Introduction
         In the 19th century a new segment of the chemical industry was recognized: the flavor and fragrance industry.  Although flavor and fragrance compounds have been used for centuries, the demand for these compounds increased and industrial manufacturing began to meet the demand.  The industry is based around aroma chemicals, which are chemicals distinguished by their pleasant and unique odors.  These aroma chemicals are named flavors or fragrances based on their use in a food or perfume type application.

         Aroma chemicals are further classified into two groups depending on their origin.  Natural aroma chemicals and synthetic aroma chemicals are available in today’s marketplace.  For the purposes of this paper, only the natural aroma chemicals will be referred to because the application of physical chemistry can more readily be seen.  Natural compounds are directly obtained from plants and animals.  These compounds exist in many different plants and animals; however, obtaining them can be a difficult process.  Natural compounds can further be divided into two groups: essential oils and extracts.  This distinction depends on how the aroma chemical is isolated.

         A question may arise as to how does physical chemistry play a role in an industry in which most of the compounds are organic?  First, effusion, a basic principle in physical chemistry, plays a role.  In order for an aroma chemical to be smelled or tasted, the chemical must be able to effuse through the air to reach and, subsequently, be detected by our senses.  Second, methods used to extract aroma chemicals from plants encompass physical chemistry.  Extracts can be isolated by solvent extraction methods by which physical chemical principles incorporated.

         The chemicals and the chemistry involved in isolating these chemicals are what make up the flavor and fragrance industry.  However, the industry itself is part of a global market, so its impact and trends are important to consider.  The trends that characterize the flavor and fragrance industry include expansion into new markets, development of new flavors and fragrances, globalization in order to encompass a larger range of aroma chemicals, definition of labeling requirements, and expansion of the business to the Internet.  The flavor and fragrance industry truly is a unique part of the chemical industry; though not a large part of the chemical industry, it is an essential part.

Background Information on Aroma Chemicals

History of Aroma Chemicals
         The use of aroma chemicals dates far back into ancient times.  Then, as well as now, people desired pleasant scents in foods and perfumes.  In ancient civilizations, people discovered that these flavors and fragrances could be enhanced by different methods of extraction.  Early extraction methods were performed with olive oil and distillation methods; some of these extraction methods are still used today.¹  As time progressed, distillation methods became more advanced and better yielding, but primitive methods were still employed.  Not until the 13th century did systematic development of natural aroma chemicals occur.  Remember at this time that synthetic production had not been discovered.  These natural aroma chemicals were mainly produced for pharmaceutical applications in the form of oils.²  By the 16th and 17th centuries, pharmacies were using the distillation methods that are used to isolate natural aroma chemicals today.  As the importance of the aroma chemicals grew, the demand grew; consequently, natural aroma chemical isolation was industrialized in the first half of the 19th century.  A very important chemical was isolated during this time: benzaldehyde.  Benzaldehyde was isolated from cinnamon oil in 1834 by Dumas and Peligot and from bitter almond oil in 1837 by Liebig and Wöhler.³  Later in the 19th century between 1845 and 1850 the first aroma chemicals were produced synthetically.  With the production of two very important aroma chemicals, vanillin in 1874 and coumarin in 1878 the flavor and fragrance industry became a new segment of the chemical industry.⁴  Today there is a push toward finding small trace aroma chemicals in products.  With advancing technology and knowledge in chromatographic and spectrographic methods, these trace amounts can be isolated.

Importance of Aroma Chemicals
         Ancient civilizations may not have understood all of the physiological reasons for desiring flavor and fragrances, but nonetheless these civilizations did place great importance on aroma chemicals.  Many organisms rely on flavors and fragrances for survival.  Animals find food and mates based on smells and tastes.  Without those known flavors and fragrances, the organisms would not be able to survive.  Although humans do not relay on aroma chemicals for survival per se, people’s lives are greatly enhanced by these chemicals.  Humans associate certain flavors and fragrances with feelings.  Especially with food, people take into consideration how the food smells or tastes to measure enjoyment.  Flavors and fragrances can produce nostalgia and are able to change emotional levels.

Aroma Chemical Constituents and Detection
         Now that there is an understanding of the history and importance of aroma chemicals, one may ask, “What makes up an aroma chemical and how is it detected?”  There are three elements of producing a flavor or a fragrance: the vehicle, the fixative, and the odoriferous element.  First, the perfume or flavor must be in a solution that allows the fragrance or flavor to be released, which is achieved through the vehicle.⁵  A vehicle must be a solvent, so that the scent can be released.  This is where physical chemistry plays a role in the flavor and fragrance industry.  Effusion is when a single substance is in motion, in this case the vehicle allows the aroma chemical to move.  The rate at which the aroma chemical effuses depends on the number of molecules that are moving (molar mass).⁶  This relationship can be summarized by Graham’s law of effusion, which was developed by Thomas Graham in 1833.

This relationship is true at a specific temperature or pressure.  Of course as the temperature increases the rate of effusion also increases, because the molecules move faster at higher temperatures.⁸  Therefore, the solvent that is used must effuse at a rate at which it can be detected by human senses.

         The second constituent of a perfume or flavor is the fixative.  Different substances in a flavor or fragrance can have varying effusion rates, which allow different scents to move to the senses faster than others.  This phenomenon is undesirable because the flavor or fragrance is not perceived as one scent together, but as a series of smells or tastes.⁹  Fixatives alleviate this problem by slowing the rate of effusion.  In fact, fixatives somewhat undo the goal of the vehicle, but to achieve a desired flavor or fragrance vehicles and fixatives are essential.  There are four types of fixatives: animal, resinous, essential oil, and synthetic.  Lastly, the flavor or fragrance needs an odoriferous substance.  These can be natural or synthetic substances, and natural substances will be discussed in more detail.

Natural Aroma Chemicals
         Natural aroma chemicals have been used for centuries and still are used today.  However, natural aroma chemicals are declining in use due to their high prices and limited supply.¹⁰  Their use is unlikely to ever be eliminated because of the following factors: some natural aroma chemicals are so complex that reproducing them synthetically is difficult, some flavors and fragrances cannot be made synthetically at a competitive price, and a push for natural aroma chemicals has been observed in recent times.  Natural aroma chemicals come from plants or animals and may be slightly different depending on the species of plants and animals.  Taking this difference into consideration, there are over 500 known existing aroma chemicals.¹¹  Species of plants and animals can differ by geographic location, which affects the quality of the aroma chemical.  Slight differences between aroma chemicals can produce widely different flavors and fragrances.  Today plants are grown on a large scale to satisfy the demand for natural aroma chemicals, and systematic breeding has become common to produce the best yielding and highest quality plants.¹²  As was mentioned before, natural aroma chemicals are declining in use.  As a result of being produced in nature, natural aroma chemicals are susceptible to weather.  Having a crop destroyed by disasters, droughts, and floods limits the supply of the aroma chemicals, which in turn increases its price.  The price also depends on how difficult the aroma chemical is to harvest from the plant or animal and on how much product can be obtained.  These are all important aspects to consider when using natural aroma chemicals.

Extracts
         Natural aroma chemicals can still be further classified into two different groups based on their isolation methods.  These two groups are essential oils and extracts.  There are three main methods for isolating natural aroma chemicals distillation, solvent extraction, and mechanical separation.¹³  Here a focus will be put on extracts, since the physical chemistry can more readily be seen.

         Extracts can be divided into five different groups that are distinguishable by how the aroma chemical is isolated.  Pomades, concretes, absolutes, resinoids, and tinctures are the names of extracts.¹⁴  Pomades are produced when plants are extracted into fats.  This method is called enfleurage and can be performed with hot or cold fat.  Typically the plant material is placed in either hot or cold fat and the volatile aroma chemicals are stored in the fat.¹⁵  Hot enfleurage occurs much more quickly than cold enfleurage does.  Pomades are mostly a historical type of extract because the process can be time consuming.  Isolating an aroma chemical with nonpolar solvents leaves a concrete extract.  Concretes are particularly useful in scenting soaps, because both volatile and nonvolatile compounds are extracted.¹⁶  The nonvolatile compounds tend to be waxy and are more applicable to use in soap rather than in perfumes.  Further isolation of concretes with ethanol makes an absolute extract.  Absolutes do not contain the waxy substances of concretes because the solution is filtered after being reacted with ethanol.¹⁷  Therefore, absolutes are used successfully in perfumes.  The fourth type of extracts are the resinoids, which are plant gums, balsams, or resins, isolated with methanol, ethanol, or toluene.¹⁸  These types of extracts are used as fixatives, which were discussed earlier.  Finally, tinctures are alcoholic solutions that are basically natural plant or animal material dissolved in ethanol.¹⁹

Solvent Extraction
         Solvent extraction is a useful method for extracting concretes, absolutes, resinoids, and tinctures.  With this process, one is again able to relate physical chemistry to the flavor and fragrance industry.  Solvent extraction can be carried out in two different ways either in a discontinuous or continuous fashion.  The difference between the two approaches is whether equilibrium is reached.²⁰  However, for both approaches it is important to carefully choose two immiscible solvents.  For discontinuous small-scale solvent extraction, a separatory funnel is used where the aqueous sample containing the aroma chemical and another pure organic solvent are put into.  This mixture is vigorously shaken for a period of time after which the organic phase, now containing the aroma chemical is extracted.  Shaking allows for maximum interaction between the two phases, so that the aroma chemical is surrounded by the extracting solvent.  As will be shown in a later example, the yield obtained by one solvent extraction may not be sufficient, so this process may be repeated one to three more times with fresh organic solvent to receive a sufficient yield.  The second approach to solvent extraction is the continuous method.  In this method, the organic solvent is constantly boiled, condensed and moved through the aqueous sample.  This method is desirable when, “…the kinetics of the extraction [are] slow, such that, the equilibrium of the analyte between the aqueous and organic phases is poor…”²¹

         So how does one go about calculating how much of the aroma chemical (which will be called the analyte) has been extracted?  First, in the two liquids will be donated as A (aq) for the liquid containing the aroma chemical and A (org) for the pure solvent.  Shaking produces an equilibrium shown by this equation:

As with many other equilibrium reactions, an equilibrium constant can be found and which can lead to other information.  Kd, the distribution coefficient, can relate the activities of the two liquid layers.  As was mentioned before, the continuous method is employed when the equilibrium is poor, which is shown by Kd having a very small value.
 

However, the activities of the aqueous layer cannot be easily calculated.  A more useful way to express the percentage of aroma chemical extracted is used where E is the fraction of analyte extracted, Co and Caq are the concentrations of the organic and aqueous phases, and Vo and Vaq are the volumes of each phase.

The previous equation is sufficient for those extractions that only require one-step; however, as was mentioned previously, aroma chemicals usually must be extracted multiple times to obtain a sufficient yield.  For multiple extractions this formula is employed where n is the number of extractions and V is the phase ratio of Vo/Vaq.

Solvent extraction can work well, but some problems may ensue.  Some plant samples may contain fatty materials that when mixed with the solvent may produce emulsions.  These emulsions can clog up the apparatus, making it difficult to perform the extraction process.  This problem may be overcome if the emulsion can be separated and removed by centrifuge, filtration, refrigeration, salting out, or adding a small amount of a different organic solvent.26  Any process used will have limitations, but keeping them to an absolute minimum is desired.

Jasmine Absolute²⁷
         An example of an aroma chemical that is isolated using solvent extraction is jasmine absolute.  From the name, one can expect that this compound is an absolute extract.  Therefore, solvent extraction has been used twice. Cis-jasmone and methyl jasmonate are minor contributors to the jasmin scent of this absolute, but are crucial in producing the scent.  First formed as a concrete, the extract is a brown waxy material, but after exposing it to ethanol the desired red-brown liquid absolute is produced.  Initially, the concrete is made from Jasmin flowers, which are found in Egypt, Italy, Morocco, and India.  Jasmin absolute is a valuable natural aroma chemical used in fragrances partly due to its yield.  To produce 2.5-3 kg of concrete, one ton of jasmin flowers must be extracted with hexane two to three times.  In this case to calculate the amount of the aroma chemical extracted one would use equation five.

Industry Trends
         The backbone of the flavor and fragrance industry is the chemistry involved in isolating and developing aroma chemicals.  After all, without these chemicals there would not be a specific industry for them.  However, it is also important to consider how the flavor and fragrance industry is affecting the marketplace as a whole.  These trends of the industry are important to understand and explore, since these trends dictate whether the industry will grow and, consequently, new chemistry can be developed.  Over the past few decades, the flavor and fragrance industry has been experiencing five major trends.  These trends include becoming a global industry, being consolidated with mergers, compounding new flavors and fragrances and entering into new markets, facing more labeling requirements and popularity of fat-reduced foods, and developing businesses online.  Many of these trends are not specific to the flavor and fragrance industry, but have been experienced by other industries in recent times.

         The market for aroma chemicals has become more global.  The United States imports and exports many different aroma chemicals from many different countries.  Some aroma chemicals are more widely available in some areas relative to other areas; so working together is essential to the ultimate goal of selling a flavor or fragrance in a product.  Not only are individual companies competing, regions are competing.  A December 1999 article from Chemical Market Reporter describes the flavor and fragrance market in the Asia-Pacific region—more specifically Japan.²⁸  Japan focuses more on flavors than fragrances and in 1999 the market slumped because of inclement weather.²⁹  Rainy weather had been prevalent and was hurting soft drink sales because consumption levels decline in rainy weather.  The soft drink market, especially in Japan, directly influences the flavors market.³⁰  Japan’s market indirectly affects the U.S. and Europe because the flavor market there is small.  Another part of the Japanese flavor and fragrances market is that it manufactures little, if any, natural aroma chemicals.³¹  Consequently, Japan relays on imports, which increases the global sense of the industry.  In 1999 these imports grew 18% and only means increases for the countries where the natural aroma chemicals originated.³²  Increasing global markets has many benefits, which explains the growing trend in the flavor and fragrance industry.
 
         Another trend the flavor and fragrance industry has been experiencing is consolidation through mergers.  Evidence of this trend can especially be seen since the early 1980’s and continuing to 2000.  In 1984, United Kingdom-based PPF International acquired U.S.-based Norda.³³  Then the industry was seeing a declining growth in sales and profitability, so by consolidating companies could merge and increase their capital and research and development funding, to become leaders in the industry.  Again in 1987, PPF merged with Naarden International to form Quest International.³⁴  At that time the new Quest was second in the industry only to International Flavor and Fragrances, Inc.  These mergers help to broaden product lines and make the companies more powerful in the industry.  Several other mergers occurred in the 1990’s and growth occurred as well.  In a Chemical and Engineering News magazine article published May 30, 1994, fragrances were growing 3-5% annually and flavors were slightly higher with the industry being a $9 billion share of the entire chemical industry.³⁵  However, in 1999 the industry faced a weak market for aroma chemicals, flat fragrance growth, and even more consolidation.³⁶  A major merger in 1999 was the spin off of Roche Holdings AG’s Givaudan-Roure, the flavor and fragrance division, making the new company the second largest in the flavor and fragrance industry.³⁷  No one can predict the future with ultimate certainty, but aroma chemical producers predict that sales will increase in 2001.

         To remain a strong player in the industry, developing new flavor and fragrance compounds and entering new markets is essential.  Predicting which scents and tastes will be popular is a challenging job.  One way to predict is by looking at the lifestyles of consumers.  According to a July 27, 1998, article in Chemical Marketing Reporter, sporty and competitive fragrances were popular in 1997, which followed modern women’s free-spirited lifestyles.³⁸  In an age were demanding careers and healthy lifestyles are dominant, consumers want fresh scents that can rejuvenate them.  As for new markets, men’s fragrances are becoming increasingly popular.  Not only will aftershaves and colognes be available, but also moisturizers, shaving gels, and sunscreens will be scented for men.³⁹  Moreover, the scented candle market has emerged in the last couple of years.  Fragrances are becoming more and more important to peoples lives, contributing to the definition of themselves as individuals, so ever changing markets are more than likely to continue to appear.
 
         Along with demanding new flavors and fragrances, consumers want more specific information on labels of products.  This phenomenon includes specifying the flavors and fragrances used in products.  There is also demand for more natural products, which challenges the industry because natural aroma chemicals are not always the most economically advantageous.⁴⁰  Reduced-fat foods are also a challenge for the industry as is stated in a March 1997 article in Chemtech.⁴¹  In this article the challenge is said to be “Reducing the fat content in foods and replacing fat with other substances can drastically alter the flavor of the food, because fat may act as a solvent and protective medium for flavor ingredients.”⁴²  Whenever consumers are involved (virtually in every industry), challenges emerge to stimulate companies to improve products.

         Lastly, a new trend of selling online flavors and fragrances has begun.  Trisenx, a new company in Savannah, Georgia, has developed a machine that will allow flavors and fragrances to be online.⁴³  The machine, Ultrasenx, will be a module that can be attached to a computer and will dispense flavors on edible wafers and fragrances on cotton-linen paper.⁴⁴  This invention is likely to increase sales of flavors and fragrances online.  A downturn is that the machine costs $1200 and additional cartridges will be sold for $5-10, but like many technological-based inventions, it will probably decrease in price over time.⁴⁵  Trisenx has broken new ground in the world of online flavor and fragrances, which is exciting and promising for the entire flavor and fragrance industry.

Conclusion
         The flavor and fragrance industry is an important part of the chemical industry—one that many people rely on.  The industry encompasses chemistry of different specializations including organic and physical.  The aroma chemical is one that is important to animals for survival and humans for emotions.  Natural aroma chemicals are especially unique because of the basic fact that they are natural.  Examining trends in the industry is an important measure of the success and future of the flavor and fragrance industry.  Overall the industry seems to be sustaining and growing in its place in the market.  From this short inquiry into the flavor and fragrance industry, one can see that it is a unique part of the chemical industry.

¹     Bauer, K.; Garbe, D.; Surburg, H.  Common Fragrance and Flavor Materials: Preparation, Properties,
       and Uses, 3rd ed; Wiley-VCH: Weinheim, Germany, 1997, p.1.
²     Bauer, p.1
³     Bauer, p.1
⁴     Bauer, p.1
⁵     Austin, G.T.  Shreve’s Chemical Process Industries, 5th ed; McGraw-Hill Book Co.:  New York, 1984,
       p. 485.
⁶     Atkins, Peter.  The Elements of Physical Chemistry: With Applications in Biology, 3rd ed; W.H.
       Freeman:  New York, 2001, p. 24.
⁷     Atkins, p.24
⁸     Atkins, p.24
⁹     Austin, p.485
¹⁰    Bauer, p.162
¹¹    Bauer, p.161
¹²    Bauer, p.161
¹³    Bauer, p.162
¹⁴    Bauer, p.164
¹⁵    Bauer, p.164
¹⁶    Bauer, p.164
¹⁷    Bauer, p.164
¹⁸    Bauer, p.165
¹⁹    Bauer, p.165
²⁰    Dean, J. R.  Extraction Methods for Environmental Analysis. John Wiley: Chichester, 1998, p. 25.
²¹    Dean, p.25
²²    Dean, p.23
²³    Dean, p.24
²⁴    Dean, p.24
²⁵    Dean, p.24
²⁶    Dean, p.26
²⁷    Bauer, p.193-194
²⁸    ChemExpo website.  “Weather Drives Production Surge in Japanese Fragrances.”  Chemical Market
       Reporter: December 6, 1999.
       http://www.chemexpo.com/cmronline/stories/12_06_99/49_12_06_99.cf  on April 22, 2001.
²⁹    ChemExpo website.  “Weather Drives Production Surge in Japanese Fragrances.” Chemical Market
       Reporter: December 6, 1999.
       http://www.chemexpo.com/cmronline/stories/12_06_99/49_12_06_99.cf  on April 22, 2001.
³⁰    ChemExpo website.  “Weather Drives Production Surge in Japanese Fragrances.”  Chemical Market
       Reporter: December 6, 1999.
       http://www.chemexpo.com/cmronline/stories/12_06_99/49_12_06_99.cf  on April 22, 2001.
³¹    ChemExpo website.  “Weather Drives Production Surge in Japanese Fragrances.”  Chemical Market
       Reporter: December 6, 1999.
       http://www.chemexpo.com/cmronline/stories/12_06_99/49_12_06_99.cf  on April 22, 2001.
³²    ChemExpo website.  “Weather Drives Production Surge in Japanese Fragrances.”  Chemical Market
       Reporter: December 6, 1999.
       http://www.chemexpo.com/cmronline/stories/12_06_99/49_12_06_99.cf  on April 22, 2001.
³³    Layman, P.L.  “Flavors and Fragrances Industry Faces Season of Consolidation.”  Chemical and
       Engineering News; July 30, 1984, p. 7.
³⁴    Layman, P.L.  “Flavors and Fragrances Industry Taking On New Look.”  Chemical and Engineering
       News; July 20, 1987, p. 35.
³⁵    Layman, P.L.  “Flavors and Fragrances Business Marked By Growth, Mergers.” Chemical and
       Engineering News; May 30, 1994, p. 10.
³⁶    ChemExpo website.  “Flavors and Fragrance 1999 Marked By Consolidation and Weak Markets.”
       Chemical Market Reporter: January 3, 2000.
       http://www.chemexpo.com/cmronline/sstories/01_03_00/21_01_03_00.cf  on April 22, 2001.
³⁷    ChemExpo website.  “Flavors and Fragrance 1999 Marked By Consolidation and Weak Markets.”
       Chemical Market Reporter: January 3, 2000.
       http://www.chemexpo.com/cmronline/sstories/01_03_00/21_01_03_00.cf  on April 22, 2001.
³⁸    ChemExpo website.  “Winter Fragrance Trends Stay On the Sporty and Spicy Track.”  Chemical
       Market Reporter: July 27, 1998.
       http://www.chemexpo.com/cmronline/stories/07_27_98/41_07_27_98.cf  on April 22, 2001.
³⁹    ChemExpo website.  “Winter Fragrance Trends Stay On the Sporty and Spicy Track.”  Chemical
       Market Reporter: July 27, 1998.
       http://www.chemexpo.com/cmronline/stories/07_27_98/41_07_27_98.cf  on April 22, 2001.
⁴⁰    Screiber, W.L.; Scharpf Jr, L.G.; Katz, I.  “Flavors and Fragrances: The Chemistry Challenges.”
       Chemtech; March 1997, p. 58.
⁴¹    Screiber, W.L.; Scharpf Jr, L.G.; Katz, I.  “Flavors and Fragrances: The Chemistry Challenges.”
       Chemtech; March 1997, p. 59.
⁴²    Screiber, W.L.; Scharpf Jr, L.G.; Katz, I.  “Flavors and Fragrances: The Chemistry Challenges.”
       Chemtech; March 1997, p. 59.
⁴³    ChemExpo website.  “Trisenx Delivers Technology That Offers Online Fragrances.”  Chemical Market
       Reporter: February 28, 2000.
       http://www.chemexpo.com/cmronline/stories/02_28_00/42_02_28_00.cf  on April 22, 2001.
⁴⁴    ChemExpo website.  “Trisenx Delivers Technology That Offers Online Fragrances.”  Chemical Market
       Reporter: February 28, 2000.
       http://www.chemexpo.com/cmronline/stories/02_28_00/42_02_28_00.cf  on April 22, 2001.
⁴⁵    ChemExpo website.  “Trisenx Delivers Technology That Offers Online Fragrances.”  Chemical Market
       Reporter: February 28, 2000.
       http://www.chemexpo.com/cmronline/stories/02_28_00/42_02_28_00.cf  on April 22, 2001.

Atkins, Peter.  The Elements of Physical Chemistry: With Applications in Biology, 3rd ed; W.H.
       Freeman:  New York, 2001.

Austin, G.T.  Shreve’s Chemical Process Industries, 5th ed; McGraw-Hill Book Co.:  New York, 1984.

Bauer, K.; Garbe, D.; Surburg, H.  Common Fragrance and Flavor Materials: Preparation, Properties,
       and Uses, 3rd ed; Wiley-VCH: Weinheim, Germany, 1997.

ChemExpo website.  “Flavors and Fragrance 1999 Marked By Consolidation and Weak Markets.”
       Chemical Market Reporter: January 3, 2000.
       http://www.chemexpo.com/cmronline/sstories/01_03_00/21_01_03_00.cf  on April 22, 2001.

ChemExpo website.  “Trisenx Delivers Technology That Offers Online Fragrances.”  Chemical Market
       Reporter: February 28, 2000.
       http://www.chemexpo.com/cmronline/stories/02_28_00/42_02_28_00.cf  on April 22, 2001.

ChemExpo website.  “Weather Drives Production Surge in Japanese Fragrances.”  Chemical Market
       Reporter: December 6, 1999.
       http://www.chemexpo.com/cmronline/stories/12_06_99/49_12_06_99.cf  on April 22, 2001.

ChemExpo website.  “Winter Fragrance Trends Stay On the Sporty and Spicy Track.”  Chemical
       Market Reporter: July 27, 1998.
       http://www.chemexpo.com/cmronline/stories/07_27_98/41_07_27_98.cf  on April 22, 2001.

Dean, J. R.  Extraction Methods for Environmental Analysis. John Wiley: Chichester, 1998, p. 25.

Layman, P.L.  “Flavors and Fragrances Business Marked By Growth, Mergers.” Chemical and
       Engineering News; May 30, 1994.

Layman, P.L.  “Flavors and Fragrances Industry Faces Season of Consolidation.”  Chemical and
       Engineering News; July 30, 1984.

Layman, P.L.  “Flavors and Fragrances Industry Taking On New Look.” Chemical and Engineering
       News; July 20, 1987.

Screiber, W.L.; Scharpf Jr, L.G.; Katz, I.  “Flavors and Fragrances: The Chemistry Challenges.”
       Chemtech; March 1997.
 
 

Last Updated: 4-30-01