Essential oils and other perfume
Perfume u d
and flavoring materials
Fluvoring Muterids
way we live.
are indispensable to the Fritzsche Brothers,
Inc., is representative of the diversified essential oil
A Sfaff-lndusfry Collaborative Report
firms that delve into all
LAURENCE J. WHITE, Associate Editor
phases of the industry
in collaboration with ROBERT J, EISERLE, Fritzsche Brothers, Inc. N e w York N. Y.
ESSENTIAL
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OILS have little trouble living u p to their name. Since antiquity, man has been mystified, intrigued, and challenged by essential oils, and has gone to great lengths to obtain them. Today essential oils are truly indispensable to the way we live. Without them our food would be bland, and many consumer and industrial products could not exist. Originally, the term “essential oil”
was not meant to imply indispensability. I t comes from the Latin “essentia.” Many alchemists believed that for every individual substance there existed a “quinta essentia” or quintessence which was responsible for its individual character. I n this sense an essential oil is the quintessence of the plant from which it is derived. Essential oils are produced in various internal and external glands of certain
flowers, leaves, barks, woods, and roots. Chemically these oils are mixtures, usually very complex, of terpenes, sesquiterpenes, their oxygena trd derivatives, and other aromatic compounds. Many contain 20 to 30 constituents covering the entire range of organic materials. “Aromatic” does not have the usual chemical meaning in the essential oil business. An aromatic chemical in
Essential oil manufacturing is marked b y wide contrasts in technology. As described in this story, producers use the latest chemical techniques and equipment. Still, many important oils are separated in primitive equipment (above) as a family side line VOL. 53, NO. 6
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PLANT P R O W SERIES
SESQUITERPENELESS
PURCHASED ESSENTIAL
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OILS ISOLATES SALES
DISTILLATION
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PLANT
CHEMICAL INTERMEDIATES
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PRETREATMENT CRUSHING,GRINDING, CHOPPING, ETC.
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OLEORESINS AND RESINOIDS
SOLVENT EXTRACTION
PROPRIETARY
SYNTHESIS OXIDATION,HYDROGENATION, CONDENSATION, ACETY LATION, POLYMERIZATION,ETC. I
ANIMAL PRODUCTS
I
FIXATIVES
PURCHASED MATERIALS FOR RESALE ESSENTIAL OILS CHEMICALS FLORAL ABSOLUTES FLORAL CONCRETES
Flowsheet for the manufacture of perfume and flavoring materials, Fritzsche Brothers, Inc., New York, N. Y.
this case, is any compound that has a specific, useful odor. As old as the industry itself is the question of whether the plant gets any specific benefits from its essential oils. I n some cases, the aroma of the oils undoubtedly attracts certain insects, thus aiding pollination, and repels others that might cause damage. But even this obvious function is difficult to prove scientifically. A number of essential oils appear to have a definite action on the transpiration of plants. Authorities have also postulated that they are a reserve food, a means of sealing wounds, or a varnish to prevent too much evaporation of water. Essential oils may be involved in plant syntheses, and perhaps are intermediates that are excreted after they have performed their assigned task in the plant. But despite all the investigations made so far, none of the explanations put forward is completely satisfactory.
In t h e Beginning The essential oil business has an ancient heritage. Oil of turpentine was described by the Greek historian, Herodotus, before 400 B.C. The traders of ancient Greece, Rome, and the
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Orient carried on a n extensive business in odoriferous oils and ointments, although these products were not essential oils as they are known today. The industry began in earnest as the art of distillation developed during the Middle Ages. Many references to essential oils in the scientific literature of the sixteenth century indicate that production and use became general about that time. Commercial scale manufacture began in the U. S. about 1800. Oil of turpentine was the first essential oil to be produced in volume in this country. This was followed by oils of peppermint, dill, spearmint, sassafras, wintergreen, and wormseed. Together with the citrus oils, these materials are still the major oils manufactured in the U. S. from domestic plants. The industry today presents wide contrasts in technology. Manufacturers operate modern distillation, fractionation, and extraction equipment, and use sophisticated analytical instruments to maintain a high standard of quality. But many important oils come from remote spots of the world where they are produced in crude contraptions as a family side line. The entire distillation system sometimes consists of nothing more than a crude condenser and a
INDUSTRIAL AND ENGINEERING CHEMISTRY
discarded oil drum placed over an open fire. The industry is gradually becoming less dependent on primitive sources of essential oils. There is an obvious advantage in using centralized plants for recovery whenever possible. However, because of the high cost of shipping some of the raw materials needed for centralized plants, primitive manufacturing is still a factor in the essential oil business. The American essential oil industry is based on imports with the exception of the citrus oils from Florida and California, and oils from several other indigenous plants. Because of the quality of imported oils, these materials are seldom sold without some reprocessing. This can vary from a simple water wash to complete redistillation or fractionation. Separation Methods
Distillation is the work horse of the industry. The process by which steam actually isolates essential oils from aromatic plants is immensely complicated, and distillation practices in the industry still mix a good bit of art with technology. Every type of plant material must be handled individually in the way that long experience has shown to be best.
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The terminology of the industry divides distillation into three types: water, water and steam, direct steam. With the method called water distillation, plant material is in direct contact with boiling water. Heat is put into the still by conventional means such as an enclosed steam coil, steam jacket, or direct firing. The second technique employs a grid to hold the plant material off the bottom of the still. The water level is kept below the grid so that the plant material is in contact with saturated steam only. Direct steam distillation also uses a supporting grid. Live steam, saturated or superheated, is fed into the still below the charge. Distillation has some drawbacks. Some components of essential oils are sensitive to heat, and the prolonged action of steam in the still can degrade the product. Some constituents dissolve in water, and cannot be easily recovered. Others boil at too high a temperature to be carried over with the steam. Oils from delicate flowers, such as jasmine, are particularly sensitive to the rigors of distillation; such flower oils as well as other oils are often isolated by extraction, Extraction with cold fat, called enfleurage, is the oldest extraction method. I t is not widely used now except in the Grasse region of Southern France and some parts of Italy. Enfleurage is used with those flowers that continue to give off perfume after picking. The petals are laid, a t room temperature, over a fat base made up primarily of lard. When the fat becomes saturated with oil, the oil is extracted with alcohol. A variation of enfleurage, also largely out of date now, is maceration or extraction with fat that has been heated to its melting point. I t is useful with flowers like the rose which do not give off perfume after harvesting. The oilsaturated fat from maceration, called pomade, may be sold as such or treated with alcohol to obtain a more concentrated product free from waxlike materials. The concentrated material is called a floral absolute. Most modern essential oil extraction plants use solvent systems based on materials such as petroleum ether or benzene. The key advantage of extraction over distillation is that temperatures can be held under 50” C. during most of the process. Extracted products, therefore, have a true-to-nature odor that is not matched by distilled counterparts. While this feature is of considerable importance to the perfumer, extraction probably will not replace distillation as the principal means of isolating fragrqpces from plant materials. A solvent extraction system requires a relatively large capital investment and
a crew of trained workers to run it. In contrast, distillation equipment can be simple, portable, and operated without much special knowledge. Moreover, operating costs of extraction are high compared to distillation because of unavoidable solvent losses. While accurate figures on the over-all cost of extraction relative to distillation are not available, the capital investment for an extraction plant is in the order of three times that required for distillation. This is because extraction calls for three separate units-the extractor itself, a solvent recovery still, and a finishing still. For economic reasons, extraction is generally limited to higher priced materials such as jasmine and tuberose concretes (a concrete is a perfume material that contains essential oils plus waxes and other extractable plant materials).
A Diversified Firm
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Large essential oil companies which offer a complete line of materials present a complex, many-sided operation. These firms manufacture oils from domestic and imported plant materials, import oils from all parts of the world, upgrade and concentrate purchased oils, make synthetic compounds, and formulate perfumes and flavors for specific applications. While there are scores of companies in the U. S. essential oil industry, the business is centered around the large, diversified firms such as Dodge and Olcott, International Flavors and Fragrances, Norda, Ungerer, S. P. Penick, Givaudan-Delawanna, and Firmenich. One good example of a diversified company is Fritzsche Brothers, Inc., of New York City. Fritzsche Brothers, Inc., was founded in 1871 by Paul Fritzsche. The firm was an offspring of a German essential oil concern, Schimmel and Co., and at first dealt only in imports. Later a factory was set up in Hoboken, N. J., which pressed croton oil and made fruit esters for flavoring candy. Production was increased in 1896 when a new factory was built in Garfield, N. J., and in 1906 manufacturing was switched to Clifton, N. J., where the company now has its main plant. The company’s growth has been particularly rapid since World War 11. Not only was it necessary to establish new sources of supply for some essential oils, but the firm was one of the leaders in the trend toward increased production of synthetics, such as cinnamic aldehyde and eugenol. During the past few years, the Clifton plant has undergone almost constant scale-up of produrtion through the installation of larger, more modern stills and reactors. Because of the specialized nature of the essential oil business, the company
designs and fabricates almost all of its processing equipment. Each piece is set up for maximum flexibility so that it can be easily adapted to produce many different products. Construction materials must be chosen carefully to avoid product contamination. Copper equipment was once used extensively, but now has been entirely replaced by stainless steel, usually Type 316. Glasslined equipment is used only with a few fruit extracts. The Clifton factory produces about 40 essential oils by distillation. The main ones are nutmeg, clove, celery seed, parsley seed. cinnamon, ginger. and black pepper. Solvent extraction is employed to make a series of oleoresins and resinoids. Oleoresins are spice extracts; resinoids are extracted gums, resins, and balsams used in perfumery. The company produces over 200 aromatic chemicals. These range from purely synthetic materials such as cinnamic aldehyde to compounds that are isolated from natural essential oils. One example of an isolate is .citral a compound with a lemonlike odor that is obtained from lemon-grass oil. Citral can be reacted with acetone to form pseudo-ionone which can be cyclized to ionone, a widely used material with a violetlike odor. Another activity at the Clifton plant is the manufacture of terpeneless and sesquiterpeneless oils. The principal odor carriers in essential oils are oxygenated compounds such as alcohols, esters, aldehydes, and ketones. Terpenes and sesquiterpenes, which account for as much as 98Y0 of some oils, are only minor contributors to odor and flavor. Moreover, terpenes and sesquiterpenes oxidize readily under the influence of air and light, and have lower solubility in alcohol than the oxygenated odor carriers. For these reasons, terpeneless and sesquiterpeneless oils are favored materials in many perfumes and flavors. They can be used to make concentrated products with long shelf life. Several methods can be used to separate terpenes and sesquiterpenes from essential oils. A common practice is to remove terpenes by fractional distillation under vacuum, and then eliminate sesquiterpenes by extracting the terpeneless oil with dilute ethyl alcohol. Concentration of the ethyl alcohol used will vary depending on the degree of alcohol solubility desired in the end product. The company has four 250-gallon stills with 12-foot fractionating columns that are normally used to remove terpenes from essential oils. The yield is around 370, and 20- to 30-gallon vessels are usually used to extract sesquiterpenes from the terpeneless oils. Pumping is avoided whenever practical VOL. 53,
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The first step in extracting an essential oil i s to break up the plant material b y grinding or cutting. The equipment shown above i s used by Fritzsche Brothers to expose some of the plant’s oil glands and to reduce the thickness of material to be handled Terpenes and sesquiterpenes account for as much as 98% of some oils, but are only minor contributors to odor and flavor. After an oil i s separated from the plant material b y distillation, terpenes can be removed in vacuum fractionating stills shown above. Later, sesquiterpenes can be removed from the terpeneless oil b y solvent extraction
Many different chemical reactions are used to make synthetic materials. These 5000-gallon reactors are used to make cinnamic aldehyde b y aldol condensation (below). After the crude product has been formed, it i s fractionated under vacuum and collected in stainless steel receivers (above)
Equipment for separating and refining essential oils i s set up for maximum flexibility. Most units can be adapted to produce many different products. Above i s shown a gas-fired, high temperature reactor and distillation unit
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INDUSTRIAL AND ENGINEERING CHEMISTRY
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Large scale processing equipment such as shown above and the solvent extraction unit at the right are used to make oleoresins and resinoids. Oleoresins are spice extracts; resinoids are extracted gums, resins, and balsams used in perfumery
A recent development is the use of spray drying to produce perfume and flavoring materials that are "wrapped" in a protective covering of gum. The homogenizing equipment illustrated here is employed to make up the emulsion prior to spray drying
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High standards of quality control assure customers that shipments will be consistent from batch to batch
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New or improved processes devised b y the research and development laboratories are carefully checked in pilot units before they are used on a commercial scale
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These Are Some of Fritzsche Brothers Products
Origin Product Oil clove, USP Oil cinnamon Ceylon extra Oil nutmeg, USP East Indian extra Oil peppermint, USP Rectified FS&CO Oleoresin celery fivefold Oleoresin ginger NF Jamaica Oleoresin black pepper decolorized Oil lemon terpeneless Resinoid olibanum extra Tincture ambergris
Method of Preparation
Raw Material Madagascar Zanzibar Ceylon
Steam distillation
Penang
Steam distillation
U. S . India
Rectification of natural oil Solvent extraction
Flavoring meat products and other foodstuffs Flavoring candies and pharmaceutical preparations Flavoring foodstuffs (soups, etc.)
Jamaica
Solvent extraction
Pharmaceuticals and soft drinks
Lampong Malabar California
Solvent extraction
Flavoring meat products and other foodstuffs Flavors and some perfume compositions
Eritrea Whales
Cinnamic aldehyde
Intermediates produced in
iso-Amyl salicylate
Intermediates produced in
Steam distillation
Careful fraction. ation and subsequent extraction Perfuming soaps and cosmetics Solvent extraction Dissolved in alcohol Aldol condensation
Perfume fixation
Esterification
Perfume compounds for soaps, cosmetics. etc.
u. s.
u. s.
to reduce the chance of contamination. Stills are charged with liquids by sucking the liquids in with vacuum provided by a four-stage steam ejector. Finished products are transported in stainless steel pails.
Oils by Distillation Isolation of essential oils from aromatic plants by distillation is a batch process which is, in general, the same for most materials. But specific conditions such as temperature, pressure, length of the cycle, and amount of pretreatment of the plant material are different in every case. Except for leaves that are relatively thin, all plant materials must be broken u p to some extent before they are charged to the still. This process, called comminution, exposes some of the plant's oil glands, and reduces the thickness of material to be handled i n the still. The over-all effect is to greatly increase speed of vaporization and distillation of the essential oil. The company does the bulk of its grinding with two pieces of equipment. A Sprout-Waldron roller mill, fitted with special rolls, is used to treat seedlike materials. A Paul Abbe rotary knife cutter is employed on roots, leaves, and other fibrous materials. Each unit has a capacity of about 2000 pounds per hour. Plant materials from the grinders drop into bins which are pushed to the distillation area. ' During steam distillation three things happen at once: Essential oils and hot water diffuse through the plant mem-
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Use
Flavoring food products; some use in pharmaceuticals Flavors
As such; and in preparation of imit. cassia oils for flavors
branes, some components of the oils hydrolyze, part of the oil is decomposed by heat. The ideal distillation, then, is one in which the diffusion rate is as high as possible while hydrolysis and thermal decomposition are kept to a minimum. Studies indicate that normal plant cells are almost impermeable to volatile oils. What takes place during distillation is that a part of the oil dissolves in the water present within the plant cell. This solution is carried by osmosis through the cell membrane, and at the surface the oil is vaporized by passing steam. The rate at which the oil becomes available for distillation is related to its solubility in water. For this reason, the higher boiling but more water soluble oil components occasionally distill over before the lower boiling, less soluble parts. Direct steam distillation, rather than water distillation or combined water and steam distillation, is usually used in large fixed installations. With this method temperature can be readily controlled by varying the steam pressure in the jacket and coil, and relatively little water comes in direct contact with the plant materials. Temperature of the steam rarely exceeds 110' C. Lnder these conditions, yields and rates are high, while the adverse effects of hydrolysis and thermal breakdown are kept small. Manufacture of celery seed oil is one example of essential oil production. The tough outer covering on the seed normally prevents evaporation of the
INDUSTRIAL AND ENGINEERINGCHEMISTRY
Specifications Must meet specifications of USP XVI Typical analysis : Specific gravity, 25/25' C. : 1.035; Optical rotation: -Oo20'; Refractive index, 20' C. : 1.5927 Must meet specifications of USP XVI Must meet specifications of USP XVI Typical analysis : Volatile oil content : 14 ml. per 100 g. ; Refractive index, 20' C. : (oil) 1.4840; Optical rotation (oil) : +60°20' Must meet specifications of the NF XI Volatile oil content, 25% minimum; Piperine content 55% minimum Typical analysis : Specific gravity, 25/25' C.: 0.894; Refractive index, 20' C.: 1.4796; Aldehyde content a s citral, 67.0y0 Free-flowing, light to amber liquid containing approximately I2y0 volatile oil 4 0 2 . ambergris per gallon of tincture Typical analysis : Specifjc gravity, 25/25" C. : 1.048; Refractive index, 20° C.: 1.6220; Aldehyde content: 99.2% Typical analysis : Specific gravity, 25/25O C.: 1.052; Refractive index, 20' C.: 1.5080; Ester content: 99.5%
volatile essential oil inside. The celery seed, therefore, is shredded on the roller mill to expose the inner materials which hold the oil. The shredded seed is moved to the distillation area and carefully packed into the still to prevent steam channeling. These two steps, shredding the seed and loading the still, are critical to obtaining good yields during distillation. The company has 10 stills that are normally used to recover essential oils by distillation. These range in size from 400 gallons to 2000. The typical still has a 1000-gallon capacity, and takes a 4000-pound charge of plant material. When steam passes through the plant material, the celery seed oil is carried over with the steam into a shell and tube condenser mounted horizontally. The condensed oil and steam flow into an oil separator where they are separated by means of the difference in specific gravity between the two liquids. Most oils are lighter than water, but a few are heavier. The specific gravity of celery seed oil is 0.895. Since large amounts of water are collected in proportion to the amount of essential oil, the water is recycled to the still along 114th fresh steam. The usual distillation takes about 24 hours. From a charge of about 4000 pounds of celery seed, 90 to 100 pounds of oil are obtained. Yields can vary greatly depending upon the oil. For example, 4000 pounds of cinnamon bark give 30 to 40 pounds of cinnamon oil, while the same quantity of clove spice ).ields about 600 pounds of clove oil.
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Staff-Industry Oleoresins by Extraction
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Oleoresin fennel is one example of the company’s production of oleoresins from herbs and spices. The Clifton plant has five extractors for making oleoresins. These range from 400 to 2000 gallons, and can take charges varying from 1000 to 8000 pounds. The extractors basically are just jacketed vessels with drains at the bottom. The solvent, acetone in the case of fennel seed, is circulated through the spice bed by means of a centrifugal pump. Steam in the jacket holds the solvent temperature at 40’ to 50’ C. After grinding on the roller mill, the fennel seed is dumped into the top of the extractor. The ratio of acetone to fennel seed is about 5 to 1. Solvent is pumped through the bed of plant material until it is saturated. This is determined by taking samples a t regular intervals and checking the evaporation residue in the laboratory. When it is saturated, the acetone is withdrawn and transferred to a solvent recovery unit. T h e acetone is distilled until the residue in the still contains about 3 parts of acetone to 1 part of extracted material. T h e stripped solvent is recirculated to the original spice material to make a second extract. Usually, four extracts are made on each batch of fennel seed before the seed is discarded. The mixture of acetone and oleoresin from the solvent recovery still is fed into a finishing still where all traces of acetone are removed. This is a critical step, since care must be taken to prevent charring of the oleoresin. Temperature is around 120’ C. Also, conditions in the finishing still must be controlled so that none of the volatile oil in the oleoresin is lost while removing the solvent.
Synthetics by Synthesis
I n the manufacture of synthetic materials, the Clifton plant employs almost every type of chemical reaction-oxidation, hydrogenation, acetylation, ester interchange, and polymerization, for example. These reactions are carried out as batch processes, usually in multipurpose equipment. One example of the varied chemical techniques used by the company is the making of cinnamic aldehyde by aldol condensation. T h e first step is the preparation of a water solution of acetaldehyde. This is added to a suspension of benzaldehyde in water which contains the catalyst, sodium hydroxide. After the cinnamic aldehyde has been formed, acid is added to neutralize the base. The crude product, which is heavier than water, separates from the aqueous solution, is washed
free of water soluble impurities, and is fractionated under vacuum. Three 5000-gallon reactors are used a t Clifton to make cinnamic aldehyde. Each vessel is fitted with a mixer and a steam coil. Temperature is a critical process control, and is maintained manually a t about 50’ C. Centrifugal pumps are used to load the vessels. The crude product is drawn by vacuum into the finishing still. One recent development that is growing in importance is the use of spray dried perfume and flavoring materials. These “locked-in” products are used in dry-mix preparations where liquid perfumes or flavors are not always satisfactory. A conventional spray tower is used to make these products. T h e material to be spray dried is first emulsified with an edible gum, such as gum arabic, I n this step, a homogenizer made by Cherry-Burrell, Cedar Rapids, Iowa, is used. The product consists of the perfume or flavor “wrapped” in a protective covering of gum. Producing custom and proprietary formulations is an integral part of the essential oil business. The company has about 50,000 active formulas on file, and each year develops 3000 to 4000 new formulas for different odor and flavor problems. Production ranges from a few ounces to drum lots. Customers depend on suppliers to be able to reproduce previous shipments with unfailing accuracy. As one means toward this end, the company retains a sample of every lot of goods received or shipped. When a customer reorders and a new batch of material is made up, the batch is compared with the retained sample to assure the customer that this material matches previous shipments. Quality
I n the essential oil business, a firm’s reputation for quality is very important. Because essential oils are costly and difficult to identify, the industry is a prime target for the unscrupulous producer, At one time, adulteration of oils was rampant, but it now has been cut to a low level through the efforts of ethical producers working with modern analytical instruments. The first step in evaluating an essential oil is usually a simple taste or odor taste. Odor and flavor are the key qualities of an essential oil, and a trained nose or tongue can detect most off-grade materials. Quality is further assured by standard tests such as specific gravity, optical rotation, refractive index, acid number, and ester number, for example. For special problems, the company uses infrared and ultraviolet spectroscopy, and vapor phase chromatography.
T h e company has an active program in research and development of new flavor and perfume materials. But like most companies in the industry only a small part of this research work is published. This is characteristic of the traditional secrecy of the industry. I n 1957, the firm set up a new fundamental research group to investigate essential oils and aromatic chemicals. This research is confined to basic problems using novel methods and techniques. At the same time, the applied research laboratory was separated from the research and development group. T h e applied research lab is concerned with current problems, developing new manufacturing techniques, and preparing aromatic chemicals by known methods. The research and development group scales u p processes from laboratory to plant. Reliable figures on total production or sales on the essential oil industry are not available. However, some indication of the industry’s growth rate can be obtained from the statistics of synthetic flavor and perfume materials published by the U. S. Tariff Commission. Sales of synthetics in 1959 came to 43 million pounds compared to only 15.8 million pounds in 1950. This growth reflects the increased use of synthetic materials in place of natural oils. Synthetics in general are less costly than natural materials. But only a few natural oils have been successfully duplicated in the test tube, and natural products will remain the mainstay of the industry for some time to come. Toilet goods, foods, pharmaceuticals, and beverages are the largest outlets for essential oils. But it is hard to name a product that does not owe some debt to essential oils. From adhesives to veterinary supplies, and from rubber baby pants to embalming fluid, essential oils today are truly essential to the way we live.
The reader might also find it interesting to refer to the article on Essential Oils in the current issue of Journal of Agricultural and Food Chemistry [Smith, D. M., Levi, Leo, J . Agr. Food Chem. 9, 230 (1961)l. The data presented and their treatment may be of value to processors af essential oils in the characterization, analysis, and quality control of complex natwal and synthetic compositions produced by the food, drug, and cosmetic industries.
Reference (1) Guenther, Ernest, “The Essential Oils,” Vols. I-VI, Van Nostrand, Princeton, N. J., 1947-52. VOL. 53, NO. 6
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