What are
commonly known as "fruity" odors belong mostly to what the chemist calls
the fatty or aliphatic series. For instance, we may have in a ripe fruit
an alcohol (say ethyl or common alcohol) and an acid (say acetic or
vinegar) and a combination of these, the ester or organic salt (in this
case ethyl acetate), which is more odorous than either of its
components. These esters of the fatty acids give the characteristic
savor to many of our favorite fruits, candies and beverages. The pear
flavor, amyl acetate, is made from acetic acid and amyl alcohol--though
amyl alcohol (fusel oil) has a detestable smell. Pineapple is ethyl
butyrate--but the acid part of it (butyric acid) is what gives Limburger
cheese its aroma. These essential oils are easily made in the
laboratory, but cannot be extracted from the fruit for separate use.
If the carbon chain contains one or more double linkages we get the
"flowery" perfumes. For instance, here is the symbol of geraniol, the
chief ingredient of otto of roses:
(CH_{3})_{2}C = CHCH_{2}CH_{2}C(CH_{3})_{2} = CHCH_{2}OH
The rose would smell as sweet under another name, but it may be
questioned whether it would stand being called by the name of
dimethyl-2-6-octadiene-2-6-ol-8.
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