This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
Compound ethers, also called fruit ethers and fruit oils, are chemical compounds obtained by etherification. They are divided into two classes, one, the oxides of alcohol radicals, and the other, compounds of these ethers and alcohols with inorganic and organic acids. Of the first class, butyric ether is a good instance, and of the second, nitrous ether. Single or several compounds (compound ethers) present a distinct fruit flavor, and are therefore also called fruit-ethers, and erroneously termed fruit oils. The solution of these ethers in alcohol are the artificial fruit essences. These remarkable products first attracted attention at the exhibition in London in 1851. By judicious mixture, the flavor of almost any fruit can be more or less perfectly imitated. The artificial essences of commerce are generally colored to represent the juice of the fruit from which they are supposed to be derived.
The use of artificial fruit essences in flavoring has grown rapidly of late years. Frequent objections are made to its use. The imitation of delicious flavors, or the production of chemicals synthetically, is a triumph of the skill of the expert chemist. The artificial flavors have a resemblance, but their odor and especially their taste is different. Instances have been quoted where certain articles, flavored with artificial representatives of the fruit, are supposed to have been harmful. A thorough investigation of the case by competent physicians, however, has proved the contrary, and chemists of good repute recommend their employment. We can see no reason why these artificial flavorings should be regarded as injurious in the slightest degree. The quantity introduced in a bottle is too infinitesimally small to create trouble.
All flavors are absolute ethers, which, if extracted from the fruit, deprives it of its chief characteristic. That these same flavors can be synthetically or artificially prepared, there is no reason to doubt; though, whether they will retain all the finer qualities of the product of nature's laboratory is another question. It is proper to state, that no amount of chemical skill can imitate the fine flavors of many fruits. With a very few exceptions, these artificial syrups are at best very poor counterfeits. In some cases the odor of the fruits may be approximately imitated, but the taste is usually very different, and in chemical composition the factitious compounds seldom have the slightest resemblance to the fruits which they are supposed to represent.
The methods of making pure fruit flavors are simple and well understood, and most carbonators can obtain the genuine article if they wish to. There is no necessity for using artificial flavors. It is true that they "go farther," and that many who indulge in the effervescent drink cannot distinguish between the real and the artificial goods; but there are many others to whom these imitations are distasteful. But, after all, the chief objection to these artificial essences lies in the fact that they are imitations. When a customer calls for straw-berry "pop," birch beer, etc., it is supposable that he knows what he wants; and, if he fails to get the genuine article, it is not strange that he resents the substitution. It is known that many persons judge of the character and the wholesomeness of a carbonator's goods, for want of a better standard, by those little things which often seem trivial. The argument is, that a man who substitutes in one case, might, with equal facility, palm off something else. While, in many instances, the facts do not warrant this conclusion, we think that it is safer at all times, and really more profitable, to keep the products of the bottling establishments up to the very highest requirements of the most discriminating purchasers. However, where a cheap product is required, artificial fruit essences will answer. Below we shall append Formulae of the known fruit flavors as they are manufactured and sold in the United States and Europe for the purpose of giving the respective flavors to syrup, candies, ice-creams, liquors and perfumes. They are prepared in various strengths, according to the intensity of flavor desired. As explained on a preceding page, small quantities of these ethers or artificial fruit essences can be introduced into the true fruit flavors to develop and animate their aroma.
It will be seen that in many cases small quantities of acid are employed. They, although not absolutely needed, develop the flavor more like that of the natural fruits. In these cases the proportions mentioned refer to a cold concentrated solution of the acid in alcohol. The chloroform and the aldehyd are added to increase the strength of the aroma, but may also be omitted without any serious detriment to the flavor. The alcohol used to dissolve the ethers should be of 95 per cent., and be entirely free from fusel oil. Some of the Formulae, as for strawberry, raspberry, pineapple, etc., are improved by the addition of a strong tineture of orris root.1 One to two drachms of artificial fruit essences should be sufficient to flavor one United States gallon of syrup. If of commercial products more is required, they are not as concentrated as set forth in the appended Formulae.
The components are various kinds of ethers, as we have already stated. Their manufacture requires considerable chemical knowledge and special apparatus, and should not be attempted by non-chemists. Any reliable wholesale drug-house will furnish them in a state approaching purity as near as possible, and all the bottlers' supply houses will furnish all the combined ethers, or the ready-made artificial fruit essences. The ethers must be kept in well-stoppered bottles in a cool room, as they readily evaporate and expand at any rise of temperature, thus endangering the bottle. To describe the manufacture of all ethers and acids required is beyond the scope of this work, and would require a separate treatise. However, in order to make the bottler familiar with the principles of their manufacture, we append the following: