The aromatic principles of many spices, nuts, herbs, fruits, etc., and some flowers, are marketed as extracts, among the best known of true extracts being almond, cinnamon, cloves, ginger, lemon, nutmeg, orange, peppermint, pistachio, rose, spearmint, vanilla, violet, rum, and wintergreen.
The majority of natural essences are obtained by extracting the essential oil from the blossoms, fruit, roots, etc., or the whole plants, through four techniques: 1) expression, 2) absorption, 3) maceration, and 4) distillation. Expression is used when the oil is plentiful and easily obtained, as in lemon peel. Absorption is generally accomplished by steeping in alcohol, as vanilla beans. Maceration is used to create smaller bits of the whole, as in making peppermint extract, etc. Distillation is used with maceration, but in many cases, it requires expert chemical knowledge and the erection of costly stills.
The distinctive flavors of nearly all fruits, in the popular acceptance of the word, are desirable adjuncts to many food preparations, but only a few are practical sources of sufficiently concentrated flavor extract. The most important among those that lend themselves to "pure" extract manufacture include lemons, oranges, and vanilla beans.
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The majority of concentrated fruit flavors such as banana, cherry, peach, pineapple, raspberry and strawberry, are produced by combining a variety of esters with special oils. The desired colors are generally obtained by the use of dyes. Among the esters most generally employed are ethyl acetate and ethyl butyrate. The chief factors in the production of artificial banana, pineapple, and strawberry extract are amyl acetate and amyl butyrate.
Artificial extracts generally do not possess the delicacy of natural fruit flavor, but usually taste sufficiently similar to be useful when true essences are unobtainable or too expensive.