OBSERVATIONS upon the ESSENTIAL OIL INDUSTRIES of FOREIGN LANDS C. A. BROWNE Bureau of Chemistry and Soils, U. S. Department of Agriculture, Washington, D . C .
I n the course of a tour of chemical observations through various Mediterranean countries in Europe and the Near East considerable attention was given by the writer to the agriculture, technology, chemistry, and.economic status of
certain essential oil industries. The observations recorded in the present paper were gathered during oisits to estates, factories, expositions, departments of agriculture, and foreign comular ofices of the United States.
THE FLORAL ESSENCE TNDUSTRY
of Grasse is better suited in many ways for a widely diversifiedfloral essence industry than any other region of the globe. There is here a sheltered location among encircling mountains, a proper balance of rain and sunshine, a.suitable soil, excellent drainage, a native population with a long background of horticultural experience, and a climate that is generally mild and neither too humid nor too dry. The one serious climatic drawback is the proximity to the high peaks of the Maritime Alps, from which in winter occasional freezing currents of air may descend and do serious injury to the plantations of bitter orange, mimosa, and other delicate flower-producing shrubs. A disastrous freeze of this character occurred on February 13, 1929, during the winter preceding the writer's first visit to Grasse, and millions of dollars worth of damage was done to the flower plantations of the Riviera. With the exception of rose oil, in which Bulgaria leads
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ROBABLY no chemical industry has been so extensively described and pictured in current literature as that of the floral essences. Not only have the subjects of flowers and perfumes a wide popular esthetic appeal but the localization of the chief center of the industry a t Grasse, in the picturesque Riviera of France, brings it annually to the attention of thousands of visitors from all parts of the world. For the chemist, who wishes to gain first-hand knowledge of the agriculture and technology of floral essences, it is more satisfactory to avoid the establishments whose chief interest in welcoming visitors is the sale of perfumes, cosmetics, and scented soap and to confine his attention to those factories which do not cater to the tourist trade. Owing to a peculiar combination of favorable climatic, agricultural, and economic conditions the region
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the world as regards volume of production, France has had a practical monopoly of the European floral essence industry for many decades. She has continued to maintain this leadership even with the growing competition of synthetic odorous preparations. In perfumes, as in styles, French manufacturers continue to regulate the popular preferences. By the artistic blending of different floral essences and by the judicious use of synthetics and other adjuncts they have produced combinations which perfume manufacturers of other countries have been unable to imitate. The chemist who visits Grasse is impressed a t once with the many-sidedness of its essential oil industry, with the ramifications of its processes, with the numerous types of its stills, extractors, and other apparatus, and with its flexible adaptation to agricultural and commercial requirements. The industry is an outstanding example of the close harmonious correlation of a highly specialized branch of agriculture with a highly specialized branch of chemical industry. As the late Professor Otto Wallach, who won the Nobel Prize for his work upon the constitution of the terpenes, remarked to the writer only a few weeks before his last illness, "For its scenic attractions and the almost infinite variety of its essential oil industry, Grasse may be called the chemists' paradise." The floral campaign in the regions about Grasse extends usually from February, with the picking of violets, until November, with the termination of the blossoming of geraniums and other autumn, flowering plants. The course of the campaign for several flowers is given in Table 1. The statistics of production are very unreliable, and the figures, which vary greatly from year to year, are only approximations. In addition to the flowers named in the table floral essences are also prepared from mimosas, hyacinths, heliotropes, marjorams,
mignonettes, carnations, and other blossoms. Besides these floral products essences are also prepared a t Grasse from the leaves, stalks, roots, wood, fruits, etc., of various domestic and imported plants such as thyme, mint, rosemary, geranium, iris root, vetivert, sandalwood, cloves, and patchouli. TABLE 1 STATISTICS* RBCAXDINC
A
Few FLYIVBRS UTILIZBDB y THB FLORAL ESJGNCB IN~VSTRVOPFRANCE
Eslimolcd A n l d F1oi"rr
Time of Pidim
P*aduc,ianof Plowars.
Violet. . . . . . . . . . . . . . . . . . . . February to April Jonquil. . . . . . . . . . . . . . . . . . March and April Rose . . . . . . . . . . . . . . . . . . . . . April and M a y Bitterorange . . . . . . . . . . . . . April to June sage . . . . . . . . . . . . . . . . . . . . . Jane to Ausuat Lavender . . . . . . . . . . . . . . . . . July to Seutember larmine.. . . . . . . . . . . . . . . . . 1"l" t o October Tuberose.. . . . . . . . . . . . . . . . August to October cassia. . . . . . . . . . . . . . . . . . . Auzurt t o November
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French production doer not, therelore, aupear crcea3ive.
PROCESSES OF MANUFACTURE
The flowers as soon as gathered are taken to the factories where, after being weighed, they are worked up as rapidly as possible, b y the various processes of distillation, extraction, maceration, enfleurage, or their modifications, the ' particular treatment depending upon the character of the flower and t i e nature of the product desired. Only a few typical operations will be selected for description. DISTILLATION
GATFIERING VIOLETSIN
T H E OLIVE GROVES NEAR
GRASSE
The process of distillation is applied only to the cheaper and more resistant floral essences, such as the oils of lavender and of bitter orange blossoms. Lanender Oil.-This is the chief essential oil of the Maritime Alps Region, the annual production varying from 100,000 kg. to 150,000 kg. The true lavender, of which there are two varieties (Lavandub delfihinensis and l.fragram), flourishes best a t altitudes above 2000 feet. The plant grows wild in stony pastures and deserted fields where the patches of flowers form conspicuous features of the landscape. The rights to gather the blossoms of
wild lavender are usually auctioned off each spring to the highest bidder by the various communities to which they belong. In addition to the crops of wild lavender there are also large areas of the cultivated plant, which are controlled by private owners, among
The flowers are placed in frames coated on the inside with fat which absorbs the volatile essence.
RECEPTION OR LEAVES AND FLOWERS O F VIOLET FLORAL ESSENCE FACTORY 1N GRASSE
AT A
whom are several of the large essential oil companies of Grasse. The yield of lavender oil varies from 0.4% to 0.8% for wild flowers and from 0.8% to 1.2%-for cultivated flowers, the general average for all kinds being probably about 0.7% to 0.8%. The main bulk of the lavender oil of the Maritime Alps region is produced by small farmers, whose output is sold to the large supply houses and exporters. There is a growing tendency of the small farmers to form cooperatives with central factories for distilling the flowers s u ~ ~ l i bv e d the individual members. These co6Derativei by the introduction of more scientific mekods exercise a favorable influence upon improving the yield and quality of the oil. Two methods of distillation are emplo ed--open-fire 4: remote secstills and steam stills. A visit to the more tions enables the chemist to observe many small rustic stills of archaic type and crude construction. The use of migratory or portable stills, which was formerly common in the hilly sections, is now of less general occurrence. The open-fire stills give a lower grade and lesser yield of oil than do the steam stills, owing to a partial saponification of the esters (principally linalyl acetate) and to an imperfect removal of the oil. In the lower altitudes of the Maritime Alps near the sea a small amount of oil is distilled from aspic or spike lavender (Lavandukz spica or kztifolia), but the product is of lower quality than true lavender oil, being deficient in linalyl acetate, which is the usual index of valuation. At middle altitudes the spike and true lavender cross to form a mixed variety known as "Lavandin" which yields an oil of intermediate character. than Bitter Orange Blossom or Neroli Oil.-More
ninety per cent. of the bitter orange blossoms of France are gathered from an area within thirty miles of Grasse. The bitter orange tree (Citrus oulgaris or bigaradiu) should be distinguished from the sweet or edible orange (Citrus aurantium), the skin of whose fruit yields the familiar flavoring product known as the essence or oil of sweet orange. The hitter orange tree gives a partial crop of flowers in eight or ten years but does not come into full bearing until the fifteenth or twentieth year. The yield of blossoms per tree is said to range from 6 to 30 kg., depending upon the age of tree, exposure of orchard, character of soil, weather, and other conditions. The yield of blossoms is variously given as from 400 to 1600 kg. per awe. the spacing of the trees in this case being also a determining factor. The growers of bitter orange blossoms are united in a large cooperative or syndicate which controls the main bulk of production. In case the Grasse factories do not pay the producer a satisfactory price, the coiiperative may exercise the option of producing its own oil in a large distillery which i t possesses a t Vallauris. At the beginning of the crop in April the flowers yield about 0.1'% or less of essential oil, this quantity increasing with the advancement of the season to as high as 0.18%, if the weather he warm and dry. The average yield under ordinary climatic conditions is probably not greater than 0.12%. Only about 6ij to 75 per cent. of the oil of the blossoms is recovered by the ordinary processes of distillation. The other 25 to 35 per cent. remains in the aqueous condensate and is sold as orangeblossom water which finds an extensive use in the preparation of scented lotions, pomades, creams, and other pharmaceutical products. The yield of orange-blossom water is about 1 kg. per kilo of flowers. The flowers must be distilled immediately after gathering, otherwise enzymic changes may set in which give the oil from stale hlossoms a very objectionable odor. With flowers which come from too remote a distance it is sometimes the practice to check decomposition by shipping them in brine, the mixture being
added to the alembics with water and distilled in the ord'mary way. In one of the establishments which the writer visited, neroli oil was distilled from alembics of about 600 liters capacity. The flowers were introduced through the removable head in perforated basket containers. The steam from the boiler underneath passes upward through the mass of flowers and carries with it the odorous volatile constituents into the condenser and recipient. After about three hours the distillation is stopped, the container of spent flowers is removed, and a new charge is introduced. The essential oil accumulates upon the surface of the condensate in the recipient, the orange water underneath being drawn off by the ordinary Florentine method of separation. The yield of essence can be increased by redistilling the aqueous condensate (cohobation), but this is not considered remunerative in view of the generally good demand for orange-blossom water. Rose Oil.-In France the rose oil industry is chiefly concentrated in the region of Grasse between Cannes and Nice. The principal variety grown for essence manufacture is the common or May rose (Rosa centifolia), the oldest of known roses, although various fancy modem creations, such as the Marechal Niel, Ulrich Brunner, and Roseraie de l'Hay, are also cultivated for purposes of distillation or extraction. The bushes are planted in rows from 1.5 to 2 meters apart; they begin bearing in the second year and under favoraljle conditions give a production as high as 2000 kg. per acre from the fourth to tenth year, after which the yield declines. The crop begins late in April and lasts until June. The roses are picked usually early or late in the day, in order to avoid the injurious effect of wilting by the hot sun, and are then transported immediately to the distilleries, where they are a t once worked up before enzymic decompositions begin. The campaign is pushed vigorously, some establishments at Grasse handling as high as 50 tons of roses per day. Only about one-quarter of the rc+e crop is distilled a t present in the Grasse region, the remainder being treated by the various processes of enfleurage, maceration, and extraction. As the fire stills have an injurious action upon the quality of the oil only steam alembics are used. The capacity of these ranges from less than 50 to as high as 1500 kg. of flowers. The yield of rose oil is much less than that obtained from lavender and bitter orange blossoms, being only about 0.02 per cent. of the weight of fresh flowers. The yield of rose water, which is obtained by the same process described for orange-blossom water, is about 1 kg. per kilo of flowers. The production of rose water being the principal aim of the French manufacturers, the distilled rose oil is virtually a by-product. Rose water, the most ancient product of floral distillation, owes its high fragrance chiefly to the presence of phenylethyl alcohol, one of the predominating odorous constituents of the rose. It finds an extensive use in the manufacture of scented lotions, pomades, cos-
metics, and other pharmaceutical preparations. For certain uses rose water is said to have an anesthetic value. In the Orient it is also employed in the manufacture of scented confectionsand beverages. The processes of open-6re and steam distillation are so destructive to the essences of certain flowers, such as the jasmine, mignonette, tuberose, and jonquil, that other processes are necessary for extracting their odorous principles. Even with the flowers which are ordinarily distilled, such as the lavender, orange blossom, and rose, the character of the essence is adversely affected so that less destructive methods of manufacture are used also for the blossoms of these plants when it is desired to obtain perfumes of the highest quality. Among the processes employed for obtaining the more delicate floral essences are enfleurage (cold maceration), hot maceration, and extraction with volatile solvents. ENFLEURAGE
(COLD MACERATION)
This process is the most expensive of all methods for extracting floral essences and is employed chiefly with those flowers which yield the most delicate and costly perfumes, such as the jasmine, mignonette, and tuberose. The method is based upon the property which fatty substances possess of absorb'mg the volatile odorous constituents of flowers from the air. In canying out the process portable wooden frames, 100 cm. long, 60 cm. wide, and 8 to 10 cm. deep, are coated on their inner bottom surface, which is of glass or plated metal, with a carefully prepared mixture of well-selected lard and beef tallow, about 1 cm. thick. The writer was particularly impressed with the great care exercised in the rendering and purification of the fats, which must be completely free from rancidity and the slightest trace of unpleasant odors. The fats for the year's operations are prepared in the winter, when the floral campaign is over, and are kept in a cool place in containers from which air, light, and moisture are excluded. The frames, after receiving their coating of fat, are filled with freshly picked flowers and then stacked one upon the other in such a way that each individual compartment is tightly sealed. They are emptied and refilled, usually every alternate day, care being taken to avoid the presence of stale.blossoms. In one establishment visited by the writer, the spent blossoms were iemoved from the frames by a pneumatic device, in order to avoid the possible contamination of the fat with perspiration from the hands of the employees. After thirty or forty changes of blossoms the perfumed fat on the bottom of the frames is removed and the resultant pomade either sold as such or else worked up for its content of floral essence. The handling of the thousands of frames in a large enfleurage establishment involves a great expenditure of manual labor, and for this reason the process is very costly. In order to hasten the slow natural volatilization of essence from the blossoms various pneumatic processes of enfluerage have been proposed by which the same
volume of air is drawn mechanically back and forth through the mass of flowers along the thin films of absorbent fat. None of these devices, however, has succeeded in displacing the old hand-frame method of extraction. To separate the floral essence from the saturated pomade, the latter is agitated with absolute ethyl alcohol in a closed mixer. The alcoholic solution is then removed and the agitation continued with fresh quantities of alcohol. The richer alcoholic extrack of the first treatment are cooled to a temperature of -15' to -20°C., in order to precipitate as much as possible of the dissolved fat, and then filtered. The alcoholic solution of the essence, which still contains a minute quantity of dissolved fat, is usually employed directly in the compounding of perfumes. If it is desired to prepare the concentrated essence (the socalled "pomade absolute") the alcohol is removed by a carefully controlled fractional distillation. The weaker alcoholic solutions, obtained after the primary extraction, are used for treating fresh quantities of saturated pomade. The extracted fat of the pomades is not used again but is utilized in the manufacture of soap. Jasmine Oil.-The manufacture of jasmine oil, one of the most delicate and costly of the floral essences, is cited as a typical example of the process of enfleurage. France has an almost unlimited monopoly of this product, nearly the whole output of the world being produced in the Grasse district. Because of their delightful fragrance jasmine extracts, pomades, concretes, etc., are finding a constantly increasing use in the manufacture of a wide class of perfumery preparations. The rapid extension of jasmine culture along the French Riviera is an index of this growth in popularity. The jasmine plant (Jmminum grandiflorum) is a shrub which attains a height of about 6 feet. It produces blossoms the first year but does not come into full bearing until the fourth year, when it yields annually from 200 to 250 blossoms. The life of the plant is about 12 years. The average production of a jasmine plantation is about 2000 kg. of blossofi~sper acre. The flowers are gathered between July and October, preferably early or late in the day, in order to prevent wilting. The gathering of damp flowers after a rain is also avoided, both because of a deficiency in perfume and also because of the risk of the adhering moisture causing the fat of the enfleurage frames to become rancid. The extraction of the jasmine oil by the frame method is conducted in the manner just described. The flowers must be fresh; otherwise enzymic decomposition may occur, with the production of indol and other malodorous substances which injure the character of the perfume. The spent blossoms, after removal from the frames, are sometimes extracted with solvents to produce the so-called "frame oil," a product of inferior odorific value. The jasmine pomade is usually sold as such; the saturated pomade is estimated to contain about a half uer cent. of floral essence. On iccount of the-immense expenditure of time and
labor in the handling of frames and also because of a belief that the jasmine essence obtained by enfleurage is always slightly contaminated, partly by indol and other decomposition products generated in the flowers after picking and partly by traces of objectionable volatile products emanatmg from faintly rancid fat, there is a preference among some manufacturers for the more rapid process of extracting the blossoms with petroleum ether immediately after picking. While this procedure eliminates some of the defects of the slower and more laborious enfleurage process, i t has the objection of removing the waxes, glycerides, and other non-odorous ether-soluble constituents of the blossoms. The residue left after the evaporation of the solvent constitutes the so-called jasmine concrete, which is thought by some to resemble the natural odor of the fresh blossoms more closely than the pomade obtained by enfleurage. Opinions upon this point, however, are a t variance. The yield of concrete is about 0.2 per cent. of the weight of fresh blossoms. The product is usually sold as such without further purification. By extraction of the pomades and concretes with absolute alcohol, chilling, filtering, fractionally distilling under reduced pressure a t low temperatures, and by other means familiar to the organic chemist, are prepared the so-called "absolute" and "superabsolute essences," which represent the highest concentration of the fragrant floral principles. But for the ordinary purposes of the perfumers' art this high degree of purification is not considered necessary. HOT MACERATION
A more thorough fatty extraction of floral essences is accomplished by the process of hot maceration, in which the flowers are wholly submerged in the melted mixture of beef tallow and lard a t from 60' to 70°C., thus bringing the essence-bearing cells into closest contact with the extractive agent. . In one establishment which the writer visited, the penetration of the fat into the floral tissues was intensified by conducting the maceration in a closed agitator under vacuum. After a contact of from 12 to 48 hours, depending upon the nature of the flower, the liquid fat is removed from the plant tissues by filtration, pressure, or centrifugal means, and then reemployed f6r macerating another quantity of blossoms. The process is continued until the fat is considered to have taken up the maximum quantity of essence which it is capable of holding without loss by volatilization. The melted fat, after the final removal of spent floral tissues, is then allowed to stand in order to permit any absorbed water to separate, this aqueous contamination being very conducive to enzymic decomposition and to the development of rancidity in the fat, with consequent injury to the character of the perfume. The pomades obtained by warm maceration are either used as such by the perfume manufacturers or else are worked uu for their content of essence bv extraction with absolute alcohol, as described u n d k enfleurage.
station operates under the patronage of the French Institute and Academy of Agriculture, whose experts and specialists constitute an advisory board (Conseil de Perfectionnemenl) uponall matters of scientilic detail. Thc grounds of the jordin d'essoi comprisc about trn acres ol land, on the slope below the city of Crasse, where are located the laboratory buildings and experimental plots. The work of the laboratories and the field cxpcriments were explained to the writer bv the Director of thc Station, IIr. 1'. ,'i,,lr ,,yI ~ M,I,. . 13"
