First of all I would like to inform all of you who preordered organic oils that the consignment has arrived and is in San Francisco. It is in the process of clearing customs and hopefully all formalities will be completed by Wednesday. I hope that I will be able to get the oils packed and sent by next Monday. For those of you who may not have noted the arrival of the agarwood incense it is here and I have enough stock to last until the holiday season. It is packed in a simple self locking cellophane package with no graphic or any other label. Suzanne and I now working with our graphic designer for making the package and hopefully in the early part of 2002 it will be ready. But already the word has spread on the beauty of this lovely agarwood fragrance which is made using the traditional masala technique explained below. Right now a lot of effort is being directed toward other incense offerings. One line is going to be based on combining the traditional masala incense technique with attars, essential oils and absolutes. A masala incense base is created by incorporating the raw powdered materials with charcoal, jigat(a natural binding agent) and resins(these vary from incense to incense the resin being chosen for its affinity with a particular aromatic material) The essential oils, absolutes and attars are also incorporated into the base. In this way an aromatic paste is formed that is then rolled onto thin bamboo sticks. Watching the dexterity of the woman who do this work is incredible. Sitting on the floor with the paste in ball, they deftly pinch off just the right amount and roll it onto a bamboo stick in a flash. The final stage is to roll the finished stick which is still moist in sandalwood powder or agarwood powder so that when the sticks dry they will not adhere to each other.They are beautiful in appearance and odor. In our offerings the emphasis will be toward single note masala incenses. Right now the formulas are being worked out for Lotus, Rose, Jasmin, and a special Frankincense/Myrrh combination. Another incense line is being developed which is based on dipping an already created incense stick composed of sandalwood powder, jigat, and charcoal into the pure essential oils and extracts of individual aromatic plants. These are very simple and pure in nature radiating the odiferous charcteristics of the named oils. Vetiver, Patchouli, Frankincense, Sandalwood, Ambrette Seed, Cedarwood, Fir and Pine are in the works for 2001. So this is an exciting new dimension of our aromatic offerings. OK. Today a subject is going to be taken up which is not an easy one to delve into. It concerns distilling techniques, the advantages and disadvantages of each, the types of materials that benefit from one type of distillation over another, etc. It is a deep and intricate subject and I have had to just focus on basics. There are many details which can only be properly understood by those engaged in this work for it is as much an art and craft as it is a science. So I would like to gently dismiss the idea that I am some type of authority on this subject. Rather this article is meant just to give a tiny glimpse into a world that concerns itself with transforming the oils produced in aromatic plants into the fragrant gems we all love and appreciate.
"Distillation represents a dynamic part of a whole process where the ethereal oils contained within a plants aromatic sacs or glands are liberated through heat and pressure and transformed into a liquid essence of sublime beauty. In a plants journey from seed to maturity, a constant natural process of distillation is occuring as it draws into itself elements from the surrounding environment and converts them into the substances that give it life, structure, texture, color and fragrance. Harvesting the plant at the appropriate time and endeavoring to distill from it the miracle of its essence, is the high art and craft of the distiller."
Dear Friends- When considering the beauty and mystery of the world of aromatic plants and their precious essences which are distilled and extracted by various methods, one comes to realize that in the short space of a lifetime one may only scratch the surface in understanding the subject. As all of you know the process of growing any crop requires a lot of skill and knowledge on the part of those engaged in such work. Working with nature over a period of many years engrains in one a respect for the wonders around one and develops a sincere humility as learns to adjust to the environmental changes that influence the growth of a plant from seed to maturity. When plants have reached the moment of perfect aromatic maturity, they then go into the hands of those engaged in distilling or extracting their precious essence. It is one more vital part in the entire process. It is a subject that has its own aura of mystery. Actually little has been written about the intricasies of the subject and certainly one must be directly engaged in this process to really understand it. The creative imagination will have to serve for those of us who have not yet been afforded this opporutnity.
First of all each and every aromatic raw material has to be considered as an individual entity. The perfect time for harvest of some plants is more straightforward than others. Flowers such as Rosa damascena, Jasminum sambac, Jasminum grandiflorum, Citrus aurantium var.amara(Neroli), must be plucked just as their buds are beginning to unfurl and at a very specific time of day in order to capture the pure essences and produce oils or absolutes of the highest quality. Once a flower has passed its prime(which in most cases happens within a day or two) the essential oil quality degrades quickly. Even in this case, there are some interesting facts to consider. Some flowers have a bloom season of a month or less(Rosa damascena) others can be as long as 6 months(Jasmin sambac) Whether the season be long or short, there are some days within that period where the the flowers have a balance of constituents which are considered the most refined and perfect of all.
But there are many plants where this is not so. Consider the grasses like Lemongrass, Palmarosa, Citronella, and Gingergrass. The balance of their constituents changes from day to day as they pass from mature grass to seed. Many times a specific balance is required by large consumers of the oil and so test distillations are done from day to day with immediate gc analysis being done to see what that balance is. This is particularly true when particular components are being isolated for for the flavor and fragrance industry. But one should not think there is only one profile for a particular oil. There are
often many different profiles depending on not only the stage of maturity of the plant, but the soil it is being grown in, the method of distillation, the length of time between harvest and distillation, etc.
In examining this subject we also have to consider that in many countries, a particular crop is not being grown by just one person on a specific piece of land. Often there are large numbers of farmers growing the crop on small land holdings. There may be a variety of cultural practices employed by each that will influence the health and vigor of the plants. Certainly the aromatic raw material will
fit into certain parameters, but it is important to realize that plants are greatly influenced by the environment in which they live and even small differences in mico climate, water, soil etc have their effect.
Very few farmers have their own distilleries and often the material growing in a certain local is taken to a central facility where the material is distilled. Prior to distillation the distiller may also be presented with the problem of how to properly disintegrate or reduce in size(called comminution) the material especially if he is dealing with dried aromatics like spices, seeds, roots, etc. These materials have to be reduced in size so that during the distillation process the maxiumum surface area of the plant material comes in contact with the distilling/extracting medium(generally water, steam. solvents, CO2) and release the volatile oils contained in the plants oil glands or sacks. It is important that this be done in such a way that the comminution process itself does not destroy the volatile oils(due to excessive heat in grinding, crushing or slicing) or that their is not to much lag time between the time when the plants are thus prepared and then distilled(as when the aromatic materials are crushed,etc much evaporation of natural oil can occur in a brief time) The ideal therefore is to effectively and carefully reduce the size of the aromatic plant materials so that the steam, boiling water can vaporize the maxium amount of essential oil.
images of oil glands of peppermint, oregano, peppermint
http://fisher.bio.umb.edu/pages/JFTrich/trichome.htm images of basil
module of glandular trichome
The cell walls of some plants are very thin and permeable which allows steam, boiling water, solvents, etc to easily penetrate them, and carry away the essential oil contained in the oil sacks or glands. But others have to be carefully prepared before their essential oils can be released. Seeds need to be thoroughly crushed and roots, stalks and woody material need to be chopped into fine pieces. A whole range of communition equipment has developed to insure that this process is done in the most efficient and sensitive manner. Some companies have even evolved crushing equipment that disintergrates the material and sub freezing temperatures. The main thing is that as soon as the crushing or grinding has occurred, the distillation process should begin as the volatile oils rapidly evaporate into the surrounding atmosphere.
Storage of plant materials prior to distillation is of importance to the distiller. Many plant materials(dried roots, seeds, woods) can be effectively kept for several months without significant loss of essential oil content provided the room is cool, dark, dry and free from air circulation. If these conditions are not meant then precious oil content can be lost due to oxidation and resinification. Some plants like peppermint and clary sage are sometimes partially dried before distillation as their very high water content makes it difficult to distill in the fresh state. It was once thought that there was little or no essential loss because of drying. But in fact this has been proved wrong. There is a loss of essential oil in general and specific components in particular. A detailed analysis of oil distilled from fresh peppermint and partially dried peppermint will reveal a host of differences especially in the minor and trace components. It does not mean that the oil from partially dried material is not beautiful, it just means that it is different.
Then of course there are the issues surrounding the type of equipment to be used. Glass, aluminum, iron, stainless steel, and copper are all common materials used in constructing stills of different sizes and shapes. The still body itself(that is the vessel into which the raw material is placed) can be designed to hold water, to have steam pumped into it, have perforated plates upon which the materials sit, have automatic or manually operated stirers to prevent materials from sinking to the bottom of the still and thus getting charred, etc.
good article on geranium and olfactory differences of geranium distilled in glass, copper, etc
Regarding distillation issues, some people say that glass is best, others copper, others stainless steel, etc. It is an interesting debate because those who follow a particular system have often attained high expertise in what they are doing and the type of knowledge they have acquired and the feeling for their equipment also greatly influences the quality of the end product. It is true that the majority of oils are distilled with a more commercial angle of vision. Large stills are created with efficient condensors, etc and many mechanical controls are put in place to be sure that the oils fit with the parameters of the international fragrance and flavor industry(which produces the majority of the oils that are sold today) But there are a growing number of small distillers who take great pride in their art and craft and are constantly refining their techniques of distillation so that the oils possess the greatest spectrum of aromatic molecules as possible.In saying this I do not mean to saythat the large distilleries are devoid of such expertise. What they have accomplished in terms of providing beautiful oils is no small achievement, but there is also much to be said for the artisian working with their unit of 25-200 liters distilling oils of superior quality. I think we shall see more and more of these intimate endeavors arise in years to come.
Then when one gets into the world of the distillation itself, one has to possess a tremendous amount of knowledge about the specific plants with which one is dealing . One, either through intuitive knowledge or scientific training has to understand the incredibly complex aromatic configuration of the plant they are dealing with. Each plant possesses a range of aromatic molecules from low boiling to high boiling constituents. The art and craft of producing a truly amazing oil lies in understanding how to "tweek" ones distilling techniques so that the the process captures both the sublime top notes and the deep base notes. One has to know how to bring up the heat in such a way that the material begins to release its ethereal oil thus capturing the widest spectrum of molecules \. This is where the high art and craft of distilling takes on its most sublime form and a person engaged in such aromatic creation happily devotes and entire lifetime to perfecting their technique. For each and every raw material that enters their still, they are having to discover the best method for distillation. Indeed, one might say that few are the noses that appreciate the nuances that they capture in their liquid gems. Most of us are acquainted with very fine oils that are produced in commercial stills but occasionally one comes across an artisan working on a more intimate level and their oils may
have a particular charging and beauty that cannot be explained by any sophisticated mechanical analysis.
In making an effort to appreciate the distillers art and craft one comes across a number of terms that require some effort to understand. Methods of distillation include steam, water(sometimes called hydrodistillation), water-steam, and hydrodiffusion. Extraction techniques include solvent and CO2.
The following site is an excellent read for the different techniques of distillation.
nice diagram of steam distilling equipment and process
nice article about different techniques of distillation
There are many technical terms which pretain to the operation of distillation-Vapor pressure, thermodynmaics, boiling point, atmospheric pressure, latent heat, hydrolysis, resinification, saturated steam, superheated steam etc. Each term has a world of research behind it and deserves careful study. It is beyond the scope of this modest introduction to the subject to go into all the exact details. All that can be presented here is a broad overview which is meant to instill in the heart a recognition of some of the intricasies of the subject(and hence the wonder and beauty inherent in it) Many of the links to be found within this article and also at the end will shed further light on the subject.
What does need to be understood about distillation though is that whether oneis doing water, water-steam, or pure steam distillation one is going to be applying heat and pressure upon the aromatic tissues of the plant and by the very nature of this exercise certain effects are produced that are going to change the chemical nature of the essential oil as it exists in the plant. The processes of diffusion, hydrolysis and thermal decomposition do act upon the aromatic material during distillation producing an oil which has some similarities and some differences from the original. An essential oil should not be understood as something perfectly representing the oil as it exists in the plant. It is what it is, a new beautiful aromatic essence which arises as a result of many factors: environment, individual plant characteristics, care and nurturing of the farmer( watering, weeding, fertilizing, time of harvesting) proper comminution of the material prior to distillation, distillation technique, the understanding and awareness of the distiller, etc. In its highest form it is like a great work of art which captures something of the exquisite beauty of the living aromatic plant but is not the plant itself. It is an act of creation arising from a long set of natural processes into which the human element enters through taking a gift of nature and transmuting into a sublime treasure which can be transported in a small vial to any place. When the vial is opened releasing the trapped precious volatile vapors, the effect it has is as powerful as the creative imagination of the person inhaling it and the many processes that produced it.
From a simple outer standpoint-one can gain a comparative analysis of the different systems of distillation(water, water and steam, and steam distillation) by studying Book 1 of Ernest Guenther's 6 volume set called, Essential Oils. In presenting his finding one has to take into account as mentioned before, that people have developed an intimate knowledge of their distillation technique may have risen above such obeservations as Guenther makes.
I will use these abbreviations to save a bit of time-
W/SD(Water and Steam Distillation,
Type of Still
WD-Simple, low priced, portable stills; easily installed in producing regions
W/SD-Somewhat more complicated and higher priced than WD. The smaller type is also movable and may be installed in the field
SD-If well constructed, usually more solid and durable than than WD and W/SD. Possibility of large size for large scale distillation
water/steam distillation unit
steam distillation unit
lighter than water seperator
heavier than water seperator
Type of Plant Material
WD-Most advantageous for certain materials, especially when finely powdered; also for flowers which easily lump with direct steam. Not well adapted for materials containing saponifiable, water soluble or high boiling constituents.
W/S -Well Suited for herb and leaf material
SD-Suited for any charge except finely powdered material through which the steam forms channels("rat holes") Especially well suitied for seed, root, and wood materials containing high boiling oils.
Mode of Communition
WD-Best results with finely powdered materials
W/SD-Plant material must be uniformily but not too finely comminuted. Granulation gives best results with seeds and roots
SD-Same as above
Mode of Charging
WD-Material must completely covered by water
W/SD-Material must be evenly charged into the still
SD-Similar to above. Proper charging is very important;otherwise the steam channels through the plant materials and low yield results
WD-Good, if material is properly charged and moves freely in the boiling water
SD-Good if steam is slightly wet. Distillation with superheated steam or high pressure stem dries out the plant material, prevents diffusion, and causes a
low yield of oil. Such distillation must, therefore, be followed by wet steam http://biology.arizona.edu/sciconn/lessons/mccandless/default.html good
introduction to diffusion, osmosis and cell membranes
role of water in osmosis and diffusion
definition of superheated water Steam Pressure
Within the Still
WD-Usually about atomospheric
W/SD-Usually about atmospheric
SD-Can be modified(high or low pressure steam) according to the plant materials
Temperature within the Still
WD-About 100 degrees Celsius. Care must be exercised not to "burn" the plant material by contac with overheated still walls. Vaporized water be continuously replaced
W/SD-About 100 degrees
SD-Can be modified(saturated or superheated steam) according to the material.
Hydrolysis of Oil Constituents
WD-Conditions usually unfavorable. High rate of ester hydrolosis
W/SD-Hydrolysis fairly low, provided no excessive wetting of the plant charge within the still takes place
SD-Conditions good, hydrolysis usually slight
Guenther-"Hydrolysis in our case can be defined as a chemical reaction between water and certain constituents of essential oils. These natural products consist partly, and in some instances largeley of esters, which are compounds of organic acids and alcohols. In the presence of water, particularly at elevated temperatures, the esters tend to react with the water to from the parent acids and alcohols."
Conditions within the Plant Charge
WD-Good if plant material is covered with water and moves freely in it
W/S-Good if material is properly comminuted and charged. Prolonged distillation causes excessive wetting by steam condensation and lumping of the charges. Stills should be well insulated
SD-Conditions good, if plant material is properly charged,. Prolonged distillation with wet steam causes excessive steam condensation with
the still and lumping of the charge
Rate of Distillation
Yield of oil
WD-In most cases relatively low, due to hydrolysis, also because water soluble and high boiling oil constituents are retained by residual water in the still
W/SD-Good, if no excessive wetting and lumping of the plant charge occurs. This would prevent steam from penetrationg the charge throughly and result in abnormally low oil yield
SD-Good if plant material is properly comminuted, evenly charged, and distillaton properly conducted. Lumping of the charge or steam channeling might cause abnormally low yield of oil
Quality of Oil
WD-Depends upon careful operation; "burning' of plant charge must be avoided, especially when distilling with direct fire
SD-Good if operation properly conducted all around
WD-Distillation water in some cases must be redistilled, or more conviently returned into the still during distillation(cohobation). Distillation waters contain products of hydrolysis, chiefly
W/SD-If properly separated the distillation water can be discarded in many cases
SD-Similar to above
In conclusion I would like to mention once again that each and every technique of distillation has its seeming positive and negative points when looked at from a strictly technical standpoint. But any one method can yield sublime results when performed by a Master Distilling Artisan. Techniques, types of equipment, etc are means to an end but there are always rare individuals who raise something from a craft to an art using the tools at their disposal combined with a unity of vision that they have cultivated over many years of application to their work. This type of direct inner inspiration is a product of a true reverence for life which arises when the seer and seen become one.
Terminology involved with the subject of Distillation http://www.xrefer.com/results.jsp?shelf=search+all&term=
Distillation, destructive distillation, fractional distillation, molecular distillation, steam distillation, vacuum distillation
natural variation in essential oils article
superb article for those wishing to get into distillation
distillation procedures for several oils
distillation of vetiver in Indonesia
really nice article on EcoAgriculture and Essential Oil Production
ylang ylang production and distillation
patchouli distillation with images
hydrodistillation units for rose in Turkey
description of different types of distillation including vacuum, fractional, and destructive
conventioal batch distillation with diagrams
good site on chromatograpy links
the alchemists laboratory
home lavandin distillation with lots of images
hydrostillation units from Australia
citrus oil extraction
distillation of cinnamon camphora leaves in Madagascar
essential production in West Africa
fractional distillation columns
mint farming industry in USA
supercritical extraction for the Carribean
patchouli distillation in Indonesia
alchemy.htm chemistry and alchemy http://courses.che.umn.edu/00fscn4345-1f/flavoring_materials.htm
good site with some simple explanations of important terms like terpenless, folded, etc
techniques of distillation with superb images(including enfleurgae
comparison of three different methods of distillation for lavandin
volatile oil of western juniper
cassia distillation china