Flavors and fragrances
     
     Flavors and  fragrances are substances that stimulate the  senses
of TASTE  AND SMELL.   With  the exception  of the four  primary taste
sensations--sweet, bitter,  salty, and   sour--flavor  characteristics
are the  result of  our  perception of odor;  the difference between a
flavor and  a  fragrance is in large part only a semantic distinction.
Thus, a  substance that provides an odor in PERFUMES may  also be used
to add flavoring to a food.
     
     Most natural  flavorings and  fragrances are  derived from  plant
substances--either from  the aromatic,  volatile  vegetable oils known
as ESSENTIAL  OILS, or from the  nonvolatile plant oils called RESINS.
The aromatic   substances derived from flowers, from herbs and spices,
and   from animal  secretions (musk  and ambergris,  for example)  are
usually costly and limited in supply.  Over the past  century, success
in reproducing  some of  these substances  synthetically has created a
new industry  that today   produces hundreds of flavors and fragrances
for use in  food, perfumes, and other products.
     
       Some fragrant substances are relatively easy to synthesize.
     
      Vanillin,  the aromatic  ingredient in  vanilla, can be  readily
reproduced by synthesis, as can benzaldehyde, the  principal component
of the  odor of  wild cherry.  Many   flavors and fragrances, however,
have scores,  if not  hundreds, of components that contribute to their
aroma.      Only recently  has it  become possible  to separate  these
components, using gas chromatography, and to determine  their chemical
structure with  the aid  of spectroscopy.   Once the chemical identity
of the  components is  known, it   is  often  possible  to  make  them
synthetically.   The search  for new synthetics continues, and some of
the most complex,  among them the substances that produce the aroma of
coffee,  have still not been duplicated satisfactorily.
     
     Many  of   the  chemical  compounds  making  up  these  synthetic
materials are identical to those found in nature and are as  harmless,
or harmful,  as the  naturally derived  essences.    New products with
unknown toxicology  must be  tested for   safety,  and, when  used  in
foods,  must  be  accepted  as  safe    by  the  U.S.  Food  and  Drug
Administration.
     
     The  availability  of  synthetic  flavors  and  fragrances  makes
possible a  large variety of products, from inexpensive  beverages, to
perfumed soaps,  to used cars with an applied  "new car odor." To cite
two examples:   the  chemical  compound B-phenylethyl alcohol, a vital
ingredient in  any  rose fragrance, may be extracted from natural rose
oil at  a   cost  of  thousands  of  dollars  per  kilogram;    or  an
identical, synthetic  substance can  be made  at one  percent  of this
cost.   Synthetic musk  is chemically different from  the musk derived
from animals, but its odor effects are  similar, and again the cost is
a small  fraction of that for  the natural extract, and the quantities
available are  basically unlimited.