaporised water into the atmosphere

Observations and CommentsThe sheathing was three ply. So that in those months that it was usedoperationally. Considerable solar heat gain was garnered. It was also light inweight. The apparatus was constructed so that it could be easily stripped down,and reassembled at a new site. Therefore it would have potential to bemanufactured in kit sets. Now that sounds like a good community project tome!The dryer is simple. However some thought must be given to the size of thedrying chamber, which in turn influences the dehydrator herb loading. The size

of the chamber must also bear some relationship to the size of the cultivation.This in order to prepare a proper harvesting and dehydration schedule. Thesize of the drying chamber will influence the size of the solar panel. The panelmust be sized to give the required heat gain needed for successful operation. Itproduced herb of good aroma and cosmetic quality. The negatives were, it wasonly operational from sunrise to sunset. There was always a risk of dew pointbeing reached in the dehydrator during the hours of darkness. I would close thedehydrator down at dusk. This I did by closing off the air inlet from the solarpanel vent and opening the dehydrator door in order to cool the heated herbdown to ambient temperature. This decreased the risk of dew point in thedehydrator. The door was then closed and the ambient air inlet flap openedslightly. Operations commenced again 45 minutes after dawn.

Different Types of Dehydrators

The Hybrid SystemConsiderable savings in energy may be achieved by including a solar airheating panel as the air inlet for the heating plenum.


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The horizontal stack and tunnel dryer are fuel burners and use electricitypowered axial flow fans. The horizontal stack is side loaded. Pride of place

must go to the tunnel dryer, for use on the larger commercial cultivation. It canbe constructed from adobe or mud bricks, soil cement bricks or concrete

blocks. It has a Solar hot air panel which forms the roof. The furnace isconstructed from a suitably modified 200L oil drum, which makes it economic inoperation. The major expense is the power required for the fans. A system ofvents allows for precise temperature adjustments and the recirculation of air.The dehydrator climate may be modified at will to allow the operator precise airand temperature control through the various drying phases. The moisture ladenwarm air on exit may be suitably condensed to produce single distilled waterwhich bears a relationship to the herb from which it has been stripped. As such,after a further single distillation, it may be used as part of a hydro-alcoholicsolvent, to extract the herb from which it was recovered.

Useful DataEnthalpy of Evaporation.

Solar Gain Chart


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Conversion Technology

Combustion and Fuel ValuesCombustion, or burning, is a chemical process involving carbon,hydrogen and oxygen. Oxygen reacts with the fuel and producescombustion products, some of which contribute to ozone layerdamage. The reaction is sensed as heat and light.

Combustibles may be solid, liquid or gaseous; and the fuel energyvalues that follow should be read as mean global values,because the hydrocarbon chemical content of fossil fuels, eg,.coal, oil or gas, vary according to the geographical source. Thesame situation applies to bio-mass fuels, eg., wood or ethanol.

Fuel Energy Values


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Extraction Apparatus.

The procedures and apparatus required for extraction purposes are simple.Skills required would be carpentry, and light engineering skills, such as metalcutting, drilling, and welding.

When considering the economics of small scale processing plant, there are fourfactors that need to be balanced.

1. Construction Cost ~ The costs may be reduced by utilizing used dairy orfood processing equipment. The main cost is for welding services.

2. Operational Cost ~ Energy use is a prime cost. Unwanted heat loss will addconsiderably to energy use, as will bad design. Faulty design producesincreased labor costs, e.g., difficult load/unload procedures.

3. Maintenance ~ Parts and fittings that are awkward and difficult to clean willadd considerably to labor costs.

4. Durability ~ Fragile parts such as sight glasses should have adequate


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protection. Seals and breakable joints that have to be dismantled should be ofgood quality. Stopcocks, taps and valves should be corrosion proof.

Contamination problems may easily arise because of the nature of thesubstances involved in the processing, from chemical action of one substanceon another, e.g., heavy metals leached from the equipment are in themselves

toxic contaminants, which may then trigger a further reaction in the substancebeing operated on.

Great care should be taken in the selection of materials that will be in contactwith solvents or herb extracts. If using plastics or rubbers, then ask the supplierfor the specifications of use. Do not use glaze ware unless you know what typeof glaze it is.There are also several physical factors that need to be considered,e.g.,

A. Strength and Weight ~ Will the equipment be fixed or portable? Will theequipment be able to withstand any stresses placed upon it?

B. It's Durability ~ Parts that are in contact with liquids and vapors must be

resistant to corrosion. Metals that are prone to rust should as far as possible beavoided.

C. Thermal Expansion and Conductivity ~ When mating materials, which aredifferent, remember that they will have differing thermal expansion rates. Thatwill produce stress or fatigue with an increased risk of fracture. Distillationequipment and condensers should possess good thermal conductivity.

D. Cleansing and Sterilizing ~ Smooth polished surfaces will simplify cleaningand sterilizing and help in the prevention of the formation of heat resistant films.

Two of the most commonly used materials for plant construction are copper andstainless steel. If considering copper, then it is most important that all linings incontact with the herbal materials, liquids or vapors, must be tin plated. Copperis a heavy metal that can cause liver damage. (hepatoxic).

Stainless steel will meet all criteria. Costs may be kept to a minimum bypurchasing and modifying used vats, fittings and tubing.

Austenitic Stainless Steels.

When nickel is added to stainless steel in sufficient amounts the crystalstructure changes to "austenite". The basic composition of austenitic stainlesssteels is 18% chromium and 8% nickel. Austenitic grades are the mostcommonly used stainless steels accounting for more than 70% of production,

type 304 is the most commonly specified grade. A higher grade is type 316

Basic properties.

excellent corrosion resistance

excellent weldability (all processes)excellent formability, fabricability and ductility


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excellent cleanability, and hygiene characteristics

good high and excellent low temperature properties

non magnetic (if annealed)

hardenable by cold work only

Percolation is a method of extraction achieved by the downward displacement ofsoluble extractive by a suitable solvent through a suitably comminuted drugplant. The process is a combination of maceration and percolation and issometimes referred to as a process of "Macero-Percolation'. Not all plant drugsare suitable for the process (see Section 11-21). There are 7 distinct operationsinvolved, they are in order of operation;

1. Comminution. The principles of size reduction are covered in section 11-16.Remember if the particles are too fine a solid cake may occur, this willsurface area exposed to a solvent.

effect the downward flow of menstruum and willmost certainly lead to the formation of 'dry pockets'within the body of the material which will escapeextraction. It the material is too coarse theninterstices are formed through which there is aspeedy percolation of menstruum which producesan incomplete extraction and will require excessivevolumes of menstruum to exhaust the marc.

The Principles of Size ReductionThe methods of size reduction (comminution) andthe classification of particles obtained are coveredlater in the article. A major factor in the solubilityof a substance is the amount of surface areaexposed to a solvent.The greater the exposed surface, the faster and more complete is its entry intosolution, e.g.

The cube has 6 sides each side is 100 cm2

-: area exposed is 6 x 100 cm2 = 600 cm2.

We slice the cube into 8 equal portions.The surface area for each cube is

6x 25 cm2 = 150 cm2 -:- 8x 150 cm2 = 1200 cm2

Therefore we have doubled the surface area.

The degree of comminution required will also depend on the composition of thecrude drug e.g. is it hard or soft ?, is it thick or thin ? If the drug is leaves orpetals then it will be easily penetrated by the solvent, therefore the degree ofcomminution need not be great, whereas hard and woody substances will


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require a greater reduction in size. Some substances such as aloes or gumresins need only be crushed, therefore it is a matter of becoming familiar withthe material being operated on. The following categories will serve as a generalguide.

(A) Broken or Crushed. Gums, resins and inspissated juices. Most seeds and

fruits.

(B) Sliced or Small Cut. Rinds, skins, pith, stalks.

(C) Rasped. This type of size reduction is of dubious value and is only officiallyused for quassia which is a hard wood. From personal experience the tediummay be avoided by pulverizing such substances.

(D) Powders. Rhizomes, roots, barks, woods, corms. There are 5 officialgrades of powder.

Table 11-16A

Further details may be found in Section 6-45. For extraction purposes we mayignore the 80 and 120 mesh with the 25 and 45 mesh being most often used.

The final consideration for the degree of comminution needed is the menstruumor solvent to be used for the extraction. Remember that our solvents are water,alcohol or a combination, i.e., dilute alcohol.

The tissue of crude drugs in the dried state will contain around 4 to 5% moisture(see Section 4-17) if it has been properly conditioned, therefore if water or adilute alcohol is used as the menstruum it will penetrate and spread rapidlythrough the plant tissue; whereas strong alcohol i.e., 50% by volume or over in


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the initial stages will cause a shrinkage or hardening of the tissue because thewater is pulled to the surface thus shrinking the interior. This phenomenon maybe explained by the fact that ethanol molecules have a hydrophilic tail.

Apparatus for Size Reduction and Particle Classification.

Classification by Sieve.

Classification by sieve,may be used directly forparticle reduction if usingwhole dried herb. Sievesare further used for sizeclassification of materialsthat have been subjectedto other means of sizereduction.

Size Reduction.

Small scale size reductionmay be achieved by theuse of a mortar or pestleor on a larger scale, the

same method that is used to produce mealie from dried maize in a villagesituation.

For larger scale work a suitable ball mill may be constructed from scrap parts. Itmay be powered by hand, pedal, or other motive force such as a suitably gearedlawn mower engine or the electric motor taken from a discarded washingmachine. The general principle is :

Alternatively an agricultural feed mill will also serve the purpose but it will requirean engine or electric motor to operate the apparatus. Size reduction is achieved

by fixed or swinging beater armsrevolving at speed within achamber.

The diagram represents a typicalpiece of laboratory extraction ware.It will be seen that the principle issimplicity itself. Larger scaleapparatus may be constructed fromdiscarded milking equipment. 50 or100 litre containers would meet theneeds of the larger cultivation. It isnot necessary for the extractor


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body to be tapered. However a domed bottom as shown in the diagram wouldfacilitate the efficient extraction of the herbal material.

The Hammer Mill.

Small Scale Extraction Apparatus.

Choosing an Appropriate Extraction Process.

When considering a crude drug for extraction purposes thought must be given towhether the drug is classified as 'organized' or 'unorganized' . If the drug has noclearly defined cellular construction it is unorganized. The maceration process isthe only method suitable for unorganized drugs such as gums, resins, oleo-resins etc. Such materials are unsuitable for percolation because the residueswould block the percolation process. The same restriction will also apply tocrude organized drugs that produce large amounts of mucilage e.g. flax orpsyllium seed. In other cases if a drug for whatever reason cannot be reducedto a powder then it is not suitable for a percolation process. Some drugmaterials e.g. Garlic and squill are extremely hygroscopic and in the presence

of water tend to fuse into lumps which make them unsuitable for the percolationprocess.

Tinctures from Unorganized Drugs.

Maceration is the only feasible method of producing a tincture from anunorganized drug such as gum benzoin or propolis resin. Further information onthe exudates will be found in Sections 9-16, and 9-51 et seq. 9-57.

The marc from the exudates is usually slimy or gummy and may also consist ofvarious types of debris e.g. insect parts, fragments of soil or plant parts. Thegums are insoluble in alcohol while the resins or oleo-resins will passcompletely into solution. The gum and debris will sink to the bottom of the

maceration vessel. The separation of the supernatant liquid is usually by simpledecantation or if required by filtration. There is no advantage to be gained byattempting to press the marc because all of the soluble constituents haveentered into solution.

2. Imbibition. The word is derived from the Latin meaning 'to drink in'. Thecomminuted drug thoroughly moistened with a portion of the menstruum. This isbest done in a lidded container of a suitable size. The moistened drug isallowed to stand for a period of four hours to allow the drug to imbibe the


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menstruum and thereby swell to its maximum capacity. The container usedshould be large enough to accommodate the expansion of the drug.

3. Packing. On completion of imbibition the drug should be passed through anumber 10 sieve (Table 6-45A) to break up any lumps that may have formed.The drug is then transferred to the percolation vessel in portions. Each portion

should be firmly packed but not so firmly that liquid is forced from the drug butsufficient to exclude any air pockets.

4. Maceration. Open the stop cock on the bottom of the percolator and pour inthe menstruum in portions and allow to percolate through the packed drug. If themenstruum drips through the stop cock in less than 10 minutes, the drug is tooloosely packed. If the first drop takes 25 minutes or more then the drug is tootightly packed. If all is well, then close the stop cock and pour in sufficientmenstruum to leave a layer 1 or 2 cm deep over the drug. Cover the percolatorand leave to macerate for 48 hours in a warm dark place at a temperature notexceeding 25C.

herbs conservation and cooperation

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